I need to know how to test the tps' I have. It is my belief that it is the cause of the idling, and driving problems I am having.
the tps seems to spike in the signal its giving to the ecm, causing a near stall during hard and soft takeoffs.
also when cruising at low speed with low rpm with the foot barely on the throttle 30-40mph, the car will seem to cut out for a split second and after that for a second or two it seems as though something is shutting off electrically and shudders, like all the injectors or spark plugs are working at %50 its noticable because as soon as this happens the resounding exhaust note gets really quiet (I have straight pipes), the tcc then disengages to get to a higher rpm and then cruises as if nothing happened...
I must have all the information about the tps posted here. as well as how to test.
ive been told I need to read the ecm in real time to adjust the tps' tab to generate the correct reading for idle. as well as read what the volts are throughout its operating range... problem is though that I dont have a scan tool... any other way to read this for adjustment? can I test this out of the vehicle, or must it be a real time read and adjustment with my car running?
nothing I seem to do seems to work. the throttle response with the tps disconnected is excellent
every tps out of every running fiero Ive swapped in seems to be fried...
if I blip the throttle ever so slightly the rpms drop a bit and pick back up. ive even tried adjusting the tab by bending (trial and error) and that doesnt seem to help with the throttle response at all.
it is a concen because i dont want to stall in traffic in a turn or something.
The easiest way I know is to use a OBD1 scanner and call up the TPS when you have the engine running and get into the monitor mode. The TPS should be .5V at idle. It is adjustable by bending the stop tab. It should increase in voltage as throttle is applied.
Best way to test the TPS is to use an external 5v source and ground. This eliminated problems with the Fiero electrical system...which is probably where the real problem is.
I've been having a similar problem with my Allante TPS. It's supposed to read from .5v to 3v and actually reads from 1.2v to 4.85v no matter which one I point on the engine.
[This message has been edited by lou_dias (edited 03-14-2013).]
the very beginning of the TPS movement wears out the first and the most this is because it is the spot it ALWAYS returns to. it is much like an old joystick that wears out near the center. and, when that happens, you get all kinds of driveability issues near the beginning of the TPS movement. the EGR & the Ignition coil will also cause low throttle issues. mix all these old systems, in questionable condition, and you end up with the complete inability to get going from a stop smoothly. you are unable to do 25 mph in top gear without all kindsa foot work.
and - yes - it is unlikely you will find a good used TPS. and, when do install a TPS, you need to let the ECM adjust itself to it. cant just throw it in, go for a spin, and make judgement. at least 20 minutes of varying condition driving.
any TPS over 5 years old (in a 20+ year old car?) is ready to be replaced. do yourself a big favor, and just get a fresh one. easy install. do the 20 minutes ride, and by the time you are done, you'll be a happy guy. if not - start looking at the ignition coil. pretty sure the EGR is poo-poo'd - they all are....
any TPS over 5 years old (in a 20+ year old car?) is ready to be replaced. do yourself a big favor, and just get a fresh one. easy install. do the 20 minutes ride, and by the time you are done, you'll be a happy guy. if not - start looking at the ignition coil. pretty sure the EGR is poo-poo'd - they all are....
TPS is the probable cause of the scary throttle on my '88 GT 2.8L. It has 40k miles, and spent most of its life just sitting in the sun. Three questions:
What is the part number? Is there any brand or source considered unreliable? Is there a guide regarding installation and calibration?
Thanks!
SOLVED!
$12 on eBay for a new one by Delco.
While waiting, I drilled the original TPS and flooded it with contact cleaner, then blew it out. Works fine, but a new one will be comforting...
[This message has been edited by notaguru (edited 12-24-2013).]
TPS is the probable cause of the scary throttle on my '88 GT 2.8L. It has 40k miles, and spent most of its life just sitting in the sun. Three questions:
What is the part number? Is there any brand or source considered unreliable? Is there a guide regarding installation and calibration?
Thanks!
I have a few (6) tps sensors sitting here. and they are all within specified calibration. the throttle response problem IS a safety concern if it stalls (ex: on a railroad, OR more commonly an intersection) nothing whatsoever that i've tested so far is yeilding an explanation for the throttle problem.
