1981 AMC EAGLE engine swap problems

[screamingeagle]

Hey guys,

I've got an AMC Eagle that I swapped a 1999 Jeep Cherokee 4.0 L into.
I did the engine swap a few years ago and have had a consistant problem with it:

The engine will throttle surge and sputter every once in a while. I need to feather the throttle to get the thing back to normal and then it's usually fine.

The problem then recently transfered into a surging idle and in low range on the rocks, a surging throttle is NO fun at all.

Here is the info:
1999 Jeep Cherokee motor (everything that was in the engine compartment)
...factory computer ... fuse box... wiring harness... etc.

its attached to a 1981 AMC Eagle 998 Auto Tranny. Ive modified the bellhousing to accept the cps sensor.

Hints:

The "throttle sputter" happens EVERY TIME I fill my gas tank.
It also happened randomly and for short periods of time once or twice each time I drive it.

Already Done:
I already swapped out the throttle body with a junk yard one and all different sensors attached. Didn;'t change anything.

What I think:
I'm thinking this may be gas tank related. A friend of mine suggested it could be due to a computer out of an auto and not having that same auto trans attached is causing it. There are THREE outlets/inlets to my gas tank: Outlet, Return, and 1 other? I dont at all know what I ended up hooking that third line to.. maybe thats my problem?

Anyhow, thanks in advance for any answers. I'd love to get this bitchin' 4.0 L in top running condition.

-Josh!

 

[screamingeagle]

here are some pics for those of you wondering what the hell an AMC Eagle is:

 

[FlexdXJ]

Haha, Awesome Eagle man!

 

[RNMedic]

never did the straight axle on mine but did lift it. Do you have a return line for the fuel?? or is it the stock eagle tank?? possibly a lack of return line. PS mine had a weber and GM HEI. Still miss it

 

[trippled]

that other line on the tank is a fuel vent for the evap system. being a 99 operating system that is emissions driven, if the evap is attempting to restore/purge tank pressure it could cause your surging problem. i would make sure you have everything hooked up correctly for all your emissions systems. also, have you done a basic tune up on this motor? (plugs, wires, fuel filter, etc)

 

[screamingeagle]

thanks guy. Answering some Q's:

I did a basic tune up w/ new plugs, wires, fuel filter etc.
I do have a return line that comes off of my grand cherokee in-line fuel pressure regulator. I believe a 99 4.0 required the in-line return and was not the 4.0 w/ the return from the fuel rail.
I do not have that third "fuel vent" hooked up to any emissions system stuff. What can I do with that line as a quick fix? (cap it off? cut it at the tank and throw a breather fuel-line filter on the end of a tube?)

 

[screamingeagle]

I used a SPX OTC code reader. It asks you to identify the vehicle 1999 Jeep Cherokee 4.0 L Automatic trans. cali car.

*P0500 ... vehicle speed signal... mil code 035
P0132 ... 02 Bank 1 Sensor 1 voltage high... mil code 062
*P0138 ... 02 Bank 1 Sensor 2 shorted high... mil code 126
*P1495 ... Leak Detection Pump Solenoid CKT... mil code 183
*P0753 ... Overdrive Solenoid Circuit... mil code 050
P0758 ... Shift Solenoid B Circuit Electrical
*P0743 ... TCC Solenoid Circuit... mil code 012
P1694 ... No Message Engine Bus... mil code 222

*=repeat codes after clearing initial codes and driving 15-20 minutes.

Does this give out any clues???
thanks.
-Josh

also note: Since I am not running the stock tranny and this is an engine swap there are certain sensors/parts that I dont have. Ex: stock tranny gone, 2nd O2 sensor gone

 

[CMNCHE]

Well the speed signal is not gonna happen because your running a different trans.

If you have a bank 1 o2 sensor I would replace it because it is throwing a code and could cause a poor running condition.

You said you dont have a 2nd o2 sensor.

LDP you don't have hooked up.

The others are related to trans. Thats expected in your case.

The bus message bother me some because if you are using the 99 PCM you should have bus communication.

 

[heyhar]

As mentioned, the third line is for evaporative emissions. Starting in '96 (we have two), there's the canister and a little pump, which actively purges the charcoal canister, and pumps the vapors back to the tank. I don't know exactly how or when the computer knows to run the pump, but I'll hear mine most often a minute or two after I start the engine. If you can find nothing else, maybe get this system off a OBDll model, and retrofit it to your buggy. After all, an OBDll system knows if you have a missing or faulty gas cap, and it's part of the same system. I know it sounds dumb, but unless you go to a carb, the ECU wants to see everything in its place

You said you dont have a 2nd o2 sensor.

The second, or 'downstream' sensor doesn't affect operation, but it may be causing problems looking for a cat.

 

[screamingeagle]

what exactly is the bus communication?

from what i researched online code P1694 could show due to:
*Transmission Control Module failure (being that I dont have the same tranny that seems like a good possibility)
*Possible CPS problem
and apparently it usually results in the vehicle not being able to start... but thats obviously not the case this time.

I think the above are "general codes" not very specific.

any more info on that code is appreciated.

 

[CMNCHE]

Bus communication is the way all vehicle systems talk to each other. This code may have come from the lack of a Trans module in your case or it could be the PCM trying to talk to something that isnt there......I think you def need to address o2 sensor codes and try to get some sort of 99 evap system before going any further.

 

[screamingeagle]

ok, can do. I just installed a fuel pressure guage and it seems to read a very very steady 52 psi even when the throttle stuttering happens. So i guess fuel pressure isnt the problem.

 

[screamingeagle]

Is it normal to have the fuel pressure drop to 10 psi when you leave the car over night?

 

[ladyeagle]

This sounds exactly like the trouble I have been having with my 85 Eagle. My Mechanic has identified that (at the very least) I have a short in my ECU wiring connector - I am trying to determine if I can replace the connector or if I have to replace the entire ECU wiring harness. (I hope not - can only find one new and it is $350) on that note - definitely check your connectors because if it goes...that it is as a pain to find a replacement.

p.s. I like what you did with your Eagle, funky.