stumbling idle and backfiring, PLEASE HELP!!!!!
 

Ok, so the fwd legacy transmission is in the car and functioning properly without the legacy TCU or the fwd fuse in. With that out of the way I now need to focus on the more severe problem I have on my hands. The car has had an ongoing problem that I have yet to figure out. The car will randomly develop a stumbling idle and misfire quite badly. I have changed the coil packs and plugs recently and this problem still persists. When i was test driving the car it started stumbling at idle, misfiring under acceleration, and backfiring. I really need this problem resolved so any useful input would be greatly appreciated.

Joe

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

I am no expert so i may get bashed for this . I had a similar problem and it was a bad injector. suspected bad gas but it was enough to clog the injector. Subi dealer replaced one injector and it was fine after that . U have tried electrical assuming you have a good coil pack so my GUESS is gas .

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

This cured same symptoms for me:

http://www.subaru-svx.net/forum/show...t=maf+resolder

Tapani

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

I started the car this morning and put my fingers over the MAF and the car didn't even try to adjust the idle, it just shut off.
:confused:

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

Ok, so I assume I need a new MAF????
:confused:

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

if you cut off all air then it would kill it. I had a problem for a while where my intake clamp came loose and the tube slipped off soon as it did the engine would die. it was getting unmetered air.

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

I just bought another MAF, the problem still exists. What could cause the car to do this!!!???
Throttle positioning sensor???
Cam positioning sensor???
Crank positioning sensor???
Coil packs?
fouled plugs?
Please, someone help me with this!!!!
:(:(:(

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

mine had a very bad idle, put new O2 sensors on, good as new. tried that? i know your misfire/backfire is deeper than that though..

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

Just a thought, is the whole breather system ok? If the engine back fires hard the rubber hoses (from the valve covers) might pop off - again causing unmetered air to enter and mess up the MAF signal. The are very "loose" fit, especially when hot (soft). In addition to the "tees" there are straight connectors under the TB, kinda hard to see if you don't know where they are.

Happened to me once when I had the MAF issue (cured by the resoldering). I secured the hoses with zip ties (used a tool to tighten).

Tapani

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

Could be the wiring to the MAF? A flaky connection might cause MAF symptoms.

Cam or crank sensors would throw a code.

Look around maybe you've got a big intake leak.

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

Looking at your other post it appears that you have modified the PCV system and rerouted the breathers.... Are you sure that no unmetered air is entering the intake flow thru these? Just a thought.

Tapani

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

Well the car has a perpetual "power" flash, so I wouldn't know if It's throwing codes. I have left the vacuum lines off by accident before and I never had this happen to me. At this point I'm leaning towards any sensors that are associated with ignition, timing, and air/fuel.
Thoughts please.

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

Maybe the engine is just rejecting the FWD trans. Like a mis-matched organ :lol:

I dunno man, I wish I could be more help. If I were you, I'd be looking at vacuum lines and wires. Fuel pump perhaps?

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

The pump is fine, WHAT I NEED IS SOMEONE WITH A FIRM UNDERSTANDING OF THIS CARS IGNITION SYSTEM TO PAY ATTENTION TO THIS THREAD!!!!!!!!!!!!!!
What regulates the ignition timing in this car?

Re: stumbling idle and backfiring, PLEASE HELP!!!!!
 

The ECU, using readings from the cam and crank sensors. Signal goes from the ECU to the ignitor (sp?) module, then to the COPs, then to the plugs.