Could it just be my TPS?
 

I've known my TPS was not 100%, as I had a bit of bouncing idle when the car was warmed up. However today something completely new happened. Now I'd like to say I did some searching (about an hour) but there are so many TPS/idle threads here that I had a hard time locating my problem.

First the changes, I've had my racing beat headers+pre-silencer on for about a month. The mufflers i'm running were a bit loud so yesterday I put on a pair of Tanabe exhaust silencers, the ones that slip inside your muffler. Took the car for a test drive last night and all seemed well, exhaust was a few db quieter, and the engine still pulled just fine.

Today though, I was driving onn the highway and everything was going fine. Took my off ramp, stopped at the light, and the car started chugging and died. Turn in over, it starts right up, but I have to hold the idle at 2500+ to keep to keep it from dying. The engine also seems to be vibrating from 1000-4000 rpms. If I take the car over 4000 rpms it seems to smooth out but it feels like not all the power is there. So I pull onto a side road and take the silencers out thinking they are the culprits. No change though, so I limp it home.

When I get home the first thing I do check engine codes, and get a #6 Throttle Position Sensor. Is it possible my only problem is the TPS, and it just happened to completely crap out right after the silencers were installed? Or is there a battery of other checks I need to start working on?

Since your TPS was suspect from the start I'd replace it ASAP. I doubt your silencers had anything to do with it.

You might want to do a compression test to make sure your engine didn't pop either.

Keep us updated. :nod:

when i first got my s5 running the car ran great..engine was strong everything was tight but after what seemed like every 15 min. the car would practically stall and run like shit....id have to pull over, kill the engine and wait about 2 min. then turn the key and it was fine for about another 5-10 min. then same thing....finally found out it was the TPS. changed it with a new one and car was mint...def change that thing out and go from there.

It may be possible to adjust the TPS if a new one is not a viable option right now. It may help your problem.

I did think about this, but as of now I can't really get the car warmed up without sitting in the driveway and holding it at +4k rpms. Since the TPS was already in need of being replaced I guess this just forces my hand to buy one (was saving for KYB's and Springs :() Just wanted to get some feed back before I dumped the nearly $200 for a new sensor.


EDIT: Did some more searching... If my O2 sensor went out, and forced my engine into open loop, would that possibly explain the shitty idle?

^ No, a lot of people don't even run an O2s and their car idles fine.

Update
 

got my TPS in today, slapped it in the car, crank crank crank, nada. checked plugs, a little wet so i pulled them all and the egi fuse (i've never had flooding problems before), then cranked it over a few times to get the fuel out. Still no luck. put an inductive pick up on each of the plug wires to check for spark, and both the trailing sides were acting weird. they wouldn't spark at first, but then after cranking for 3-5secs it would start showing a pulse. both front and rear trailing coils were doing this.

seems kind of odd that both coils would crap out at the exact same time, but it makes sense to me that if they went out when i was driving it might explain why it couldn't hold an idle below 4k rpms. wanted to get some feedback from the rest of you before i look for coils. might be something here i'm missing? i'll test the coils as per the manual tomorrow and post the results.

I think you should check for vaccum leaks since the 7 isn't able to hold any idle.......

ok but any ideas where to start? none of my hoses are dry or brittle, so i'm not sure what could've gone wrong while i was cruising. other then visibly checking the hoses, i'm not sure how i can check vacuum on a motor that i cannot get started.

Just reread your first post. Yes you need to check for certain things and eliminate them. Could be a number of things. Hard to diagnose online. Check for compression, then spark....

i have to the same thing with my S5 because if i dont give it some gas for a few seconds it will die on me its an idle problem something wrong with my air control volve but tomorrow im going to see if i fix it i got some really good help from the guys here.