92 yj... I'm stumped

[4x4phil]

Idles kinda rough, and at a lower rpm than it should. loses power and cuts out like it has a spark plug wire jumping around while driving. Runs hot and very lean. It's turbocharged so we thought it might be fuel delivery. Changed the filter, then the pump, tested the fmu, fuel pressure is great. Fuel to air meter reads very lean at idle and won't even read when you hit the throttle. Back fires a little bit when you let off the gas. It's not pulling any codes. Plugs and wires are fine. Boost retard and msd ignition are good. I noticed the wires going to the timing sensor on the bell housing melted on the manifold so I changed them, but not the sensor. I figured if it was bad it'd pull a code. It does seem like a timing issue, but why then would it be running so lean? I'm lost. This isn't a problematic vehicle, and nothing's half done. I don't think it's upgrade related. But I cant figure it out so what the hell do I know. Somebody throw me a bone. Maybe it's something simple and Im just too flustered to see it.

 

[RockMonkey]

You've got a lot of symptoms there. I have very little to contribute, but the low idle symptom sounds like the idle speed control motor wich is problematic in YJs. Good luck. Let us know what you find.

 

[78mitsu]

have you checked your timing - also knock sensor (If it has one I'm not that up on YJ injection)

-Sounds to me like a fuel delivery problem (accounting for lean-burn) and the heat problems. May want to check to see if it has a couple bad injectors or mis-firing injectors. Since it's turbo charged may also want to check the waste gate on the turbo, too much boost can cause what you're talking about too.

 

[4x4phil]

I changed the tps and the idle control motor tonight in hopes it might help. I no longer have problems with low idle, but still with it running lean, getting hot, and cutting out. I'll check the timing and fuel delivery again. I'll also check the injectors. Any tips are appreciated.

 

[wr250]

change the fuel filter
check the fuel volume; should be ~ 8oz in 15 seconds. the pressure may read fine ,but if the volume isnt there, then it will run lean.

 

[jeeponthebrain]

You said "nothing is half done", I seem to remember getting tangeled up in some wires and gagues on the floor...... Just kidding!

I remember seeing an article in one of the four wheel magazines about a four cyl with a turbo. Maybe you could do a search on their web site to find it. It may give you some ideas of things to check out. Good luck!

p.s. Come get these revolver shackles! And, since you have enough to worry about, I will take your offer, $80 and the're yours!

 

[4x4phil]

LOL, You're right about the guages. I got them mounted finally. wr250 how do I check volume?

And I changed the injectors tonight, Ive already changed the filter. Timing is good, but I'm gonna change the plugs, wires, cap and rotor sometime this week. I'm also gonna change the thermostat. I pulled the o2 sensor again and made sure it wasn't fouled, even though it's new. I pulled apart the fmu to make sure its clean.... it was. I changed the fuel pressure regulator 125$ when I pulled the rail to install the new injectors 79$ each. After everything I've done it still runs the same, with the acception of the idle (trying to look at the glass half full.) Can anybody find me a good deal on a grenade?

 

[wr250]

wr250 how do I check volume?

you need to turn on the pump for 15 secs, toyota has a jumper for this. turning the key on/off 4x will work to (electric pumps run ~2 secs per key on) if mechanical, you will need to crank the motor (works for electric pumps too), with the coil wire off.

should of changed the plugs/wires/cap/rotor 1st. just because the check engine light isnt on, does not mean there is no codes.

 

[Samuraiman]

It's a JEEP THING I DON'T UNDERSTAND>

 

[wr250]

also check your cat. if its come apart and restricting exhaust, may cause the symptoms you describe.as i recall the 02 sensor is on the muffler side of the cat, if partially plugged, will read lean.
just crawl under it and hit it with your hand (eng cold lol). if it rattles or sounds like it has sand in it replace it. if the 02 sensor is behind the cat then you have to replace it. if the 02 sensor is in front , you can gut it (not recommended).

 

[4x4phil]

I still haven't had time to change the plugs and stuff. Thanks for the volume tip. I'll check that out when I get a chance. I have no cat. Took that out when we rerouted the exhaust.