Zj won't start idle!

[rtpalko]

So my 1996 zj 4.0 needed a tune up. Replaced the plugs(0.05 gap), distributor cap, rotor, plug wires, accel coil, spectre air filter and changed the oil while adding some Lucas oil stabilizer. Finished it and started it up. Fired right up and idled perfectly. Sounded great. Took it for a ride and was running so smooth then I came to a stop light about 10 mins down the road. And it sputtered and sputtered then died. Cranked it and after a while started back up. Then it died again 50 yds up the road. Thought it was gas, so I walked and got a gas can and filled it up to half tank. Checked all fuses and they're good. Battery died cranking it. Jumped it and it would only start when the pedal is to the floor. But will not idle. So I limped it home shifting in and out of neutral. Charged the battery to 100% and cleaned the air idle sensor. But still won't idle or start. Any suggestions? I have diagnostics software but it won't work unless it's running?(auterra Bluetooth software)

[HOT METAL M]

So my 1996 zj 4.0 needed a tune up. Replaced the plugs(0.05 gap), distributor cap, rotor, plug wires, accel coil, spectre air filter and changed the oil while adding some Lucas oil stabilizer. Finished it and started it up. Fired right up and idled perfectly. Sounded great. Took it for a ride and was running so smooth then I came to a stop light about 10 mins down the road. And it sputtered and sputtered then died. Cranked it and after a while started back up. Then it died again 50 yds up the road. Thought it was gas, so I walked and got a gas can and filled it up to half tank. Checked all fuses and they're good. Battery died cranking it. Jumped it and it would only start when the pedal is to the floor. But will not idle. So I limped it home shifting in and out of neutral. Charged the battery to 100% and cleaned the air idle sensor. But still won't idle or start. Any suggestions? I have diagnostics software but it won't work unless it's running?(auterra Bluetooth software)

3 basic thins for that motor to run, air fuel as spark. Since you did all the "spark" work, I would confirm fuel pressure at the rail and once established, go over the parts of the ignition system you overhauled. Something probably lossened up.

[HOT METAL M]

P.s freak occurence, could be CPS crank sensor symptoms as well.

You're obd2 right?

[rtpalko]

I went over ignition and everything is good so I am getting spark. And yes I am obd2. I wish I could try fuel pressure but I can't get it to idle so I won't be able to check that. My AIC was pretty dirty but I cleaned it quick with brake parts cleaner. I feel like it's getting fuel but maybe no air and I will check the crank position sensor. And I will try to check vacuum leaks as well might have loosened something up

[DMG]

Most obd2 tools will read stored codes with the key on. If you can't get any codes try this.
Disconnect the battery for 10 minutes, reconnect and do an idle learn. If that doesn't do it, try swapping your old coil back on.

[HOT METAL M]

Also your fuel pump should prime at a certain psi, just see if you have any pressure at the schrader valve during prime.

Evap / vaccum leak could also be a good culprit. Im with DMG, spay old ignition parts piece by piece.

[rtpalko]

Checked to see if I have fuel pressure. I just unscrewed the cap and then pushed the nipple and got a face full of gas so I think I have fuel pressure. I load tested the battery and it checked out and I also cleaned up the terminals which were covered in grease. Then I hooked everything back up and tried to start it but it just cranks and won't start regardless of me stepping on gas or not. I think I'm gonna try a new battery just because, and I have a couple sitting around.

[HOT METAL M]

Check cps real quick, swap w a known working one. And when you said you checked your spark, did you just look it over or confirm actual spark?

Also check to see if you foweled the plugs as well.

[rtpalko]

Just checked the fuel pressure. Just turned key to on and it primed and read about 45 psi. Then I let it sit for a 10-15 and the guage did not drop at all. It was weird though when I primed it and was watching the guage I heard a clicking noise from the throttle body. So I took off the tube and kept listening. It came from the AIC. I disconnected to see if it would stop and it did. Then I reconnected it and it would keep clicking every 20 seconds or so. I feel like I might have messed up the stepper motor in the AIC when I took it off to clean it because the spring and collar ended up coming apart and I spray the crap outa it with brake cleaner.

[rtpalko]

I put the old coil back on and it would finally fire back up but you would have to have the throttle to the floor. Next I tried taking the AIC off and disconnecting it and it would fire right up but would just be idling a tad high. So looks like I am going to replace the AIC and see if that does the trick.

[OverkillZJ]

Every damn ZJ i've owned acted like that once in awhile, and would need to be reset. Made no sense...

[HOT METAL M]

Nice find, keep us posted.

[rtpalko]

Air idle control it was! Runs great now especially with the new ignition parts. Next high flow cat and 3 in cat back exhaust then will run the dyno. Before all these mods 112hp and 125ft/lbs. Then short arm and some 33's. I'll put up a build thread soon for my college budget zj build!

[HOT METAL M]

Awesome

[rtpalko]

This thing is making me so mad. Thought I had the problem solved with the AIC. Started to stall when going to class last week coming down into town. Limped it to my local mechanic to see if he could take a look at it because I was out of ideas. He had it for two days and he couldnt figure anything out. Towed it home and replaced the battery because it would not hold a charge($120 wally world battery jeez!). Fired right back up no problem and hooked up my diagnostic software. Everything checked out. After getting to running temp in the driveway it was idling at like 750 rpm and my O2 sensors were putting out correct voltage. Thought I had fixed the problem with the new battery and took it to class the next day and when coming to a stop sign after driving it for 10 mins it would idle super super low about 300-400 rpm. In fear of it stalling again and not making it to my exams I two foot drove it to class and to then to my other mechanic and told him everything that has been going on so now we'll see what could possibly be the problem. If he doesnt know whats wrong then I am out of options. I have a summit perf 3in cat back and a 3in performance catalytic converter in boxes ready to go on but I think im going to hold off until I get a second opinion. Starting to think it might be a plugged cat. So we'll see!

[hyperbuzzin]

I had a plugged cat on my TJ. Never had any issues of stalling, just had no power.
Got plugged to the point of only being able to get up to 25-30MPH but no stalling.

[rtpalko]

Turns out that the problem was the brand new accel coil that I put on was faulty. Called summit and it was under warranty so I will be getting a refund for it. Replaced it with a new stock one. The new summit 3 in exhaust and high flow 3 in cat make it sound like a pissed off vacuum, but it runs so much better than what it did before. Off to the dyno to see the real gains!