Stange Miss (2000-2500 RPM)

slader99 · 05-31-2008, 09:14 PM

Car is running great, idles smoothly at 650RPM and pulls hard to redline. The timing is set correctly, but it has a strange miss at the 2000-2500 rpm range. Its a stock, manual 7mgte.

It is quite often repetable and occurs when the engine has been running from 2-7 minutes (seems to happen during warm up but not when engine is cold or hot).

It also only happens under light throttle and low boost. If the acceleartor is mashed to the floor, there is no hesitation or miss during that rpm range regardless of engine temp.

It seems to be more of a backfire or mis-fire rather as there is a noticible lurch and momentary drop of RPM. The engine is throwing no codes, and other than this little issue runs great. Any ideas?

supramacist · 06-01-2008, 01:43 PM

I have nearly the same problem.

It just has to be tuned out. How? IDK.
I think it could be a few small things causing mine.

What plug wires are you using?
Did you build them yourself?
I think this was my problem. somehow.

tsupra89 · 06-02-2008, 05:23 PM

mine is doing the same thing. when its hot it doesnt do it when i crank it doesnt do it. but when im letting it warm up the rpm fluctuates like hell. it is my brake booster the diapraghm inside the booster is cracked or the seals have gone bad. cause one massive vacuum leak. try when your car is crank press the brake pedal down in a steady but fast pace. repeat the step and if its the brake booster it will really wanna kill your engine. im not talking about the flucuation because of the brake booster taking the vacum from the engine im talking about violent shaking and it feels like the car wants to stall.

05-31-2008, 09:14 PM	#1
slader99 Stock Join Date: Apr 2008 Location: canada Posts: 26	Stange Miss (2000-2500 RPM) Car is running great, idles smoothly at 650RPM and pulls hard to redline. The timing is set correctly, but it has a strange miss at the 2000-2500 rpm range. Its a stock, manual 7mgte. It is quite often repetable and occurs when the engine has been running from 2-7 minutes (seems to happen during warm up but not when engine is cold or hot). It also only happens under light throttle and low boost. If the acceleartor is mashed to the floor, there is no hesitation or miss during that rpm range regardless of engine temp. It seems to be more of a backfire or mis-fire rather as there is a noticible lurch and momentary drop of RPM. The engine is throwing no codes, and other than this little issue runs great. Any ideas?

06-02-2008, 05:23 PM	#3
tsupra89 3" Exhaust Join Date: Sep 2007 Location: asheville Posts: 71	mine is doing the same thing. when its hot it doesnt do it when i crank it doesnt do it. but when im letting it warm up the rpm fluctuates like hell. it is my brake booster the diapraghm inside the booster is cracked or the seals have gone bad. cause one massive vacuum leak. try when your car is crank press the brake pedal down in a steady but fast pace. repeat the step and if its the brake booster it will really wanna kill your engine. im not talking about the flucuation because of the brake booster taking the vacum from the engine im talking about violent shaking and it feels like the car wants to stall. __________________ 89 Supra Boosted 11psi lexus afm k&n air system aeromotive fuel pressure regulator walboro fuel pump stage 3 weitght reduction koki style tail lights silver and black 2 tone paint Enkei rs7 17" 17.5lbs each hankook ventus hr2's 225/45/17 apc hood pins yellow fogs ----------------- Soon To be Megan racing seats, roll bar, either takata or sparco harnesses

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06-01-2008, 01:43 PM	#2
supramacist 1000whp postwhore Join Date: Apr 2007 Location: Escape from the Prison Planet Posts: 1,356	I have nearly the same problem. It just has to be tuned out. How? IDK. I think it could be a few small things causing mine. What plug wires are you using? Did you build them yourself? I think this was my problem. somehow.