Motor is 350 with TPI. Will not stay running. Earlier today I had the car running for about 10 minutes (just got the motor back in the car). Then I shut the car off, and was going to check the timing. When I hooked up the timing light and grounded the aldl, the car would not start! So I unhooked everything, and it still will not start.
The car will start and run, ONLY, if I keep my foot on the gas and have the throttle part way open. If I force the motor to idle at 1500 or 2000 rpms, it idles and sounds like its running pretty good. But as soon as I take my foot off of the gas it dies out and shuts off.
***my avatar is my motor*** ***most, if not all parts are new*** ***motor DID run, and ran really well about 45 minutes before it developed this "problem"***
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10:03 PM
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chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
I am not sure what year 350 tpi you are using, but when you ground the diagnostic connector it resets the IAC. You can simply drive the car so the computer can relearn the IAC counts. Not sure if this is your problem, but it sure sounds like it.
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11:27 PM
Jun 16th, 2007
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
I am not sure what year 350 tpi you are using, but when you ground the diagnostic connector it resets the IAC. You can simply drive the car so the computer can relearn the IAC counts. Not sure if this is your problem, but it sure sounds like it. [/QUOTE
My motor is either '90 or '91 (speed density). I actually didnt even get the car back on the ground sitting by itself yet! I had just got the motor back in the car, and all wires and all hooked up. Then fired it up, it started right up. I let it run for a while - it was running really good for about 10-15 minutes (didnt even put the back wheels back on yet).
Then I let it sit for about a half hour or 45 minutes. Went to hook up the timing light and when I tried to start it, it would not start!
Motor turns over just like it should. Motor will start if you open the throttle body, or push the pedal a little. BTW - I did try to unhook the battery to reset the computer and codes... then hooked it back up - no difference
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08:08 AM
fieroguru Member
Posts: 12477 From: Champaign, IL Registered: Aug 2003
With your new combination, you are going to need to reset the IAC, reset the base idle speed, and TPS.
The GM service manual states the following:
- Turn ignition to "on" - Check TPS voltage, adjust to .54 volts +/-.08V - Turn off ignition - Insert a paper clip in slots A & B of ALDL (or enter 'Field Service Mode" with a scan tool) - Turn ignition to on - Wait for "at least 45 seconds", disconnect IAC. - Exit field service mode (remove paper clip) - disconnect timing connector - Start the motor and adjust the minimum idle speed to 450rpm in park/neutral (you man need to hold the throttle open slightly to maintain idle.) - Shut off the engine - Reconnect IAC and EST -Turn ignition on and recheck TPS and adjust.
Reset IAC:
-depress accelerator pedal slightly -start and run engine for 5 seconds - turn engine off for 10 seconds - Restart and check for proper idle.
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10:14 AM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
Follow the procedure above through all the steps in sequence. The next step will turn the IAC all the way in, then you will start and set the min RPM and lastly set the home positon for the IAC.
Although some cars are pretty picky with Idle control when electrical power is cut, it doesn't to my knowledge explain the codes. I've owned 2 TPI camaros and Idle control particularly after battery disconnect when it tends to be a problem, was never an issue. It almost sounds as if he has a wiring problem or ignition problem that developed with the terminal grounding.
If the idle reset procedure doesn't work;
Disconnect power and check for the same codes that should not be present upon battery re connection with the memory cleared. Check for proper MAP voltage and ground at the plug though I don't believe that's the problem. Make sure your distributor timing mode lead is plugged up, which in order to set timing you are aware has to be unplugged I don't have my chevy shop manual handy but I know some bad sensors can cause others to set a false code on that engine. If you still get a code for a bad ignition module then it's probably bad, producing an incorrect timing advance interfering with idle.
WAIT! you don't ground the ALDL to set the timing on a TPI engine, that's for the Fiero 2.8L.
[This message has been edited by Joseph Upson (edited 06-16-2007).]
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01:02 PM
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rogergarrison Member
Posts: 49601 From: A Western Caribbean Island/ Columbus, Ohio Registered: Apr 99
MMMMMM, so he may have shorted and fried the module or ECM ?
Possibly if I'm correct. He's using speed density so the ESC control is embedded in the Calpak, but I don't recall GM changing the method of timing set for the TPI motor. I do know that during the timing set with the ESC disconnected for setting the timing it sets a code. That's one way of letting you know you forgot to plug it back up after you finish setting the timing.
Follow the procedure above through all the steps in sequence. The next step will turn the IAC all the way in, then you will start and set the min RPM and lastly set the home positon for the IAC.
