Hi Everyone,
My name is Tim and I must say this website and all of the members are so very resourceful. I have owned a 1988 Iroc-z since fune of 2003 with 89923 original miles. With much work and time the car was bone stock and I have replaced and tuned this engine since then and has run like a champ with excellent performance and ride. The car was repainted last summer with dupont and is beautiful. Well to my question I felt that it was time to remove the stock plenum with a ported unit I purchased seperatley and port match the gaskets and runners, I purchased also a pair of beautiful polished stock runners and TB unit. I spent much time with the porting and matching and finally a week ago spent the weekend placing the newer upper intake. Let me say that all the vaccum hoses were checked and rechecked for crack, leaks, and routing and checked out. I retourqed the runner bolts to spec. I reworked everything to initial settings with resetting the tps and iac valve before staring the car.
Well here's the problem when I start the car the fuel pump primes the 9th injector as heard upon iniation of start up then will fire strong and the engine starts right up. Then after a second or two the engine will not come to idol and will stall. After a few more attempts the same happens again and again. The maf sensor is a new bosch unit with new maf power and burnoff relays, the ignition mod and coil are all new with cap,rotor, plugs, and wires. The firing order was rechecked and is the same as always with the iac and tps are also been replaced recently. Well I unplugged the maf and the engine will fire right up and idle rough, but with the maf reconnected the engine will stall. Also the most important note is this with only at idle I can here a dramatic popping noise which I believe is coming from the runner or runners. I was wondering if maybe which I am thinking the plenum gaskets are on the wrong sides and are cut air off at idle. I wanted to put this out to you people to see what you thought thanks Tim

 

considering your observations: popping sound from the runners, and the fact that the car can idle w/o the MAF sensor, but not with it... I'd say that the source of your problem is a vaccum leak. This may sound pretty obvious, as "popping" is a dead giveaway. Since the job of the MAF is to tell the ECM exactly how much air is entering the plenum, any type of "dirty air" getting sucked in after the MAF is obviously not accounted for as far as the ECM is concerned. Basically, you've got more air going into the engine than the computer thinks, and therefore there is not enough fuel being delivered to match the amount of air. Or rather, you've got too much air being delivered to match the amount of fuel. Fix the leak and you'll fix the problem.

 

Thanx for the reply I was figuring that as a possibility and I am going to remove the plenum and recheck the upper gaskets because I believe they are on the wrong sides right is on left and left on the right. Thanx Tim