rough idle
#1
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Car: '89 Formula
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rough idle
I'll start from the beginning. installed a JET stage 1 chip the other night (I know, better off burning my own, so we can skip that) After the drive to work the next morning, took it right back out.
I also installed an airfoil, noticed smoother throttle, but at idle it was very rough, figured it was due to computer relearning and dismissed it. also had at least one injector stuck open, dumping fuel.
Today I installed a new set of Bosch III's i got from FIC. no more over fueling, acceleration is awesome and smoother than ever, but it still has that rough idle after yet another computer reset....My question is, is the rough idle just the computer relearning? Or is there an issue with the air foil?
also, no vacuum leaks, all gaskets good, sensors good, tps adjusted to .54. Timing is set to 5 degrees BTDC. just to get a few of the obvious questions out of the way. Anyone who can point me in the right direction?
I also installed an airfoil, noticed smoother throttle, but at idle it was very rough, figured it was due to computer relearning and dismissed it. also had at least one injector stuck open, dumping fuel.
Today I installed a new set of Bosch III's i got from FIC. no more over fueling, acceleration is awesome and smoother than ever, but it still has that rough idle after yet another computer reset....My question is, is the rough idle just the computer relearning? Or is there an issue with the air foil?
also, no vacuum leaks, all gaskets good, sensors good, tps adjusted to .54. Timing is set to 5 degrees BTDC. just to get a few of the obvious questions out of the way. Anyone who can point me in the right direction?
#2
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
ok, removed air foil just to see, made little to no difference. really stuck here, anyone have an idea?
#3
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Car: 1991 z28
Engine: 305 tpi
Transmission: 700r Automatic
Re: rough idle
egr?iac? maybe check those...spark plugs/wires/coil?they could be on their way out if old ...just some thoughts
#4
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
iac was just replaced, egr is blocked off, was disconnected for a year before that, haven't checked plugs, but wires, cap and rotor are all good. coil is new, done about a week before the plugs about a year and a half ago. what's tripping me up is that under acceleration it's perfectly fine, its just the idle thats rough. and i'm not smelling any unburnt fuel.
#5
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Car: 1991 z28
Engine: 305 tpi
Transmission: 700r Automatic
Re: rough idle
it sounds like something in the computer possibly need a new ecm? or get a prom that is in a car that runs fine and see what yours does? i do not know much about the electrical end of things but what i do know is that if a chip isnt stored properly any bit of uv light (ie. sunlight or just bright light in general) they can goof up on you..i dont know how the relearning process is with these cars i had a honda though that you had to drive it for 20 minutes normally to relearn,but i dont know if that will help ?
#6
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
hopefully not a new ecm, just replaced that three months ago, definitely hoping its not a prom issue, those are even harder to find
#7
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Car: 1991 z28
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Re: rough idle
nah proms are found pretty easy junkyards have them a dime a dozen...plus there are ppl on TGO who burn custom chips for a fraction the price of what they go for like jet or hypertech...i forget where i read it but one guy will burn a chip for like 100$ anyway you want it (even stock) all you gotta do is send specs (unless stock) and a stock prom
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#8
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
yeah, the bad part around here is when a tpi car goes into the jy, its usually stripped before it ever hits the yard. i'm hoping at this point that after i drive it for a few days it will level out. from what i remember, it takes a few cold starts for it to completely relearn...we will see
#10
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
thanks, just in case, anyone know where i can get a prom? again, just in case.
#12
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Re: rough idle
I'll start from the beginning. installed a JET stage 1 chip, I also installed an airfoil, today I installed a new set of Bosch III's, also, no vacuum leaks, all gaskets good, sensors good, tps adjusted to .54. Timing is set to 5 degrees BTDC. iac was just replaced, egr is blocked off, haven't checked plugs, but wires, cap and rotor are all good. coil is new, what's tripping me up is that under acceleration it's perfectly fine, its just the idle thats rough....
