XJ error codes

1992 Cherokee, bored and stroked. header, larger throttle body, etc

I'm getting error code 27; "injector control circuit - bank outputdriver stage does not respond properly to the control signal"
and
error code 51; "air/fuel at limit - oxygen sensor signal input indicates LEAN air/fuel ratio condition during engine operation"

It runs like crap. can anyone point me in the right direction?

What size injectors?

It has the stock injectors. I've been thinking I might need to move up to the #24 Ford injectors.

Kind sounds like a bad or disconnected injector. The error is because the voltage the computer is seeing across the injectors looks wrong. Check that you have 12-volts to all the injectors. The computer switches the ground side of the injectors to fire them, so if you hook a voltmeter across the injectors you should see some voltage if they are getting signal.

92stroker said:

It has the stock injectors. I've been thinking I might need to move up to the #24 Ford injectors.

Click to expand...

Definitely. The stock injectors are way too small for a stroker and they'd already be maxed out just to prevent the engine from running lean. I have Ford 24lb'ers in my 4.6 stroker '92 XJ and I still needed to richen tham up a little with a home-made MAP adjuster that I have set at 5.25v.

Lawsoncl – you nailed it. There was a bad connector on the #5 injector. Once I fixed it, the codes were cleared and it’s running smooth.

Dr. Dyno – Thanks for the input. I’m shopping around for some 24# injectors. I have the plans and components to build a MAP adjuster. I just didn’t dare add anything more until it was at least running smoothly.

Thanks for the help.