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I am assuming those number were with KOEO?
Most TPS readings should be around 0.9v idle and 4.9 WOT.
Does this have the 3.8 SC motor?
There was a TSB for fuel pump delivery issues due to a ballast resister they used.
And you say your issue is only evident on deceleration? No problems at all at idle or acceleration?
Quoted From dreamer2355:
I am assuming those number were with KOEO?
Most TPS readings should be around 0.9v idle and 4.9 WOT.
Does this have the 3.8 SC motor?
There was a TSB for fuel pump delivery issues due to a ballast resister they used.
And you say your issue is only evident on deceleration? No problems at all at idle or acceleration?
Yes KOEO. I just checked google and thats right around what most people see at idle (In these motors)
Yes it is the 3.8 3800 S/C (L67)
Yes only evident on deceleration. No issues whatsoever with idle or acceleration.
http://www.youtube.com/user/briansmobil … XBogMCgIvY
Seeing as you have ruled out the TPS, i would be inclined to look at the IACV. The best way of testing those is with a bi-directional scan tool.
Did you ever do a power balance test?
Is this issue also present if you load the engine with the brakes applied?
Quoted From dreamer2355:
http://www.youtube.com/user/briansmobil … XBogMCgIvY
Seeing as you have ruled out the TPS, i would be inclined to look at the IACV. The best way of testing those is with a bi-directional scan tool.
Did you ever do a power balance test?
Is this issue also present if you load the engine with the brakes applied?
Not sure what a power balance test is..
Now that I think about it, when I apply the breaks, the revs will stay up around 2000 (depending on how fast I am going) for a bit then it will go back to bouncing between 900 and 2000 (depending on speed)
http://www.youtube.com/user/EricTheCarG … AOmUjAjNjE
Above is the power balance test by Eric.
I would suggest you may have an ignition system issues but, you do not have any issues on acceleration. Ignition faults are usually found under a load.
I would like to see scan tool data to and view the fuel trims as well as IACV position when this issue is present.
Did you check your throttle linkage?
Do you have any way of testing your IACV?
Quoted From dreamer2355:
I would still go ahead and sweep test the TPS for any flat spots.
I would suspect an issue with the IACV but only if the idle was ‘loopy’ at per se a stop light.
Did you do a visual inspection to see if there is any damage to any vacuum hoses?
And i don’t suppose you have access to a scan tool that shows PID data do you?
I do have a scangauge and i also noticed that my ignition timing changes as the RPM’s bounce, I have also looked at the TPS input on my scangauge as the rpms are jumping and there is no change in the reading, it stays at 0. I read somewhere that it could possibly be the TCC solenoid not allowing the car to go into overdrive. I have checked all vacumn hoses and they all seem to be in good condition.
Quoted From dreamer2355:
http://www.youtube.com/user/EricTheCarG … AOmUjAjNjE
Above is the power balance test by Eric.
I would suggest you may have an ignition system issues but, you do not have any issues on acceleration. Ignition faults are usually found under a load.
I would like to see scan tool data to and view the fuel trims as well as IACV position when this issue is present.
Did you check your throttle linkage?
Do you have any way of testing your IACV?
I will try the power balance test tomorrow.
The throttle cable has no slack and is tight.
I will get my scangauge to read fuel trims, but im not sure if it can read IACV position.
Quoted From Beefy:
I just want to make sure I’m reading this right. Does the engine actually seem to be changing speeds? Or is it just that the tach needle is bouncing around?
I can hear the engine changing speeds aswell.
The IACV on that vehicle is a 5 wire stepper motor design so using a DVOM would be difficult. This is where the correct tools would come into play.
The reason i am asking for fuel trims is to see if the vehicle is trying to adjust for a vacuum leak.
Quoted From Cameron92:
I do have a scangauge and i also noticed that my ignition timing changes as the RPM’s bounce, I have also looked at the TPS input while im driving and it stays at 0( I dont know if that means anything). I read somewhere that it could possibly be the TCC solenoid not allowing the car to go into overdrive. I have checked all vacumn hoses and they all seem to be in good condition.
I meant to edit the above post^^
Quoted From dreamer2355:
The IACV on that vehicle is a 5 wire stepper motor design so using a DVOM would be difficult. This is where the correct tools would come into play.
The reason i am asking for fuel trims is to see if the vehicle is trying to adjust for a vacuum leak.
Oh, I wont be able to see fuel trims, I dont have access to a scanner that would read that. I will re-inspect all hoses, and valves to check for leaks again.
if the tps sensor is showing zero while driving. then I would say thats a problem. usually it shows a 0-100 its a percentage of how open the throttle
body is. sounds like you need a new tps.good luck and keep us posted.Quoted From college man:
do you have a egr valve? if that is passing it would make the idle surge. if its mechanical push on the diaphragm.see if its hard to move.
The EGR is unplugged, the problem stays whether its plugged in or not. I have the PCM tuned so I dont get a CEL for it.
I just went to grand prix forum. according to other people with your symptoms they disconnected the battery to reset the computer and the problem went away.
you say you have the engine or trans tuned? try the reset or return the tune to stock and see if problem goes away. also I don’t know about having the egr
disconnected.does’t sound good.
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