jeepcherokee89

hi,
I hate for my first post to be questions but thats usually why you look for a forum.

So here goes i just bought a 89 cherokee larado 4.0 inline 6 auto.
it runs but if i tap the gas it will die. Idleing is rough it idles good then will drop down real low then back to good, if i pull a vaccum line like the one that goes to the valve cover it idles great.

also while driving it has no power it will go ok through first but not like it should then all other gears have no power at all. i can get up to like 40mph but takes a while.

Replaced fuel filter and cat dont seem to be plugged

Thanks in advance, hope to be on here for a long time.
Thanks,
Kenny

Donnie_K

Take your throttle body off, take the sensors out of it and give it a good thorough cleaning to start with. Then get a can of starter fluid and check for vacuum leaks.

Frostracing

I know what the problem is, it's this company called Renix. They built a terrible engine management system and cleverly stuck it in your car....
All kidding aside there are a ton of things that can go wrong that will cause these symptoms. Get very familiar with this link because it's a great source for checking your sensors and getting an overall understanding of the Renix engine management works. I had the same problems when I first got mine. Nothing has completely cured it but the car is a usable dd now. I would do what Donnie K said then check the ground connection on the pass. side of the block. Those grounds really need to be secure for the system to work properly. Then do the basic tune up since even if it doesn't fix the problem it's good to have done.

http://www.lunghd.com/Tech_Articles/...iagnostics.htm

jeepcherokee89

I figured out the no power is that the transmission (automatic) is shifting way to fast. not sure what would cause this.

Also i belive the idle problem is the IAC is there any way to test this checking resistance or something

ezab

This might help your shifting problem. As far as testing the IAC, all I can find is a procedure which requires a scanner of some sort.

1. Shift transmission into Park, shut engine off and raise hood.

Throttle Cable Components

1. Press cable release button.

Throttle Cable Adjustment

1. Push cable conduit back into cable sheath as far as possible.
2. Rotate lever on throttle body to wide open throttle position. Cable will ratchet to correct adjustment point as lever is rotated.

jeepcherokee89

Thank you i will try that

AVjeeper

I had similar symptoms many years ago. Took it to the dealer and scanned it. TPS Throttle Position Sensor was the culprit.
Good luck.

jeepcherokee89

ok i swapped out the iac and tps from a parts jeep and it starts and runs fine but once i go down the road it dies when i stop, then its hard to start. i put new plugs and wires in, when i pulled the old plugs all 6 were solid black (guessing not getting enough air)

ezab

On the older 4.0 you need to adjust the TPS. Here is the procedure you will need a meter though.

1. Turn the ignition switch to the ON position.
2. Find the Four-way TPS connector and insert the black lead of the voltmeter into the back side of terminal (D). Insert the red lead of the voltmeter into the back side of terminal (A). Make sure that the throttle plate is completely closed against the throttle stop. Note the voltage reading of the voltmeter as it is connected across these two terminals, this reading is the input voltage.
3. Remove the red lead of the voltmeter from the back side of terminal (A) and reinstall it into the back side of terminal (B). Make sure that the throttle plate is completely closed against the throttle stop. Note the voltage reading of the voltmeter as it is connected across terminals (B) and (D), this reading is the output voltage.
4. Divide the output voltage reading by the input voltage reading. The ratio should be between .825 and .835 (.830 optimum).
5. If the voltage ratio is not within this range, adjustments can be made using the two mounting screws. To make large adjustments, loosen the bottom mounting screw and pivot the sensor. To make small adjustments, loosen the top mounting screw and pivot the sensor.
6. Disconnect the voltmeter, and tighten the mounting screws securely.

jeepcherokee89

could a stuck egr cause this??