bcumbie

I have a '99 Jeep Cherokee, 4.0 I6, with AW4 trans. It is showing 135K. When I am driving it at steady speed it goes to back-firing and bucking pretty bad, and seems to get worse the longer I drive it. As I am driving the tach seems to jump around (not a whole lot) within 400-800 rpms. I can floor it and it will clear up and take off, I can also let off and it will run better. I was thinking TPS at first, but I am not sure. The CEL is on and I am planning on bringing my scanner home from work tomorrow. I have scanned it before and it had a rear o2 code in it. (Wires are cut and broken at the sensor) I really dont feel like the o2 would cause this. I am thinking something along the lines of CKP or CMP. What do you guys thinK? I just dont want to go throwing parts at it. (Not alot of money around here nowadays!) But anyways any ideas would be great. Oh yea I did do a tune up. Plugs (champion) Wires, cap and rotor. And it runs fine when cold and seems to act worse as it is driven.

ol"blue

You can check the codes without a scanner. Here's how. >-> Jeep Horizons :: View topic - Jeep Computer codes (OBDI & OBDII)
Dan

bcumbie

Thanks for link, I tried it but it didnt give me a code number. All the gauges moved around and it counted from 0-9 in the odometer screen. like 000000 111111 222222 and so on to 999999. Then showed the milage of the jeep. Again though thanks for link, maybe I am not doing something right. I for sure am bringing the scanner home tomorrow.

Another question, do you think the CMP or the CKP could be bad and not throw a code?

ol"blue

Yeah the connector might be causing an issue. It sometimes needs to be unplugged and checked/cleaned and maybe some dielectric grease applied.
Dan

bcumbie

Ok thanks I will try that too, I am about to go do a ohm test on it. Oh and BTW I use to drag race 4cyl fwds (hondas) and always loved watching them OMNIs kick ***!!

gintaras

I tried it to but then I tried the OBDI method and I got a code on the digi and the CEL blinked.. I just turned it to on (but don't start), and then click off and then on twice.. don't go too far back, it is a very close click.. on.off.on.off.on (or mayve it was 4 times, I forget now) then you will get your codes.. kind of weird since we have OBDII but I still got a OBDI code 21

bcumbie

I'll try that. I just ohmed it and it read 8.9 between B and C and 9.2 between A and B. I believe that means the sensor is faulty? It does run though.

ol"blue

Yeah if you can get them to hook without breaking you're in for a wild ride!

bcumbie

Yea I ran a N/A honda with slicks best E.T. 12.2 but without the slicks it would slip and slide for a while..hahahahahaha...
Anyways what do you think about my ohm results? Thats ohming the sensor unplugged from the harness.

ol"blue

I'm at a loss in the electrical dept. Maybe someone smarter than me can chime in here with some help on that. Sorry.
Dan

ol"blue

That's pretty good times for that Honda. What engine were you running in what body?

bcumbie

LS/Vtec with roughly 12.5-12.8-1 compression, Cams, Edelbrock Victor X, RAGE tri-Y,tuned on hondata s200 and some other goodies. In a 92 Civic hatchback, stripped out but still "Streetable". It just got way too expensive and not really a "family" thing. Also the K-series engine was getting really big and I couldnt afford to step-up to one of those. I have and proably will always be a N/A guy at heart. Had a few turbo civics but always went back to N/A.

ol"blue

That comp ratio makes the big difference.

bcumbie

Yea I am pretty sure it was around 12.5-1. I ran flat top valves, and a single layer headgasket with aftermarket pistons.

bcumbie

anybody got any opinions on my ohm findings?


" I just ohmed it and it read 8.9 between B and C and 9.2 between A and B. I believe that means the sensor is faulty? It does run though"
I just ohmed it and it read 8.9 between B and C and 9.2 between A and B. I believe that means the sensor is faulty? It does run though. Today 06:24 PM