Fieroguru, thanks. I tried what you posted above exactly (for the best I could tell). No difference. I also unhooked the battery for 15 minutes, hooked it back up and no difference. Car still starts, but only if I hold the idle to atleast 1200 (that was the minimum I could hold it to. Once I let off of the gas pedal, instead of going back to idle, it just shuts off.
I kinda understand what you are saying... but how can I "set" the home position for the IAC? Do I do that manually by taking it out and moving the pintle by hand? Or does it just do it by itself?
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03:19 PM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
Follow the wires coming from the distributor, one wire should have a connector on it that will allow you to disconnect it. I believe it's tan. I don't have the wiring diagram so I can't point out which one it is exactly.
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03:52 PM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
Follow the wires coming from the distributor, one wire should have a connector on it that will allow you to disconnect it. I believe it's tan. I don't have the wiring diagram so I can't point out which one it is exactly.
Found the wire. Thanks
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04:03 PM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
You need to get the engine running and able to stay running and work from there (timing, vac leaks, codes, etc).
Turn the set screw on the throttle body in about 3 to 4 turns - this will mimick you pressing on the gas and from what you shared should allow it to run. It could take some trial and error to get it to stay running without running too fast (I would not mess with adjusting the TPS when you turn in the set screw, this is just to get it running and you will adjust later). Once it is able to run on it own, start adjusting the screw back down to see how low you can get it to run (the lower you can adjust it, the better, but keep it running). If it will not run less than 1000, then there is something wrong.
Check the timing (disconnect the connector as described above) it will not be 100% accurate due to the higher idle, but if you are within a few degrees the timing will be close enough for now.
Once the timing is close, clear the code you set by checking the timing and restart and run the engine to see if any codes become set. If no codes, then go back and redo the procedure I posted above to reset the base idle, TPS and IAC.
Why are you running so much fuel pressure? Is this a 350 or have you punched it out. My TPI is a 350 MAF 85 vintage with AS&M runners, Ported plenum 113 heads,Comp XE 272, headers, performance igntion (running 10* advance) and if my fuel pressure is higher than 43psi it runs like crap. You may also have a leaky injector. Did you have the injectors checked when you worked on the engine?
The ESC is the Tan wire. What does the exhaust smell like? I would cut back the fuel to begin with and see if that allows that to idle better.
Why are you running so much fuel pressure? Is this a 350 or have you punched it out. My TPI is a 350 MAF 85 vintage with AS&M runners, Ported plenum 113 heads,Comp XE 272, headers, performance igntion (running 10* advance) and if my fuel pressure is higher than 43psi it runs like crap. You may also have a leaky injector. Did you have the injectors checked when you worked on the engine?
The ESC is the Tan wire. What does the exhaust smell like? I would cut back the fuel to begin with and see if that allows that to idle better.
He didn't have an idle problem until after he took the incorrect approach to set the timing by grounding the diagnostic terminals in the manner that you would to set the timing on the V6. A rich condition shouldn't set a code for the ESC, probably not the MAP either which is what happened afterwards. A code 13 would be in order for a problematic O2 would have been more likely. I do agree that his fuel pressure is on the high side but it wasn't a problem initially and if he doesn't have mods that are going to push his power band further up the rpm range he'll probably have more stability at idle with a rich condition than what your modified engine would particularly since shifting the power band upward tends to cause a poorer idle compared to stock.
He needs to be able to scan his sensors to verify proper voltage at start up. He also needs to check his ground wires for the MAP code which I recall is more likely to come on with an EGR code instead of an ESC code. Maybe back probing the ECM terminals for each of the associated wires with the codes back to the sensor plug in the engine bay to rule out a short or open is in order.
I don't think grounding the A B terminals on the ECM ruined it.
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07:37 AM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
Why are you running so much fuel pressure? Is this a 350 or have you punched it out. My TPI is a 350 MAF 85 vintage with AS&M runners, Ported plenum 113 heads,Comp XE 272, headers, performance igntion (running 10* advance) and if my fuel pressure is higher than 43psi it runs like crap. You may also have a leaky injector. Did you have the injectors checked when you worked on the engine?
The ESC is the Tan wire. What does the exhaust smell like? I would cut back the fuel to begin with and see if that allows that to idle better.
