POOR RUNNING, YET, NO CODES

[Rocketman]

Can I have MAJOR fuel issues, pump, mixture, etc and not get ANY codes?(except ol 55) It's a 93. When ICE cold, runs fine, as soon as it heats up, it starts sputtering with no power. Pulled exhaust thinking it was an issue since it got WAY hotter than normal setting the padding and carpet above my rot holes in the back on fire!!! 3 years running like that never got it that hot!

Haven't pulled the plugs to look at them yet. Thinking about it while talking about it makes me realize the issue has gotten worse each time I start and test it out. Actually ran worse without exhaust and cat.

Will disconnect the battery to reset the computer and try again in a couple hours. Almost 100 here in Chicago area today!!! Doesn't cool too fast.

IDEAS??

[langer1]

Coolent temp sensor can cause that problem.

[go4wheeling]

Wow... its pretty funny that he is asking that question... I just came on the site to ask the same question... mine runs fine when cold but when it heats up it will sputter when gas is applyed. What I think is wierd is that it idles fine. I know that it is NOT the fuel filter, spark plugs, distributor, or the wires because I replaced them all.

[go4wheeling]

I dont think its not the cooling senser because I dont think mine has one. Well it at least doesnt have one going in to the hose where the thermostat is.

[Rocketman]

BTT

[Rev Den]

Just off the top o the head....

Sound like you are running rich.

Leaky injector
O2 sensor
Cooloent sensor

HTH

Rev

[Rocketman]

Thanks Den, I've decided to use the week to do my SYE, and new DS. I'll get back to the engine later in the week.

[Matthew Currie]

If it's a stock 93 4.0 it certainly should have a coolant temp sensor somewhere. I thought that the CTS was on the thermostat housing, but may be wrong for a 93. No FSM where I'm at this week. I don't know what year Go4wheeling is running. But if it's a 4.0 it should have a CTS somewhere.

I had trouble with a 93 which had a defective wiring harness to the fuel injectors, causing a bad splice to heat up and shut off one injector when it got warm. A resistor (or a resistive connection) will increase resistance as it heats up. It was very frustrating to track down. I posted on this long ago when it happened, and not long after, another 93 owner reported the same problem. It might be worthwhile getting an ohmmeter and checking the harness. In the Chrysler injection system, the computer switches the negative side of the injector system, and the positive is supplied by a circuit originating at the ignition module. It branches via internal splices to the individual injectors.

If you have an injector cutting out it will idle well, but sputter under load. You can test whether or not it's an injector by unplugging injectors one by one. If it's a good one, the engine will bog a little, then recover when the computer makes a correction. If it's a bad one, it will make no change at all. To determine whether or not it's the harness or the injector, swap connectors between two adjacent injectors and try the test again. If the fault follows the connector, it's the harness.

The above problem sounds more likely for Go4wheeling than for Rocketman though. Rocketman's problem sounds more like rich running or a timing issue. A vacuum gauge would be handy to sort that out. A bad CTS might make the computer think the engine is still cold and continue in startup mode.

[go4wheeling]

Thanks a lot Matt, it sounds like a start, I will give it a shot tomorrow. OH yeh my jeep is an 89.

[badron]

When she is running good "startup mode"
The start up mode blows off the O2s and runs rich. She still reads air,water temps the MAP, TPS RPM.
The startup mode is to give the engine, O2s and cat(s) time to reach operating temp. 90 seconds now adays. Before bring them online or sampleing them. The EGR value is keep off line in startup mode too.

[Rocketman]

PROBLEM DIFFERENT NOW...

Doesn't matter, cold or hot.

Starts OK, idles pretty rough. Give it any gas, it sputters and dies.

Changed the coolant sensor as per above, no joy. Have been wiggling and reseating the wires on the injector harness. IN ADDITION, 1 month ago put in new OEM distributor. Don't think that matters much but thought I'd add it.

STILL NO CODES except 12 and 55 (battery disconnect and end of codes)

Looks like some FSM reading tonight on vacuum and injector checks are in order.

Anyone with shortcuts on injector checking other than disconnect while running or swapping connectors??

Thanks.

Rob

[Matthew Currie]

PROBLEM DIFFERENT NOW...

Doesn't matter, cold or hot.

Starts OK, idles pretty rough. Give it any gas, it sputters and dies.

Changed the coolant sensor as per above, no joy. Have been wiggling and reseating the wires on the injector harness. IN ADDITION, 1 month ago put in new OEM distributor. Don't think that matters much but thought I'd add it.

STILL NO CODES except 12 and 55 (battery disconnect and end of codes)

Looks like some FSM reading tonight on vacuum and injector checks are in order.

Anyone with shortcuts on injector checking other than disconnect while running or swapping connectors??

Thanks.

Rob


Only way I know to check injectors for full operation is with an injector tester and a pressure gauge. You use the tester to fire the injector with engine off and fuel rail pressurized, and read the gauge to check the pressure drop with each tick. The tester I have does a single firing and a series. A mismatched injector will show up by dropping more or less than the others. A dribbling injector will drop pressure after firing. When I was dealing with my recalcitrant 93, I bought an injector tester and a gauge (the stealership quoted 989 bucks for a new PCU as an experimental first step, so I figured I had some slack to play with. Any excuse to buy a tool!). The wiring harness problem did not show on the tester, because the low voltage was still enough to fire the tester - just not enough to fire the injector! Trusting the harness check function of the tester led me down a few other blind alleys. But it should show up a faulty injector pretty reliably.

