car bucks at 5,500 rpm

[Hunts_13]

Hey guys so here the deal cars a 1990 tsi awd.
560cc injectors and 195 walbro pump, 16g Big turbo and turbo back exhaust.

just running stock boost right now too. car drives fine until I mash on it. boost kicks at 3000 rpm and holds at 11 psi until about 4700 rpm where it starts creeping about to about 19 psi. as soon as I hit 5500 rpm the car just bucks. (it was doing this before i put the bigger injectors and fuel pump in too)

If I put the pedal about 3/4 of the way down and build up to it slowly it does the same thing but at like 4000 rpm WTF. From what I've read from other threads it sounds like fuel cut but I wasn't sure. Any other Ideas? or why would I be fuel cutting?

 

[98mitsubishigst]

Hey guys so here the deal cars a 1990 tsi awd.
560cc injectors and 195 walbro pump, 16g Big turbo and turbo back exhaust.

just running stock boost right now too. car drives fine until I mash on it. boost kicks at 3000 rpm and holds at 11 psi until about 4700 rpm where it starts creeping about to about 19 psi. as soon as I hit 5500 rpm the car just bucks. (it was doing this before i put the bigger injectors and fuel pump in too)

If I put the pedal about 3/4 of the way down and build up to it slowly it does the same thing but at like 4000 rpm WTF. From what I've read from other threads it sounds like fuel cut but I wasn't sure. Any other Ideas? or why would I be fuel cutting?

What tuning device are you using? or are you even tuned for that matter?

 

[Hunts_13]

No tune yet. Was trying to find dsm limk or safc locally, but no luck. have to buy in online I guess, And ya i know I should have one, but thought the problem could be from something else since it was doing it before the injectors and pump when in.

 

[98mitsubishigst]

Well; one get a tune immediately!.. your creeping to 19 PSI without a tune..

I have a jerking around that RPM in top of 3rd at WOT..
and i have a check engine code on for wastegate actuator..

I have read up on symptoms of wastegate actuators going bad and jerking is one of them.
Kinda like hitting a brick wall right? and it feels like fuel cut?

 

[Hunts_13]

Ya I know I need one bad. Looking at dsm link as we speak.

yup thats what it feels like pulls hard and then bam just loose everything and then kicks back in then right out again. I checked for codes not showing anything. Any way to check for proper operation of the wastegate?

 

[98mitsubishigst]

Ya I know I need one bad. Looking at dsm link as we speak.

yup thats what it feels like pulls hard and then bam just loose everything and then kicks back in then right out again. I checked for codes not showing anything. Any way to check for proper operation of the wastegate?

Hmm that i do not know of.. But it sounds like the exact issue im having.. Im just throwing a 16g on this weekend and calling it a day hahaha.

Im sure there is a thread about operation of the wastegate somewhere on here... ill check

 

[Imback]

Sounds like fuel cut. And you running 550's with nothing to tune with them is making your car run rich. So install your stock one's until you get something to tune with. Are you also on the stock 1g maf?

 

[Hunts_13]

Stock MAF right now. would put the stock injectors in but i replaced them becasue to were dead. ya jnew the car would run rich when I put them in.

 

[SBstar]

A. Tune for your injectors, you are undoubtedly running rich being your ecu still thinks you have 450cc injectors and will treat your 550's as such. Meaning it think it's injecting alot less fuel then it is. Then the O2 sensor sends back some funny readings and really starts screwing with things. Once you get an SAFC, DSMLink, whatev, make sure you log, chances are when you're creeping to 19psi you're experiencing knock.

B. Boost leak test, probably 90% of bucking problems are related to these.

C. Exhaust leak check, pre-turbine will cause the bucking you're experiencing.

D. Check your ecu's caps, bad caps can and will cause bucking, mine happened to be at about 4500, but it varies for some reason. If the caps are bad you can try replacing them and hope you haven't damaged your board, or look for a new one.

E. You're creeping, you need to find a way to control that. Look up porting and get to work.

 

[viprez586]

Hey guys so here the deal cars a 1990 tsi awd.
560cc injectors and 195 walbro pump, 16g Big turbo and turbo back exhaust.

just running stock boost right now too. car drives fine until I mash on it. boost kicks at 3000 rpm and holds at 11 psi until about 4700 rpm where it starts creeping about to about 19 psi. as soon as I hit 5500 rpm the car just bucks. (it was doing this before i put the bigger injectors and fuel pump in too)

If I put the pedal about 3/4 of the way down and build up to it slowly it does the same thing but at like 4000 rpm WTF. From what I've read from other threads it sounds like fuel cut but I wasn't sure. Any other Ideas? or why would I be fuel cutting?

Rather then start another thread try searching: Bucks, hesitation, hesitates,etc. and sort by titles and replies. That will get you started. Keep the search field narrow and limited. Works like a champ every time - now you should be a searching pro.

Here's what you need to do and research on:
2G MAF + 550(or 560cc) injectors
Boost leak test aka BLT
Boost creep, porting, etc.


Your hitting fuel cut because your open exhaust is causing your boost to creep past what the wastegate can flow and what your fuel system and mass air flow sensor can handle.
You can't just increase the boost and let the ecu handle it, you need to research and understand what you're doing before you do it.


I have a hard time believing you read/researched that much.

 

[Hunts_13]

thanks for the help guys. Ya I just bought dsm link. I know that is probly a huge part of my problem, but since it was doing it before the mods I was trying to figure out what else it could be too. I had done a boost leak test already and had no leaks. I'll work on getting rid of the boost creep till my dsm link is here. I'm pretty surer my ecm is good but I'll double check to be safe.

 

[TurboAnything]

Even with EcmLink you are going to have problems. The 1g MAF is only good for about 14-15psi out of a 16g. You need to also upgrade to a 2g-3g MAF to get good results.