I have had the fuel pressure set at 50 psi since ive had the motor in the car. Never really had much of a problem. Maybe someone else could verify this, but I do believe I read somewhere (in a TPI swapping manual) that higher fuel pressure usually isnt totally about MORE fuel quantity, but will give a better spray for better atomization. ***Please let me know if someone knows for sure****
As for whats done to the motor: -350 (from '91 Camaro) -bored .030, approx 9:1 or 9.5:1 compression ratio -cam lift .487/.495 lift (i forget the other stats on the cam) -stock heads milled / ported / valve job / springs / roller tip rocker arms / etc etc etc -TPIS large tube intake runners. Upper and lower intake plenum ported to match the tubes -larger throttle body from TPIS - 52mm -injectors are 24#/hr. from a Mustang Cobra **yes, they were professionally cleaned by TPIS before I installed them** -the whole ignition system is MSD - coil, wires, distributer, and 6AL box -Archie's headers, from Sanderson Street Rod Headers -3" single exhaust with cat. converter and Camaro style flowmaster muffler
I think thats all for mods, may have forgotten something...
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10:01 AM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
JosephUpson, and fieroguru. Thank you guys a million for ALL the help! You have been extremly informative, and helpful with giving me ideas on what to do next. +'s for both of you, and +'s to everyone else who has helped and taken their time to type information to me as to what to do next.
The car is running now. Also, sounds, feels, and acts like its running really good. Actually seems to be running better than what its ever ran before with the V8. I did not set the timing yet. I do not have marks on the harmonic. I have a mark on the flywheel that lines up with a mark on the transmission that marks TDC for #1 cyl. So, I should set it 6 degrees before top dead center?
Anyway, what was wrong? I replaced the ign. module. Made no difference. After testing continuity between several wires and the plug at the ecm, I finally had a bright idea. Take the T.B. off, and remove the IAC. The tests that you told me to do either didnt work, or I was not doing them right... When I removed the IAC, the pintle to seat distance measured 1 5/16". Of all the manuals I have for Corvettes, Camaros, Firebirds, and TPI fuel injection, I could not find any information as to how far the pintle should be sticking out of the IAC valve. So, I happened to remember when I put an IAC in my 2.8 Fiero, and the "instructions" that came with it said the distance between the IAC seat and tip of pintle should be less than 1 1-16". So, I pushed the pintle back in until that distance measured 1". I put it back together, fired it right up, and idled at 850-900. Perfect.
I took the car for about a three mile or so drive. Ran good. Didnt want to drive it too much farther due to the fact that the car did not have a recent inspection. Thats just what I need, getting pulled over and fined just trying to figure out if my car is running or not... Forgot to mention: motor and trans are solid mounted to the engine cradle. Cradle is polyurethane mounted to the car. My wife and I were in the car during the little drive, and we had NO complaints about excessive vibration because of solid mounts!!! I think that before you can even think about complaining about vibrations, you should complain about the noise of the exhaust first!
I know thats about as long and drawn of an explanation out as I could be, but if anyone has any other information of what to look for, please let me know.
Thanks again to everyone who helped while correcting this problem!!!
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10:18 AM
fieroguru Member
Posts: 12477 From: Champaign, IL Registered: Aug 2003
I am glad to here it is running again. While it is running, I still strongly encourage you to properly set the base idle rpm. Most likely when you jumpered the connector trying to set the timing, you bottomed out the IAC motor (that is what jumpering the connector is supposed to do - bottom out the IAC), but the base base idle (set screw on throttle body) was/is not set properly to allow sufficient air to flow past. Most of the times the IAC can compensate for this, but not always. You might even have and issue with idle RPM in limp-home mode.
If the base idle is properly set, the engine will idle about 200 RPM lower then normal, but still run even with the IAC bottomed out.
Until you set the base idle properly, this issue could come back... most likely at the worst time.
I am glad to here it is running again. While it is running, I still strongly encourage you to properly set the base idle rpm. Most likely when you jumpered the connector trying to set the timing, you bottomed out the IAC motor (that is what jumpering the connector is supposed to do - bottom out the IAC), but the base base idle (set screw on throttle body) was/is not set properly to allow sufficient air to flow past. Most of the times the IAC can compensate for this, but not always. You might even have and issue with idle RPM in limp-home mode.
If the base idle is properly set, the engine will idle about 200 RPM lower then normal, but still run even with the IAC bottomed out.
Until you set the base idle properly, this issue could come back... most likely at the worst time.
Cleaning out the IAC passage crossed my mind then I dismissed it. As for the idle set screw it comes sealed from the factory so it is likely where it is supposed to be. Since he is subject inspections it's probably best to just make sure the timing is spot on before making anyother adjustments that might cause an emissions issue since it's running good. If they are actually going to check your exhaust emissions your elevated fuel pressure might cause your pullutants to be a little high, so I would drop that before uping the idle.
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03:18 PM
fieroguru Member
Posts: 12477 From: Champaign, IL Registered: Aug 2003
Originally posted by Joseph Upson: As for the idle set screw it comes sealed from the factory so it is likely where it is supposed to be.