#13
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
once it's warmed up it's a lot better, still can't really describe what its like, almost like its idling too low, but the tach says 750. (as reliable as that is). Forgot to list another part, i also installed a new IAC housing to eliminate the coolant passages, im thinking the IAC may be overextended, gonna check it tomorrow. It's the only thing that makes sense to me because there are absolutely no other symptoms other than poor idle.
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Car: 1991 z28
Engine: 305 tpi
Transmission: 700r Automatic
Re: rough idle
Mine just started acting up again...before I couldn't accelerate and would stall comming to a stop...now when it warms up it idles poorly and very low around 500rpms sound familar? Ha I think it's either tps voltage or iac not set right ugh back to work wth this thing
#15
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
does sound familiar, let me know what you come up with, ill do the same
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Car: 1991 z28
Engine: 305 tpi
Transmission: 700r Automatic
Re: rough idle
havent tried anything yet but driving it home from work it stalled on me at about half throttle,started right back up , but the i had no power and i can smell fuel...im gonna check and see if it threw a code to the ecm via paperclip...i think my mechanic is an ****** ..i think it may have a ruptured fuel line and/or injector leaking out the seal i havent even had it back one full day and im getting more problems ill post more when i look at it tomorrow it limped the last mile home and its past midnight here so im gonna sleep on it
#17
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Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
IAC is good, while checking things with the car running, unplugged the TPS and the idle leveled out, haven't checked the voltage yet, but could this be a sign the TPS is bad?
#18
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Car: '89 Formula
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Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
finally hooked up the scanner, in closed loop getting High INT and BLM numbers, 134 and 155 respectively. No vacuum leaks, TPS is good, IAC is good, MAF is good. i'm stumped here, its running rich to the point of giving me a headache, im stumped.
#19
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Re: rough idle
Originally Posted by xdevenx
finally hooked up the scanner, in closed loop getting High INT and BLM numbers, 134 and 155 respectively. No vacuum leaks, TPS is good, IAC is good, MAF is good. i'm stumped here, its running rich to the point of giving me a headache, im stumped....
#20
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Car: '89 Formula
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Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
Yes, computer is recording a lean condition, but the exhaust is telling me there's too much fuel as for Injectors, haven't ohm tested yet, but they're a week old. Fuel pump is within a year old. Looked at a spec chart at my shop and it calls for tps to be set at 1.25 volts at idle, when everything I've read says .54 which is where its set.
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Car: 1991 z28
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Re: rough idle
I've discovered I have a faulty fuel pump that may be the cause I ordered a new one this a.m when I install it I'll update with how it runs, it seemed ok but it won't stay pressurized very long and I have new fpr and 1 new and 7 cleaned injectors and new filter I will keep you updated
#22
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Re: rough idle
Originally Posted by xdevenx
Yes, computer is recording a lean condition, but the exhaust is telling me there's too much fuel....
#23
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Car: 1991 z28
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Re: rough idle
How is it telling, by a smell that can be coming from anywhere lol? If the smell of fuel is getting to you, then it is obviously coming from the engine bay, and not your tailpipes. If O2 correction is reading lean, then the ECM is dumping more fuel to bring BLM's down. Just because you are smelling fuel does not mean you are running rich, as the scent of raw fuel can be coming from anywhere, even by the vapor canister filter, which would be the reason why you are running lean in the first place. You can tell me over and over again that the injectors are new, and that the fuel pump is okay, but only your fuel pressure will tell the actual truth. What is your fuel pressure? Have you pulled your plugs to see if you are running rich, or are you basing the rich condition solely on the scent of raw fuel? BLM's are reading lean, yet you did not confirm fuel pressure as of yet, and you do not know what your plugs look like. The scent of raw fuel can be coming from anywhere (eg; fuel filter fitting leak, regulator diaphragm leak, hair line crack in a fuel line leak, vapor canister filter, etc), and is more than likely the reason why you are running lean because pressure is dropping and not making it to the injectors. Check your fuel pressure, and don't base everything on smell, and if you are, is your exhuast at least black indicating rich....?
#24
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Re: rough idle
Never said I was smelling RAW fuel, the smell is coming from the tailpipe, and it is burnt fuel, excessive burnt fuel.
