f550maranello2

Hi fellas my cousin in Poland has a 94 Cherokee that originally had the 5.2 liter motor, he bought it with a 5.9 swapped in to it. The issues hes having is at idle it runs rough and runs real rich. When i was there looked at it and noticed that the pcm was still from a 5.2 liter and so was all the wiring. Since im a GM guy, to me it would make sense to have the correct pcm for the 5.9 liter and from my understanding the 5.9 liter is from 1998 and up?

Also hes using a universal 02 sensor.. if anyone knows anything about a swap like this I would appreciate any info..

Bustedback

There is a difference between the 5.2 and 5.9. The 5.2 is internally balanced, the 5.9 is externally balance. The universal O2 is not a good choice either.

f550maranello2

Thanks, i already told him get another on (im assuming its gonna be for the 5.9 liter?)

Bustedback

I think the torque converter is different between the two engines because the way they are balanced.

f550maranello2

so i talked to him yesterday, he says it idles low also at less than 500 rpms and black smoke comes out of the tail pipe.. also he had code 24 AND 51 but they went away. He just told me that he replaced the whole throttle body and idle air control, map sensor, throttle pos sensor. so far no codes but the idle is still low..

also he disconnected the battery for 20 minutes to clear the codes and now the car will not idle.

f550maranello2

so can anyone confirm my theory here.. if the engine is a 5.9 all the sensors and junk should be coming out of a 5.9 liter correct.?

Also about the pcm, we looked at it and it seems like its the 5.2 liter one, will this larger motor run on this old pcm?

dave1123

IMHO, if you can find an electronic genius, he MAY be able to reprogram it.