If he was running a stock engine, then I would tend to agree and just foucs on cleaning the IAC port and the backsides of the throttle blades (toothbrush and carb cleaner works wonders). However, his engine is far from stock and most likely needs more air at idle - thus the need for adjustment. If you want to get sneaking for the inspectors, use pliers on the stud end of the adjuster screw to turn it and keep the capped end capped.
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07:38 PM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
I am glad to here it is running again. While it is running, I still strongly encourage you to properly set the base idle rpm. Most likely when you jumpered the connector trying to set the timing, you bottomed out the IAC motor (that is what jumpering the connector is supposed to do - bottom out the IAC), but the base base idle (set screw on throttle body) was/is not set properly to allow sufficient air to flow past. Most of the times the IAC can compensate for this, but not always. You might even have and issue with idle RPM in limp-home mode.
If the base idle is properly set, the engine will idle about 200 RPM lower then normal, but still run even with the IAC bottomed out.
Until you set the base idle properly, this issue could come back... most likely at the worst time.
I plan to attend the GM Nationals at Carlisle, Pa fairgrounds this coming weekend, so I need to get the car inspected... and cleaned.
I will follow the instructions you posted earler to set the base idle, probably tomorrow (monday). Is there a way I can tell for sure if its set properly? Anything to look for? My tach is a 3 1/2" AutoMeter that I have installed in the dash, its hooked directly to the "tach" port on the MSD 6AL box - so the rpm on the tach should be pretty accurate... What should the TPI motor idle at when the base idle is properly set?
I checked my codes after driving for a couple miles, and had no codes. Motor ran pretty good too. BTW, I did not "set" the timing, its just running really good right now...
When I checked my codes, I did hear a sound of some kind of motor running with the 'a' and 'b' terminals jumped on the aldl. I traced the sound to where it was coming from - it was coming from the IAC motor. And the more that I thought about it, when I jumped the aldl trying to set the timing the other day, it must have made the IAC motor push itself the whole way out, and was not able to pull the pintle back in - which caused the idle problem. Sound possible?
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10:18 PM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
Cleaning out the IAC passage crossed my mind then I dismissed it. As for the idle set screw it comes sealed from the factory so it is likely where it is supposed to be. Since he is subject inspections it's probably best to just make sure the timing is spot on before making anyother adjustments that might cause an emissions issue since it's running good. If they are actually going to check your exhaust emissions your elevated fuel pressure might cause your pullutants to be a little high, so I would drop that before uping the idle.
As for the throttle body... It is a bored out and rebuilt t.b. from TPIS. Everything on it is either new, or clean, so carbon isnt really much of a problem. Good idea though! Also, since the t.b. is aftermarket, it doesnt have the sealed idle screw - I can change or adjust it as needed.
I do not have to pass an emission test. Emmissions are tested on vehicles around here - a Fiero (due to age) would have to pass a visual test anyway (to make sure everything is there and hooked up properly), BUT my car has been driven less than 5000 miles since the last time it was inspected... SO, I am exempt from any emission test anyway. What I DO have to have and pass is just a vehicle "safety" inspection. Lights working properly, brakes not worn, brake hoses good, shocks/struts good, ball joints, tie rod ends, etc etc. Stuff like that. I have another post asking about where to get a good rack and pinion, because I need one - mine's bad.
Also... I notice that you seem concerned about my fuel pressure. What would you recommend for a fuel pressure with my mods? Also, if you dont mind, what is suggested for the STOCK tpi fuel pressure? (I have a friend who has a stock tpi, and wants to know)
[This message has been edited by chrishahn87 (edited 06-17-2007).]
As for the throttle body... It is a bored out and rebuilt t.b. from TPIS. Everything on it is either new, or clean, so carbon isnt really much of a problem. Good idea though! Also, since the t.b. is aftermarket, it doesnt have the sealed idle screw - I can change or adjust it as needed.
I do not have to pass an emission test. Emmissions are tested on vehicles around here - a Fiero (due to age) would have to pass a visual test anyway (to make sure everything is there and hooked up properly), BUT my car has been driven less than 5000 miles since the last time it was inspected... SO, I am exempt from any emission test anyway. What I DO have to have and pass is just a vehicle "safety" inspection. Lights working properly, brakes not worn, brake hoses good, shocks/struts good, ball joints, tie rod ends, etc etc. Stuff like that. I have another post asking about where to get a good rack and pinion, because I need one - mine's bad.
