New Engine Problems

Ok recently i had to replace my motor because the last one's rod broke in half so i put the new motor in there and it will start in run well for a bit maybe about a minute if that then it will start miss firing and running really bad the local mechanic i talked to said he thinks it's the timing is off but there is no way to adjust it because it's supposed to all be done by computer so are there any suggestions Thanks

There are a lot of differences between years and engine size. More details would be really helpful. Also any parts that you may have changed while you were at it (sensors, etc) and how long it sat are all helpful. With any engine 87 and up the CPS is easy to damage when removing or reinstalling an engine, but usually won't cause your symptoms.

OK Sorry about details the jeep is a 1994 jeep cherokee its just a stock inline six changed just everything over from one motor to the other but most of the parts were new because i had already changed the motor once but it was in good running order when i went out but it sat there from june to december if that is more helpfull

It's pretty common to get the distributor 1 tooth off, I'll try and find a link to help you check. Does it miss only at idle or above idle also? Are you throwing any codes? Double check that all connectors are connected also.

Try this, if that's not it let us know and we'll keep trying. http://www.angelfire.com/my/fan/dist_index.html

It misses at idle and when it's actually driving also and i dont know how to check if it's throwing any codes

nmcommando said:

It misses at idle and when it's actually driving also and i dont know how to check if it's throwing any codes

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Get codes with ignition. Ignition on, not starting. Key on, key off, key on ,key off, key on and leave it. The check engine light will flash two - digit codes.

"55" is the end of sequence and always present.

"12" is common, and means battery has been disconnected within last 50 starts. Often comes on anyway.

All other codes are significant.

Post back with any you find, or read them here: http://www.allpar.com/fix/80s-codes.html

Not all the codes above will be on an XJ, but most are the same as standard Chrysler OBDI.

If your vehicle sat for a long time, make sure that the gas is good, the fuel filter good, and check that mice have not nested in your exhaust system or your air cleaner!

Are you sure that the spark plug wires are in the right order?

Punctuation.

Yea i checked the order more than one time by several different people and checked the manual so that i rotated in the right order

Well i just checked my codes and it gave me a 24 and a 33 im pretty sure

24 is throttle position sensor.

33 is AC clutch relay circuit.

I'd check wiring first, including making sure that all your grounds are good. then, I'd suspect the throttle position sensor.

A basic test of the TPS uses a digital voltmeter. Test is done with the sensor connected, so you must "back-probe" it by inserting a thin test lead or paper clip into the back of the terminal to make contact.

With ignition on, back probe the center terminal (with other lead to vehicle ground). In idle position, voltage should be greater than 200 millivolts. At wide open throttle, it should be less than 4.8 volts. Voltage should increase gradually when you open the throttle.

If you've had a lot of engine problems, and just done a swap, make doubly sure that there is no accidental mechanical damage to wiring harnesses and plugs.

Check to see if you damaged you crank positioning sensor. I broke the tit off when i swapped engines and it caused it to run like yours is.