Major Problem Trying To Pull Engine Codes.

[Fisher88ttop]

I have an 88 lx 5.0 that I have converted to mass air. I am having issues with a backfire through the intake so I checked all of the normal causes, timing, vacuum leaks ect. I was going to pull the codes today and when I connect the code reader to the plug the engine surges to 3000 rpms and stays there until I disconnect it. I have been wrenching on these cars for over 20 yrs and never ran into this problem. Thanks

 

[jrichker]

Do the Key On Engine Off codes first - KOEO
Then do the Key On Engine Running codes - KOER
Otherwise strange things will happen...

 

[Fisher88ttop]

I did that. I didn't get any strange codes. Just emissions stuff that I already know because I deleted all of that. I also did not get the code 10 or pass code. I will try it again

 

[Fisher88ttop]

OK so now I feel like an idiot. My problem was a loose power ground. My guess it wasn't grounding the computer properly. Car seems to run fine now. Thanks a lot for the response