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slow.
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1,016 Posts
Discussion Starter #1
ok guys i would appreciate it if you could give me with some input. I've got a 87 turbo. Fresh rebuild. (this doesnt really matter because i had this problem before the rebuild.) Around 2000-3300rpm i get a hesitation... almost like the car is pulling backwards. its very slight but it makes accelaration feel very choppy. I've got new wires.. new ngk plugs gapped correctly...new fuel filter.. even tried the 112v mod thinking it was the fuel pump changing over, didnt help. i had a tps code thrown, but drjonez and i fixed that. Problem is still there. No codes at the present time. I just cannot figure this out!!!!!!!!!!! I assume its an electrical issue, but i just dont know. At WOT i get some hesitation around 2-3k and the it runs like a bat out of hell. any ideas fellas? :(
 
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Does the engine hesitate? Or can you just feel it not accelerating as much? Your turbo is gonna start to kick in around 3K, and run from there. Maybe your EFI needs to be cleaned.
 

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slow.
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Discussion Starter #5
yes, the engine hesitates. almost as if its missing. but i know its not. the acceleration is "choppy" between 2000 to 3300rpm. and to your suggestion of "cleaning the efi" thats a rather vague answer. I've tried all that injector cleaner BS. i highly doubt its not getting sufficient fuel. The SOB pops and crackles like its getting gallons of fuel. *sigh* this is so frustrating.
 
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The dreaded boost leak maybe? check all your hoses for cracks or anything suspicious.
 

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slow.
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Discussion Starter #7
hmm, i'll do a pressure test, but it doesn't feel like a boost leak. it almost feels like the engine is pulling timming at that rpm range. hmm.
 
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check and make sure you don't have a plug wire resting against
something that would ground it out.

don't touch them while the engine is running, of course. you'll get
the shock of your life :D

sure your cats aren't clogged?
 

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slow.
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1,016 Posts
Discussion Starter #9
no cats, just 3" all the way. the ignition system is in tip top shape. any other ideas? :(
 

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the clever guy
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782 Posts
I have had a similar problem intermittently since I turned the boost up on my car. I have a walbro, 12v bypass, RC cleaned 440s, and no codes like you. I have two guesses. Boost leak in stockish pipes and/or bosch bypass valve. I hit fuel cut in second my first couple times boosting after coolant and oil are at operating temps so that right there spells boost leak but it goes away after a few hard pulls. I still get the weird hesitation around the same rpm as you about 40% of the time. The other possibility is clutch slip. Most of the time, first and second break traction but sometimes the torque plateaus (sp?) like I have traction control. I've never gotten any solid suggestions on this but there have been a few good info exchange threads. :dunno: I'd really like to figure this one out. Hardpipes and a real bov are in the near future for me so that will eliminate the problem or a couple more possibilities.
 

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Go All Electric
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1,183 Posts
I think I may have experienced this before. I remember stabbing at the throttle one night in second gear.. and my car acclerated like a champ .. and then it felt like it was hopping/skipping a bit for a second or two but it also felt like when it was doing this it would slow down for that little "chop" .. but I was still accelerating quickly. It was almost as if I had a chain tied to the rear end tow hooks and something was yanking at the back of my car a couple of times ... hard enough to jerk me back/slow me down just a tad bit. It only hapened on that one pull though for the rest of the boosting for the evening. Also, this was the first time I had ever noticed it and it was on one of the first cold nights I ever floored it in 2nd gear. Also, I do not remember this happening in any other gear than 2nd. I was thinking it may have something to do with back pressure more than anything else. I have a stock turbo elbow TMK and only 2.5inch exh with highflow cat and muffler. I never really thought much of it. I figured that if after I increased exhaust and intake flow a bit more with IC pipes and ported elbow/fullexh ... and it still did it ... then I would start analyzing it more. I do not think that it is my bpv because I have the Bosch 110 and even though people have run this model bpv to 20+psi, mine has never seen anything over 15psi. Just some short thoughts that I thought I would share.

