Hey all, this is my first time on this site and i was hoping someone might have an answer for my problem.
I have an 86' IROC with a 305 TPI and auto trans. Everything is stock and relatively clean. Car has about 88000 mi. Before i put it away i was driving and it started sputtering. Ever since every time ive started it up i have to feather the throttle to get it going and keep feathering to keep it going. Once a week ago I started it and it ran fine for about 10 minutes then started missing again to the point where i had to feather the throttle. Replaced the fuel filter, cap and rotor today and thought i had it. Ran fine for a half hour and let it get up to temp until i shut it off. Tried it again a couple hours ago and its back to running rough. I have no idea what this could be since it comes and goes at cold temps and hot temps. Any ideas???

 

any probs with the trans?? could be the torque converter. the tcc engages and disengages when it wants to and causes the car to stall. i've been through this no long ago. change out plugs and wires while youre at it. and check your map sensor. map sensor also causes these symptoms

 

The car is on stands and i put it in neutral while running and there didnt seem to be an issue with the torque converter. New wires and plugs too. Ill check that map sensor though.

 

ok, i unplugged the MAP sensor temporarily and the car seems to be running much better for the time being. Sine the problem is intermittent i am going to see if the problem returns even though i unplugged the sensor.

 

coule also be the correct me if my spelling is off the iac valve on the throttle body my wifes went out and it wouldnt run worth a crap try tapping it and turning it out it is on the underside of the throttle body if the car starts running fine u can get one at oreillys. i could also be completly wrong nissan is my speacilty not chevy but that worked for her

 

yeah ummm....you cant leave it like that for long. it'll guzzle gas like a stroker. eventually the engine will flood itsself because the map sensor regulates the air ratio to the fuel ratio so the engine dosent read that its getting the right amount of air and increases the rate of fuel to keep the car running where it now thinks is right. the longer you leave it that way the more it increases the fuel ratio and eventually you'll flood the engine trying to start it and you'll hear it sputter and backfire alot whenever you hit the throttle where it tries to fire but basically floods and ignites explosively. usually ends in damage to plugs and the intake manifold possibly sensors. i just fixed the same problem you had with my 89 camaro but got to it before much damage was done but i still have to rebuild the block because of it among other problems

 

So what are possible fixes to this problem? Is it likely that i have a vacuum leak or that the sensor is bad? I thought possibly the sensor itself just because the problem would come and go, any ideas?

 

So I did some research and found that I actually unplugged the MAF(Mass air flow) Sensor, and not the MAP sensor. Does this make any difference? Still running fine unplugged too.

 

try unplugging the temp sensor on the front of the intake manifold while running when it runs smooth.

if it reproduces your symptoms then thats it.

mine went bad and i had to feather the idle to start and idle

the comp thinks its warmed up since the temp sensor isnt working right or isnt gettting a connection so it adjusts the engine to normal opperating rather than cold startup

thats just what ive guessed
i cant explain any other way for the temp sensor to cause rough running like mine

 

OK, consistently the car runs very rough with the MAF sensor plugged in and normal when it is unplugged. Actually it idles better than it did before with the MAF unplugged. Now i am going to look into wether it is actually the MAF sensor itself that needs to be replaced or if it is something else that may be causing the MAF to send incorrect information i.e. vacuum. Ill post what I find out.