SVT tech, please look at TPS readings.

hotmustang331

Active Member
Apr 29, 2004
2,967
3
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Bastrop,TX
Or anyone else who can help :nice:

Ok so I just installed my aeroforce tech gauge and it basically reads every parameter the diagnostic port is throwing out and fits in my A piller...anyways I was looking at my TPS votage and the TP open %. (car off obviously)

Volts = 0.91 fully closed to 4.68 fully open

Not sure if thats good, but here is where it gets weird.

Throttle position percentage= 17% fully closed to 92% open

Im thinking thats why my car has drivability issues....it thinks my throttle is 17% and im not even reading 100% @ WOT. WTH? Maybe my BBK TB just screwed everything up...it was around that time when my drivbility issues occured...also installed the cams the day before so I sortof blamed them.

Opinions? Thanks for any help!
 
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It's perfectly fine.

The reading from 17% closed to 92% WOT is a percentage reading from 0 to 5 volts... it's not REALLY how much it's open persay...

The TPS is a potentiometer that, with the throttle opening, changes its voltage accordingly from around .7~1.1v at idle to around 4.4~4.6v at full throttle... all your diag tool is doing is converting that to a percentage on a 5v scale. In all reality the TPS never gets below .7v or above 4.6ishv

EDIT: sry, gauge not diag tool >.<
 
Ah thanks! And yea its a scan reader/clear and can monitor all functions...shift light, ect. Im lovin it so far, but thats the only range that looks weird. Glad its ok....well actually im not, I was hoping that was my issue LOL
 
Car bucks and has a stuble @ 1400-1700RPM. Also, if you let it idle in almost any gear it will start bucking violently. Been dealing with it for a good 35,000 miles now...its very annoying and difficult to control. Anyone else drives the car and you will look like a total newb to 5spds...I can actually hide most of it by my driving style though.
 
With your gauge can you check A/F? Also is there any rough/varying RPM at idle? Any codes?

If our cars didn't have COPs I would think it would be one of the coils but with the severity of the bucking you're talking about, it'd have to be a number of the coil over plugs... Of course if your A/F trim goes lean it'd mean the ECU's cutting fuel back because theres too much hc in the exhaust being metered by the O2s, so if you can check that it's be amazingly helpful.
 
^ Yes I can, directly by the front 02s...and it can monitor seperate wideband 02s, but I just dont have one...yet. So ill have a narrowband to deal with.
Problem is that I JUST put it in...but the car is pulled down right now. We are installing the T-61s :D ...but it requires some pretty precise fab work due to being a VERY tight fit. So I havnt been able to crank her up.

Also my Vac/boost gauge reads steady durring the bucking....along with the fuel pressure. I REALLY wish I could figure out the problem...and hopefully like said the front 02s are reading strange/ruined and are causing the issue. And I did replace a COP just for the heck of it and it didnt do anything....also moved it around and nodda. Car has a slight miss when held at a steady RPM.

And just for grins here, I will tell you when it clears up.

ONE time for the first 50 miles of a spark plug change. 0 miss and no bucking...then it came back (all plugs look great when pulled)

After resetting the EEC by pulling the battery, it immediatly runs alot smoother and then gets better and better until its like PERFECT with 0 bucking or anything, and then very quickly it starts getting worse until everything is fully back up to speed and then its back to normal.
 
Well the boost and fuel pressure holding steady definitely close a lot of doors on the problem... i'm still thinking one or more COPs are not necessarilly bad, but limping.
 
^ I hope so....cause you know what that means?

A. My issue is fixed
B. Im going to gain ALOT of power under boost :D :banana:

I just want to eliminate EVERYTHING else before I take the plunge on that expencive route lol.