#25
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Re: rough idle
and i ohm tested the injectors, all are good.
#27
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Re: rough idle
nope. no back firing, and steady rpm while driving. at idle its just rough/shaky, rpm's only move withing 100. it's basically acting like it's flooding, but the computer says its lean. all this started with me disconnecting the ecm, i have a backup, gonna try that and hope that thats it and not the prom.
#28
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Re: rough idle
Originally Posted by xdevenx
Never said I was smelling RAW fuel, the smell is coming from the tailpipe, and it is burnt fuel, excessive burnt fuel....
#29
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Car: '89 Formula
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Re: rough idle
I haven't checked the plugs, or hooked up a pressure gauge, haven't had the time. I do know what a rich mixture smells like. Computers are not infallible, and my o2 sensor is good. Like I said in the beginning, this problem didn't present itself until I installed, and uninstalled a jet chip. I'm leaning toward damage to the ecm.
#31
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Re: rough idle
Originally Posted by xdevenx
I haven't checked the plugs, or hooked up a pressure gauge, haven't had the time. I do know what a rich mixture smells like. Computers are not infallible, and my o2 sensor is good. Like I said in the beginning, this problem didn't present itself until I installed, and uninstalled a jet chip. I'm leaning toward damage to the ecm....
I'll start from the beginning. installed a JET stage 1 chip the other night (I know, better off burning my own, so we can skip that) After the drive to work the next morning, took it right back out. I also installed an airfoil, noticed smoother throttle, but at idle it was very rough....
Edit: What is the part number on that Stage 1 JET chip by the way?
Last edited by Street Lethal; 04-11-2011 at 03:58 PM.
#32
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Car: '89 Formula
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Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
havent really been running the car long enough in its current state to be able to tell anything on the plugs. As far as what i "think" i smell, ive been working on carb'd cars for most of my life, i know what a rich condition smells like. The JET chip was uninstalled 24 hours after install. That is when the problem started. I installed the airfoil after the chip was taken out, didn't improve or worsen condition, it was removed 2 days later.
As i've learned in the past, if you change/upgrade parts, and a problem presents itself, returning to previous configuration is the only way to determine the problem.
I have smoke tested the car and found no vacuum leaks, ohm tested my new bosch III's and found that all are good. I haven't been able to check fuel pressure.
As i've learned in the past, if you change/upgrade parts, and a problem presents itself, returning to previous configuration is the only way to determine the problem.
I have smoke tested the car and found no vacuum leaks, ohm tested my new bosch III's and found that all are good. I haven't been able to check fuel pressure.
#33
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Re: rough idle
my header flanges were leaking just a little causing the blms to go crazy...couldn't hear them....had them resurfaced problem went away...off brand new o2s will sometimes do this
#34
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Re: rough idle
i think he may be right id try testing puel pressure its kind of pointing towards a faulty fuel pressure regulator or a slight clog in the fuel line somewhere that only affects low rpms (idle) ... just some thoughts maybe worth looking into? good luck i hope you get her runing right
#35
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Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
i am gonna test the pressure, first thing im gonna do is swap ecm's and see what that does. partial blockage in the fuel line or sudden drop in pressure just seems way too coincidental, like i said, it all started when i started messing with the ecm. that is the central event surrounding this problem. if that doesnt work, i'll proceed from there
#36
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Car: 1991 z28
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Re: rough idle
i only suggets the fuel lines and or regulator because it happened to me once before, might not be the cause only from what youve said about the ecm and the car being fine pre-jetchip...itd be nice if it was just that because ecms are sh!tty expensive but as i said and ill keep saying good luck with you car,its refreshing to see people taking interest in these cars to stay on the road,mine was just slavageable from the previous owner who just liked to do burnouts and didnt like to properly fix things
#37
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Car: '89 Formula
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Axle/Gears: Borg Warner 9 bolt - 3.70 posi
Re: rough idle
swapped ecm, running like a dream now. very slight miss at idle, but its 100 percent better than it was.
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Re: rough idle
i need an ecm for mine then im thinking, idk if it went bad or what but my car runs right when it wants and shitty when it wants,
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