The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support Rix Racing
Please Support Rix Racing

1G Backfires after fmic

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

dsmBear

10+ Year Contributor
387
10
Aug 27, 2012
Carmichael, California
I just installed my vsrf kit which was a pain in the ass to install btw, but now it back fires? should i be worried and the gas pedal kinda stuck at idle and have to give it a decent amount of pressure then revs high... any ideas?

1g 6 bolt
 
Last edited:
Look at all electrical connections and everything around where you was installing piping and intercooler. Maybe you bumped something. What do you mean by a descent amount of pressure? Like the actual pedal is difficult to press? Like it's sticking?
 
Did you lose a wrench somewhere in there and it's causing the throttle to stick? Cruise issue (if equipped)?

Installation of a FMIC would have zero effect as your describing unless a) electrical connectors are unplugged, b) you have a leak, c) you forgot a towel shoved somewhere.. maybe at the throttle butterfly.
 
You should be running a little leaner with the front mount but if your backfiring your running too lean. So check your fuel pressure and injectors and pressure regulator and how many lbs of boost are you running.
 
7 :L it has a leak somewhere im assuming then, I got a rebuilt tb in the mail and had to manually calibrate the tps with a voltmeter, also could the isc be bad? when i did a blt i couldnt hear any air leaking out at 15 psi, but driving i hear a leak somewhere, do a blt again no leak.
 
You should be running a little leaner with the front mount but if your backfiring your running too lean. So check your fuel pressure and injectors and pressure regulator and how many lbs of boost are you running.

Why do you say he would be running leaner?

7 :L it has a leak somewhere im assuming then, I got a rebuilt tb in the mail and had to manually calibrate the tps with a voltmeter, also could the isc be bad? when i did a blt i couldnt hear any air leaking out at 15 psi, but driving i hear a leak somewhere, do a blt again no leak.

What is your BLT methodology?

You wouldn't hear a leak when you're driving. You might have another problem altogether.
 
is there a way to to test that? i installed an mhi big 16g and appeared in overall good condition, and it was taken off a running car i guess pull off the jpipe and do the gasket?
 
I can hear the boost screaming out and no power.... I put a coupler on my turbo and shot 15 psi through

Yeah, again, not a boost leak. You wouldn't hear it and if you were losing so much pressure that it's audible ABOVE you sound of your engine, your engine simply wouldn't run.

By shooting 15 psi through, did you mean you pressurized the entire intake system (valves closed) to 15psi, and then shut off the compressor and monitored how long it took to bleed out, keeping track of everywhere you heard hissing and used the soap-spray method?

"Shooting 15psi through" means nothing. Please take more time to answer if you expect meaningful troubleshooting advice.
 
We are not getting near enough information here. How are you boost leak testing? Compressor? How are you looking for leaks? What are you checking for leaks? What has been changed, messed with, adjusted, removed or touched since the car last ran right? New parts? Used? Rebuilt? What have you checked? How did you check it?
Some more information on what's going on will help everyone assist you.
 
Okay, bough a rebuilt tb, but didn't come with a tps so I had to manually do it with volt meter .9 at close 5k wide open. Or whatever vfaq showed. Iac came with (no idea of condition) the 3rd sensor, with the little black slide on clip I had to replace that with a spare I had. Other than tht nothing, mounted fmic and pipes rtc, put new tb on and now idles at like 1500 but then sometimes like 2k. And I'm getting cel codes 13,25,43. Boost leak tester I have a coupler to turbo and shoot air through the valve. I also only do 6-7 psi max but feels like a poInd or 2.
 
Okay, bough a rebuilt tb, but didn't come with a tps so I had to manually do it with volt meter .9 at close 5k wide open. Or whatever vfaq showed. Iac came with (no idea of condition) the 3rd sensor, with the little black slide on clip I had to replace that with a spare I had. Other than tht nothing, mounted fmic and pipes rtc, put new tb on and now idles at like 1500 but then sometimes like 2k. And I'm getting cel codes 13,25,43. Boost leak tester I have a coupler to turbo and shoot air through the valve. I also only do 6-7 psi max but feels like a poInd or 2.
Are you using a compressor? Are you spraying with soapy water while air is in? Try opening the throttle body by hand? Try that to eliminate throttle cable. Stock 1g throttle body? Rebuilt by someone reputable? I would definitely test higher. At least like 18 or 20. A 20 will show leaks. An air compressor regulated is the way to go. You should spray every coupling, vacuum line, bov, afpr, injector seals, brake booster line and all over the tb. I'm guessing you don't have an aftermarket boost gauge?
 
I have an autometer boost gauge yes it was rebuilt by reputable throttle does seem kind of hard to open but I'm curious of that can cause the cels? Or you think there's additional problems
 
Could be Hitting something or a poor rebuild job. What kind of throttle body? Using a compressor? Soapy water? I still think it's a boost leak and you're not testing right. A reputable tb rebuilder would bench test it before shipping. Make sure everything is legit. How are you only running 6-7 psi max?
 
Yeah the maf is plugged in though the filter I had on there was loose as it's old and broken, so I put a new kn on and reset the codes
 
If you've checked fuel pressure and components I mentioned check the ecu open it and look for leaking capacitors.
 
Also forgot to mention a bent kinked or burned valve could also cause backfires so do a compression test.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top