4lo4fun

So, I have an 85 xj with a 4.0 renix swap.
2" lift on 31's
I don't know a whole lot about the swap, as it was like that when i picked it up.
It has many issues that I am planning on addressing in the near future, but I'll start with the easy ones, I hope.

It has about 10-17 plugs that are not connected to anything.
But it runs and drives ok ish.

I'm getting around 10-11 mpgs and would like to see that number bump up to the mid to high teens if possible.
I was poking around on the web and noticed that I don't have an IAT sensor. I had a few laying around from other cars, so I put one in, and it started spitting and sputtering when cruising at a steady rpm, but seemed to have more power when you step on it.
I hooked up the ohm meter to the sensor, and it read correctly. I also tested the other 2 IAT sensors I have just to get a baseline reading, so to speak. they all tested the same, and were within spec from the info I found online.

I'm not finding much usable info on google.
I'm so confused.

DFlintstone

First, 85? Are you sure? Maybe "decode" the VIN here > https://www.decodethis.com/

85 didn't even come with the Puter' a 4.0 uses!

Actually there is only one Incoming Air Temp sensor, rearward of the TB on the intake manifold. I find it to be a pretty minor player, maybe matters more in uber cold weather, Idk. The engine temp sensor below the manifolds matters plenty. The sender at the rear of the head is just for the temp light or gauge. The senders are different, light or gauge.

You might nose around a bit in the link in my signature. On top is a link to Cruisers tips, excellent info. Also there is a link somewhere to a set of engine pics you might find handy.

4lo4fun

Yes, for sure it is an 85. ran the vin through dmv when I bought it.

When I picked up the Jeep, it was missing a few sensors and things on the intake, so I plugged up what i could to get it to run decent.
Now, I am seeing that one of the ports I plugged was for the IAT sensor.
So i relocated it to the intake boot.
I also noticed that the MAP sensor was moved to a random port on the manifold. I just ran it to the TB about 10 minutes ago.

DFlintstone

A bit puzzled here. The Renix Puter', called an ECU came out in 87 I think, and is normally located sort of above the gas petal. The MAP can indeed use intake vacuum from anywhere, but I prefer having it from the TB as designed.

Gotta run, Cruiser will be along soon I'd bet......

4lo4fun

All the research I've done on the VIN shows it as an 85.
It does have the mount for the ECU above the throttle pedal.

This thing just keeps confusing me more and more every time i work on it. lol

DFlintstone

What month of 85? (manufacture date). There was fuel injection in 86. I've just learned sometimes they put the wrong year on the title. Guess it's for marketing, you can buy what is really an 86 in 85. Then there the decoder should have caught that......

Looks like someone is blowing smoke up your pipe. Facing the windshield from the front, look at the dash at the bottom right corner. Is there a VIN there? Can you read the sticker on the drivers door?

4lo4fun

The VIN decodes to a 1985 AMC Cherokee with a 2.5L L4 OHV 8V engine.

That is from the vin decoder site.

DFlintstone

If you post the VIN that is on the dash, (not what is on the title), maybe someone here can help you. Nothing makes sense right now. 2.5 is a 4 cyl, and that puter won't run a 4.0 (which is not an 8V or a V8). Plus fuel injection came out around 87 after they stopped putting carbureted V8's in them, (or a carbed, 2.5 4 cyl) I'm wondering if you are using the correct VIN!

Jimbo Slice

Perhaps the PO took the puter from the donor vehicle along with the 4.0l engine?

I mean... that's what I would do.

4lo4fun

Yup, full swap. Well, mostly.
Like I said, it still has a bunch of plugs that go to nothing.

Jimbo Slice

That's awesome. I'm curious how they handled the firewall clearance issue.

Could you post up some detailed pics of the engine compartment for us? Specifically the firewall area and the radiator area?

4lo4fun

From what I can see, there appear to be no clearance issues.
Loads of room up front between the radiator and block.
No issues with firewall either

Jimbo Slice

The front end was not actually shorter... I misspoke in my previous edit of this post.

They notched the firewall to accomodate the 4.0 when it was introduced in 87 (per the XJ Wiki).

Supposedly there are modifications that need to be done to shoehorn a 4.0 into an 85.

So now I'm really curious... what tranny/transfer case combo are you running?


I ask all these questions because I have a line on an 85 myself. Was thinking of either SBC or 3800 V6 swap.

4lo4fun

It has the autotragic with a 231.
I had to replace the trans when I got it.

4lo4fun

OK, so I had a chance to tinker with it a little over the weekend.

I tried swapping in the other 2 IAT sensors I have laying around. Still having same problem. So I just left it disconnected.

Google is not being much help at all.