1997 Jeep Wrangler with a 5.3l vortec (lm7 gen3) Manual trans

Recently did a different cam swap in the engine, did a remote mail order tune from black bear performance. Needless to say the jeep runs very strong. My only issue , and its driving me nuts is erratic idle issues. I installed the cam for more lower end torque along with an aggressive sound so I know I was going to end up with a choppy idle. The jeep will idle around 850rpms but on some occasion it would drop all the way down to literally 100rpm and I would hurry up and try to rev it so it doesn't stall out on me. After that happens I usually receive a check engine light with 2 codes. P0106 (Manifold Air Pressure (MAP) Barometric Pressure Sensor Electric Circuit Output Range and Performance Problem) and p0500 (general OBD-II code that indicates a malfunction has been detected in the vehicle speed sensor circuit)

I went ahead and replaced both the MAP sensor and PCV valve and it didn't fix anything. I only get that CEL when the idle goes way down like that.

The guys from black bear performance think I had a vacuum leak since the MAP would read anywhere from 2-9psi on average. Anyone experience this issue?

I can almost certainly stall the engine by pushing the clutch in at the last second when approaching a stop.

The specs for the cam are :

Comp Cams 54-601-11
Dur at .050 227 IN 241 EX
LSA 109
Installed at 103 which is what the ICL was on the cam card

 

Sounds like tune issues. A mail order tune is only a starting point, especially with swapping to more radical cams. Get it tuned.

 

When I did the tube, they sent me the efi live cable. I had to drive around through all types of daily driving conditions and it recorded the engines data log. From there they were able to design a tune to fit specific for my jeep. So i though it's the closest thing besides an actual dyno tune

 

Oh OK, you did more than "just" the standard mail order tune. It just looks like there is more to be done.

 

Thats a pretty big cam for a 5.3.

Edit -- meaning just doing the typical base airflow and spark adjustments may not be enough

 

I'm not sure to what extent they made the tune. I was shipped a completely different pcm as well. I still have the efi live wire that I can still grab engine data from. I also messaged comp cams to see what they recommend the idle be at and manifold psi should be at.

Other than this issue the jeep runs awesome. Very strong response and able able to chirp 3rd gear with 35" tires

 

You might need idle speed around 950 to stabilize it. That and increased base idle air. If you have a mechanical throttle you might need to open the set screw also

 

Not sure that would be my choice of cam in an LM7 in a heavy vehicle. With that being said. Did you check for vacuum leaks?? If you have access to a tuner locally with a dyno I would take it there and have them check the tune out.

 

What's a proper way to check for a vacuum leak?

 

Smoke test is the easiest.