Backfire

[twizdt]

About 3 days ago i installed a new 3" downpipe due to mine having a hole in it. I removed the cat and cut off the rear o2 sensor while i was under there. From manifold to muffler it is 3" straight piped. I am now getting a very bad backfire during acceleration. Any ideas on what i could have done?

 

[96eclipzGsT]

Mine was backfiring bad once. It turned out the main wiring harness plug under the fuel rail wasn't pushed down all the way. The clip was broken off it.

 

[DaisyTuner]

im having similar problems, ignition coils may be going bad. is Check Engine light still on or not? since you say its getting worse to the point of you cant drive it it makes me think that you may be misfiring in a cylinder or two. is it hard to reach high rmps? ask a local shop to do a cylinder check to see if your spark plugs are sparkin the cylinders. if 2 cylinders are not firing, this is your prob most likely. seems identical to whats happening to me now.

 

[twizdt]

yea im just gonna cut my arm off to pay a mechanic to fix it. Unless i just go back down to the stcok downpipe size. Cheaper than all this other stuff that somehow happens when you put a 3" pipe on .

 

[twizdt]

Just bought an eprom ecu so ill see what happens when that gets here and installed.

 

[gofer]

yea im just gonna cut my arm off to pay a mechanic to fix it. Unless i just go back down to the stcok downpipe size. Cheaper than all this other stuff that somehow happens when you put a 3" pipe on .

im not so sure a "joe shmoe" mechanic can fix something like this or even look at it, you'd probably have to take it to the dealership.

Just bought an eprom ecu so ill see what happens when that gets here and installed.

EPROM's dont fix boost leaks...

 

[twizdt]

just took my plugs out. they look as if they have been in the car for a year. but have been for only a month. One of my wires ripped out so im buying wires too.

 

[rarson]

WHAT IS THE GAP ON THE PLUGS?

I guess you missed it when I said "the first thing you should have done was check the plug gap."

 

[twizdt]

When i bought the last ones they told me they were gapped right and even "checked" the gap on them. When i bought these ones i cheked the gap myself and the gap was .049. I was like WTF no wonder they lasted a month and i got 175 miles on a full tank of gas .

 

[rarson]

Gap should be no wider than .028". My car will blow the spark out under boost every time if they're gapped much wider than that. I like to run them a little tight.

My experience has shown me that no matter what anyone says, unless the spark plug is in my hand and I'm staring at the gap, chances are the gap isn't correct. I've had "pre-gapped" plugs that measured anywhere from .032" to .040" for a set of 4. I've had friends tell me they checked their gap only to check it myself and find that their gaps were incorrect. The only way you can really know what the gap is is to check it yourself. It takes me less than a minute to gap a set of plugs, so every time they're out, I do it.

I also recommend using NGK copper spark plugs. I have found that iridiums will sometimes blow out even with the stock gap. Your mileage may vary.

 

[twizdt]

One last thing. With this 99' ecu in i think the last owner has my spark plug wires hooked up backwards. Would that be right since its a 99' ecu in a 95'? Just need to know since i have a 95' eprom ecu on its way.

 

[gofer]

One last thing. With this 99' ecu in i think the last owner has my spark plug wires hooked up backwards. Would that be right since its a 99' ecu in a 95'? Just need to know since i have a 95' eprom ecu on its way.

boost leak test results?

 

[twizdt]

No boost leak. Something happened and it fried my plugs completely.

 

[rarson]

One last thing. With this 99' ecu in i think the last owner has my spark plug wires hooked up backwards. Would that be right since its a 99' ecu in a 95'? Just need to know since i have a 95' eprom ecu on its way.

Yeah.

 

[twizdt]

Okay thanks for the help everyone

 

[Swish]

a lot of people don't recirc their bov either, does it mean its the correct thing to do?

the ecu uses the front o2 sensor to control AFR's and the rear o2 sensor to check the efficiency of the catalytic converter. you will throw a CEL and since your running 3" turbo back your going to have a little hiccup back fire every once in awhile. now if your shooting flames 10ft and it sounds like a stick of dynamite blowing up then your running way too rich.

ok i know i may be a little late on this but after reading that reply i busted out laughing because i could only imagine the look on a persons face if it happened

 

[Silent_White]

Did you make sure your MAF is plugged in tight?

X2

this is the exact symptom of an unplugged maf... still do the boost leak test

 

[twizdt]

haha so now my passenger front balljoint broke and tore my drive shaft in half. Its all fixed but its always something.