OK lets back up. If you want to see glitches in a TPS use an old gauge type volt meter. DVM screen refresh is normally slow. With the analogue or DVM check your ground and 5v reference voltage first. Do this to rule out a ground or reference volt feed problem in the wiring or PCM. IF you do have a ground 5v problem, most of the time it is right at the connector or at the grounds at the transmission. If you got that, with the analogue meter, one lead on ground, the other on the signal return terminal. Slowly open the throttle. You should see a steady increase in voltage as you increase throttle. The meter needle should not bounce or drop down. This was the old school way to check before hand held scopes came out. If that is OK, get to the PCM connector. With a pin diagram, check your ground, 5v reference and signal return. A problem with your ground or 5v reference there will also cause the MAP readings to screw up. If you TPS is adjustable it has to be under .75 volts at closed throttle or the PCM won't bother trying to control idle speed.
In my experience the stock ignition components (coil, module) were the most dependable. Flakey coils do have a habit of causing bad tip in response.
Originally posted by cmechmann: If that is OK, get to the PCM connector. With a pin diagram, check your ground, 5v reference and signal return. A problem with your ground or 5v reference there will also cause the MAP readings to screw up. If you TPS is adjustable it has to be under .75 volts at closed throttle or the PCM won't bother trying to control idle speed. In my experience the stock ignition components (coil, module) were the most dependable. Flakey coils do have a habit of causing bad tip in response.
pcm...? Do you mean ecm? I did the analog test, with every single tps I have laying around and on every good working fiero at my shop, they all work. this isnt a coil issue. because I have the oe coil bolted in place in case the msd 6al setup I have does actually fail. plugs and wires are newer and this happened within the first month of owning this car before I did anything to it.
There was a time when the car worked correctly electrically, when all of a sudden slowing downto go into a 90* turn at 15 and then slowly getting on the throttle to 30, the whole car chugged like the Torque convertor was stuck locked and lugged with a low rpm fluctuation. for the 2 or 3 seconds it happened., and then it calmed down. and ever since then the car has had this throttle problem.
it has happened to me twice with both of the 2.8 GT's I've had. and IDK wtf to check anymore. its the same wierd chugging coming out of a slow turn. and then blam, its like an on/off switch. from good. to bad. and it wont flip back to good...
And I bought an 85 SE V6 that had this problem already... I want to find out what is causing this...
[This message has been edited by AL87 (edited 12-25-2013).]
I apologize for calling it a PCM. I consider most a PCM unless it does not have any transmission controls or has a separate transmission controller(TCM). If you disconnected the TPS and the throttle response was better does not indicate a TPS error. It only causes the ECM not to use it's readings and goes into a predetermined program. They normally will not use many other functions and not go into closed loop with the TPS disconnected. I know problems like these can be frustrating. Especially when it deals with an electrical problem. The information I gave was to possibly check without a scanner or scope. It is going to be hard to duplicate at a stopped condition. When you have meters on it. Now by the description of it originally happened after a hard turn, then now during moderate turns I would lean towards a wiring issue. See if you can move the wiring around with it running. Of course stopped. To try to move/wiggle the wiring around duplicate take off/turn conditions. Can you get it to happen while lightly power braking? At this point it could be a broken baffle pushing against the fuel pump sump, causing the supply hose to be closed off. The only way you would see that is with a gauge hooked up and getting it to happen There are many things that can cause a tip in response problem.
[This message has been edited by cmechmann (edited 12-25-2013).]
OK just watched you video. That seems to be classic secondary ignition dropping out. Is it the same coil wire and/or rotor before and after the swap? Are you getting decent voltage at the positive side of the coil?
OK just watched you video. That seems to be classic secondary ignition dropping out. Is it the same coil wire and/or rotor before and after the swap? Are you getting decent voltage at the positive side of the coil?
