backfiring after around 3k rpms
#1
Rotary Enthusiast
Thread Starter
backfiring after around 3k rpms
So im working on the fc and from what the previous owner of the motor said its a large aggressive street port, bnr stage 1 turbo, rtek 1.8 and upgraded injectors (unknown size cause i cant find the guy who sold us the motor ne more). Rats nest deleted. Fmic and supra or walboro fuel pump. The motor was installed begining of the yr but its only been started a few times since then cause ive been to busy with other things to get workin on it. So i have time now. Heres the problem.
When it first started the idle would stay at around 1500 rpms but bounce up n down and not rev past 3000k. So i just changed the afm n tps. It starts n wont idle with out me holding the gas for a while. After that it stays at around 1200 rpms but bounces from time to time. When i rev it, it revs fine til like a lil past 3k where it just sounds like its breaking up n starts backfiring everytime past that.
Kinda stumped here and would like help on it. thanks
When it first started the idle would stay at around 1500 rpms but bounce up n down and not rev past 3000k. So i just changed the afm n tps. It starts n wont idle with out me holding the gas for a while. After that it stays at around 1200 rpms but bounces from time to time. When i rev it, it revs fine til like a lil past 3k where it just sounds like its breaking up n starts backfiring everytime past that.
Kinda stumped here and would like help on it. thanks
#4
Going Nowhere
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the bouncing idle could be two things, aws or tps. but i beleive the rtek gets rid of the aws so i would check to make sure your tps is good a set up correctly, do a search many threads on it here or the procedure is also in the haynes manual if you got one handy
#6
rotors excite me
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could be 3800RPM hesitation which I think is usually caused by the secondary injectors having bad grounds. could be a vacuum leak. was this motor rebuilt recently? because if it was you're not going to have excellent compression until it's broken in, but wouldn't necessarily explain why it doesn't like revving over 3k. another common problem is a bad TPS (throttle position sensor), I had a bad one and couldn't rev over 6500RPM.
#7
Rotary Enthusiast
Thread Starter
it was rebuilt but from what i was told only has less than 10k on it. ill recheck the tps. it seemed to in spec the last time i changed it. vac leaks were fixed b4. ill also add some grounds to it.
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