samsu402

My intake manifold was in need of replacing because I cracked the thermostat housing on the old one when I replaced the thermostat.

So I picked up an intake manifold, put it in, and now my car is running like crap. Before getting a new manifold my car ran very good and did not mis fire. Now its chugging and the engine light went on as soon as I gave it WOT.

Anyone have any suggestions? I will be checking the light tomorrow.

J_Rod

the new manifold could have a hairline fracture in it or its an npi intake which i doubt?

Xemeth

Did you connect all the vacuum lines?

ChucksBullitt

^^^ what he said

samsu402

I hope so, the idle is fine. Not lumpy at all. Its when im driving where it kind of chugs and feels like its misfiring.

ezking

Hmm. Sounds like your leaking air somewhere. Check those rubber EGR tubes, they were a major pain for me. Dbl check all of your vacuum lines, and make sure you installed the Upper plenum correctly. If you installed a non PI manifold, the ports wont match up, so it would do that, but you would be able to tell the difference just by looking at the 2 manifolds side by side, the PI one is much much larger.

also, did your gaskets fit correctly? the plastic tabs went in and lined everything up?

BOSTANG

did you buy the intake with the built in gasket on the bottom of the intake?

pcs

slowly work your way backwards and check everything. check what fault code set off you check engine light. if all else fails and you think you got a cracked manifold their are many ways to check it. the way ive check a plastic one before was by covering all the ports with some really good duct tape then filled it with air, only a few #'s, from a compressor with a small gauge on it to see if it would hold pressure. then i sprayed it with soapy water to see if you find a leak or you could try to submerge it in a bucket of water too. im sure that others here can give you different ways to check it. good luck.

Davojan59

i had the same problem before and it ended up being a bit of coolant leaking into the plug holes, so check that first. Just pull some of the COP, especially on the Tstat side and check in the hole.

WhiteFoxGT

Did you remove all the plugs and crank the motor over when you replaced the intake? If not, theres good possibility that you got coolant into one of the intake ports and hopefully all you did was foul a plug. People skip this step too much and it can lead to bent valves/rods....