POOR RUNNING, YET, NO CODES

[dizzymac]

Hope you figure this out ...my wifes Saturn is doing the same thing....NO codes or check eng. light. Will change O2 and fuel filter in the AM.
Floor pan will be here monday (woo-hoo) can finally get XJ back together.
She to will soon know the joy of XJ's , will be giving her the one I picked up the other day.

 

[Rocketman]

Replaced all of the above as well as Throttle Position Sensor. Problem is still somewhat there but NOWHERE NEAR AS BAD. Seems to get better as time passes. I refilled tank with fresh gas as THAT TOO may have been the issue. Again, it's not as hot as last weekend (100+ in Chicago)

Before replacement of sensors and filter, problem got worse until undriveable. I'm sure hoping this was just BAD GAS. O2 sensor looked like it was covered with thick bright white frost, really bad looking.

After this, next step is a new MAP sensor (mine tested OK but...) and then new injectors or a harness. (last resort is harness) Athough injectors too tested OK (14-15 ohms)

Are there any aftermarket new harnesses?? Or am I doing the junkyard search online?

 

[JEEPTUBE]

Does your xj eat electricity? Like when u leave a door open for like 30 min or less does it drain the battery so bad that it wont turn over?
I did everything u have done and have very simaler problems. The only thing i havnt done is find out why mine eats batteries. And replacing the MAP sensor. Im taking mine in for electrical problems.
Dont replace harness or injectors, if your getting good readings like i did, it was a waste of money.

 

[Rocketman]

OK...

Still acting up but it "fixes" itself. So bad around the nighborhood had to pull over and coast. Exhaust shook like it was running on 5 cyl. Let off the gas, brought to a slow idle, applied gas slowly and problem suddenly vanished.

WTF, OVER...

Looks like checking fuel pressure and or pump may be in order. Ahhhhhh fuc it...
I'll take it to my mechanic. He has diag tools, I don't.

 

[Rocketman]

FINAL DIAGNOSIS, and definitely fixed.

Leaky fuel pressure regulator and a weak coil. Coil was a NOS I bought off eBay with a distributor. Worked fine for a couple months. FPR was prolly the original and even though it tested fine by the FSM test procedure, it was leaking.

Runs smoother than it has in a long time. Gas mileage should improve too.

NOW all I need is a passenger floor pan... Have the Amazon/MOPAR special from Discount Jeep Parts, just need to install. Next step in that project is clean up remaining edges with a nibbler tool and then cut the passenger side off the full pan with the nibbler.

 

[titan4u2c]

Must be nice to have it fixed. lol. Similar issue and no solution still. Mine didn't just start of a sudden though, put on a high flow cat and flowmaster exhaust. Afterwards ran like crap, bought adj map sensor as many thought I needed to recurve my fuel or adjust the voltage to the map sensor but no dice. Yes it will idle nice now with the adj map sensor but still bogs under load. Have replaced tps, iac, plugs, wires, rotor, cap, fuel filter and fuel pressure regulator. Seems like a fuel/air problem cause when I depress the gas I can hear it struggling to intake air and combust it, sorta haha. Here's my .02, so someone please chime in on wtf this is. I noticed there is a white box on the driverside fender with 2 green wires attached and when I pull one of these off it stumbles and dies. I tried this on the vacuum line to the fuel pressure regulator and it will stumble but regains idle smoothly, so I think not a vacuum issue? Anybody on this box and it's purpose as to if it is in connection to the thing running properly? I'm gonna do the injector trial to end that possibility. Thanks guys.

 

[Rocketman]

The little "white box" is the ballast resistor. You'll start but not continue to run without it. Have you tested your coil. Mine was almost new but a cheap one and it got weak!

I didn't fix mine by the way. My mechanic with thousands of hours of experience behind him did!!