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Quoted From college man:
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.I meant it shows 0 when the problem is happening. It will show numbers when I actually press the throttle.
Quoted From Beefy:
Does you scan tool read in volts or percent throttle angle? If it is volts, and reads 0.0 with no throttle input, then you may have a problem with it. If it’s percentage, I still seem to remember there being a slight angle at closed throttle, like in the single digits. I’ll dig my scan tool out and test my car tomorrow if you haven’t got a better response before then.
I believe it reads percentage, this is from the owners manual : TPS Throttle Position Sensor In some vehicles, a closed throttle will read 0 and full throttle will read 100. Other vehicles will have a higher value than 0 for a closed throttle and a full throttle value less than 100.
This is the scangauge I have : http://www.scangauge.com/products/scangaugeii/
If it helps determine the problem, I could get a video of some parameters as the RPM’s are bouncing?
Quoted From dreamer2355:
I would just use a DVOM and sweep test the TPS. Find a wiring diagram and probe the GRND ad SGN RTN.
And you have no pending codes correct or any freeze frame data?
No pending codes, and I will go do a sweep test asap.
Ok, so I just did a sweep test with my voltmeter and I saw around 4.4 volts at WOT and .25 at Idle. There were no major jumps in voltage as I slowly put on the throttle.
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.
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)
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 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.
Quoted From 619DioFan:
How many rpm’s is the tach jumping ? do you feel an actual surge/drop in the engine idle at that speed ? are you using a cruise control when this issue occurs ?
It depends how fast I am going, Ill get another video, but when im crusing at 110km/h it bounces from like 1500-900 rpm constantly and only if I have my foot off the gas. I dont feel the car surging or anything. The rpms are just bouncing.