high end misfire and lots of backfiring - 3000GT/Stealth International Message Center

1320VR4 · 09-29-2008, 07:56 AM

I noticed two days ago while it was raining that when I got on it in low gears at high rpm (like 2nd from 3 - 6k) I woud get alot of misfiring / studdering.

It was like I was bouncing it off redline but like at 5000rpm, eventualy it broke through and went to 7k or so

I'm also noticing my car is backfiring a bit now.

My battery is not in the best shape, its only two years old but for whatever reason its POS and half the time the engine cranks really slow because of it, I just havent gotten time to get to the store to get a new one.

Could it be the ECU? my friend had a similar problem and it was leaky capacitors.

Could it be a TPS adjustment? Its possible we fiddled with it or didn't adjust it correctly when putting on my polished / halfshafted throttle body.

lawdogg · 09-29-2008, 08:00 AM

Have you worked on your engine / changed or replaced anything lately?

1320VR4 · 09-29-2008, 08:01 AM

nope. only thing is i changed my intake filter from an ebey one to a not ebay one

lawdogg · 09-29-2008, 08:16 AM

Change it back. See if it goes away.

Friend had a similar problem with an air filter too.

1320VR4 · 09-29-2008, 08:23 AM

really? how could that affect it?

I went from an ebay filter to an INJEN filter

lawdogg · 09-29-2008, 08:36 AM

I have no idea man. I guess some filters are just bad. My friend Jordan has a 92 RT/TT and his bad filter gave him very similar symptoms. He swapped back to stock and it got better.

Of course it's just hypothesis at this point .. try it out! Maybe it fixes it, maybe it doesn't. But it'll eliminate that potential.

1320VR4 · 09-29-2008, 08:40 AM

i have to get my ebay filter back, my friend has it at the moment, he put it on his saturn but then he went and bought a real intake for it since he was noticing a definate gain in fuel mileage with it.

I'll try it

Keyan · 09-29-2008, 09:03 AM

a misfire could be the cause of a couple issues. Obviously the 3 things an engine needs to run are air, spark, and compression. When one of those falls out of spec and/or changes for the worse it can cause a misfire.

A spark issue could be caused by spark plugs, wires, coils, or ECU.
An air issue could be caused by a vacuum leak, a restricted air filter, or improperly metered air
A compression issue could be caused by a leaky valve, cracked piston, fried rings, etcetc.

those are the things you have to look at, which sadly, is just about everything lol.

1320VR4 · 09-29-2008, 09:07 AM

Quote:

Originally Posted by Keyan

a misfire could be the cause of a couple issues. Obviously the 3 things an engine needs to run are air, spark, and compression. When one of those falls out of spec and/or changes for the worse it can cause a misfire.

A spark issue could be caused by spark plugs, wires, coils, or ECU.
An air issue could be caused by a vacuum leak, a restricted air filter, or improperly metered air
A compression issue could be caused by a leaky valve, cracked piston, fried rings, etcetc.

those are the things you have to look at, which sadly, is just about everything lol.

I hope you realize that my car is sitting in your garage, lol.

chansigril · 09-29-2008, 09:10 AM

the important part of this statement is likely "when it was raining".

i would check your ignition coils and spark plug wires first. spray them down with a fine mist of water when the car is running. sparkling is no good. be careful spraying down the coils, you don't want them arcing.

the high humidity was likely affecting something electrical, most likely ignition related but other sensors or wiring is possible.

09-29-2008, 07:56 AM	#1 (permalink)
1320VR4 Redlight to Redline Join Date: Mar 2007 Location: north NJ Drives: 93 Dodge Stealth ES Trader Rating: (15)	high end misfire and lots of backfiring I noticed two days ago while it was raining that when I got on it in low gears at high rpm (like 2nd from 3 - 6k) I woud get alot of misfiring / studdering. It was like I was bouncing it off redline but like at 5000rpm, eventualy it broke through and went to 7k or so I'm also noticing my car is backfiring a bit now. My battery is not in the best shape, its only two years old but for whatever reason its POS and half the time the engine cranks really slow because of it, I just havent gotten time to get to the store to get a new one. Could it be the ECU? my friend had a similar problem and it was leaky capacitors. Could it be a TPS adjustment? Its possible we fiddled with it or didn't adjust it correctly when putting on my polished / halfshafted throttle body. __________________ *1993 Dodge Stealth ES - 15.2 @ 92.4mph - September 2008 ROTM* *1992 Mitsubishi 3000GT VR4 coming soon*

