Hello all,

Struggled with this problem for months and found your forum today,

I can be driving with everything running well and then suddenly the jeep will hesitate or misfire with no change in throttle position, sometimes on the flat, sometimes uphill usually over 40mph. MPG will then drop from indicated av of 23-25 to 12-15 very quickly. This can happen soon after start up but usually after 15 miles or so and will run rough until end of journey. If I leave car overnight it might be better in the morning or it might not - no real pattern. I have OBDII scanner and get no stored or pending codes. So far have replaced IAC valve, MAP, CPS, TPS, CTS, 2x O2, Leads, Plugs, Rotor and Cap. Have also checked vacuum hoses and cleaned throttle body. Have also run car with injector cleaner.

I'm sort of out of ideas, any suggestions would be a great help

 

Lots of misfire threads, suggest a search.

Here's my misfire: https://www.cherokeeforum.com/f2/mis...-p0203-172123/

 

Thanks, I'll check the harness by the fuel rail. I have searched a lot of threads on a lot of forums and replaced all the bits mentioned previously, any thing else new to try would be a great help.