Spark control computer under dash

PursuitSpecial

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Has anyone ever seen a spark control computer like this one? Usually the ESA/ELB computers were mounted on the side of the air cleaner, but in my '81 Gran Fury police car the computer is mounted under the dash on the driver's side near the parking brake. It seems like a really good idea, getting it out of the engine bay and into the air-conditioned, protected interior. Never seen another one like it though, which is odd seeing as it is a drastic improvement. The computer actually still works and the car runs happily using it to trigger the coil, though the timing advance is broken since the throttle feedback module on the thermoquad is long gone. I checked for the part number in my 1981 parts manual and the closest number is for cars with the E48 318 4bbl engine which mine has, so the mopar part number is likely 4145944. I read about this possibly being a feature on cop cars, but running down interchanges with the number in the manual it looks like it may have been used on Cordobas until about '82. I have no clue what else this computer does, I assume it's like the normal N94 ESA module but if it's a police-only feature maybe it has a different timing curve in it for chasing bad guys or something, who knows

Screenshot_20230323-223743.png
 

AMC Diplomat

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I know the AHB computers were under the dash, but this is the first time I've seen a description of where exactly it goes. I've come across this style of computer before when I was making offers on computers on ebay. And I thought nah that's not the right one! They're out there. Definitely not listed by part number though on ebay
 

Mikes5thAve

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Yes it was an AHB thing.
I think having them under the hood was an accessibility move. The air cleaner is a strange place between heat and vibration bit they did seem to last there. A lot of vehicles have them under the hood but on the fender which seems like a better spot.
 

PursuitSpecial

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Interesting. So I guess Chrysler knew about the problems with air cleaner mounted computers and gave the police a much better system, but why not use that on all cars? Was it more expensive to route the wires to the interior? That was like the main complaints with the ELB system and they had a solution the whole time but never gave it to the public
 

Mikes5thAve

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In most cases after the 70s ones the computer is fine and its usually
other components causing problems. They put the police one inside because they saw more heat under the hood then normal cars from the way they are used.
 

LSM360

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In most cases after the 70s ones the computer is fine and its usually
other components causing problems. They put the police one inside because they saw more heat under the hood then normal cars from the way they are used.
I think this is why also. High idle hours with tremendous heat build up under hood. Same goes for the Thermoguard. Not a battery problem, just a use issue.
 

GregG48213

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'81 Gran Fury police car
Just to muddle the picture somewhat, my 1980 R-body Gran Fury police had the computer mounted under the hood on the air cleaner. My car also had the 360 four-barrel, its final year for a passenger car. The size of that transistor and its heat sync tells me that this computer needed some air circulation for cooling.
 

8T2TOP

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Looks like your part # is 4594581 A Mopar reman would have an R in front, probably superseded countless #s untill a more common R-------.
I had an 85 dip AHB,I thought the computer was on pass side inside under dash,but that was 23 years ago . Maybe it was on drivers side, memory not what it was and been thru plenty of Mopars in 25 years .
If the Carter tq is stripped of electrical then convert to Standard ECU ignition..
 

Ele115

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My 81 LeBaron has it under the dash. It hasn't been hooked to anything in many years, but it is still there. My 80 Aspen FHP car came with it on the side of the air cleaner. It's still there for looks.
 

PursuitSpecial

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Interesting, so it looks like they started using this box in 81 then. Is your LeBaron a police package? It appears the only cars that got these were M body police cars and the very last R bodies. Even though it still works in my car I've switched it over to MSD ignition with proper timing advance and replaced the thermoquad with a Holley 4011 and it doesn't even feel like the same car. Interestingly the original orange plug wires from 81 have no issue with MSD, no arcing or misfiring whatsoever...
 

Ele115

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Yes. It was one. R bodies got them too. F bodies didn't but they are the same really, so this really comes down to when they decided to make the change. Or I could see it this way: Someone at Chrysler decided the heat was too much and they did it on the R. Then for whatever reason they did it on M's in 81, and everything else in 82. So 1980 R body was probably an experiment or a fix. And it helped a lot. But I can tell you, they didn't do it in the F in 1980
 

81ImpNC

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I saw a 1980 St. Regis within the last year or two V8 probably 318. It was clearly a civilian model having a vinyl roof, upgraded interior, and wire wheel covers. It was a low-mileage car and authentic. Perhaps it was a non-emissions car I didn't look at it too closely. I clearly was not removed by the current owner. Part of why it was mounted on the air cleaner is the incoming air cooled the internals. On the Imperials at least (mine still has EFI) there is an intake air temperature function that the ECM uses to adjust the tune. I have a picture of the engine compartment somewhere in my files.
 

Ele115

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Anything could have happened in the last 43-44 years. Half the cars of that age don't even run carburetors anymore or they have been "LS Swapped yo"
 
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