S4 turbo swap

I've encountered an odd throttle issue. When trying to start the car I blip the throttle a bit. I've always done this by habit. Now, it will not react to the throttle pedal at all. The car started yesterday without any throttle aid. While running, I attempted to rev the engine using the throttle pedal, and got absolutely no difference in the RPMs. It is as though the car is completely ignoring the throttle pedal.

I thought perhaps this could be a TPS issue. Both TPS' that I own have checked out to be good. I inspected the throttle cable and made very sure that the cable was properly set-up and tensioned. The butterflies are opening. I've also removed the throttle body and thoroughly inspected it. I performed the "TB mod" long ago. The car has always ran fine. (I wish I wouldn't have messed with the throttle body in the first place.) - Anyway, the only possible thing I can think of is the AFM. The car ran for roughly two minutes yesterday, though. There was just absolutely no throttle whatsoever.

 

Make sure the AFM door is opening properly. And are you sure the TPS is sending the signal to the ECU and it is received properly. If the signal is not being received at the ECU then that would be a red flag.

 

I not only checked the TPS voltage at the TPS, but also at the ECU.

Is it possible that the AFM is capable of causing such an issue??

 

I would think if the door is not opening as it should that it could cause a problem. And you can unplug the unit and jumper the fuel check connector and try to start and run the car. A problem w/the primary injectors could also be a source of your problem as well as a failing fuel pump/fuel supply issue. And did you check the range of the TPS ( 1 volt at idle 5 volts at full throttle).

 

I rewired all of the fuel pump wiring last year. I use a Walbro (with an adjustable FPR) with less than 6k miles on it and all four fuel injectors have less than one hundred miles on them. They were serviced recently by Witch Hunter.

Yes, the TPS range goes all the way from 1V to ~5V. I'll be checking the AFM very soon.

 

This sounds exactly like the issue I had when my TPS was unplugged. I know you said you checked your TPS and it was fine, but try cleaning the connections on the TPS and the wiring harness it plugs into. This is all I know from my own experience.

 

first... have you done any work to the vehicle recently?

second... i always have to ask, have you shoved a rag in the intake while servicing the engine recently?!?! it wouldn't be the first time that's happened on this forum

in the meantime ... you have 3 things to look at... air, gas and ignition

i find it odd that the engine would not fall flat on its face and die if you gave it throttle and something with the one of the 3 things was a miss...

however..

check fuel pressure, you should also do a fuel flow test as well (per the factory service manual) if you don't have either pressure or flow, check voltage at the connector in the rear for the fuel pump...also, if you can hear the pump but don't have pressure or flow, try checking before the fuel filter( you may have a dirty filter)... if that doesn't work you may have a bad pump. it is also possible that the pressure regulator is not functioning properly...

check base timing... check for erratic spark, this can be done using a timing light... chances are you would have a miss-fire if it was an ignition issue,

check for air leaks/vacuum leaks

check the flapper in the air meter make sure it moves freely.. i doubt its the AFM , they don't really go bad that often

 

does it bog at all when u floor it? or does it seem like the throttle cable is just disconnected and nothing happens

 

I feel like an idiot.

I laughed when I first read this... You may now laugh at me, though. "Rag in the intake"... Bingo. That explains why it seemed as though there wasn't any air flowing through the throttle body.

Very rarely do I forget things like that... I suppose it happens to all of us. Luckily there is no damage. All of the help and suggestions were much appreciated.

 

There's a demerit waiting for you at the front desk.

 

LMAO... like I said, it wasn't the first time its happened