1998 pontiac fiero gt. The car is just running lean somehow now after fixing the EGR system. All the rear side plugs are white. The car runs sluggish as well, hesitates a little, rough cold start and rough cold idle. The car runs alittle better warm. The car runs with a BLM of 135 and a INT of like 140 to 160 at idle but drops to 128 as soon as you give it throttle. the BLM how ever stays at 135 ish. THE IAC value is around 70 which I assume is somewhat high? (20 to 50 range is normal)
Fuel pressure is 44psi key on ignition off. maintains around 42 ish psi with the engine running. It will jump to 45 psi or so when you blip the throttle and will come back down and hold at around 40 to 42ish psi when holding at a constant rpm above idle (i think like 1500 rpms or so). Fuel pressure holds at 40 psi with key on ignition off after fuel pump stops and drops very slowly to just hair and holds around 38psi. I only checked for like 5 mins or so with no movement but maybe go back and check longer?
New AC Delco EGR Valve, New rodney dickman EGR Tube, all the ignition components are fairly new. I checked the Timing is close to around 11 or maybe 12 degrees before top dead center no codes thrown, no map sensor leaks as map sensor puts out the right voltage on the scanner 1.2 volts at idle. 4.5v at key on ignition off.
The fuel filter has not been changed in a long time atleast 60k miles so I bought a new one from K&N still waiting for delivery but ill install just because.
IAT sensor records normalish temp reading like 100F to 105F? (I live in South Florida) Coolant sensor reads 220F at idle engine warm to 227F engine warm fan turned on. Although my water temp gauge in the car is off by 30F on the low side and jumps around like an idiot?
O2 sensor is fairly new but its a Bosch product, It does trip over and under 0.450 volts constantly which assumes its working ok? I can always get a AC Delco one for cheap if I have to.
When in the WinALDL program though the car is saying at idle under ADVANCE to be at 15 Degrees and jumps to like 20 or 30 degrees with throttle idk if thats right or not maybe the harmonic balancer has slipped and read the timing on the car wrong? I didnt adjust the timing and from the looks of the harmonic balancer It doesnt show very much wear maybe just moderate. Any one having ideas? Could it be vacuum leak elsewhere I would assume the car would want to run rich if I had a vacuum leak.
------------------ 1988 Pontiac Fiero Gt (fully optioned, factory leather, 5-speed, CJB T-Tops: Black w/ gray interior and blk wheels) 1992 GMC Typhoon #0203 1971Chevorlet Corvette 454cu/ LS5/ 4-speed/ convertible 1993 BMW 850 Ci 6-speed V-12
[This message has been edited by gmctyphoon1992 (edited 10-12-2016).]
It might be best to clarify that. Do the front plugs look normal... or was it only the rear plugs you looked at?
Yes sorry, for clarification I only checked the rear plugs facing the back of the car because they were easiest to get to I have not checked the front plugs. All back three were white so I was more assuming that the problem is more consistent throughout than a possible bad or clogged injector on an individual cylinder. I can however if necessary try to get to the front plugs when I have a chance.
I only checked the rear plugs facing the back of the car because they were easiest to get to...
I figured that was the case.
It would be rather surprising if the front plugs looked much different than the back ones... but I just wanted to make sure that this wasn't what you might've been implying.
[This message has been edited by Patrick (edited 10-12-2016).]
If all 6 plugs look the same, I would change the O2 sensor.
Okay ill check and I might just go ahead and get an AC Delco one since its cheap and see if there is a difference. I did however notice that I didn't re-tighten the clamps on my intake snorkel on both sides If that matters at all.
I don't have an answer, but I'm not sure its the O2 sensor. If you are getting fast response on either side of .45v as you've indicated, its responding appropriately. Also, a BLM of 135 (as I understand it) says based on the 02 feedback the ECU needs to add more fuel over what is called for by the fuel table. ECU added more fuel to get the A/F to aprox 14.7. The point being is that it was able to add the fuel to get you where you need to be. If you were maxed out at 160, that would mean that it wasnt able to add enough fuel to get you to 14.7.
Are TPS and MAP values what you would expect them to be?
