Still cant get this POS to idle right!
Still cant get this POS to idle right! 99 C5 A4
80k miles
intake, !cats, borla catback
I've replaced the spark plugs and wires, cleaned the MAF along with the rest of the intake, and only run 93.
It doesnt matter if i'm in drive, neutral, or park, idle still jumps around.
750 to 500 to 900 to 250, it goes in a pattern just like that.
the only code i am getting if for a bad O2 sensor (bank 2 sensor 2)
Driving at highway speeds, if i go into neutral, it idles perfect at 900.
But as soon as i get down to less than 5 mph, the engine sputters to 250 and starts the pattern again.
The car drives perfectly fine except when i come to a stop if feels like i'm slamming on brakes at the last few feet bc of the engine srewing up.
I've done the Idle Relearn Procedure from C5fourm, and that didnt help either.
Someone please help!
80k miles
intake, !cats, borla catback
I've replaced the spark plugs and wires, cleaned the MAF along with the rest of the intake, and only run 93.
It doesnt matter if i'm in drive, neutral, or park, idle still jumps around.
750 to 500 to 900 to 250, it goes in a pattern just like that.
the only code i am getting if for a bad O2 sensor (bank 2 sensor 2)
Driving at highway speeds, if i go into neutral, it idles perfect at 900.
But as soon as i get down to less than 5 mph, the engine sputters to 250 and starts the pattern again.
The car drives perfectly fine except when i come to a stop if feels like i'm slamming on brakes at the last few feet bc of the engine srewing up.
I've done the Idle Relearn Procedure from C5fourm, and that didnt help either.
Someone please help!
Last edited by bigleman; Jan 3, 2008 at 01:11 PM.
Closed ex-Sponsor Account
Joined: Jan 2008
Posts: 2
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Yes...first thing is to replace/fix your O2 problem.
Secondly, your mods are; Intake, Hi-flow Cats and Borla cat back system...correct?
Did you change to a larger/different size throttle body? I have seen this with C5's that have gone to a different TB. The engine will "hunt for idle", dropping/flaring by 200RPM from target.
Any other changes to the air inlet system? Cold air intake, etc?
Chad
Secondly, your mods are; Intake, Hi-flow Cats and Borla cat back system...correct?
Did you change to a larger/different size throttle body? I have seen this with C5's that have gone to a different TB. The engine will "hunt for idle", dropping/flaring by 200RPM from target.
Any other changes to the air inlet system? Cold air intake, etc?
Chad
MAF Sensor?
Fuel filter was changes at my last oil change
No cats.
"Twin Flow" Intake, No Cats, Borla Catback
No change to the TB
No other changes that I am aware of. I'm sure i might need to check my PCV falve.
Correct on the No cats. Which wires should i check? I dont think i want to play with the TB Motor wires while the car is running 
Fuel filter was changes at my last oil change
No cats.
Yes...first thing is to replace/fix your O2 problem.
Secondly, your mods are; Intake, Hi-flow Cats and Borla cat back system...correct?
Did you change to a larger/different size throttle body? I have seen this with C5's that have gone to a different TB. The engine will "hunt for idle", dropping/flaring by 200RPM from target.
Any other changes to the air inlet system? Cold air intake, etc?
Chad
Secondly, your mods are; Intake, Hi-flow Cats and Borla cat back system...correct?
Did you change to a larger/different size throttle body? I have seen this with C5's that have gone to a different TB. The engine will "hunt for idle", dropping/flaring by 200RPM from target.
Any other changes to the air inlet system? Cold air intake, etc?
Chad
No change to the TB
No other changes that I am aware of. I'm sure i might need to check my PCV falve.
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Verdad Gallardo MAF Sensor?
Fuel filter was changes at my last oil change
No cats.
"Twin Flow" Intake, No Cats, Borla Catback
No change to the TB
No other changes that I am aware of. I'm sure i might need to check my PCV falve.
Correct on the No cats. Which wires should i check? I dont think i want to play with the TB Motor wires while the car is running
Fuel filter was changes at my last oil change
No cats.
"Twin Flow" Intake, No Cats, Borla Catback
No change to the TB
No other changes that I am aware of. I'm sure i might need to check my PCV falve.
Correct on the No cats. Which wires should i check? I dont think i want to play with the TB Motor wires while the car is running
No changes, i wanted to get HPTuners or EFILive for Christmas, but no luck with that.
I'll give that a shot.
How would I check the Air Temp Sensor? I have a feeling it could be that. In he cold temps (30*-40*) we were having last week, idle was REALLY bad. But now that it has warmed up (70ish) the idle hasn't been anywhere near as bad. Would the Intake Air Temp Sensor cause that much of a problem?
Just use a multimeter while the car is parked when its doing the idle surgine and check the voltage from the back of the plug on the TPS sensor, won't cause anything. Also I was thinking you may have a problem with the IAC (idle air control). I don't know what color the wires are on it.
How would I check the Air Temp Sensor? I have a feeling it could be that. In he cold temps (30*-40*) we were having last week, idle was REALLY bad. But now that it has warmed up (70ish) the idle hasn't been anywhere near as bad. Would the Intake Air Temp Sensor cause that much of a problem?
Just use a multimeter while the car is parked when its doing the idle surgine and check the voltage from the back of the plug on the TPS sensor, won't cause anything. Also I was thinking you may have a problem with the IAC (idle air control). I don't know what color the wires are on it.
Need some scan equipment.
12 Second Club
Joined: Jan 2007
Posts: 32
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From: Greenwood SC
I will be in Charleston for My weekend duty...I have HPT...I can bring it if you like but you will have to buy credits for your car....If I can't figure out what is wrong we could at least data log it and that will make it tons easier for some of the bright guys on here to figure out.
Last edited by 99T-Top Z28; Jan 11, 2008 at 12:23 PM.
12 Second Club
Joined: Jan 2007
Posts: 32
Likes: 0
From: Greenwood SC
he is correct on the credits and license...will be able to tune out the rear o2s if necessary, change rev limit and torque management...May be able to scan for free haven't ever tried...if I can scan and log for free I will...you just won't be able to change anything in the program...but will most likely tell you what is wrong.
i tried testing the TPS sensor, but i couldnt get my voltmeter probes to get a reading.
I know the TPS sensor is doing something, bc when i unplugged it, everything went to hell!
I know the TPS sensor is doing something, bc when i unplugged it, everything went to hell!
so i figured i would replace my PCV valve today while i was changing my oil
when i went to remove the valve, the hose to the intake manifold just fell apart in my hands. It looks like it just rotted right through.
Idle is perfect now.
when i went to remove the valve, the hose to the intake manifold just fell apart in my hands. It looks like it just rotted right through.
Idle is perfect now.
