[ubu]

I just bought a 93 ZJ with a 5.2L for $500. Previous owner said it will start, then die, sometimes if you hold your foot in it, it will stay running. This thing isn’t in the best shape. The ignition switch is buggered up and uses a different key than the door and the VIC doesn’t work, also “security” is illuminated on the dash. It was cheap, so I took it anyway. It seemed to run OK, just with a irratic idle. I figured the IAC as the culprit, so I picked one up on the way home along with plugs, cap and rotor.I got everything done Friday night and it ran great. Drove it about 5 miles down the highway Saturday to the park. After sitting for 2 hours, it wouldn’t run. It would start, rev, then die, even if I held my foot in it.

I finally got it home and was able to get codes using the key on-off. I had to replace the fuse for the VIC in order to do this. The CEL wasn’t on, but it still flashed codes
12-Memory cleared (because I disconnected the battery)
27-injector control circuit bank output driver stage does not respond properly to control system or, injectors 1,2,or3, control cuircuit and peak current not reached.
31-purge solenoid open or short
32 EGR circuit open or short, failed to adjust air/fuel ratio
53 internal control failure, failed self test.

OK. Wow that’s some codes. The 27 and 53 scared me into pulling a used PCM from from Pick-n-Pull. I installed that Sunday morning. I also replaced some vaccum lines I broke leading to the purge solenoid. After running with the replacement PCM, I got weird idle and more codes. Also started, then died once.
25-IAC (which I already replaced)
31 Purge solenoid
32 EGR
53-internal control
I din’t get 27 this time, unless I read the flashes wrong the 1st time and it was 25.

I double checked my vaccum lines and realized I got the check valve to the TB backwards. That made the idle smoother, but still a bit high. I disconnected the battery and left it overnight. I’ll if it still throws the EGR codes tonight.

I don’t really know what to do at this point. Maybe I got a bad IAC or I buggered it up by twisting it? What really bothers me is the start then die problem is intermittent. Also wondering if it has something to do with the security system.

[ubu]

OK. I did some searching and formulated a plan.
The battery is disconnected right now hoping to reset the PCM. The thing runs ok when it runs. I think the security and ignition are confusing the PCM.
1. Tear apart dash and remove security module. The security light comes on intermittetly and sometimes I have no MIL. Probably more problems to address behind the dash.
2. Fix ignition switch. I pulled a used one already, but I don't know if I should get it keyed or if I can switch out lock cylinders.
3. Exchange idle air controller (don't know if the one I bought is defective or what)
4. Clean throttle body-couldn't hurt.

I suspect the EGR issues are separate from the start/die problem. Either way step 5 will be to check vaccum lines and possibly replace the EGR valve. The vaccum lines are all hard and brittle.

[tirus89]

The ignition sometimes uses a different key than the door. Dont pull the dash, just disable the alarm on the driver side door, theres a write up here somewhere, IAC is probably not defective, and the TB cleaning will help.

[craddock01]

I had a starting problem similar it was corrosion on the prongs of the fuel pump relay. Getting low voltage/no voltage to the fuel pump.Cleaned it up never had a problem since.

[ubu]

I pulled the security module from behind the glove box last night. Didn't take long at all. That wasn't the problem, though.
I swapped fuel pump relays and that didn't do anything. What do I need to do to check that circuit?
I'm going to try and get my replacement ignition switch keyed today. I don't know it's part of the problem, but it should be replaced anyway. as the lock cylinder just flops around.

[skilled1]

have you checked the grounds for the dash frame. i know zj's are notorious for the bolts that bolt the main dash frame to the body will build corrosion or work loose causing some really wierd stuff to happen. might be worth checking. also i would recomend a fuel pressure test and put a fuel filter in it if you havent alredy always a good idea if fuel is suspected as a problem.

[SouthZJ]

Could be fuel presure regulator, you should check the presure on the fuel rail just to make sure its not that

when you dont get it to start, do you have spark?

do you got any play in your destributor? And dont take it out without marking the place where it was befor as good as posible even when it is just a bit off it will cause your engine to sometimes start but then die

[ubu]

Originally Posted by skilled1

have you checked the grounds for the dash frame. i know zj's are notorious for the bolts that bolt the main dash frame to the body will build corrosion or work loose causing some really wierd stuff to happen. might be worth checking. also i would recomend a fuel pressure test and put a fuel filter in it if you havent alredy always a good idea if fuel is suspected as a problem.

That's part of the reason I decided to just take the dash apart. The security system was becoming a PITA every time I disconected the battery, so I just got rid of it. The radio doesn't work correctly, not really a problem, but I suspect some issues behind the dash. Also, I noticed now that the brakes lights are stuck on.

[ubu]

Originally Posted by SouthZJ

Could be fuel presure regulator, you should check the presure on the fuel rail just to make sure its not that

when you dont get it to start, do you have spark?

do you got any play in your destributor? And dont take it out without marking the place where it was befor as good as posible even when it is just a bit off it will cause your engine to sometimes start but then die

I still need to get a gauge to check fuel pressure and replace the fuel filter.

It fires, so I'm pretty sure I've got spark and fuel. Maybe not the correct amount, though.

I could wiggle the rotor a bit, but it didn't seem any different than any other vehicle I've changed a rotor on. It fires but doesn't stay running. The problem is intermittent. It ran great Saturday after new plugs/cap/rotor. Then wouldn't start at the park. Sunday I got it running, but it ran like crap. Last night if fired, then died.

[ubu]

OK I guess I screwed up by just removing the module. The module sends an ok to start signal to the PCM. It needs to be running before you can remove it. I guess I'll just ground out the purple/yellow at the door.

$80 bucks to re-key my used ignition. I checked the junkyard and no key for that one. But, there is another 93ZJ there with the key. I snagged the key and I'll grab that switch.

I'm not sure if any of this is THE problem, but it all needs to be addressed sometime, right? What did I expect for $500?

[BliZZard911]

Check the condition of the wiring to the fuel pump. I had this problem for several months and it was driving me crazy. When I decided to actually re-wire the harness I discovered that water must have entered in through the harness plug and the wires were black and rusty inside the insulation. I rewired from the fuel pump forward about 3-4 feet (basically kept cutting until I got to good wire). This solved my starting/stalling issues completely.

The wires will test GOOD for continuity but they won't carry a consistent 12v to run the fuel pump.

[the88thpianoman]

I don't think anyone mentioned this... try replacing the TPS to smooth out the idle. That'll run you about 40 bucks at advance auto, part number EC1089P.

[ubu]

Last night I got the TB cleaned and reinstalled with my new TPS and IAC motor. Put a used ignition switch in along with the security module and PCM, all from the same vehicle. Oh, and the new fuel filter I've been meaning to put in. Started up and ran, but the idle was around 2 grand. Swapped IAC, nothing. unplugged IAC, nothing. Unhooked TPS, no change. No MIL, no check engine light. Basically no engine control, so I checked all the fuses.

I went to bed stumped.

This morning after a brief T-storm, I decided to check for power to through the fuse block to the ECU. Just for the hell of it, I attempted to start. It fired right up and settled into a nice idle. I had MIL and check engine light.

Looks like I'm on the hunt for a ground, short, or relay somewhere in this maze of wiring

If anyone has a clue as to where, I'd appreciate it.

[Jcamaro123]

ever figure this out?

[Rich93ZJ]

Originally Posted by Jcamaro123

ever figure this out?

Last post was almost 4 years ago