backfiring out the intake; won't rev pass 3000rpm

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06-05-2003, 06:03 PM

chef_tickwon

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backfiring out the intake; won't rev pass 3000rpm

Hey there…I got a problem I can’t seem to figure out. My car doesn’t rev pass 3000 rpms and runs very lean as well as backfire out the intake. Big problem, huh? I’m thinking it’s a sensor of some sort or possibly the AFM. I’ve already changed the fuel pump and fuel pressure regulator. The injectors are running fine. Can someone help? I appreciate any help you can give.

Thanks,
Chris

1981 280ZXT

06-06-2003, 11:47 AM

Bleach

The Evil Twin

Join Date: Mar 2001

Location: Seattle, WA

Posts: 9,294

It does sound like it might be running lean. I would suspect the throttle position sensor. You can open it up and clean the contacts as well as clean the connector that plugs into it.

have someone spray some throttle body cleaner or carb cleaner into the front of the AFM (with air filter disconnected of course) while you reve the engine a bit. If you get some more power to revv up higher and more smooth then you know it is a fuel problem.

06-06-2003, 02:11 PM

chef_tickwon

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Thanks...I did clean the connectors...they had a greenish look to them. So I cleaned it up the best I could and it still runs the same. At idle it runs about 950rmps and it runs like it's healthy at idle, but as soon as I start to drive at around 3000rpms, it bogs, backfires and just does not rev any higher.

Thanks again,
Chris

06-06-2003, 02:17 PM

icice9

Super Siver & Black Stud

Join Date: Apr 2003

Location: Hayward Ca

Posts: 1,526

you might want to check to see if you have any vacuume leaks..specialy around the air flow meter... also id check your timing posistion too.. make sure to see that the AFM boot is on tight and is not leaking any vacuume...

06-06-2003, 02:25 PM

chef_tickwon

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Hey icice9...yeah, I'll have to double check that, but if you have a vacuum leak would it idle erractic? I know when i pulled off a vaccum hose one time it sounded like it was running wihtout one cylinder. I'll have to check those lines again too.

Thanks,
Chris

06-06-2003, 03:26 PM

icice9

Super Siver & Black Stud

Join Date: Apr 2003

Location: Hayward Ca

Posts: 1,526

i use to have the same problem with my Z... when i took out my NOS system i still had a hole from where my nitros injector went in and when i would reve the engine it would backfire pretty bad.. then i plugged the hole and it went away... thats why i was thinking it might be a leak somewhere... if its not that id check the AFM...

06-06-2003, 06:12 PM

chef_tickwon

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Hey there again…as of right now…she running fine and storich at full throttle. The problem was the ECU had to be resetted (unplugged for about ten mintues)…I’m guessing, cuz it fixed the problem or hid it. She no longer bogs or backfires out the intake, very good news for me. I hated that feeling. I, somewhere, along the line of changing some electrical components didn’t reset the ECU. I didn’t know I had to do that, but I live and learn right? I’ll definitely keep a close eye on her though. And thank you all for the help.

Thanks again,
Chris