Also... I notice that you seem concerned about my fuel pressure. What would you recommend for a fuel pressure with my mods? Also, if you dont mind, what is suggested for the STOCK tpi fuel pressure? (I have a friend who has a stock tpi, and wants to know)
Static fuel pressure is around 43-45 psi at idle with the stock 22 lb/hr injectors, and it goes up with throttle opening, you may want to look into getting an air fuel ratio meter to give you an idea of what your fuel delivery is like, they can be acquired at very reasonable prices and I would recommend one for any FI engine with modifications unless you have software that will allow you to follow the data from the engine. Since you are exempt from emissions 50 psi might not be an issue however you should set your timing before you fiddle with the pressure because the timing will affect air fuel ratio.
[This message has been edited by Joseph Upson (edited 06-17-2007).]
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10:37 PM
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chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
Static fuel pressure is around 43-45 psi at idle with the stock 22 lb/hr injectors, and it goes up with throttle opening, you may want to look into getting an air fuel ratio meter to give you an idea of what your fuel delivery is like, they can be acquired at very reasonable prices and I would recommend one for any FI engine with modifications unless you have software that will allow you to follow the data from the engine. Since you are exempt from emissions 50 psi might not be an issue however you should set your timing before you fiddle with the pressure because the timing will affect air fuel ratio.
I have an a/f ratio gauge also. Its not anything special, just the run of the mill AutoMeter Ultralite 2" gauge with LED lights. While at idle, of course, it varies a good bit... but usually stays pretty happy fluttering around in the yellow LED area, which is in the stoich. zone.
The fuel pressure that you recommend - is that with the vacuum plug hooked up to the regulator, or unhooked? The 50 psi that I mention is while the motor is at idle (850-900rpm) and with the vacuum hooked up - just like it would be if I were driving down the road.
*btw, I have 24 lb/hr injectors. I know I dont NEED 24# but they are what I had, and were professionally cleaned before installation...
I have an a/f ratio gauge also. Its not anything special, just the run of the mill AutoMeter Ultralite 2" gauge with LED lights. While at idle, of course, it varies a good bit... but usually stays pretty happy fluttering around in the yellow LED area, which is in the stoich. zone.
The fuel pressure that you recommend - is that with the vacuum plug hooked up to the regulator, or unhooked? The 50 psi that I mention is while the motor is at idle (850-900rpm) and with the vacuum hooked up - just like it would be if I were driving down the road.
*btw, I have 24 lb/hr injectors. I know I dont NEED 24# but they are what I had, and were professionally cleaned before installation...
With the vacuum signal connected the pressure should be around the mid 40s, if it's 50psi on top of 24 lb/hr injectors that should be a bit much but if you trust your A/F gauge and it shows everything is in order then it's probably okay.
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11:10 PM
Jun 18th, 2007
Alex4mula Member
Posts: 7405 From: Canton, MI US Registered: Dec 1999
Too bad I was away during this. When you ground the ECM (diag mode) the IAC pintle will close. At that point (while hearing the click click) you disconnect the IAC to keep it close. Then you take the ECM out of diag mode and start the car to set the idle screw to minimum RPM that the engine will run (around 600-650 rpm). Then you reconnect the IAC and all should be fine. It is exactly the same procedure as a V6 Fiero. Remember that the TPI and Fiero SD systems are almost the same. On the fuel pressure 50psi at WOT is not a problem. Go to thridgen.org and get good info on TPI there. Everybody agrees that a stock engine (& PROM) will pick up some HP with increased fuel pressure. But the right way to do it is with a custom PROM. Increased timing also helps. Stock is 6° but I read up to around 10° benefits. Glad it is running fine now.
Originally posted by chrishahn87: .. The 50 psi that I mention is while the motor is at idle (850-900rpm) and with the vacuum hooked up - just like it would be if I were driving down the road.
*btw, I have 24 lb/hr injectors. I know I dont NEED 24# but they are what I had, and were professionally cleaned before installation...
Oops! 50psi at idle is not the same as 50psi at WOT. The pressure regulator job is to increase it when vacuum goes low (i.e. WOT) so it will go up 4-6psi in addition to the idle one. With lack of a custom PROM that will add needed fuel (together with the 24# injectors) at WOT but will also add uneeded fuel (i.e. rich) under normal driving conditions. The A/F gage is only good to let you know you are not going lean at WOT but it won't tell you how rich you are. Lean may cost you an engine but too rich will cost you power. I strongly suggest you to get a custom PROM for you mods.
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11:14 AM
chrishahn87 Member
Posts: 1584 From: East Berlin, Pa - USA Registered: Dec 2004
I strongly suggest you to get a custom PROM for you mods.
Thought I mentioned that... guess I didnt.
I do have a custom prom from TPIS. I called them, told them what was done to the motor and all and they sent me the chip. As much as I paid for it, it better be right!