I was taking an easy 90* turn at 15mph. that is pretty standard for any vehicle I would say. I've taken the same turn sideways at 30 soo... yeah... I also bent the TPS tab off the throttle body finger to give the engine a little go before the rpm drops with na changed tps sensor input for some reason with all the tps I tested on car and drove around, the tps sensor input only responds like this at an idle or near idle, it seems to drive fine above 2500 rpm.
I changed out the coil, wires. cap and rotor after this.
I even installed an msd 6al thinking it would have eliminated the problem. but no matter what I do this problem wont go away.
I visually inspected the harness when I took it out and didn't see any rub points, and restored the harness with new plastic conduit and wrapped some new heat wrap tape on it. when I swapped the engine out about 6 months ago.
EDIT: maybe there are some values I need to measure through the wiring to the coil/icm/ecm?
[This message has been edited by AL87 (edited 12-26-2013).]
With electrical issues on older cars it normally isn't rub through problems as much as breaks at the ends of the wiring. You don't have to take back out the harness because you would concentrate on the ends. This makes it a pain to find because the shielding would still intact. At all of your connectors. TPS, MAP, COIL, ICM start pulling on the wires. IF any ends stretch, the copper has broken inside the shielding. Your problem looks to be common to all cylinders. May help to find if you concentrate on areas that would effect all. Example, don't bother with individual injector connectors but injector power. Not spark plugs or wires but coil and rotor. Without being able to see a live data stream through a scanner you can't tell if you readings are effecting something else at the same time. Example TPS ground would also effect MAP signal. unless it goes out of range, Your ECM won't set a code. As far as a ECM error, it would normally be something that it controls with heated output drivers like injectors or Idle air control motor. With injectors you would loose half, the others use a different driver. If it was a signal in problem, such as TPS, MAP it wouldn't act as if you were shutting it off. Fall on it's face/loose power yes but not completely shut off unless both MAP and TPS are effected at the same time. Example if the ECM sees low TPS and a high vacuum signal it would assume you are decelerating. In that case it would shut down injectors to keep it from backfiring in the exhaust. In that condition it should also be looking for steady decrease in RPM. I would however look at your MAP reading with the analouge meter the same way as the TPS to see if it is glitching out. It's readings should swing the way you would expect from a vacuum gauge, but in voltage form. Wish you had a way to see what the ECM is doing with injector pulse width. IF it didn't widen pulse width you could tell it was a signal in problem. If it did increase pulse width, you start looking for ignition and fuel starvation problems. By what I saw in your video it seems not to be random enough to be a stressed wiring issue. It did it in and out of gear from a low speed that's why I leaned towards ignition. The 2 times when ignition is at the most demand is low speed tip in right before the ECM has a chance to fatten the mix up and higher gears, under load before it has a chance to down shift. Can't tell you how many times I have had a rotor through me off like that. When was the last time you had the ICM out of the distributor? Are the screws holding it down clean? Distributor plate not loose? That's the only ground your Ignition has to use to switch by. This may also sound stupid, but disconnect the tach lead to the coil. I don't have the specifics in front of me for coil voltage. With coil disconnected you should see near battery voltage. With no load, even crappy wiring will show good voltage disconnected. With it connected any more than a 3 volt difference from battery would mean resistance from the key or the coil drawing down that circuit too much. I'm sorry that this is being done with type. It makes it frustrating with the odd back and forth questions and answers.
how do I test the map sensor? I already tested the tps sensors as I said in the above posts. they are all within calibration and they smoothly increase. I am assuming one will be ground, one a constant positive, and one a variable voltage based on vacuum, so I can knock this test out easy. I just have to figure out what is what, lol.
I had to redo the icm mounting to the distributor, I was getting erratic signal one day making acceleration skiddish and hesitant and it was because the mounting screws stripped out. I through-bolted them with toothed lockwashers, nuts and stove-bolts. And I put the correct thermal grease on as well. in case that mattered.
what were you saying about the tach lead to the coil? disconnect it why? to test voltage? also. I forget which wire of the 4. can you tell me that as well? you want me to test voltage to the coil from that tach-lead wire when its connected to check resistance in the wire?
I may have answered my own questions, but I'm double-checking.
