Shortly after replacing my throttle body with a bored 60mm one my jeep started bucking like a horse and dropping out of third into second at 40 and having idle issues and setting off miss-fire codes. I was told by the xjfiles dude that It really sounded like my Tps. I bought one and I have had no transmission based issues but I still have to rev my engine to like 1500rpm's at stop lights to get my idle to rest at like 750 from around the 1000 or so it sits at. Every time I clear the pcm I don't get the multiple cylinder missfire code on cylinders 2 and 5 unless I Gunn-it! I feel and hear no loss of power etc but It keeps setting off Multiple Cylinder Missfires on Cylinders 2 and 5. I followed the Pcm data clearing instructions that were included with my bored throttle body multiple times. Any ideas? Before getting the throttle body replacement the only code I ever acquired was a miss-fire because of heat-soak which is normal when it's hot as hell outside and my car sits and boils the gas in the injectors.

 

You got an air leak somewhere??

 

The very back intake bolt has a habit of backing out on the later models causing a leak in the gasket. This is usually accompanied by a whistle when letting of the throttle. Sometimes this can be fixed by simply snugging the bolt back to proper torque specs. And..... in my case it required replacing the gasket.

Mine got so bad that I could disconnect the battery to clear the codes and it ran fine during 50 mile drive cycle. As soon as it hit 50 miles and the computer started recording the sensor data it would literally fall on its face like it was only firing on 3 cylinders. Finally found the time to change the intake/exhaust manifold gasket and I have had no more issues.

 

Did you use a new throttle body gasket?

 

No reused the one that was there

 

That could be the problem. Spray some throttle body cleaner around the base of the TB with the engine running and see if the idle speed changes when you do.

 

Ill try that and respond

 

Air leak...

 

Probably at the TB gasket.

 

Odd are. Its the logical conclusion, most likely.

 

The saturation of throttle body cleaner had no avail..as far as the idle sitting at 1000 I actually can see the hair gap it has at the idle adjustment screw and I can push it that hair and it returns to normal. When engine is off it returns fully to the set screw everytime.