I don't have an answer, but I'm not sure its the O2 sensor. If you are getting fast response on either side of .45v as you've indicated, its responding appropriately. Also, a BLM of 135 (as I understand it) says based on the 02 feedback the ECU needs to add more fuel over what is called for by the fuel table. ECU added more fuel to get the A/F to aprox 14.7. The point being is that it was able to add the fuel to get you where you need to be. If you were maxed out at 160, that would mean that it wasnt able to add enough fuel to get you to 14.7.
Are TPS and MAP values what you would expect them to be?
The TPS sensor is reading appropriately with no dropouts into the throttle. Map sensor voltage goes from 1.4 to 4v into throttle and and drops below 1v out of throttle but comes back to 1.4v when at idle. The car doesn't get passed 160 for the BLM or the INT. I drove the car around today with the laptop hooked up and the INT is now 127 to 130 at idle but the more important BLM is 140 at idle.
As far as the fuel injectors I haven't checked I would have to assume they are all dirty than to be causing the lean problem in all cylinders
If it also means anything the car sometimes loses idle and idles all over the place but it catches itself and smooths out after 10 secs or so the car rarely if ever stalls due to idle problems though
If it also means anything the car sometimes loses idle and idles all over the place but it catches itself and smooths out after 10 secs or so the car rarely if ever stalls due to idle problems though
hummmm. That's interesting. Makes me think you may have a bad ground.
hummmm. That's interesting. Makes me think you may have a bad ground.
I actually just went through an ordeal where I was. blowing control modules due to a broken ground strap on the right cabin firewall which was fixed and I had to fix the one coming from the battery to the frame as well. I also cleaned the c500 connector and got that melted wax gunk out and resealed it
is there another ground strap I can look for to be broken?
You are going to have corrosion issues where you live.....Hurricanes and salt air. Did you evacuate in the Fiero?
When the ICM goes, there is often another issue like bad spark plug wires or coil. That 'wax' in the C500 is important....hope you put the same stuff back in. There is a slim chance that the ECM was damaged too.
As for the injectors - you won't know if all cylinders are lean or just some or maybe just one just by ECM data/trouble codes. There is only one oxygen sensor and it pretty much averages all the cylinders output. I would clean the injectors anyway and see how they operate - just my 2 cents.
You are going to have corrosion issues where you live.....Hurricanes and salt air. Did you evacuate in the Fiero?
When the ICM goes, there is often another issue like bad spark plug wires or coil. That 'wax' in the C500 is important....hope you put the same stuff back in. There is a slim chance that the ECM was damaged too.
Lol. No luckily the storm hit the upper east coast of Florida not the Deerfield beach, fort Lauderdale area where I was at. Although this storm brought some really nice non humid 80F weather the past few days.
The wax stuff is definitely important but the problem was that the wax due to the high heat melted and was actually preventing some of the pins from getting good contact as well some of the pins were bent. Similar thick corrosion and all weather inhibitor goop was applied in there. I am hoping the ECM wasn't damaged The car ran good after I fixed all the ground problems that was about a year and a half ago. The ignition coil was replaced, the ICM was replaced and the pick up coil was tested good after the ground problems were fixed. New cap, rotor, AC delco plugs, and good quality plug wires were just put on about 7k miles ago.
I also just noticed that after air intake snorkel clamps were tightened down my INT numbers have dropped from like 160 at idle to 128 to 130 at idle and moves around from 90 to 140 during driving but my BLM numbers are still around 135 to 140.
I do recall reading some criticism here of the Bosch O2 sensor not working as well as the AC Delco units with the 2.8 (and possibly 2.5).
I heard that too but at the time my 02 was non functional so I just grabbed what the advance auto parts had at the time. Im guessing a bad idea the new AC Delco 02 sensor is coming friday and im going to replace my fuel filter with a K&N unit at the same time as preventative maintenance item the other one has at least 60k miles on it if not more
Ok so, changed the 02 sensor to a delco unit, New K&N fuel filter, fuel pressure is still good the old filter wasnt really that dirty either.