ALSO; I can do an ohms test on the wires to check resistance and make sure of if anything is good or bad. I don't mind disconnecting the engine/transmission harness from the ecm and pulling the connector end into the engine compartment and setting it on top of the motor to test each wire if I have to, just please let me know which color wires I need to test on the ecm harness connector, and where the ends are supposed to be.
[This message has been edited by AL87 (edited 12-27-2013).]
Go back over your grounding points for your distributor. Not that bad to look at and free to do. If your distributor was that crusty, double check to make sure your mounting plate is not loose on the distributor housing. Sometimes the tach buffer(capacitor)will cause too much draw from the switching side of the coil. Most wiring diagrams I've seen it was a white wire at the coil. On DIS cars it was a white wire at the ICM and later white wire from the PCM. The ends of the harness that will fail from age will be on the engine end. You would check at the ECM end to verify readings. You normally won't get breaks in the harness there unless someone has been in there a lot. Not to sound like a broken record, but I do have a lot of problems with non-stock type ICMs and coils. The performance ICMs and coils are just not needed. The stock systems put out plenty. The older MAPs use the same 0-5 volt as the TPS. SO yes one ground, One 5 volt reference and signal return. Wasn't till later or if you had a ford they used frequency. If you are used to watching a vacuum gauge, You would notice deceleration/high vacuum, dump the throttle the vacuum drops and comes back up. Steady cruising/steady vacuum slightly dropping when adding throttle and slightly increasing while letting off a little. That's why some use an aux map sensor on cars with Mass Airflow sensors as a vacuum gauge. So if you have a meter on the signal return, key on engine off low vacuum/high voltage close to 4.5v. When you first turn the key on It uses it as a BARO sensor. Start it up, vacuum comes up/voltage drops 1.2-1.5v (that is not a spec). Cruising and you decelerate, vacuum climbs/voltage drops more. Let's say .8v. Again I don't have the spec in front of me and also some systems use the reverse. High vacuum/ high voltage. But you readings should correspond to the vacuum you would expect. If at any time the voltages drop below .5, or over 4.5 or let's say you opened the throttle and the MAP readings swing wrong way it's bad. Remember, vacuum readings are you quickest response readings. If you have an analog meter on it, looks pretty cool, acts just like a vacuum gauge. Watch a vacuum gauge first to get an idea what to expect.
[This message has been edited by cmechmann (edited 12-27-2013).]
you've been a help. and I am familiar with vacuum gauge readouts. I learned early on from the stock car boys I was around that its an engine checkup in a gauge, I have some info on what different gauge readings mean.
I'll disconnect the tach filter and see if anything changes.
I'll take another look at the cap and rotor and the distributor again. I'm going to end up getting another cap and rotor soon anyways.
I have not done ANY testing, but for a good reason. my car's ecm FINALLY decided to tell me that there's something wrong.
the codes read as follows. #21 throttle position (high) #33 Map Circuit (high) #45 Oxygen Sensor (rich)
SO... yeah... I'm going to clear everything in the morning before I go to work to see what pops up again. for some reason, the ecm is starting to flash the check engine light, on every drive I take like its getting a consistent readout on an issue now.
[This message has been edited by AL87 (edited 12-28-2013).]
If you are getting codes for high MAP,TPS, and O2 and you did not trigger them. It is loss of ground. You should have 3-4 grounds that come together and bolt to a stud at the head or on one of the bolts on the bell housing. The tan/black is the O2 ground. That is also one of those you want to verify at the ECM. However most likely you problem is at the engine end. Find a pinout with the color code for your EC. Should be black/white. Should have less than an ohm between ECM, body and engine.
I'll have to drive this car around for a little while, just to make sure. I was playing with the tps tab a little trying to get a little more throttle response, without the car lagging much so I may have inadvertently triggered everything when I was messing with the tps.
okay, so the only code being thrown is a 45. so I'm running rich. the code only flashes at idle. no other time does the check engine light come on.
the other two codes were caused by me messing with the tps arm and adjusting it when the engine was idling, and ive replicated the same results. so we'll ignore them for now.
the grounds for everything are tight and clean.
the current position of the tps tab is about two pennys thick of a gap away from the throttle body finger, with the tps set this way I don't get lag with throttle input accelerating from a stop.
