S13 backfiring, runs like sh!t

[Wildebeest]

I have a 93 240sx s13 5 speed. Have a KA24de that seems to want to be naughty lately. I had a problem before where it was runnin bad so i changed the #1 injector and it ran fine. Got a cat less than a month ago and installed it. Got home the other night ( a few days after I changed the injector) and it was running like poop again. we had checked the plugs, wires and compression test and everything checked out BEFORE I got the injector. Now i get home and look under the car and the back of the < month old cat is glowing red!! I take it back and was told that it came apart inside, got another and just put it on... STILL runs like poop. injectors- ok, plugs/wires-ok, cylinders- ok. When i drive down the road it backfires really bad. My GF stood outside and i drove pasts her and she said when it was backfiring that it was shooting flames . when im going down a hill and stay off the gas in about 2nd and just let it cruise, i can barely put my foot on the gas and it sounds like a gunshot. When i dont have my foot on the gas it has a rhythmic popping sound.. My GF's brother says that i might have a valve that is sticking? I have tried nearly everything.

OH, and checked the MAF, and its fine too.. Sucks ass, this is the first time in over a year that it has really messed up.

[JITB]

maybe it jumped timing? does it have any power?

[Barefoot]

timing

[Wildebeest]

ya it feels like there is a loss in power, especially when i first start going, it sputters pretty bad, almost like a turd is trying to come outta the tail pipe.

[Me86Rob]

have you tried to replace the MAF like i told you to in your other thread?

[Echonova]

Exhaust system backfires occur in engines that have an emission system malfunction, like an air injection system diverter valve problem, an exhaust leak, or when the catalytic converter has been removed. In some high-performance vehicles, when a driver shifts up and lets off the accelerator, the engine has a moment of running rich. This causes an incomplete burn which causes the fumes to explode in the exhaust system along with an audible clacking sound. However this condition is a result of working smog equipment, and is unlikely to cause any damage.

A fuel injected engine may backfire if an intake leak is present (causing the engine to run lean), or a fuel injection component such as an air-flow sensor is defective.

Common causes of backfires are:

* Poor or unregulated engine timing is often a cause of intake backfires, but can also be responsible for exhaust backfires
* Improper wiring in the ignition can also lead to timing issues and backfires
* Low fuel pressure, clogged fuel filters, and weak fuel pumps could cause a severe lean air-to-fuel ratio during fuel injection
* Missing or damaged catalytic converter can result in backfires out the tailpipe

[Me86Rob]

Exhaust system backfires occur in engines that have an emission system malfunction, like an air injection system diverter valve problem, an exhaust leak, or when the catalytic converter has been removed. In some high-performance vehicles, when a driver shifts up and lets off the accelerator, the engine has a moment of running rich. This causes an incomplete burn which causes the fumes to explode in the exhaust system along with an audible clacking sound. However this condition is a result of working smog equipment, and is unlikely to cause any damage.

A fuel injected engine may backfire if an intake leak is present (causing the engine to run lean), or a fuel injection component such as an air-flow sensor is defective.

Common causes of backfires are:

* Poor or unregulated engine timing is often a cause of intake backfires, but can also be responsible for exhaust backfires
* Improper wiring in the ignition can also lead to timing issues and backfires
* Low fuel pressure, clogged fuel filters, and weak fuel pumps could cause a severe lean air-to-fuel ratio during fuel injection
* Missing or damaged catalytic converter can result in backfires out the tailpipe

its this

[Wildebeest]

its this

ok rob, can you tell me how to check and see if the MAF is bad? and I got another question. are you the same rob that works down in powder springs with a dude named turbodave?

[Me86Rob]

ok rob, can you tell me how to check and see if the MAF is bad? and I got another question. are you the same rob that works down in powder springs with a dude named turbodave?

no im not that Rob.
Its hard to diagnose a MAF, but first things first, check the inside and make sure that the little fillament is still intact. If it is, you are more than likely going to just have to replace it and see if it is. If its not intact, then you know thats your problem. So you may have to guess and check

[Wildebeest]

no im not that Rob.
Its hard to diagnose a MAF, but first things first, check the inside and make sure that the little fillament is still intact. If it is, you are more than likely going to just have to replace it and see if it is. If its not intact, then you know thats your problem. So you may have to guess and check

aight man, ill give that a try. Thank you

[AnTi-PooN]

my ls-vtec backfired almost everytime i shifted and almost all the time wen gearing down coming to a stop. ran fine though and definately no loss of power.

[Wildebeest]

my ls-vtec backfired almost everytime i shifted and almost all the time wen gearing down coming to a stop. ran fine though and definately no loss of power.

I can live if it was just backfiring, I love it lol. but the problem is that my cat is glowing red and shooting flames from my pipe. lol . I was told that i might have an injector runnin wide ass open, causing it to dump too much fuel into the motor, it burns it and the excess fuel is causing the cat to get hot? sound familiar to anyone?

[HMGDRFTER]

no im not that Rob.
Its hard to diagnose a MAF, but first things first, check the inside and make sure that the little fillament is still intact. If it is, you are more than likely going to just have to replace it and see if it is. If its not intact, then you know thats your problem. So you may have to guess and check

it's not hard to diagnose a MAF just read what i told you on your other thread.

[StaYdUbiN87]

yooo my cars having the same problems ? haave yu found out what it is yet...let me know if yu did i needa get my car fixed asap..nd thanx

[Barefoot]

I can live if it was just backfiring, I love it lol. but the problem is that my cat is glowing red and shooting flames from my pipe. lol . I was told that i might have an injector runnin wide ass open, causing it to dump too much fuel into the motor, it burns it and the excess fuel is causing the cat to get hot? sound familiar to anyone?

thats becasue of the sudden changing in a/f ratio.

[DirtyMechanic]

no im not that Rob.
Its hard to diagnose a MAF, but first things first, check the inside and make sure that the little fillament is still intact. If it is, you are more than likely going to just have to replace it and see if it is. If its not intact, then you know thats your problem. So you may have to guess and check

MAFs are not hard to di-ag if you know how to di-ag them. why are you in this section?

I can live if it was just backfiring, I love it lol. but the problem is that my cat is glowing red and shooting flames from my pipe. lol . I was told that i might have an injector runnin wide ass open, causing it to dump too much fuel into the motor, it burns it and the excess fuel is causing the cat to get hot? sound familiar to anyone?

if your cat is glowing red that means its getting way way to much fuel. why did you just change out 1 injector and why. sounds to me like you have a injector wide open all the time. which is either a stuck(highly doubt it) or a short causing it to stay wide open.

does your exhaust smell like raw fuel and your cat still glowing? they you are running stupid rich.

you might want to have someone that knows what they are looking for help you out and look at the car.

[whatever210]

needs sr

[Wildebeest]

Problem has been fixed! The plugs had a tremendous amount of carbon build-up on them, It was because i never get on my car lol. It was also idling pretty rough afterwards. Bought a new MAF, and now it runs absolutely perfect now. Thanks for the help guys