[XgeekstarX]

i'd pull the vacuum line off the map sensor and see if it runs the same

[Rocketman]

Metered out the injectors, all read around 14.5 to 15 ohms. DCV on MAP sensor 4.75 volts. BOTH great according to FSM.

Pulling the connectors off of injectors is a PITA. The little wire retainer is a bitch to remove. I'm assuming there is a special tool the dealers use?

Replaced coolant sensor as well. Still no joy. Pulled plugs and wires out for inspection. Cap is new as is rotor. All look OK.

According to FSM, mechanical issues are the most likely cause of no codes since they are not electrical. Found out the Chiltons/Haynes manuals are WAY OFF with their test procedures. If you tested your injectors and used their results, you'd think all your injectors were bad. Only thing they are good for it seems are the disassembly photos the FSM doesn't have. They aren't even printed well. My version is a Taiwan printing as the pages have very little ink on many of them. (books I bought there while in the NAVY were the same way. That's how I know)

Oh well, I'll finish up the SYE install,(having a hard time getting the front yoke off, gonna buy the IR2135Ti impact wrench. Tired of fartin around with the cheap Craftsman I have. YEAH I know, pipe wrench and a breaker bar BUT, I'll never use that pipe wrench again!) my DS will arrive tomorrow.

After I reinstall plugs and replace wires, if it still is hosed I'll take it to my engine mechanic. His specialty is ELECTRICAL, perhaps he can find it quicker. Has to be something originally related to heat. High temps (weather) caused the original issue. Fuel mixture related as well as it runs way rich and HOT. Should be easier to find for someone who does it for a living.

Could a TPS or the IAC cause this? Thinking of things I can change in the interim. I'd even be willing to try another distributor with a new cam position sensor. Even a new Crank position sensor. Seems I'd get codes with those though as they are electrical.

Any more ideas out there???

[Matthew Currie]

Metered out the injectors, all read around 14.5 to 15 ohms. DCV on MAP sensor 4.75 volts. BOTH great according to FSM.

Pulling the connectors off of injectors is a PITA. The little wire retainer is a bitch to remove. I'm assuming there is a special tool the dealers use?

Replaced coolant sensor as well. Still no joy. Pulled plugs and wires out for inspection. Cap is new as is rotor. All look OK.

According to FSM, mechanical issues are the most likely cause of no codes since they are not electrical. Found out the Chiltons/Haynes manuals are WAY OFF with their test procedures. If you tested your injectors and used their results, you'd think all your injectors were bad. Only thing they are good for it seems are the disassembly photos the FSM doesn't have. They aren't even printed well. My version is a Taiwan printing as the pages have very little ink on many of them. (books I bought there while in the NAVY were the same way. That's how I know)

Oh well, I'll finish up the SYE install, my DS will arrive tomorrow. After I reinstall plugs and replace wires, if it still is hosed I'll take it to my engine mechanic. His specialty is ELECTRICAL, perhaps he can find it quicker. Has to be something originally related to heat. High temps (weather) caused the original issue. Fuel mixture related as well as it runs way rich and HOT. Should be easier to find for someone who does it for a living.

Could a TPS or the IAC cause this? Thinking of things I can change in the interim. I'd even be willing to try another distributor with a new cam position sensor. Even a new Crank position sensor. Seems I'd get codes with those though as they are electrical.

Any more ideas out there???


If you suspect mechanical issues, I cannot stress enough the usefulness of a vacuum gauge. If you have valve or compression issues, this will show there. Many ignition problems will also show. If you have fuel injection problems it probably will not affect the vacuum at all.

As for the little wire retainers, what I did for testing was simply to remove all 6 of them for the duration of the test. The plugs will still stay on well enough to run. Not all Jeeps have them. There are at least 3 different versions of the connectors.

[thewrath]

anyone have anymore info on these injector wire retainers. last time i tried to remove one i couldnt figure it out. was worried i was going to break it, and just gave up. on my 2000 it seems like you just slide the red thing to unlock it, then press the release thing and it should just unplug no prob, but it just wouldnt come undone.

[dyna]

Loose intake manifold,leaking gasket.

[Rocketman]

OK... here's the list and it IS FIXED. Don't care what specifically but it's back to normal.

O2 sensor
Fuel Filter
Depressurizing and flushing fuel lines.
Reseating all injector connectors (as part of checking injectors.)
coolant temp sensor (not the fix but I did put in a new one)
New plug wires
New rotor
New cap

One thing... seems the fuel filter MAY have been the original. 240K+ on block. I know I've never changed it in 50K miles. Only have to wait now until I get my TC back together to get it out and road test.

By the way... I bought a IR2135Ti impact wrench, ($216 shipped from Gator Tools) you know the one with 1000lbs of "nut busting torque." Still cant get off the front yoke on the TC. Looks like mongo pipe wrench and the 1/2 breaker and a pipe cheater.

[SLAYER]

Did u get to road test it yet?

[Rocketman]

Road test OK. Short run. Need to remount exhaust before I go and heat it up. Don't care to esphyxiate myself by having exhaust pumping into the cab.

I'll give details later.

[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!!