I did change the o2 sensor recently when I did my header gaskets, so I'm assuming my other one wasn't good. since the 42 flashes 3 or 4 times on every drive I take.
[This message has been edited by AL87 (edited 12-30-2013).]
Leaky headers will cause 44(lean). 45 is more along the lines of high fuel pressure or too much fuel,(Bad pressure regulator, leaking vacuum hose to regulator) leaking injector(cold start), and/or leaky vacuum hose to MAP(not enough to fail, but enough to show lowered vacuum at idle). Or broken ground. On O2 ECM supplies around 0.5v It is the sensors job to draw it down a little or bring it up. With a bad ground it can't draw it down. O2 sensors fail down. Other than that, Ignition misfires show up as excess fuel(high HCs, low O2) and fool the ECM. You ECM cannot determine a misfire. And when it sees too much O2 readings(low O2), the programming assumes too much fuel. This is why ODBII compliant systems made it mandatory to monitor ignition. Also ALDL ECMs should not be looking at O2 at idle. Unless the MAP readings are off and the ECM assumes it is under load or you have a vacuum leak causing a uncontrolled high idle. I might have to dig around and see if I can find an ECM pinout so you can check you voltages at the ECM. Or see if someone you know has an older ALDL scanner so you can bring up data stream to watch you MAP, O2 and TPS readings at the ECM. To see if your ECM is seeing the same readings as out at the engine. Win ALDL will work if you can find a cable.
You would be looking for the wires in the end of the ground wires to be broken. The eyelets and studs would look fine. Again the copper strands will break in the plastic shielding. On each of your grounds pull on them enough to stretch the shielding. If any stretch, the copper is broken inside.
[This message has been edited by cmechmann (edited 12-30-2013).]
I have an adjustable fps, so I'll turn it down some and see what happens.
as far as the tps sensor goes, I guess I should have it set at the OE neutral position IF anything...
as for the grounds, you want me to check the ones that are supposed to be on one of the bolts that hold the engine and trans together, right? where do the other ends go? I may just run new grounds... how many are there supposed to be, 3 right? and what is each for?
I'll have to re-check the vac lines, any way I can check the map sensor with a vacuum pump to decide if its good or not?
I really don't see how the ignition would misfire. this thing lopes on a cold start, but it throws code 45 after its upto normal operating temp, and usually idling in gear at a stop.
The idea is just to see of the wires gave broken inside. There is normally one to The ECM(some have 2). One for sensor ground and another that should be tan with black for O2. Those normally go to a transmission bolt. Some years have a ground on a head bolt. I had looked at 85 diagram and it shown 2 to engine 2 to body, but sometimes the Mitchels diagrams are wrong or GM brings them together somewhere in the harness. Another area I have forgotten about is the ground strap from the engine to body.
You can check with a vacuum pump, but it is a little tricky to slowly raise the vacuum while looking for a steady climb/decline in voltage.
Is your TPS reading around .5 at idle position? Any over around .75-.85 The ECM assumes you are stepping in it. Mitchels shows dark blue wire at the ECM for TPS signal return. Check both ends to see if you are getting the same reading. It shows light green for MAP return. I would double check another diagram If I were you to make sure. However while you are there check your power ins ORANGE and PINK/BLACK. Orange being you battery ins pink/blk key power. The grounds at the ECM should be black/white.
On cars with a single wire O2 sensor there are no internal heaters. The sensor cools down at lower rpms and stops reading correctly(normal). If TPS voltage is reading off where it should be at idle position or if the ECM sees a load reading at MAP(leaky vacuum hose to MAP), it would start to try to read the O2.If it is rich and the ECM can't lessen injector pulse width enough to lean it back out it throws a 45. But at idle exhaust speed should not be high enough to keep the O2 heated. Also if there is something keeping you exhaust speed up enough( vacuum leak, sticking IAC, internally leaking EGR, someone opened the idle stop screw) O2 can heat back up and start reading again. While cruising, If the ECM can't make it swing back lean, it would also throw a 45. But it is not normal to get a 45 at idle. Even if you have something causing it to be rich.