EDIT: For clarity.
 

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slow.
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1,016 Posts
Discussion Starter #12 (Edited)
man this is a hard one to point a finger at. im gonna change out my bov and see if thats it ( i doubt it). btw, thanks for your input guys.
 

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Go All Electric
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So does my story sound like what you are experiencing? I guess since you have full 3inch turbo back and IC piipes<---this eliminates my theory about back pressure from the exh/intake :(.

Oh yeah ... "stock car phone"?
 

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slow.
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Discussion Starter #15
man, that looks pretty close to what i feel! now i wonder what could be causing it! i mean, i've experienced a whole lot of problems with a supra and i'll tell ya, this is nothing like i've experienced before. Its definatly hard to diagnose. any more input would be appreciated guys!
 

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Go All Electric
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Couldn't resist this one.

Bostedstr8six quotes: "This ASSCAR thing is quite a sport! It takes a real athlete to sit behind the wheel of a souped-up hotrod and go loop-de-loop while thousands of working class inbreds swill beer and inhale carcinogenic exhaust fumes while incurring permanent hearing loss!"

I believe it's a whole lot more demanding than most people think. How would you like to drive ~200mph in nose to tail traffic for 500+miles? http://www.1800bepetty.com/intro.html

Regardless, thanks for the dyno post. What are your mods exactly? I'm wondering what boost control you are using and what kind of restrictions you may have that would yeild that type of curve.
 

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the clever guy
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782 Posts
Couldn't resist this one.
:lol: Let's not get into this. My stance on the rolling billboards is immovable. Driving really fast in a circle for a long time does not impress me one bit. Give me WRC, F1, GT series, scca, etc.

Back on topic: That dyno is old (6/1/02) and at the time my mods were: 3" DP, exhaust, turboxs mbc (dyno 10 to 11 to 12 to 13 psi), blitz sus filter. Everything else was stock. Oh, and the vacuum line to the fpr was unintentionally disconnected so i was detonating quite well above 10 psi. Look at the dip. The shape is the same in all four pulls, more pronounced with more boost and inverted on 10 psi. When I get the hesitation, it's either the nice meaty spike in torque, or the dip/plateau feel.
 

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Go All Electric
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1,183 Posts
Boostedstr8six said:
:lol: Let's not get into this. My stance on the rolling billboards is immovable. Driving really fast in a circle for a long time does not impress me one bit. Give me WRC, F1, GT series, scca, etc.

Back on topic: That dyno is old (6/1/02) and at the time my mods were: 3" DP, exhaust, turboxs mbc (dyno 10 to 11 to 12 to 13 psi), blitz sus filter. Everything else was stock. Oh, and the vacuum line to the fpr was unintentionally disconnected so i was detonating quite well above 10 psi. Look at the dip. The shape is the same in all four pulls, more pronounced with more boost and inverted on 10 psi. When I get the hesitation, it's either the nice meaty spike in torque, or the dip/plateau feel.
3inch dp .. what diameter for dp-back exh? Stock IC pipes were definitely not helping then either. What are your current mods?

Total agreement for preferences of driving circuts. BUT ... lets not forget how tough of a job NASCAR can be .. regardless of whether or not other circuts require different strengths and talents or whether or not they are more entertaining to the individual. NASCAR must be strenuous activity. I would hate the repetative oval laps and traffic congestions. WRC/F1/GT etc definitely own for entertainment and for enjoyment etc .. IMO ... but thats not to say that each circut doesn'yt have it's differences of difficulty.
 

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HMOOB VWJ NYOB MINNESOTA
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1,352 Posts
Have you tried a different AFM on your car? How dirty/clean is that black plastic thinging inside the AFM. If its dirty, try cleaning it a little it might help.
 

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slow.
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Discussion Starter #20
hey, thanks for jacking my thread guys. take your nascar talk elsewere. jza71, no i haven't tried changing it, or looking at it for that matter, but i will give a peek, thanks.
 
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