The car still reads 133 BLM at idle and jumps to 140, 141 when driving. However the short term fuel trim INT reads like 145 to 170 at idle and drops to 128 as soon as i give it gas and when driving the INT never goes above 133
My wide average table is posted below. Anyone have any other suggestions of things I can look for to fix this problem?
it just got colder in florida for a few days and the car ran alot better but as the outside temperature rose back to 85 degrees the car started to run worse again like it did before. I will also say that when the engine is cold the idle is all over the place and evens out once the car warms up . I am asumming vacuum leaves somewhere I just cannot find it
edit to add: I just drove the car now and it's running peppy and good but It's so intermittent when it doesn't run good though it almost sputters and feels sluggish. the idle was spot on with no variation when I just drove it. I did drive it 2 hours earlier and it was running real sluggish and almost sputtering now it's driving good and I bet when I get back in to drive it later it will drive sluggish again.
[This message has been edited by gmctyphoon1992 (edited 11-04-2016).]
I'd go back and undo, or recheck the last change made prior to the onset of the problem. From what I can tell is most significant, you replaced EGR components which can certainly affect performance if they are not working correctly. Despite being new there can still be a leak internally (valve) or externally (mount surfaces). Temperature sensitive performance irregularities are a good reason to be suspicious as metals expand more with more heat. The last fiero EGR are worked had an uneven EGR mount surface. If the O2 sensor was the problem I wouldn't expect ambient temps to have much of an effect as it would still be sending an errant signal.
Have you checked the fuel pressure while the lean out condition is happening? This is intermittent. If you happened to check when the problem isn't happening, the problem could be intermittent low fuel pressure.
The computer thinks your engine is running lean and is adding all the fuel it is allowed to. I don't think this is a bad computer input. You think the engine is running lean. The plugs show the engine is running lean.
So why is the engine not getting enough fuel?
Low fuel pressure Plugged injectors Maybe low voltage on the pink wires of the injectors (while the problem is happening) Bad ground wire from the ECM to the block?
Originally posted by gmctyphoon1992: it just got colder in florida for a few days and the car ran alot better but as the outside temperature rose back to 85 degrees the car started to run worse again like it did before. I will also say that when the engine is cold the idle is all over the place and evens out once the car warms up . I am asumming vacuum leaves somewhere I just cannot find it
edit to add: I just drove the car now and it's running peppy and good but It's so intermittent when it doesn't run good though it almost sputters and feels sluggish. the idle was spot on with no variation when I just drove it. I did drive it 2 hours earlier and it was running real sluggish and almost sputtering now it's driving good and I bet when I get back in to drive it later it will drive sluggish again.
I'm not to sure about the interfacing program you're using as it has been well over 12 years since I tried it briefly. Have you considered Tunerpro? You need to log the car while its running bad and have detailed second by second playback of when it is running poorly. I had a bad MAP sensor that wouldn't set a code, probably because it was static at about 59 Kpa and would actually run okay as long as the pedal was not pushed in too far at which point it would fall over. I was at a loss until I looked at the datalog values of the most important sensors and noticed the MAP value never changed.
If you have the ability to burn your own chips and have been doing so, you may need to remove and reinstall the chip as I'm dealing with that issue at the moment. It's causing intermittent idle hunt, and intermittent lean cruise. The reason I know it's my chip is that it also causes my odometer needle to bounce around at idle.
TunerPro RT is nicer, is free after a 10 second nag screen and has many more functions.
You can download my install disk that has TunerPro RT on it along with the .adx file for the 2.8 Fieros. The yellow box at the bottom of this page - http://reddevilriver.com/aldl.html
---- Odometers don't have needles, but more so, the VSS signal is sent from the VSS to the Speedo/Odometer and then to the ECM. The ECM shouldn't be able to make the speedo needle bounce around.
[This message has been edited by phonedawgz (edited 11-05-2016).]
TunerPro RT is nicer, is free after a 10 second nag screen and has many more functions.
You can download my install disk that has TunerPro RT on it along with the .adx file for the 2.8 Fieros. The yellow box at the bottom of this page - http://reddevilriver.com/aldl.html
---- Odometers don't have needles, but more so, the VSS signal is sent from the VSS to the Speedo/Odometer and then to the ECM. The ECM shouldn't be able to make the speedo needle bounce around.
That's what I use and yes it is a lot nicer and more versatile but I figured coming from something as old as WinALDL there'd probably be a steep learning curve getting it sorted out and suggested the basic program instead.