Do you have any back pressure in your exhaust? Just open pipes? A lot of stock configured engines will run like crap cold without some kind of baffle. The cylinders get scavaged too much (air/fuel drawn out) with open pipes. Look at a motorcycle with open header, look at the blue spots on the pipe right at the head. Under load, they are filled enough to combat that but at low speeds it can hinder performance. I dought this is your primary problem, but it doesn't help. Stock, opening up the exhaust doesn't really help much except for the cool factor. The stock Fiero exhaust is open enough.
I just got back from a ride, its throwing code 45 at cruising speed, I've been diligent about the light flashing recently, to give the most accurate info as possible. I have a code 32 as well, I completely deleted the egr system. (not sure if this really affects anything, if it does, I'll have to get a custom chip)
I am running straight pipes. 2 inch all the way out. the cat was deleted, and so was the muffler, I'd say its flowing a little faster than if it were to have a cat and muffler.
I'll have to check when I have time. first thing though is to take the top plenum off, re-check the vacuum lines (I will inspect it piece by piece) and then adjust my fpr for less pressure. I'll use heat shrink if I need.
If I have an adjustable fpr, will I be able to read any difference in fuel pressure at the Schrader valve on the fuel rail?
I'll have to check the wiring where you said, after. I'm going to recheck the tps. and I will check the map. (both have to be under .75v at idle, right?) will check grounds!!!
I KNOW FOR A FACT, that if measured, the tps on a full sweep reads .5-3.5v the swing arm of the tps doesn't operate on its full swing though, it isn't back all the way for it to read at .5v because it sits on the throttle body, swung out a little off from the .5 reading. I guess I'll have to set it real time for the best outcome!
[This message has been edited by AL87 (edited 01-01-2014).]
Code 32 shouldn't be much of a problem very typical. Code 45 cruising makes a lot more sense. Otherwise a very odd condition. Yeah check fuel pressure at shraeder (man I can't type). The nylon hose to the fpr do have a habit of breaking, causing high pressure at high vacuum conditions. Check your pressure with no vacuum at the port and with vacuum added. Also it is easy to have the wrong vacuum line on the fpr. It has to manifold vacuum, not ported(off idle). Just a stupid question. Is the tang on the throttle on the proper side of the TPS lever? The tang should be against the lever and should not move away from the lever but push the lever as the throttle opens. Not to sound redundant, the TPS has to be opened a little when installing it on the throttle. Otherwise the throttle tang won't move the TPS when it opens. The TPS lever will end up behind the throttle tang. ECM wouldn't see when you are opening the throttle. You should be able to move the TPS lever with your finger, without opening the throttle. If not it is on the wrong side. When you release the TPS lever it should rest back on the throttle tang. If the lever is on the proper side, It is odd that the lever for the TPS does not swing back far enough to allow the TPS to return all the way back unless it is badly bent. IS the idle stop screw is way too far in? That can cause you not to be able to adjust the TPS right. That screw should hold the throttle just off fully closed. It is really there just to keep the throttle blade from getting stuck in the bore when it closes. Idle air should go through the IAC port. That could have been throwing things off from the start. I'm just trying to get all the symptoms from you, so I can help. What mods, if any were done to the engine. Your other post. All GM 60 degree (2.8, 3.1, 3.4)with distributor or stub shaft is oring only no gasket. 90 degree V6 or V8 has gasket.
[This message has been edited by cmechmann (edited 01-01-2014).]
complete egr delete 252H comp cam. ported and polished intake, heads, exhaust. adjustable fpr, and newer style replacement injectors.
I took the plenum off, I had to check everything, vac lines are okay. and also when I put my hand over the throttle body to test it, it sucked my hand to it tight and it stumbles but didn't die (a good way to check for vacuum leaks)*** and when I did that, I realized the intake just sucked part of the upper intake plenum gasket in. I checked with a hose to my ear to hear around, and it was obvious.
I'm going to end up adjusting the IAC after I put everything back together, and put a tps on that doesn't have a bent tab.
