Anyone else experience this? any fix? Only happens when the car is not in gear... when driving, it pulls hard and fast. S5 T2. already adjusted tps, already checked for vacuum leaks, already re-adjusted tps, already re-checked for vacuum leaks four more times, already pulled the TID off to check for cracks.

Another thing that i think might be related....

Either the ACV or the BAC is making an intermittent buzzing noise... sort of like a solenoid hitting metal very rapidly... like a relay chattering sort-of. I can't tell whether it's the acv or the bac. If someone can shed some light on this, that would be wonderful.

Thanks guys!
-Ross

 

As for the ACV, try taking It out and seeing If the Poppet Valve (anti after burn valve) has eroded. This particular valve will wear all the faster with the snail below It omitting all that heat.

The BAC Valve. Apply 12v to It to verify It Is working. Then do the same repeatedly. This time with a shot of wd40 In their. After, blow out and reinstall.

It seems you've had some strange Idling problems since you picked up the s5. No?

 

Yes sir. They were evident during the test drive too, but i figured since i've successfully fixed the idling issues with my s4 na before, i figured it wouldnt be a problem. but i've tried just about everything and still can't figure it out.

Now the anti afterburn valve... i don't think that is the case. The engine was replaced 20,000km's ago, so i believe they inspected everything.

I'll try the 12 volt thing, but i want to pull the bac off and inspect it

What i wanted to know was what would cause such a buzzing noise? sticky bac? Intermittently working bac?

The buzzing noise seems to correspond with the idle issue. I'm about to throw the bac out tha friggin window

 

I have a similar problem on my S5 TII as well. Except the misfire is intermittent, somtimes I'll pull to a stop and the idle will be higher than usual with a misfire and other times it's fine at 800rpms.

I think it's part of the throttle system sticking and keeping the plates slightly open. I'm pretty lazy and the car drives fine otherwise, so I haven't looked into it much.

//Ent

 

wow, you just described my issue to a T!!!!
holy crap!!!!
But my throttle system isnt sticking. I inspected it thoroughly when i had my intercooler off.

 

Well ****, I guess I'm out of ideas then

I haven't been able to figure out how to reproduce the misfiring on demand so as of now, it's completely random. Oh well.

I guess I'll be keeping an eye on this thread.

//Ent

 

K, pulled off bac... installed new air supply hose (the old one was a bit cracked)... tested using 12v, and resistance came out to 13.7 ohms. it was very clean inside...

I'm so bloody confused. i've been told it might be due to leaking injectors. So I'll start saving up for some injectors/safc.

 

Check the resistance of the FI's. If they are within spec, don't buy new ones.

But for an absolute cheap ensureness, replace the Upper/Lower Grommets and O-Rings. I'm finding alot of people having misterious leaks that are attributed to these seals.

 

Yeah but nuts to that. If i'm going to take off the intake manifold, i'm going all out! lol ... unless you can think of a better way to test the resistance of the fi's

Please dont say ecu

 

My 87 base did this before I messed up an apex seal. I think it was dirty injectors needing a good cleaning and balancing. It ran great other than the 3800 rpm hesitation that I almost got rid of with grounding and fuel injector cleaner run through the engine. It idled perfect, warm or cold. It would misfire when I had it in neutral, engine warm, and held the gas in a little so the engine would run 1000-2000rpm.

 

yup, you described it exactly.

 

I just put my rebuild together and I'm stummped and this is the exact problem I am having. Any solutions yet?