HELP! Barely starts, runs horribly...seemingly no reason

[mentzZ]

So ive had this problem and have been trying to fix if for the past 3 weeks. I'm totally out of ideas and right back at square one (91 240, redtop sr, cone air filter, FMIC, hks SSQV, 3 inch from turbo back, profec e-01 boost controller).

It all started coming home from practice one day, i got in my car and went to start it and it turned over normaly then right before it came to life it kinda stuttered a bit. I didn't think much of it and figured my hand twitched or somthing stupid like that but then when i went to start it the next day in just turned over, stuttered then died and wouldnt start again, it just kept turning over.

If i let it turn over for long enough if will BARELY start, its Idles horribly, shakes ALOT, and pops way more than usual when i let off the throttle. However when i give it some gas and the engine is under load it runs quite well, not normal but alot better than i thought it would have going from the way it started and idled.

I started out by checking my plugs and spark and all 4 were fine. So next i made sure i had pressure in the fuel rail so i knew my fuel pump was fine. I figured it was a problem with the fuel pressure regulator so i replaced it with an aem adjustable one and still nothing. I made sure the grounds for the injectors and the main grounds were good. I took out my ECU and it had water corrosion on the case and in the harness so i took the cover off and saw what i thought was a short. I replaced the ecu only to realize that although my ECU was shorted it was already repaired previously and i was too stupid to notice. So i checked for codes (with both ECU's) and got nothing but 55 (i will note that i unplugged my MAFS and still got a 55, should it not throw a code when i do this?).

The side of the harness that had the corrosion on it was the one with the ECCS power and ground pins on it so I tested both circuts for resistance and got the same reading from both. i checked the signal from the MAFS and CAS with a volt meter and got faily steady voltage from both. So i figured it was a problem with the injectors, I checked them with an ohm meter and got almost no resistance from all of them. I started it up and pulled the plugs of all of them one by one and each time the engine started dying accordingly.

I have had my SR in for almost a year now and this is the first problem i've had with it. It was just so sudden and out of the blue...I have no clue what might have caused it (even though there was water damage on the old ECU the new one perfomed identically). The water came down the harness because i cut the rubber sleeve and the middle was all wet but the outside looked fine. there are no bare wires in the harness so although it is super ghetto, it shouldnt cause a problem like this should it? Any suggestions would be greatly appriciated!

[pEcHeP]

had same symptoms with my KA, turned out to be a vaccume leakage coming from the intake manifold. I opened the sucker up to replace the gaskets and Come to find out that the OEM ones were still on there 200k miles. The way to check for a vaccume leakage is to try and get it to idle/rev somewhere consistant then spray carb cleaner around where you suspect a leakage using the supplied straw. If the idle (consistant rpm, the lower the better) changes when you spray around an area consistantly then there is a vaccume leakage. the idle will change if carburetor cleaner is inhaled by the vaccume leak.

[Z U L8R]

you definately have a vacuum leak. you can spray carb clean on potential problem areas, don't use brake clean it's not o2 sensor safe. don't know if you have access to it, but the best thing in the world for finding vacuum/boost leaks is a smoke machine. basically you hook it up to a vacuum line and it pumps smoke through the intake and intercooler piping through the turbo and comes out the air filter, any smoke not coming out of the air filter is coming from your leak and you'll see the smoke coming from the problem it's pretty pimp. anywho good luck with it, keep us posted.

spray your intercooler couplers first with the carb clean and just work your way to the motor

[mentzZ]

Thanks for the advise guys, I'm gonna go get some carb cleaner today after work and give it a try. I will be psyced if it is actually a vacum leak, they are usually fairly easy to fix no?

[Z U L8R]

pretty much, i mean it could be a crack in an intercooler couple, it could be a clamp on one of the couplers, it could be a cracking vacuum hose, or an intake gasket/throttle body gasket, i've even seen the grommets the fuel injectors sit in on the intake manifold not seal properly, all the above can be "vacuum leaks"

you're looking for the idle to change when you spray carb cleaner on it, it should smooth out when you spray it on there, if you spray and no change move to the next place

[mentzZ]

Excellent, thanks again Z U L8R, i can't wait to try it.