Intake manifold swapped now rough idle

options2rx7

New Member
May 7, 2011
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Tampa
Hey guys all all new to this Forum so to every one HELLO!

I just finished swapping my non pi intake to a new non pi intake and now I have this super rough idle. I replaced the spark plugs while everything was out and I replaced the wires, coil packs, fuel pump, fuel filter all within 4000k miles.

I have a feeling I might have messed up when cleaning my stock factory injectors. I cleaned them externally with simple green and I wonder if that might be the reason. i haven no idea what else it could be.

Any ideas?

Thanks
 
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Does it run OK above idle? How long have you been driving it since the swap? The PCM may need to relearn the idle trims:

[wmburns]Once it's warmed up to operating temp, let it idle for one minute with A/C off and the one minute with A/C on [/wmburns]

Simple Green shouldn't have hurt the injectors, assuming the electrical connectors are not still wet. I think I sprayed mine down with SG to get the gunk off before I soaked them in injector cleaner.

Most likely cause would probably be a vacuum leak - NPI means at least 12-15 year old vacuum hoses and lines and you touched them all if you're swapping an intake manifold - check them all thoroughly for cracking or rotting. Those thin little hard lines get brittle and can break or crack too.

Did you replace the gaskets? If not, were they still in good shape - not crushed or deformed, cracked/torn, still pliable? Did you torque the manifold and throttle body plenum elbow down in the correct sequence and to the correct in/lbs values? That's another good source of vacuum leaks after a manifold swap.

An ignition issue could cause a rough idle too - any coolant, cleaner or water get in the spark plug holes? Are all the plug wires seated solidly - double check, they can fool you in those spark plug holes.
 
^^

What he said, Bear in mind the inlet manifolds from PI sn95s are plastic so don`t go overboard with the tightening of the Plenum bolts. Is there a good seal between the Plenum and manifold? Did you use a sealant?
 
Ya everything was torqued to spec. All vacuum lines touched were replaced during the swap. The car has an ok idle but when you give it gas its stumbling and really hesitating when its being driven.

Before I had this issue I did have a check engine light for after cat o2 sensor. Maybe this might be a clogged cat situation?

Im going to be getting the in line spark plug tester tonight to test spark. With the coolant leak I know for a fact the spark plug wires did get wet. Before I put everything back together I did make sure everything was dry.