Hello all,

I have a 1990 jeep cherokee and it is having a problem running/idling, I can start the jeep and it will run but not a smooth idle and smells like its running a bit rich, I can drive the vehicle and it will drive for about 5 min with good acceleration but after that 5 min or so, it will die and takes a few min to restart also it will idle for about 5 min as well but will die and takes a few turn overs to start again. I have replaced the fuel filter, and the plugs(old ones had a bit of carbon on them)

any help would be great thanks

 

I'd start with the upstream o2 sensor

 

Thanks I'll give it a try

 

90s' should only have one o2 sensor (if I looked at mine right)
you can also look at the MAP sensor and the tube and connectors for it, any leaks will cause a run rich and the engine may die under throttle.

 

That'll help with the running rich and even the rough idle you have. And I'd pick up an NTK o2 sensor, rockauto.com has good prices. As far as the issue of staying running, test the alternator to see if it is working as it should. May as well test your battery while you're at it. Good luck!

 

Good place to start^^.

 

Thanks guys! so today was my day off so I went after it. Just replaced the o2 sensor pulled off the throttle body and gave it a good cleaning(was pretty dirty) looked up for the MAP sensor and noted that the van line had melted so replaced that. Now it idles so much better and smoother if not a bit faster. but now seems to like to die when I step on the gas? not sure about this one any ideas?

Thanks again!

 

Adjust your TPS on the "engine" side per these instructions..

RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS be sure the throttle body has been recently cleaned.
It's especially important that the edges of the throttle butterfly are free of any carbon build-up.
IMPORTANT NOTE: Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector
of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post.
If you see more than 1 ohm of resistance some modifications to the sensor ground harness will be
necessary. The harness repair must be performed before proceeding.
I can provide an instruction sheet for that if needed.
MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body.
This manual transmission vehicle TPS provides data input to the ECU. The manual transmission
TPS has three wires in the connector and they're clearly embossed with the letters A,B, and C.
Wire "A" is positive.
Wire "B" is ground.
Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors..
Note the voltage reading--this is your REFERENCE voltage.
Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your
OUTPUT voltage.
Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For
example: 4.82 volts X .17=.82 volts. Adjust the TPS until you have achieved this percentage. If
you can't achieve the correct output voltage replace the TPS and start over.
AUTOMATIC TRANSMISSION:
RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-
wire connector, same as the manual transmission vehicles have, and it is tested the same as the
manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES.
However, the automatic TPS also has a square four-wire connector clearly embossed with the letters
A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module.
Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your
REFERENCE voltage.
Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT
voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage.
For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage.
If you can't, replace the TPS and start over.
So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and
the other side feeds the TCU. If you have TRANSMISSION issues check the four-wire
connector side of the TPS. If you have ENGINE issues check the three-wire connector side of
the TPS.
For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is
stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 11-28-2011

 

Thanks all who helped out. I replaced the Cam sensor and a coolant sensor and now its running great. but now I have a really weird one.. I was leaning over the engine with it totally cold and I heard a noise almost like a switch turning on than off in a simi rhythmic tone. it was coming from the fuel rail area.