03 GTX S/C Mild Surge

[IDoSeaDoo]

Hey guys, ever since I got this engine installed in my Challenger, I noticed it has a very mild surge. It fluctuates within a 100rpm range. It seems to do this at all RPMs. It's not really a big issue, just mildly annoying. It's especially noticeable when I'm going just a bit faster than idle. The whole boat will pull ahead a little each time.

Anyone know what causes this? My buddy suggests the oil pressure sensor. Everything on this engine is stock.

 

[IDoSeaDoo]

This problem has gotten worse, and new plugs didn't help. Any idea what it could be? Do the idle air controller motors go bad on these motors?

 

[CovertRam]

I would suggest looking at the plug wires.

 

[IDoSeaDoo]

It's a 4tec... coil-on plugs

 

[Coastiejoe]

I'd check for a vacuum leak. Most use either and spray around the intake. If it raises or lowers in RPMs you have found the issue. Pretty much any aerosol can work. WD-40, CRC ect ect.

 

[IDoSeaDoo]

Good idea! I will have to plumb the intake away from the manifold. One time I did that and the fumes themselves actually changed RPM.

 

[Coastiejoe]

Assuming all the stuff that ran the ski before was good and was re-used. Then it pretty much has to be a bolt on issue. So anything you removed and reinstalled is where you should start.

 

[IDoSeaDoo]

I took the entire motor apart and rebuilt parts, like the timing chain and valves, flywheel bolts, etc.

 

[Coastiejoe]

I'd still take a good look at the potential of a vacuum issue.

 

[IDoSeaDoo]

I wonder if it's just a matter of needing to reset my tps...