Ok here is the deal!! On warm up my car runs just fine.. after hitting operating temp it starts to hesitate almost stalling(only under throttle)tach just falls..When i floor it just goes dead and then starts to sputter back to life before doing it again....when i take my foot off of it after flooring it will go back to idle like nothing happened. It does not have to be at full throttle to do this.
Iam leaning toward a fuel pump.

 

sock filter, fuel pump, or injectors IMO

 

TPS?

 

Changed all filters regarding fuel...Also when it does this if i stop and pull the egi and head fuse it seems to quit for a lil while before starting again, Leads me to believe it could be goin into limp mode. But how>??

 

its an s4 right? then no limp mode. TPS? you may be on track with the fuel pump. But this is the blind leading the blind.

 

It is a true s5 turbo....It's one of the two and iam thinking the omp being that the walbro has less that 8000 miles on it if that..??

 

damn, is it throwing a CEL?

 

Thats the strange thing it isn't!! I was at a parking lot when it started doing this so i stopped pulled the egi and head fuses while it was running then pu them back in started and ran fine. For a lil bit then back to the same ole ****!!!

 

Also the omp is unhooked but plugged in i run 2 stroke.

 

I'm just stabbing in the dark man....... what mods are you running?

 

Alot haltec is waiting to be installed by bdc......It's pt-67, 4x720cc, safc neo, walbro 255, 3"turbo back, 2 1/2" fmic piping, etc...

 

Iam thinkin omp pump do they have a rep for going out??? Because it might do it for lil bit then quit and i can boost to redline without a problem....

 

yea, the s5 OMPs are pretty sheitty.... but if it were the OMP causing it to limp out two things would happen:
1) a CEL would be thrown
2) the car would be limping until you restarted it.
That's what happened when mine went out.

Sounds like some hardcore hesitation man, I would check all the grounds, especially the ECU, and then take a look at those secondary injectors; check the electric connections, check the rail, check how they fit.

 

I am with you. It might be the fuel pump. You could throw a DMM on it and make sure it's good electrically. Otherwise is there a way to check fuel pressure?

 

Yea also thought the fuel pump could be the culprit...but that would rule out it doing it on the highway and then going back to normal like nothing happened. Maybe???
Also if i keep the throttle at the special spot it will drive but the wideband is showing lean as hell!!!!! 16 plus!!!

 

so it's like this then: you floor it on the highway and it falls flat on it's face, then after a second it's fine, and you can cruise like nothing happened? I am so sticking to the secondary injectors.

 

you could have an air leak where they sit in the rails, this would cause extra air in the system, leaning you out.

 

Yes this did occur before and i was like dammit so i redid them aand still here i sit!!! Also if was them it would do it all the time not just every now and then....Looks like i will be buying a new fp maybe!! hahah....Also I unhooked the omp connections and felt the way it drove and it is awfully simular!!

 

yea, maybe they are just starting to come loose..... make sure you are using all the right grommets and all.... big pain. I'm about to get down and take care of mine too.

 

i know it suck doesn't it!!

 

yup.... but I'm going to wait till my 1600cc's come in so I can move my 720's to the primaries and then...... oh yes..... BNR stage 3

 

looked at my lower fuel rail and it looks as though the fuel pulsation damper screw in the middle has fell out could this be the culprit??

 

Possibly, wouldn't hurt to replace it and find out!

 

Read a thread and it says s5's do not come with the screw in the middle also what the hell does a fpd do??

 

yea, I thought that was confusing... on the s5's the pulsation dampener is integrated onto the fuel rail. It absorbs pulsations in the rail from injectors opening and closing.... keeping the rail evenly pressurized. I'd check the secondary rail as being the primary culprit here, but indeed check the primary injectors as well.