Actually the "basic program", TunerPro, only functions as a bin editor. TunerPro RT adds the ability to scan along with the bin editor. When you said TunerPro, I just figured you meant the RT version since we are talking about scanning.
[This message has been edited by phonedawgz (edited 11-05-2016).]
TunerPro RT is nicer, is free after a 10 second nag screen and has many more functions.
You can download my install disk that has TunerPro RT on it along with the .adx file for the 2.8 Fieros. The yellow box at the bottom of this page - http://reddevilriver.com/aldl.html
---- Odometers don't have needles, but more so, the VSS signal is sent from the VSS to the Speedo/Odometer and then to the ECM. The ECM shouldn't be able to make the speedo needle bounce around.
Thank you for the help I am going to get to everything you and Joseph Union are saying one at a time. I am going to however first say that my WinALDL works fine for me but I installed the TunerPro RT from the website and installed and ran the autorun for Red devil rider online CD with the ADX file. I went through your setup for TunerPro RT and everything went smooth except when I tried to interface my current ALDL cable that I have. TunerPro RT is saying Cable not found no matter what COM i set it to including switching USB ports on my laptop and trying it again. The current ALDL cable I have is the one DodgeRunner was selling awhile ago before he stopped selling them in order to no step on anyone's toes. I am wondering if this cable can even interface with the TunerPro RT program? It worked perfectly fine for WinALDL and it interfaced with COM3 set at 2400 baud. Any ideas first and foremost?
Edit to ADD: I installed the cable drivers software and checked in my control panel that I am using the correct COM port which is COM3.
[This message has been edited by gmctyphoon1992 (edited 11-07-2016).]
On another note I unplugged my MAP sensor and started the car and my INT dropped to 115 to 120 at idle although the car did run alot worse. I re-plugged in my map sensor again and I also checked my fuel pressure again and it read 42psi. I than turned the key engine off the fuel pump primed and the car showed 40ish psi fell to 38psi slowly and held there for atleast 10 minutes no bad regulator no leaky injectors. I am assuming I am just going to have to check at the right time when the car is running bad and sluggish.
Low voltage at the injectors is the next thing I can check I am assuming 12v at the pink wire? As far as a ground issue I just had a problem in the past where my bad grounds were blowing ICMS I had them replaced with I think 12 gauge wire on both the battery negative end to the bottom of the tower and the block to the chassis on the right front side of the motor. I will however check the ground from the ECM inside the cabin to the car.
[This message has been edited by gmctyphoon1992 (edited 11-07-2016).]
Just took the car around the block this is the RAW data from the last 13 pulses or 20 seconds of this drive including stopping and backing into my garage
[This message has been edited by gmctyphoon1992 (edited 11-07-2016).]
I'm not to sure about the interfacing program you're using as it has been well over 12 years since I tried it briefly. Have you considered Tunerpro? You need to log the car while its running bad and have detailed second by second playback of when it is running poorly. I had a bad MAP sensor that wouldn't set a code, probably because it was static at about 59 Kpa and would actually run okay as long as the pedal was not pushed in too far at which point it would fall over. I was at a loss until I looked at the datalog values of the most important sensors and noticed the MAP value never changed.
If you have the ability to burn your own chips and have been doing so, you may need to remove and reinstall the chip as I'm dealing with that issue at the moment. It's causing intermittent idle hunt, and intermittent lean cruise. The reason I know it's my chip is that it also causes my odometer needle to bounce around at idle.
I somewhat watch my map sensor voltage and Kpa as I drove the last few times it would read 1.5 volts at idle would increase voltage up to 4.5 volts as soon as light to heavy throttle would be applied and if cruising the volts would be under 1 volt which I am assuming no vacuum leaks and correct operation unless I am incorrect.
The car seems to run at the right mixure in the short term when im driving my INT is in the 128 range its when I am at idle is when the INT number increase and stay around 150. The BLM however does the opposite it sits at 133 at idle and increases to as much as 140 when driving.
I also notice with the ALDL cable is connected and watching sensor values that when I start the car somewhat cold and let it sit running, before the car starts to use the 02 sensor and change the INT values the car runs rough and the idle is all over the place and after about 30 seconds or so the INT values increase and the car smooths out dramatically and the idle becomes constant.
