idle problems after motor swap PLEASE H E L P !

[jon c anderson]

guy brought me a 98 chevy suburan with motor locked up , i swapped a junk yard motor (complete) . had a very hard time getting motor to fire up and when it did it seemed to be running away (4-5k rpms) black soot out exhaust, so i shut it off. it did this about 3 times then finally now it will just rev up and down 2-3 k rpms. check engine light on now & will scan tonight , any one ever experence this ?:confused:

thank you for your time
jon anderson
229 456 6047 (call or text if you can)

[Robyn]

Hi, and welcome to TDP :)

Without more info, my "GUT FEELING" :eek: is that the PMD is bad.

There are few things that can cause a runaway.

Unhook the PMD on the engine in the rig and "fish" the harness out from under the manifold.

Plug in a known good PMD and try it.

The PMD must be on a "cooler" or heat sink, but you can try it for a quicky with the PMD laying loose.

If this solves the issue, obtain a remote cooler (aftermarket) and an extension cable and the pmd behind the grill or other COOL SPOT

Keep us posted

Missy

[jon c anderson]

Hi, and welcome to TDP :)

Without more info, my "GUT FEELING" :eek: is that the PMD is bad.

There are few things that can cause a runaway.

Unhook the PMD on the engine in the rig and "fish" the harness out from under the manifold.

Plug in a known good PMD and try it.

The PMD must be on a "cooler" or heat sink, but you can try it for a quicky with the PMD laying loose.

If this solves the issue, obtain a remote cooler (aftermarket) and an extension cable and the pmd behind the grill or other COOL SPOT

Keep us posted

Missy

it has what your talking about , but will change it with another , thanks for the advise !