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Horrible hesitation - Help!


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Ive got a vw beetle with an ea82t in it (hotwire MAF) it was running great until i switched to a spyder intake (xt turbo) and added an intercooler and a k26 turbo with external wastegate. so i started it up.....idles like a champ, revs good, turbo seems to want to spool. the problem comes when i want to move......i can start to go and it will drive normal just easing it in first but if i step on it, it has a really hard (and long) pull through the RPMs???? any ideas of where to start the ecu isnt showing any codes. Thanks

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Ive got a vw beetle with an ea82t in it (hotwire MAF) it was running great until i switched to a spyder intake (xt turbo) and added an intercooler and a k26 turbo with external wastegate. so i started it up.....idles like a champ, revs good, turbo seems to want to spool. the problem comes when i want to move......i can start to go and it will drive normal just easing it in first but if i step on it, it has a really hard (and long) pull through the RPMs???? any ideas of where to start the ecu isnt showing any codes. Thanks

 

 

Sounds like a grounding problem.

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i have an o2 sensor and it is located just after the turbo (not after the wastegate though).....i was thinking it could be a fuel problem.....it just has no jam to it.... at WOT it takes for ever to climb the rpms and doesnt sound like it wants to. but just sitting in neutral it revs great and idles perfectly. i will definatly check out the grounding issue and get some pics tomorrow after work. Thanks

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i have an o2 sensor and it is located just after the turbo (not after the wastegate though).....i was thinking it could be a fuel problem.....it just has no jam to it.... at WOT it takes for ever to climb the rpms and doesnt sound like it wants to. but just sitting in neutral it revs great and idles perfectly. i will definatly check out the grounding issue and get some pics tomorrow after work. Thanks

 

 

Whats your boost at?

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Was there any connection (like for the TPS)

that wasn't correct when you went to the XT manifold?

 

 

Did the MAF get any ruff treatment lately?

 

Those two items (MAF and TPS) are crucial items in

hard pull fuel delivery.

 

You mention just installing an IC.

I have had this type of problem

when the connection to the thrrottle body leaked.

 

In my circumstance, the rubber hose connection to the TB

was fine when the engine had negitive intake manifold pressure.

But as soon as the manifold pressure went positive

the connection separated and WHOOP no mo go.

 

Back off and the vacuum sucked the connection closed.

That one was a tuff nut to crack.

 

The fuel filter getting semi clogged is a long shot unless

the gas tank was involved some how.

 

Good luck hope it's something simple, you did use new gaskets and did not separate the spider before installing I will assume.

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well i checked all my grounds on the ecu and wiring harness...everything appears fine. i got a fuel pressure gauge and i read 35psi. the maf hasnt suffered any trauma that im aware of. i really dont think its a vacuum leak i checked everything and if the intake were separating i should be able to hear it. i ran it with the test connecters hooked up and it didnt change anything, i unplugged the maf and the car was undrivable. anything else to check? when im in second and step on it seems to stumble on it self (it doesnt buck like it wants to go). tomorrow morning im going to try switching out the ecu and see if that makes any differance. annnyways for heres some pics for ya (take a close look and see if you can spot any screw ups)

 

795701_42_full.jpg

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Sorry, Dneu, but this statement is not

what I found when my engine was acting very similiar to yours

 

"i checked everything and if the intake were separating i should be able to hear it"

 

As descibed this only happened when boosting .

I could not simulate (i.e hear) the situation just reving it while standing still.

 

Good luck, sounds like you covered all the bases.

Throwing parts at it?? What else are you going to do?

Do you have a spare MAF, TPS, fuel filter?

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well i have been driving it during these little tests and my first time out i did indeed seperate the intake and it made a very distinct sound....it has long since been repaired and when i drive it now it doesnt sound like there is a leak when its boosting...i will double check in the morning, i wish i had a spare maf to try, my only other one is screwed (when its hooked up the car will not idle) i suppose i could get a new fuel filter they are cheap and easy so it couldnt hurt....thanks guys i will report back tomorrow:banana:

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well i think ive tried everything now, it still isnt running worth crap. it feels like its not boosting at all, and it doesnt run smooth at all feels like its knocking (short quick stumbles when you give it some gas). im going to go pick up a boost guage and see if i can confirm this.

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well i think i just may have found my problem......one of the studs on the exhaust manifold is stripped out and there is a decent sized exhaust leak. that would probably explain why i have no boost. (its hard to hear exhaust leaks with an open turbo:) ) now would the exhaust leak cause the stumbling/hesistation as well????? i will have to helicoil the head sometime next week.

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If the leak is at the manifold, I.E.: before the O2 sensor, yes. That means that the A/F ratio is probably going haywire. Definitely get the exhaust leak fixed, then if the problem still exists, you can troubleshoot from there. Just my 2 cents worth. Hope it helps.

 

Patrick

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  • 2 weeks later...

ok well on the weekend i finally got some time to continue my work...i manged to fix the exhaust stud so there arnt any more leaks....i replaced both fuel filters, i ran an 8 guage wire from the Neg. post to the alternator bracket, i added an extra ground wire for the coil bracket, and i even switched coils. same problem!!:mad: with the help of some new gauges i have more info.

 

Vac at idle 15-16 lb/hg

boost at WOT 1st gear 2psi (some stumbling)

boost at WOT 2nd gear 2-3psi (with noticable stumbling)

Fuel pressure at idle 30psi

Fuel pressure at WOT 36psi

ECU code 44 - boost control (i took it out since i didnt have a problem without it last year)

 

and something else i observed today was that at idle (900 rpm) if i turned on the lights the idle would drop by about 100 rpm the rise again however the car would seem to miss or stumble maybe every 15-25 seconds???

 

Anyone have any clue:confused::confused::confused::confused::confused:

Thanks

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"dont really want to give up now!! its really wierd it wants to go i know it!!"

 

LOL. I have been there just after finding a leak. Everything was good and It still did strange things after fixing... until one day in a very powerful rain storm... something came back and the hesitation left it (over a year ago!). I could only ponder the speed of the ecu clock and ecu truly remembering a long run with a mistake, even after it was gone. Mine was complete with after fire detonation. Try your ecu's complete reset, clear codes, unhook from battery? and then go real easy for awhile, target where it just starts to miss /hesitate and leave throttle there, if it still doesn't stop, you still have a problem.:)

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well i think its finally working now. i swapped out the k26 turbo for a stocker, and i layed down 11 psi at 5500rpm. it built boost alot slower than i remember but i found the cause...another exhaust leak on the wastegate flange. so since the k26 is a no go can anyone recommend a suitable turbo that will pull all the way to redline and run 14-18psi all day long?

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