So the car was losing power slowly and we decided to do a tune up. We seafoamed the car, New spark plugs, new plug wires, New o2 Sensors, Oil Change, Cleaned the MAF and the TB out. The car started fine and idled fine. About 5 minutes later it developed a backfire. The car runs pretty crappy, it shutters under load and obviously its backfiring. Its backfiring out of the exhaust and my buddy said he saw flames (no cats but some exhaust leak in their place).

What could cause backfiring. We ruled out the o2s, plugs, wires and now its going to be expensive as we get into the bigger stuff.

Any help would be awesome

 

EGR

 

Ill check it.. what should I look for? The car is at the shop and they said they will start monday which means monday is D-day and my goal is to hopefully disprove any theory of something expensive and find the problem before then.

I plan to:
Turn the car on at night to see if theres any arching anywhere
check, recheck, check again, and one last check that all the plug wires are correct.
hook up a fuel pressure guage to see what Im getting
check the plug wires again
maybe replace the fuel filter.. i did run seafoam through the gas tank before this all happened
and thats all I can think of.. how do I check the EGR?

 

Not saying it will solve your problem, but the fuel filter certainly won't hurt after the Seafoam.

 

yea.. as a matter of fact the tank mixed with seafoam is still in there.. ha I never got a chance to run it empty

 

To check the EGR, find the voltage at the EGR solenoid. I think it's 3 wires on the connector. Signal wire (PCM), Ground, and 5 volt reference (power). See if the signal wire is reading 0 volts at idle. Should be 0 volts at WOT as well.

This only reads if the right info is getting to the EGR. The component could be faulty. I'm not even sure if it's the EGR, but that's how to test it regardless.

 

Alright.. If I can get my neighbor with a scanner to come along and hook it up to the car what should I look for? Or what should I write down so I can put it hear and you guys can tell me whats up?

 

TTT any other ideas?

 

Sounds like an ICM or more likely your opti is going out.

 

am I going crazy or do I have a misprinted Haynes Manual.. On the Optispark: cylinder four is on top and cylinder two is on the bottom. I found these were mixed up in the very beginning. Today I went to the shop the cars at today to take a look at a few things.. besides an ugly *** spark plug wire job that needs some real cleaning up and two boots not being snapped on the spark plugs.... I had my dad pull on wires and me under the car pulling back to find out if they were all correct. Sure enough he pulled on a wire and i found it went to the top.. I said that should plug into the second cylinder.. he says "no its plugged in the first" So i grab the wire connected to the bottom terminal and tug a little until he finds it.. and i say wheres that one? and he says "in the second cylinder back"

so do I have a misprinted haynes manual or did the mechanic that I took the car to and said that all I know so far is that 2 and 4 were mixed up.. mixed them up again?!? (I had to take them out and damaged them so I never got the chance to just swap them back and see what happened before I took it to the shop)

WTF?

 

Here is the opti diagram from the manual (courtesy of ShoeBox)

 

yep.. exactly what mine is.. so the mechanic mixed up 2 and 4.. cant figure out why its still backfiring.. and wants to take apart my opti now..