Swapping a jeep into another vehicle

XJ9694 · Sep 16, 2016

Hi guys,

So I have owned an XJ for most of my life and I love it. Its reliable, the 4.0 has lots of power and junk yard support is plentiful.

In my spare time I race in a series called "The 24 Hours of Lemons". Basically you take a $500 car, cage it and race against other idiots and engineers who are dumb enough to put their junk on a track. Which brings me to the 1968 Mercedes 280se that my Grand Father has had sitting in a field for the last 15 years. Functionally speaking the car is pretty sound except for the seized engine. It too is a OHV i6.

What I need everyone's help with is the sticky electronic portions of swapping Jeep guts into a another car. Fabricating motor mounts, trans, mounts, cutting/welding is not where we are in trouble. I'm looking for info on stuff like (yes I used the search feature, and I cannot find guides for this stuff):

how to make the PCM ignore a missing AW4.
how to hide airbags from the computer.
If I remove the HVAC system is that going to pull a code?
What other non essential systems are going to cause issues with the pcm if removed.
Basically what are the major wiring and electronic steps to convert a automatic 4x4 jeep to a manual 2wd?

Additionally I would like to use an OBDII donor for better data logging on the race track.

Thanks in advanced guys!

donthelegend · Sep 17, 2016

XJ9694 said:
Hi guys,

how to make the PCM ignore a missing AW4.

Leave the TCU unplugged and ignore the CEL or source an ECU from a manual trans XJ.

how to hide airbags from the computer

Leave them unplugged and don't hook up the ABS warning light

If I remove the HVAC system is that going to pull a code?

No

What other non essential systems are going to cause issues with the pcm if removed.

If its not essential, the jeep ECU probably runs just fine without it.

Basically what are the major wiring and electronic steps to convert a automatic 4x4 jeep to a manual 2wd?

Start with a 97-00 2wd manual jeep and it'll be a lot easier. You'll want the federal emissions package if you get a '00 so you don't end up with pre-cats and extra O2 sensors to deal with.

Additionally I would like to use an OBDII donor for better data logging on the race track.

Thanks in advanced guys!

Additinally, read about Team Petty Cash Racing's lemons build, they had trouble keeping 4.0s alive and suspected oil starvation issues.

Warlock1 · Sep 17, 2016

donthelegend said:
Additinally, read about Team Petty Cash Racing's lemons build, they had trouble keeping 4.0s alive and suspected oil starvation issues.

The 4.0's are all low end grunt, like a tractor. They are not a high rpm motor, stock. I think that's where the problem lies. Geared correctly and they might live in that racing environment.

cruiser54 · Sep 17, 2016

Warlock1 said:
The 4.0's are all low end grunt, like a tractor. They are not a high rpm motor, stock. I think that's where the problem lies. Geared correctly and they might live in that racing environment.

I respectfully disagree with the tractor analogy. I've been driving a 4.0 since it hit the dealership I worked at in late 1986.

It's always been a passenger car engine from it's earliest roots.

And, mine all wing up to 5000 RPM easily and frequently. The lowest mileage on one is 194K. Highest mileage on one is 277K.

Warlock1 · Sep 17, 2016

I think you misunderstood what I was trying to say or I just didn't explain it well enough.

I'm not saying that it is an actual tractor motor, I'm saying that is shares some of the same attributes. The way it was designed and the with the type of cam, it is a motor that is more comfortable at low and mid range rpms. That is where it makes it's power in stock form. As opposed to like a 340 Mopar that is good up to 7,000 rpms +. Yes you can turn it at 5k rpms but it kind of runs out of steam up there in stock form. And I'm pretty sure that the OP was dealing with, a stock engine as the whole car had a $500 limit.

I was just responding to "Donthelegend's" post of him saying "Additinally, read about Team Petty Cash Racing's lemons build, they had trouble keeping 4.0s alive and suspected oil starvation issues."

Now, if modded it could easily live at higher rpm's happily. But I was simply suggesting that if geared correctly, the rpm's could be kept within the limits that the engine lives best at, low to mid range. That's all.

I also started turning wrenches professionally in the mid 80's and have had much experience with these engines and I love them.

JohnX · Sep 18, 2016

I suspect rpm and gearing matters very little if the oil is pinned against the side of the pan during high G cornering.

Warlock1 · Sep 18, 2016

JohnX said:
I suspect rpm and gearing matters very little if the oil is pinned against the side of the pan during high G cornering.

Ah, lots of hard cornering, I wasn't aware of that part. In that case, a windage tray, a high volume pump, baffles in pan and an accumulator should help with that. Old school racers trick, something I've been doing for decades, is to run an extra quart in oil pan.

cruiser54 · Sep 18, 2016

Warlock1 said:
I think you misunderstood what I was trying to say or I just didn't explain it well enough.

I'm not saying that it is an actual tractor motor, I'm saying that is shares some of the same attributes. The way it was designed and the with the type of cam, it is a motor that is more comfortable at low and mid range rpms. That is where it makes it's power in stock form. As opposed to like a 340 Mopar that is good up to 7,000 rpms +. Yes you can turn it at 5k rpms but it kind of runs out of steam up there in stock form. And I'm pretty sure that the OP was dealing with, a stock engine as the whole car had a $500 limit.

I was just responding to "Donthelegend's" post of him saying "Additinally, read about Team Petty Cash Racing's lemons build, they had trouble keeping 4.0s alive and suspected oil starvation issues."

Now, if modded it could easily live at higher rpm's happily. But I was simply suggesting that if geared correctly, the rpm's could be kept within the limits that the engine lives best at, low to mid range. That's all.

I also started turning wrenches professionally in the mid 80's and have had much experience with these engines and I love them.

Gotcha. And Team Petty Cash is not the normal use for a 4.0. They're having fun with it though.

Warlock1 · Sep 20, 2016

It actually sounds like fun

Swapping a jeep into another vehicle

XJ9694

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donthelegend

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Warlock1

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cruiser54

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Warlock1

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JohnX

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Warlock1

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cruiser54

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