The car also has hard starts when cold usually 2 turns of the key to get started it kind of slowly rumbles up in RPMs to idle. When the car is warm it usually starts right away.
[This message has been edited by gmctyphoon1992 (edited 11-07-2016).]
Just took the car around the block this is the RAW data from the last 13 pulses or 20 seconds of this drive including stopping and backing into my garage
I've never used WinALDL before, perhaps there is a conversion happening that I don't understand, but these numbers look strange. Why does RPM show 42,43,44,etc ?? 420, 430, seems too low, and 4200 would be much too high for backing into your garage. What does MALFLG2 indicate? Seems this is the Malfucnction Flag / Check engine indicator. Is there a code set? Why doesn't the TPS value change?? You indicated driving and stoping, surely this should be changing.
yes there is a code set I have to reset the ecm thankyou for pointing that out. the code that was set was code 42 low pressure MAP sensor because I unplugged it in earlier diagnosis TPS is proven good no dropouts I checked 3 times slowly and drove around watching the TPS as well.
[This message has been edited by gmctyphoon1992 (edited 11-07-2016).]
Originally posted by gmctyphoon1992: The car seems to run at the right mixure in the short term when im driving my INT is in the 128 range its when I am at idle is when the INT number increase and stay around 150. The BLM however does the opposite it sits at 133 at idle and increases to as much as 140 when driving.
I also notice with the ALDL cable is connected and watching sensor values that when I start the car somewhat cold and let it sit running, before the car starts to use the 02 sensor and change the INT values the car runs rough and the idle is all over the place and after about 30 seconds or so the INT values increase and the car smooths out dramatically and the idle becomes constant.
The car also has hard starts when cold usually 2 turns of the key to get started it kind of slowly rumbles up in RPMs to idle. When the car is warm it usually starts right away.
It's definitely lean on startup with BLM and INT readings in that range. You need to adjust the idle fuel table if you have one and the Base fuel table. You also should seriously consider switching to TunerproRT because it has a cell follower, a yellow box that highlights the particular cell the engine is running in on the particular table you are viewing for more accurate table changes.
You may also want to consider making a single global change by manipulating the base pulse width by telling the ECM you have slightly smaller injectors than you really do which should in theory increase your base pulse width throughout.
If your spark advance is too high at idle that can also cause the idle to hunt as well as affect the air fuel ratio seen by the ECM. Then there's fuel injector latency where some larger injectors may have a slight delay on opening relative to the ones they are replacing and still end up not delivering enough fuel at idle without any changes to control values.
[This message has been edited by Joseph Upson (edited 11-07-2016).]
Is it just a vacuum splitter? if so you could make one out of T or Y fittings s and vacuum lines.
yeah I just bought rubber hose and clamped it over each vacuum line. I pulled the EGR solenoid checked and cleaned the solenoid and fixed the crack replaced all the rubber lines on the solenoid and the cruise control servo, cleaned and checked the cruise control can.
although aha I did find alittle wetness at the bottom of the map sensor fitting when I took it of to fix the other vacuum lines.
so I did two leak down tests both showed a 44 psi hold with key on engine off now?? both also showed a 20 psi drop in about 5 minutes time so I am assuming bad fuel pressure regulator ?
[This message has been edited by gmctyphoon1992 (edited 11-09-2016).]
yeah I just bought rubber hose and clamped it over each vacuum line. I pulled the EGR solenoid checked and cleaned the solenoid and fixed the crack replaced all the rubber lines on the solenoid and the cruise control servo, cleaned and checked the cruise control can.
although aha I did find alittle wetness at the bottom of the map sensor fitting when I took it of to fix the other vacuum lines.
so I did two leak down tests both showed a 44 psi hold with key on engine off now?? both also showed a 20 psi drop in about 5 minutes time so I am assuming bad fuel pressure regulator ?
f
man, i really think you are all over the place.. go back to the original work you did...
what prompted you to replace the EGR system in the first place? i it was running fine before, and then the poor idle and hesitation came after changing the EGR tube and valve, then the new tube and valve is very likely your issue, or rather something that you unhooked to remove the EGR stuff... the symptoms you have sound like you have a huge vacuum leak.
