Side Effects Of Wrong Computer?

FastDriver

My dad had a bra
SN Certified Technician
Sep 5, 2001
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Fort Knox, KY
So, the fox-bodiest guy in my area besides me is a buddy of mine. He's actually got a nice collection. Gen 1 and Gen 2 lightnings, a Harley Truck, and a built mod motor coupe in addition to this car.

He's putting together an SSP 1993 CHP coupe I haven't seen, and I was helping him look for an A9L. In fact, I've sent him several links that he missed out on. Anyways, this weekend he told me that he pulled a computer off of a '90 Grand Marquis and installed it. He was pretty happy about it and said it ran fine. I didn't think anything of it, but today it hit me that a G.M. should have the same firing order. I assume that means that the injector phasing is going to be out of whack on cylinders 3,7,5, & 4. I know sometimes computers are run in batch fire without issue. So, that's got me wondering if he's likely to have a lean condition. What other things should he be thinking about?
 
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Mustang5L5

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I'm pretty sure that's a batch fire ecu. I'd probably pull the pinout of both ecus and compare wiring to see if any differences
 

vristang

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fire order should be the same, right?
batch fire vs sefi could cause some issues though, depends on setup and what he is willing to accept as 'ran fine'
Wire diagram is a great place to start when swapping ecus.
 

Mustang5L5

i'm familiar with penetration
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It's batch fire with the non HO firing order. Not sure if that really matters with batch fire though.

It's probably not running ideal. I also think its speed density and the pinout may differ from a mass air harness
 
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FastDriver

My dad had a bra
SN Certified Technician
Sep 5, 2001
4,543
1,247
214
Fort Knox, KY
I didn't think anything of it, but today it hit me that a G.M. should have the same firing order.
Meant to say *shouldn't*: non-HO firing order 15426378, I think.

Batch fire, hmm? I guess that would be not ideal. Thanks for the heads up on the the speed density vs. mass air issue, as well. I wonder if he just cranked it without driving it. If SD depends on a MAP sensor he doesn't have, then I would expect the car to run like dog dung.
 
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FastDriver

My dad had a bra
SN Certified Technician
Sep 5, 2001
4,543
1,247
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Fort Knox, KY
I'm gonna take a look at the car this weekend. I don't really know what I can do other than check the firing order, which I assume must have been set up in the HO order, and pull the model # off of the computer.

I sent him a link to this thread and he responded that it came out of a GM with mass air. I looked it up and AFAIK the 90 Grand Marquis did not come with Mass Air. Perhaps that motor was a transplant.

If the car's running and driving, I'll report back with my impressions.
 

FastDriver

My dad had a bra
SN Certified Technician
Sep 5, 2001
4,543
1,247
214
Fort Knox, KY
He never got back to me. I had a couple issues with one of mine that kept me busy, this weekend. I'm probably gonna let it rest unless he has issues with it and brings it up.
 
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