engine stalls at idle.

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ok here is my situation.

i just swapped the engine on my 93 saturn sl2 (the old one blew rings on number 3 cyl). I got it in ok and everything hooked up no problem. i go to start it, and it starts, as long as the throttle is at least partially open. it runs real well but as soon as i let off the pedal, the car stalls and dies. to me this screams suffocation, the engine isnt getting enough air. i checked the ignition system, and i am getting good even spark at all four cylinders, i know there is fuel getting to the injectorsbecause when i first hooked it up, and tried to start it i forgot an o-ring on the fuel line, and gas was squirting everywhere (oops). but i got that fixed and cleaned up. so methinks that it is an intake system issue, im leaning towards the idle pipe on the throttle body being clogged, but i cant say for sure. otherwise it may be a vacuum issue, but ive got everything routed right (i think ;)). im not really too sure. any suggestions would be appreciated


posted by  Buehler11

Definitly check routing of all vacuum lines as well as make sure all your intake sensors are connected like TPS and IAC/AIS. Does it run normally with a little throttle pressure or is it missing and running rough? What about codes???? Are you setting any trouble codes? Check that out because that will pin the problem down to a certain area if you are setting a code. Something is probably just not hooked up right and you are either not getting enough air to it, OR you are sucking air. Did you just pull the intake off the old engine and install on the new block? Check all the routings really well. Another thing that might be happening is that the idle air control system may be dead as the battery was probably disconnected for a while when you were working on it, correct? It might need to reset itself. After doing an engine job, sometimes these things happen and it is probably fairly simple. Let me know what else is going on if you have more details. :thumbs:

posted by  cmeseadoin

Well the manifold and throttle body came with the engine, which i bought used from a yard. a couple of the sensors i replaced with those from the original one, one didnt fit and one was busted. and unfortunately im not getting any trouble codes, (first thing i checked) so i think all of the sensors are good and sending good data. i did have to take the manifold off to get the new engine in, but i put it back on with a new gasket and everything. the problem with checking the vacuum lines is that i dont have a really good diagram. the one on the car is worthless, and the one in the book isnt much better. do you know where i could get one that would be better, that would maybe show photographs of each of the sensors. im coming off of 3 yrs of working almost solely on a hyundai, so i can name every sensor on that car, but only about half of em on this one. also i tried to clean out the idle bypass pipe in the throttle body, but my brush would only go in about halfway, i dont know if its clogged, or if it just has a turn that is too sharp for my flexible brush. im planning on swapping it out with the one from the old engine, (the busted connector was on the throttle body) and seeing if that helps

thanx for the advice and any to come


posted by  Buehler11

Timing Belt/ Timing Chain to make sure it is set properly?? My Camaro right now is doing the same thing and it seems to be related to the Timing Chain advancing (thanks in part to Electronics controlling it..lol)...Just a thought...ItsMe aka Stephanie

posted by  ItsMe


I hate to rain on your parade but the ignition module and or ECM has nothing to do with the timing chain.

You are right in the fact the camshaft and crank shaft must be synchronized properly if the engine is to run

posted by  tbaxleyjr

yeah definitely not a timing issue. as i sed i was going to do, i swapped throttle bodies with the one that i knew was good, and voila it works. i pulled out the iac valve and lo and be hold, the pintle was jammed all of the way out, and the spring was shot. spot on guess. props 2 u

posted by  Buehler11

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