Rebuilt Engine!!

I just had my engine rebuilt on my 91 Jeep Cherokee Limited about 3 months ago, was running great for the past two months, now it is running odd, at idol the RPM's drop way dopwn then go to like 1500 then when you try to go it wants to stall out, never has but wants too, and once you get moving and its doing this a odd noise, like a clunk or clank comes from about under the brake pedal(but in the engine compartment) on the old engine I had the TPS replaced at the dealership, I pulled codes off the check engine light, 12, 21, 12(again), 52, and 55 12 came up twice!!Thinking maybe the computers is bad, anyone that may know something can shoot me an email at [email protected]

thanks

Problems???

cbert1234 said:

I just had my engine rebuilt on my 91 Jeep Cherokee Limited about 3 months ago, was running great for the past two months, now it is running odd, at idol the RPM's drop way dopwn then go to like 1500 then when you try to go it wants to stall out, never has but wants too, and once you get moving and its doing this a odd noise, like a clunk or clank comes from about under the brake pedal(but in the engine compartment) on the old engine I had the TPS replaced at the dealership, I pulled codes off the check engine light, 12, 21, 12(again), 52, and 55 12 came up twice!!Thinking maybe the computers is bad, anyone that may know something can shoot me an email at [email protected]

thanks

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I’d check the TPS and or the CPS. Some one that has a factory service manual can give the voltage readings. I thought that 12 was supposed to be the beginning and ending codes, to let you know it had cycled through all of them. BTW how did you pull the codes from the check engine light? I own a ’91 Limited as well and have been told that you can cycle the ignition off and on to get the codes. I’ve tried it several different times and never gotten it to work.

Response!!

Wiley Coyote said:

I’d check the TPS and or the CPS. Some one that has a factory service manual can give the voltage readings. I thought that 12 was supposed to be the beginning and ending codes, to let you know it had cycled through all of them. BTW how did you pull the codes from the check engine light? I own a ’91 Limited as well and have been told that you can cycle the ignition off and on to get the codes. I’ve tried it several different times and never gotten it to work.

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you get the codes off your check engine light by turning the igition 5 times on and off, dont start the car but cycle the igintion 5 times. on off, on off, on, off, on off, on off, then leave it on and count the number of blinks from the check engine light!!! any other questions let me know!!

Thanks for the info. I’ll have to try it out and see if it works. According to my manual the trouble codes read as follows:

12 – Memory to controller has been cleared within 50-100 engine starts.
21 – Oxygen sensor signal – neither rich or lean condition is detected from the oxygen sensor input.
52 – Air/fuel at limit – oxygen sensor signal input indicates RICH air/fuel ratio condition during engine operation.
55 – End of message.

My guess would be a bad O2 sensor or TPS. Some one that has a Factory Service Manual can give you the volt/ohm readings to check these sensors with a voltmeter before you buy new ones. The way that code 12 keeps popping up makes me wonder if you have a bad ground. Either the battery to the chassis or the ECU to the chassis.

cracked exhaust manifold.

the clack/clunk from the other side of the firewall and 02 code is a DEAD giveaway.