Engine running issue

[junglejuice]

Hi guys I had a guy here today who requires some help regarding an issue he has with his 96 Xj, when it is cold it runs fine but once upto temp it will feel severely restricted over about 2000rpm, below this it is fine.
He has replaced both CPS's, the TPS, the entire distributor with new cap, leads, plugs etc, the coolant sensor was also replaced along with a new coil but no change.
So today we replaced the complete throttle body, no change, the cap, leads coil etc swapped out with one from a running car, no change.
We also swapped the Cam sensor, no change.
We swapped the PCM, no change.
We swapped the manifold temp sensor, no change.
We disconnected both O2 sensors, no change.
A brand new fuel pump was fitted and it appears to have plenty of fuel pressure but I don't have a pressure guage to verify the pressure is correct.
The battery is almost new and larger then stock.

Nothing we did made any difference, all parts were removed from a running car, the engine sounds willing, and pulls strong till it feels like the handbrake is pulled on, it doesn't feel like it would if it was a typical ignition break down issue, it is like the PCM is regarding the power.
The catalyltic convertor was checked for blockage but appeared to be clear.
Can anybody suggest anything that I have overlooked?

I,d like to try to help this bloke out as he has just bought this car, I suspect the PO sold it due to this issue and he is new to Jeeps from Toyotas.....

Any constructive comments will be greatly appreciated......

[Roler]

when u say restricted over 2000 rpm, does it go beyond that or ur not getting up to higher revs?

[junglejuice]

No it is like a rev limiter, that would have been a good way to describe it.....

[The Smiths]

We disconnected both O2 sensors, no change.
......

petrols are not my thing - but would have thought doing the above should have made a difference (for the worse), unless they were fubar and not working??

Sounds like a limp mode of some sort

[kjparker]

any codes?

[anthonygubbin]

Have you got another OBD2 ECU to try JJ?

Regards A

[COFFMAN]

Check Exhaust cat convertor ...................

[junglejuice]

Have you got another OBD2 ECU to try JJ?

Regards A


We swapped the PCM, no change.



Of course....

[junglejuice]

Check Exhaust cat convertor ...................


The catalyltic convertor was checked for blockage but appeared to be clear.


Done.......

[junglejuice]

any codes?

Yeah I thought about that, didn't realise while the car was here that it was similar to retrieve codes t othe OBD1 in mine, I am not used to working on OBD2 Xj's, I normally only work on OBD1 models.
I will check next time I see it....

[kjparker]

easiest way I find is to get a Bluetooth odb2 reader, and use a pda with torque on it (android). Can view and clear them.

[junglejuice]

As mine is OBD1 at the moment I have very little use for an OBD2 reader....

[mud_slut]

hey JJ i have a spare one im not using currently i live in VIC but could post to you express if you like


spare elm327 that is

http://www.igshop.mx/assets/images/escanervgatescan1.jpg

[Richard buttocks]

i know you said it appears to not be blocked, but i would run it without the cat and see what its like.
ive had LOTS of cars with blocked cats with this same problem.

also, when its cold does it go like any other 4.0? or worse?

[Mitch]

Have you run it at nite and looked for sparking in the engine bay??Has worked for me in the past,good luck with it.

[junglejuice]

i know you said it appears to not be blocked, but i would run it without the cat and see what its like.
ive had LOTS of cars with blocked cats with this same problem.

also, when its cold does it go like any other 4.0? or worse?

Apparently when it is cold it runs fine, only when it gets hot....

[rainman]

break switch input to the tcu?

[ApacheResistance]

I have the same problem, except at 3,000RPMs. Still haven't figured it out.

Hot cold doesn't matter though. Is it an auto or manual? Are you feeling this "engine limiter" when in drive or what? Put the transmission in 1-2 and try to get the engine over 2k RPMs. If that works try to put it in 3. Does that get over 2k RPMs, or is the problem only in drive?

My problem seems to occur when the jeep gets into 3rd or 4th gear. Haven't figured it out yet.

If you do go to test the cat again to see if it's clogged, just simply remove the front 02 sensor and drive like that. If the cats clogged, you should be able to tell because instead of getting limited in the clog it will come rushing out the hole where the o2 sensor would be. Will be really loud though.

Will be monitoring this thread.

[Dustbowl]

Check earth on the dipstick and behind the battery, worth a look.

[kj69]

jj i have a scan gauge if u need it .

[junglejuice]

Is it an auto or manual?

All petrol Xj's here were autos, that was the only option....

[junglejuice]

jj i have a scan gauge if u need it .

Cheers Kj, that may vome in handy, I'm out of action for a week or so at the moment due to a skin cancer removal.

I was talking to the owner yesterday and he was saying that it does do it when cold not just hot so that may change things some....

[undecided]

If it simply feels breathless and shows no signs of breaking down it may be worth checking the cam lobes have not worn away. The only other thing I could suggest in a similsir vain would be to grab some Subaru upper cylinder cleaner and run it through to remove any carbon build up,

[Roler]

JJ, just on a side note: you might wanna post this issue on cherokeeforum.com , the tech section.
In the past, I've had lots of input/help from some good mech's on there. Might be worth a try, since suggestions here appear to be drying up a little.