94 engine swap problems

W

Wags89SC

Registered User
I finally got the used 94 motor to put in my 91 SC and the mech. has it installed(had to switch everything - long block to LB). He is still working on starting & idle issues. Sometimes it starts and runs fine, other times it seems to "load up" on fuel & blows out a black cloud and is difficult to start. He has been stumped for the last 2 weeks(since it's an intermittent problem). Went for a ride in it last week and runs strong when not having the fuel(?) issue.
He also said it starts sending seemingly unrelated codes when the "problem" occurs - like brake, wipermotor, etc codes.
Any ideas???
 
What codes, exactly...

How are the plug wires connected at the coil?

Like this?
 

Attachments

  • Firing_order_coils.jpg
    Firing_order_coils.jpg
    31.4 KB · Views: 49
Last edited:
I've been working 10 - 12 hour days for the last few weeks so I haven't had time to get by and check things out myself (except for the test, ride last week). I'll have to call him to get some of those details, he is a pretty good diagnostics guy though
 
>he is a pretty good diagnostics guy though

Sorry, but I'm tempted to question anyone that claims to be getting codes about the wiper motor...

>He also said it starts sending seemingly unrelated codes

Make sure he is using the SC specific codes.

>had to switch everything - long block to LB

How did he deal with the different sensor(s)? Which year computer was used? Any changes to the harness? Was the old style supercharger used or the new one?
 
Last edited:
Everything was switched from the old motor to the new - sensors, accessories, everything - he said pretty much nothing was interchangable.
I do recall when I was there for the test drive; that after a few starts without a problem - when it finally "acted up", it was hard to start, when finally started it was backfiring and blowing black smoke.
 
The only thing that would need to be swapped to make a 94 motor work in the older cars is the crank sensor, harmonic balancer and knock sensor I believe.

Frit
 
Wags89SC said:
Everything was switched from the old motor to the new - sensors, accessories, everything - he said pretty much nothing was interchangable.
I do recall when I was there for the test drive; that after a few starts without a problem - when it finally "acted up", it was hard to start, when finally started it was backfiring and blowing black smoke.
Click to expand...

Definitely sounds like a cam position sensor issue due to the out-of-time symptoms you are describing although if it is also sending random codes I would suspect a possible main power/ground issue. Try swapping cam sensors from your other motor.

As Damon said, if he didn't change the injectors that will create another issue but that one would be consistent.
 
What about the plugs and plug wires?

Did you install new ones or reuse the old ones?

How does it idle?

Does it back fire at random times, or only when you go into boost?

I suspect you might have a vacuum leak somewhere.....:rolleyes:
 
fturner said:
The only thing that would need to be swapped to make a 94 motor work in the older cars is the crank sensor, harmonic balancer and knock sensor I believe.

Frit
Click to expand...

And timing cover....

You have to bolt the crank sensor bracket on there....
 
If removed and reinstalled properly, they can.....

I have reused one on three different SCs....:eek:

Knocks on wood.....:p:

It was in pretty good condition, so I reused it.....
 
You must log in or register to reply here.
Back
Top