Serious Idle issues after engine install

[brockkrak]

Hey all i need some help real bad. I have a 1998 Monte with 3.1. I pulled engine out had it 100% rebuilt by a machine shop i have used for years.After i re installed it i have had some idle issues. The first time i started it it was hard to start and stalled until i gave it a little throttle. I shut it down and started again to work on checking fluids and getting coolant in engine. Shut it off. Came back started it up but now it idles at 2-2500 RPM. I have checked all wires, grounds, installed new MAF sensor, checked IAC, and TPS,vacuum leaks,plugs,wires,coils. It has three codes a MAF sensor code, random misfire code, and a TPS code and it wont let me clear the trouble codes. The engine is responsive as it should be. Engine sounds magnificent and starts fine now but the idle is outta control. Do i need a idle relearn? any ideas? please help been days troubleshooting.

[Z26-T]

Did you replace the MAF before or after having the idle issues? I'd suggest double checking the wires for the MAF and for vac leaks.

[pocket-rocket]

It sound like a big vacuum leak to me. You can use a propane torch turned on but unlit to find the leak. Just run it along vacuum lines and intake mating surfaces and when the idle changes you just found the area of the leak.

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[brockkrak]

i installed it after the idle issue. Ok i will check for vac leaks once again. Also whats a good vac reading ima put a gauge on it to see if its off the charts or not. Thanks guys apperciate your time

[brockkrak]

PROBLEM SOLVED! my dumb ass didnt tighten the bottom two throttle body bolts. Now i just have a misfire code p0300 i bought new plugs and wires gonna check that there on good.

[Z26-T]

Yep, that would cause a vac leak :P. Is the misfire code current? That code would have set due to your vac leak.

[pocket-rocket]

Yep, that would cause a vac leak :P. Is the misfire code current? That code would have set due to your vac leak.

Agreed. I've tripped that code because I forgot to hook up the vacuum booster a couple times.

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[brockkrak]

another prob now

ok now i have another problem i have a p0300 random misfire code and it runs like hell. I installed new plugs and wires with the engine and double checked them for broken connectors or a cracked plug. it starts but barley. I guess i next thing is to check spark at all cylinders? maybe a coil pack went bad convientley. any other things to check tonight when i get home. Thanks guys you all are great.

[pocket-rocket]

Yes, check for spark. If you don't have it on a pair of cylinders that share a coil, swap coil locations and see if the loss of spark follows the coil. If it does, the coil is shot. If it doesn't, the ICM could be bad on that channel. If it's only 1 cylinder, check over your wires and plugs really good. One way is a spray bottle full of water at night to check for arcing. Also make sure your wires are in the right order.

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[brockkrak]

alright gang. I checked for spark spark is good on all coils. Holds a constant 12-15lbs vac on idle. checked firing order checked to make sure everything was clicked on tight as it should be. im lost here

[pocket-rocket]

I would wait till dark and watch for lightning strikes under the hood. If you see any, that's a bad spot in the plug wire insulation. Electricity looks for the shortest and easiest path to ground. Jumping through a bad spot in the wire is easier than jumping a gap in the plug while in a highly pressurized environment (thanks to the compression stroke). If that doesn't show anything I would move to a compression test.

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[Z26-T]

didn't accidentally cross a plug wire when you installed the plugs? How're the gaps on the plugs? What type of plugs are you running? If they're not NGK or AcDelcos... take them out.