OutbackOz

Hi all I have just gone through the most Frustrating time getting my 96 going again Too Long of a Saga So the quick version
A year ago the Jeep became hard to start when Cold then all the Time
Fast Forward changed fuel pump and press reg valve got worse ended up being the PCM I got a Numbers Matching PCM from a wreckers
To get it to Run I had to change the PCM Crank Sensor and the TPS.......... What a trip it has been So you can Start it up the Idle isn't too bad It drives It changes gears but you cant Accelerate its a struggle to get to 40 kph No Power? It is not missing just Gutless? Like the Fuel/Air mixture is out of wack? Like its choking or clogged up or blocked if these descriptions make sense?
I got the codes 22 tps low voltage (fixed with new tps) and 32 egr valve? Only Diesel XJ's have a EGR Valve?
Does the Emission Control Canister Purge Solenoid have any thing to do with Performance? I checked all the vacuum lines they all seem fine and there is no Miss when Running?
The Cat is not Blocked its near New the whole system is
The Check Engine Light is Not On..................................... (I had to move the Upstream O2 Sensor wires away from the exhaust manifold I cut them rather than remove the power steering pump and lengthened them to go around the intake manifold Been Caught by Melted Wires before... it was hard to read the colour coding BUT If I Stuffed it up the check Engine Light would be ON?)
Some thing is Amiss ............... Brains trust any Ideas?..................
Starts and runs Ok..... No Miss No Power ...... Has the Horsepower of a ride on mower

gat

Ensure that the are no cracks or gaps in the air intake from the filter to the head. It's be good to give it a "tune-up": splark plugs, their wires, distributor's cap and rotor, fuel filter, air filter, and a fuel system cleaner in the tank.
Please post the fuel pressure at the rail with key in on position before cranking, while cranking, and while running. Post the compression of the cylinders dry and wet if possible. That will considerably assist us to assist you. We could try to diagnose other things all day, but it could be the compression of the engine after all.

OutbackOz

Hi gat all of the above is fine I recently had the head off and all is good it was running perfectly before the PCM committed suicide about 8 weeks ago so its not the engine
It has to be something to do with fuel/air mixture?

GreaseMonkey17

So you have these problems but haven’t performed any diagnosis that you’ve mentioned . You simply gave us a string of symptoms that could be caused by any number of things . Did you test fuel pressure ? Spark ? Compression ? Vacuum leaks ? Timing ?

OutbackOz

the head was off and machined about 2000 klm ago new plugs wires rotor everything even the injector rubbers I know what low compression is like and this not it if it had a carby I would say the mixture is out
I did some google-ing and a Faulty Emission Control Canister Purge Solenoid Valve can stuff your fuel/air mixture up? we shall see I have one coming in the mail it will take about 10 days to get here from the USA
as for fuel pressure the pump is new the reg valve is new pressure is about 48/49 with the key on that is not a issue it has spark as it runs?

DCWinterXJ

That fuel pressure seems kinda high for a 96...I may be wrong about that but my 96 engine primes to about 36psi.... unless your pressure is in a different measurement value...is that your pressure at the rail?

jordan96xj

His fuel pressure is correct for a 96.

DCWinterXJ

I was gonna say after careful thought my setup is a bit different/ I believe I have an older fuel rail connection from my 94 which my mechanic installed during the engine swap. But yes I did look it up and I was about to post that his pressure is correct...As you know my setup is interesting...but she is running like a beast now. Guess I need to learn more before helping others!

nickfancher1

Broken catalytic converter. Not clogged, broken. Doesn't matter if it's newer.

OutbackOz

It's Fixed and it was the Emission Control Canister Purge Solenoid Valve it was dumping gas after the mixture was set and making it run bad ......but Just to Top it Off
Mine has dual fuel it also runs on LOG (Propane) .. the heater hoses that run to the heater tap have T pieces in them for extra lines to run down to cool the gas converter they had sagged and the heater tap had dislodged and warped the metal insert on num 5 plug lead giving me a bad cylinder
But Beware the Emission Control Canister Purge Solenoid Valve it can stuff your mixture up .................................................. .......................

jordan96xj

Did your mechanic tell you this?

awg

hopefully the gents long saga, which we followed on Aussie forum is over, (currently offline due to server move)

He was systematic, replaced many parts, this final fault was called out by OBD code

presumably the fault must have been causing a vacuum leak or mixture issue ?

a weird one, something to file in the memory, the test is in the eating...if it stays fixed...

OutbackOz

hey awg the mixture was altered by dumping the gas after the sensors and pcm set the mixture.........
Jordan it took a long time but I figured this out myself a lot of forum research and googleing and testing it was a saga it took a long time but it is fixed and running good

jordan96xj

I'm glad you got it sorted out!

The purge solenoid does not dump gas. It purges air from the fuel system and tries to keep a slight vacuum on the system.
The mixture is constantly adjusted from the time you start the vehicle until it is turned off. About once or twice every second.

It was a vacuum leak. Which likely caused a rich mixture condition as the computer added more fuel to compensate for the high level of free oxygen being measured in the exhaust stream.

awg

Interesting..late in the piece I suggested the OP connect a vacuum gauge..I often suggest this early, for weird faults..because it will give very strong clues if an issue is mechnical or electrical

thinking I was wrong here, but the FSM calls out the part as being not electrical, but soley vacuum operated

would have been a confusing fault to diagnose...presumably plugging the relevant vacuum port or hose would have stabilised engine operation?...but still called an OBD fault ?