09-29-2008, 08:00 AM	#2 (permalink)
lawdogg Here for the tuna. Join Date: Jul 2003 Location: Williamsport, PA Drives: The Speed Limit Trader Rating: (65)	Re: high end misfire and lots of backfiring Have you worked on your engine / changed or replaced anything lately? __________________ 94 VR-4: 11.8 @ 116, 17psi, pump, 13Ts

09-29-2008, 08:01 AM	#3 (permalink)
1320VR4 Redlight to Redline Join Date: Mar 2007 Location: north NJ Drives: 93 Dodge Stealth ES Trader Rating: (15)	Re: high end misfire and lots of backfiring nope. only thing is i changed my intake filter from an ebey one to a not ebay one

09-29-2008, 08:16 AM	#4 (permalink)
lawdogg Here for the tuna. Join Date: Jul 2003 Location: Williamsport, PA Drives: The Speed Limit Trader Rating: (65)	Re: high end misfire and lots of backfiring Change it back. See if it goes away. Friend had a similar problem with an air filter too.

09-29-2008, 08:23 AM	#5 (permalink)
1320VR4 Redlight to Redline Join Date: Mar 2007 Location: north NJ Drives: 93 Dodge Stealth ES Trader Rating: (15)	Re: high end misfire and lots of backfiring really? how could that affect it? I went from an ebay filter to an INJEN filter

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09-29-2008, 08:36 AM	#6 (permalink)
lawdogg Here for the tuna. Join Date: Jul 2003 Location: Williamsport, PA Drives: The Speed Limit Trader Rating: (65)	Re: high end misfire and lots of backfiring I have no idea man. I guess some filters are just bad. My friend Jordan has a 92 RT/TT and his bad filter gave him very similar symptoms. He swapped back to stock and it got better. Of course it's just hypothesis at this point .. try it out! Maybe it fixes it, maybe it doesn't. But it'll eliminate that potential.

09-29-2008, 08:40 AM	#7 (permalink)
1320VR4 Redlight to Redline Join Date: Mar 2007 Location: north NJ Drives: 93 Dodge Stealth ES Trader Rating: (15)	Re: high end misfire and lots of backfiring i have to get my ebay filter back, my friend has it at the moment, he put it on his saturn but then he went and bought a real intake for it since he was noticing a definate gain in fuel mileage with it. I'll try it

09-29-2008, 09:03 AM	#8 (permalink)
Keyan New User - Please be kind Join Date: Oct 2007 Location: Sparta, NJ Drives: friend owns a vr4 Trader Rating: (0)	Re: high end misfire and lots of backfiring a misfire could be the cause of a couple issues. Obviously the 3 things an engine needs to run are air, spark, and compression. When one of those falls out of spec and/or changes for the worse it can cause a misfire. A spark issue could be caused by spark plugs, wires, coils, or ECU. An air issue could be caused by a vacuum leak, a restricted air filter, or improperly metered air A compression issue could be caused by a leaky valve, cracked piston, fried rings, etcetc. those are the things you have to look at, which sadly, is just about everything lol.

09-29-2008, 09:10 AM	#10 (permalink)
chansigril og Join Date: Apr 2001 Location: pennsylvania Drives: 93 stealth rt tt Trader Rating: (48)	Re: high end misfire and lots of backfiring the important part of this statement is likely "when it was raining". i would check your ignition coils and spark plug wires first. spray them down with a fine mist of water when the car is running. sparkling is no good. be careful spraying down the coils, you don't want them arcing. the high humidity was likely affecting something electrical, most likely ignition related but other sensors or wiring is possible. __________________ 93 stealth r/t tt: mildly modified, 12.4@109 94 stealth r/t na: used to drive, 13.9@100 93 dodge stealth r/t tt: personal parts car 03 ford focus se: beater