I am currently using a tps where the tab is bent about two pennies thick away off the throttle body finger. because of the weird stumbling throttle.
Seems like you have a few issues to contend with anyway. I'm just trying to wrap my head around what you are describing on the TPS. The throttle finger sits about an 1/8 inch away from the TPS lever. Sooo, it takes about 10% throttle or more before the finger contacts the TPS
Get things back to near normal. (fuel pressure, intake leaks, disfigured TPS)
With the TPS connected see what the volt meter reads, key on engine off with throttle closed from the signal return terminal. You may have to put a paper clip through the weather pack in the terminal to get to the connector. Open the throttle and if the voltage raises smoothly and the the idle position voltage is around .5, you don't have a TPS issue. If you have to bend a LITTLE to get in range. So be it. If it is too low,(near 0) you have a 5v reference issue. If you have 4.5 or more or you can't get the idle range without bending the crap out of it. It is normally a ground problem. If that stuff looks right DON'T manipulate it to get the idle or response problems to go away. You are dwelling too much that it is a TPS issue. If your voltage ranges are OK it is something else. Unless you are replacing an IAC and the ECM needs to relearn its limit ranges, it should not need to be reset. This being that the idle stop is where it is supposed to be. It shouldn't have to be tampered with. Unless you have done something drastic to the throttle body leave it alone. Unless you already changed it. Fuel, vacuum, timing eic., have to be right before attempting an Idle stop adjustment Even with extreme cam duration and lift, you let the ECM control idle. If it is that extreme, idle programming would need to be changed in the Eprom. But that is very extreme. Unless you were having a problem with it leaning out under load, higher RPMs, because of the engines mods, raising fuel pressure would just cause more problems. You would confirm this by having it on a scanner after engine changes. Just try putting your stock fpr back. If you find it starving later, then maybe think about raising fuel pressure.
[This message has been edited by cmechmann (edited 01-01-2014).]
I swapped the whole fuel rail out, and transferred the current injectors over too. I did a fuel pressure check just for the heck of it. and the rail would reach about 50 but then when the pump clicked off, it dropped to 40 and ended up dropping at a steady pace from there. until there was nothing.
The hose or cavatation/pulse suppressor that is connected between the pump and top of tank unit can leak. Cold start injectors tend to leak more than the regular injectors.
[This message has been edited by cmechmann (edited 01-02-2014).]
I have submersible fuel injection hose connecting the fuel lines in the tank where the pulsator is supposed to be, so it shouldn't leak, its only been in the car for a year. (by theory) nothing is leaking out of the rail, its all sealed up pretty tight.
I guess I'd have to cap off the part of the fuel rail that goes to the cold start injector to see if it is leaking. would an injector leak at this point, of just priming the rail?
I put a third fuel rail in, complete with a different set of injectors (tested before install) since the second rail wasn't holding any pressure after a minute.
tested fuel pressure on the third rail to check for a difference. fuel pressure primes to 45ish and when the pump clicks off, it drops slowly down to 20 over a minute.
man... what turned into a simple plenum gasket replacement to test a tps and iac sure turned into a project...
any other possible places I should check for leaks? is it possible the fuel pressure regulator is bad internally?
The FPR can leak down. The best way to check is to cap off the return line from the rail. If it is the regulator, it won't leak down. If it is an injector or supply it will. Supply leaks will come down very rapidly instantly to under about 2 seconds, but normally your volume suffers to, and pressure doesn't come up enough. Injectors, just a little longer. Regulators are where they normally take longer. I think the cold start can also be capped off. In warmer areas, some delete them. Just take a little longer start time on cold start.
The FPR can leak down. The best way to check is to cap off the return line from the rail. If it is the regulator, it won't leak down. If it is an injector or supply it will. Supply leaks will come down very rapidly instantly to under about 2 seconds, but normally your volume suffers to, and pressure doesn't come up enough. Injectors, just a little longer. Regulators are where they normally take longer. I think the cold start can also be capped off. In warmer areas, some delete them. Just take a little longer start time on cold start.
which line is the return? the thick line or the thin one?
