My 89 xj idles rough and wants to stall out. If I don't touch the gas it will sit around 3-500 rpm. Sometimes it will die right when I give it gas. It won't make it out of the drive way because you have to go up a 20 ft hill, backwards. Here's what I know:

-Fuel pressure is constant 31 psi when running
-Vacuum is around 15-17 mm Hg when idling
-I am using Ford Yellow bodied injectors (Bosch)
-CPS terminals A and B tested out to 225 ohms
-Brand new TPS, adjusted to make ECU terminals C and B read .8 volts
-Recent semi-rebuild, ( headgasket, lapped valves, valve stem seals, intake/exhaust gasket, ect..)

I am clueless, one thing I do know is this Jeep is reminding me of my last v6 Toyota!

 

Have you done a compression and/or leakdown test? Did these symptoms appear before or after the "semi rebuild"?

 

Has the o2 sensor ever ben replaced?

 

Haven't done a compression test, and it doesn't seem to be missing. Compression is on my list to check out though.

I bought the jeep and replaced the engine, the old one had water frozen in it and not of the valves shut.

The weird thing is that I had it running (nicely) and driving before, but it wouldn't shift. So I checked out the TPS and it was junk. Now it shifts like a dream, but runs like crap.


And no for all I know the o2 sensor could be 22 years old.
I attached a pic of my garage floor after idling for 5 minutes. And no I am not a splatter paint artist.

 

o2 sensor would be on my list of things to check. Before a compression test, that's for sure.

 

"Now it shifts like a dream, but runs like crap"

If thats the only change is this situation, it's got to be something with the TPS.

 

Good call. I just unplugged it and tested resistance between A and B (red and black) and got a 1, which is infinite on my meter I believe. Left it unplugged and started the Jeep, starts great, but same symptoms or low bouncing idle. Oh yeah and it still smells like a two stroke outboard.

Are there any specific brands I should be looking for? I know Bosch o2 sensors aren't good in anything but Audi's and BMW's.

 

I used these adjustment instructions:


Located on the right side of the front of the throttle body. To test, disconnect the connector at the TPS. Check the voltage at TPS connector pins B (Ground) and A (5.0 volt supply) with the ignition on. If you see about 5 volts, hook up the connector again. and check the voltage at TPS terminals C (positive) and B (Ground) with the ignition on and the throttle plate closed. You should notice approximately 0.8 volts. If you see that voltage, your TPS and wiring should be ok. If not, you'll have to adjust the TPS to get that voltage. If you cannot adjust the TPS to get that voltage, you'll have to replace the TPS and adjust the new one properly. Also, with the voltmeter hooked (terminal C) up and the ignition on, move the TPS arm down and back up slowly and watch the voltage. The change should be increasing and smooth. If there are any dead spots or it is not smooth, it probably needs to be replaced.




I can't seem to find consistent instructions on forums and other sites, maybe I should try these: http://autorepair.about.com/library/faqs/bl232i.htm

 

Check TPS voltage with the ignition on you should see a steady rise from the inital .8 to 5 volts. (The engine off, ignition on)

You can also check resistance by leaving the ignition off and opening the throttle valve. You still want to see a steady sweep (an analog meter is a better choice than digital).

Are the connectors in good shape? Corrosion can cause all kinds of problems.

ETA: Can you get an inital setting of .5 volts? If you can, see if that makes a difference. As well, have you checked the coolant temperature sensor? (not the sensor for the dash gauge btw.)

 

What do you mean .5 volts? Is that for the ECU connector voltage?

I checked the CTS and it was at 1600 ohms cool (100 degrees or so)

The new oxygen sensor is in and it runs a lot smoother, but it still wants to die.
If I keep it above 1000 rpms with the gas pedal its fine, but if i stay off the gas or even gas it below 1000 rpm it will bog down and die. I'm wondering if this could be because my cooling system wasn't properly burped.

 

Wrong fuel line...

 

Today I took the jeep out to a "jeep guy" (owns a jeep parts yard) and they helped me by switching out IAC's. Did nothing at all.

They even gave me an EGR valve to try, no change either.

So after getting stuck in a round about at Fred Meyer's, and then having the engine stall 3 times while looking for a parking space. I was pretty mad. On top of that I stalled out on the turn lane to the freeway.

I'll post a video tomorrow. But an update for what the jeep is doing: Starts great, but the idle will drop to 150 - 300 RPM (first mark on tach) and it WILL idle there fine.

Once you hit the go pedal it does the exact opposite and will just die. Like your legs fall from under you when you stand up is the best way to describe it. The only way to avoid this is to floor it, which isn't and option in traffic and on gravel.

 

Just a thought. I have those injectors. I was running them with the.pintle caps not knowing our bosses don't have a lip for them to sit against. Mine started idling real rough like it had a cam. I pulled the.injectors.and found.two pintle caps.cocked sideways on the injector messing up the flow.

 

I don't think mine have the caps on. How do you like the injectors? have they given you any other problems? And did you notice any difference from stock?

 

Much better throttle response! Prob partially cause they're clean.