2.5 to 2.2, flashing CEL that goes on/off?

[alexandermf]

Ok so I swapped a 2.2 into my 99 2.5gt. Once the entire 2.2 was swapped in the iacv was acting up and throwing a malfunctioning iac cel. We decided to swap my throttle body from my 2.5 to the 2.2 since the iacv was good on that and everything ran well and no codes! Well after a day of running fine I fill up at a gas station and all of a sudden there is bad misfire and I have to give it a little gas to get it running, from there a cylinder 3 misfire cel is thrown, but its flashing first for like a minute, then goes solid. Stays there for 4-6 hours and then goes away. From there we install brand new plugs/wires and the cel goes away again. Then, 4 hours later it popped up flashing again and then solid, same cylinder 3 misfire.

Why is it flashing, why does it go on/off, and what else could be the potential problem? I'm running my 99 2.5 ecu... should I swap over to a 2.2 ecu? Was thinking of getting a better iacv from the subie yard down the street, the one from my 2.5 coulnd't be any better than the one from the 2.2.

the 2.5 had 115k, the 2.2 has 56k if that matters at all. Besides the flashing on/off cel code the swap was successful and everything else runs great!

[alexandermf]

any ideas/thoughts?

[alexandermf]

Ok so no joke, the cel only comes back on after I'm empty and go fill up at a gas station!!! 3 times in a row I'll try to start it up and itstarts spitting trying to start till I give it some gas. Then the idle gets really harsh and exhaust starts backfiring with that misfire sound... :/

[elislider]

my car would do this too sometimes, honestly no idea what it was. sometimes id go to fill it up and afterwards it would want to start. never figured out what it was. you might try running some seafoam through the lines? on my car it only happened a couple times randomly and then never again

[alexandermf]

I did run seafoam through the gas tank... that was right after we swapped the 2.2 in and I filled up. but wth is making it do it after every fillup, and ONLY after I fillup. It will run fine for more than half the tank, then once I fillup it will throw that flashing cel at me, then go away after 4 ish hours... so frustrating. I'm gonna buy a new coil pack tommorrow to see if that does the job. We replaced wires and plugs, but not the coil pack, even though everything on the engine was practically brand new already

[alexandermf]

new update. replaced: coil pack, plugs, wires cleaned:maf, egr, iacv checked:fuel lines, vaccuum lines
I also reset the ecu to get a fresh start on the the thrown cel and it immediately came on upon trying to startup after resetting everything. this makes my mechanic think its an electrical sensor somewhere... He said that it couldnt be the timing belt being off otherwise it would constantly run harsh/bad, in my case sometimes the car is running perfect half the time, and half crappy/misfiring/backfiring etc...

I need some more input por favor, I've been dumping money into the car even after I freakin swapped the 2.2 just to get this problem taken care of

[alexandermf]

Maf code was thrown and I tried to clean it but still no good. Gonna buy a new maf and see of that fixes the problem

[elislider]

suppose it could be the MAF, who knows. it sounds like something related to your fuel/evap system. check your stuff in the rear by the gas tank. any bent/kinked/clogged lines? if it has an charcoal canister in the rear (under the fender/bumper on passenger side), check it out to see if anything looks odd... also maybe you switched the fuel lines on the fuel filter?

[1996Battlewagon]

When I was running a 2.2 (on a 2.5 ECU), my CEL would do this as well. A flashing CEL SHOULD mean a misfire is happening, but I was never really sure. In the end, the 2.2 was running like such balls (ungodly rich, bad EGR and valve noise everywhere) that I swapped back to a 2.5.

If I were you, I'd source a 2.2 ECU just to be safe. I was chasing down codes every other week it seemed...

[jey]

If it's only happening when you get gas, it's probably an evap problem. I've seen the evap solenoid go bad - you can try just plain disconnecting it from the intake manifold to try to eliminate that as the possibility.

[alexandermf]

hoookay... so alot has gone down since I last posted. I threw a good used maf to replace mine and that took care of the flashing cel (so far). also we fixed the gas station problem! we had T'd a vaccuum line together with one of the fuel lines that sit right to the left of the alternator... so that was creating a double vaccuum with the fuel pump making that problem after I filled up lol. So we just took that off, and its unplugged as of now, looks like it was an old intake line to the 2.2 stock box? Ill post pics up later, sorry if Im not sounding right. The only problem I have now is that same cylinder 3 misfire and the maf one still.

We still decided to take it on a road trip with those 2 cel's throwing. ran from colorado springs to lake havasu, arizona completely fine! I mean the cel turned off for a few hours like normal and came back on eventually... its been staying on longer now too, around a day or so it stays on, then will turn off for a few hours till it comes back on. But as of the car running, it runs fine...? I have no idea what else to check for to get these damn codes off :(