Car Died, Stranded, No Codes, Replaced Practically Everything

[Marccus]

I've been struggling through this hard cold start, loping idle / tach, stall problem for eight months.

The other night, the car shakes and stutters and stalls - typical CID problem or loose ground which I have had before.

Ran codes and got #18 (CID), and #48 (DIS). But these are continuous codes not hard fault codes picked up in KOEO. They just clear when I clear the memory.

But I just replaced those the CID and DIS 6 months ago. Then drove this morning and again same hard cold start problem but it stalls at a red light and that was the end.

Pushed it off into a parking lot and ran codes - none. Everything comes back as 11 11 - everything is OK. But I changed out the CID and DIS back to the old ones and it will not turn over.

Here's what I've done in trying to solve this problem:

New CKP, CID, DIS, fuel pump, fuel filter, plugs, wires, fuel injectors, MAF, starter.

I am waiting for a new PCM but I ordered regular delivery (to save $30 in shipping) instead of 2-day so I have to wait 5 days and be stranded.

What gives?
What else is there to check?
How can I diagnose and trouble shoot the problem if there are no codes?

So if nothing works I guess that it is just time to put it to rest in the junk yard.

Please any help and at least getting it started and back home would be appreciated.

 

[LOUDSHO92]

Well for the DIS a very thin film of dielectric fluid is sometimes used. If too much is used it can casue problems.

The idle might be due to a bad IAB. You can clean it and test it with a 9v battery.

 

[Marccus]

But why am I not getting any codes?

I've replaced the IAB three times in the last several years.

 

[shonuffmine]

have you had the crossover tube off the manifold???You know where the DIS module mounts!are the 2 bolts back on and it is not hanging just off the clamps? if they are out you motor will act ape shit and not throw codes! Ask me how i know this and i can tell you a horror story from ****.From Rehobeth bch. delaware to bangor maine 4 days (2 nights in the car cause of no hotels within 30 miles and waitin for parts) a DIS MOD,2 CPS mods and a TPS ,ALL cause of 2 freaking bolts causing the DIS not to have a ground

 

[Devin]

Speaking of which, make sure your bolts that bolt the DIS to the intake are clean, as one of them provides the ground.

 

[itwonder]

Troubleshoot. Get an LED type 12V test light and probe each of the pins at the DIS while cranking the engine. The SHO engine book, link http://alfitz.com/sho/index.html has the pinout. You can observe the signals for CPS, CID, ECM, coil packs. See if anything is missing. Run temporary ground wire from battery negative to one of the lower DIS mounting bolts to rule out ground issue. Unplug MAF and try it.

 

[kevinspann]

Timing/Timing Belt?

 

[Marccus]

I replaced the timing belt along with the CKP.

 

[Marccus]

Here's the problem .... I think.

I thought I'd try to start the car one more time before abandoning it for the night.

Just prior to starting it, I looked for the blue cap that fell of the A/C suction line port. It fell between the firewall and the engine. I moved the large bundled wire harness around with my hand. A long time ago, my harness fell off that bracket that held it up and I couldn't remount it. But the harness looked OK.

The "harness" at this point is a bundle of many smaller harnesses. One of the smaller harnesses had settled lower and a small portion of it was resting on top of the exhaust manifold heat shield. There was a very small amount of black residue on the heat shield perhaps from some adhesive of the harness wrap.

But the harness wrap is extremely fire and heat resistant. It didn't look damaged at all and I could feel the white Christmas tree holder on the underside that rested against the manifold as complete and intact; I could feel the sharp points on it. I never smelled any melting plastic odor.

I couldn't find the cap, so I went back in and started the car. It started up perfectly - like it was brand new - like it had always started up before this 8 month nightmare. The tach immediately settled exactly on 1000 rpm and didn't move a nanometer. It idled smoothly.

I decided to take a chance and drive from where I was stranded back home. No problem. After about 2 hours, I decided to start it again. It did not start up smoothly and did not idle smoothly. It settled after awhile but was chugging a bit. After 5 minutes it stalled without warning and the tach dropped like a rock.

I went back out and moved the bundled harness again; lifted it high and then let it drop down smoothly. I still couldn't avoid keeping the smaller harness from having a small portion of it settle on the exhaust manifold heat shield.

I started the car back up and it was perfect again.

I don't believe the heat damaged the harness or any of the wiring, but something happened to a connector and/or wire from the strain of the settled small harness that has led to a bad connection which gives rise to code #19 showing up - bad CID.

To me this is going to be impossible to find, so I'm thinking that I can wire the CID connector separately in it's own harness to to the terminal points of each wire in the connector. Either that, or I will have to pay my four year old nephew to get under the hood and hold the harness up while I drive the car. His mother, my sister, did not find the humor in the latter solution.

I'm going to lift the large bundled harness up at this point closest to the fire wall with zip ties to hold it high off the exhaust manifold heat shield. But prior to this, I am going to disconnect and reconnect each of the connectors on each of the smaller harnesses. I'll use some electronic cleaner on the contacts and smear some dielectric grease on them before I reconnect them.

Perhaps the problem is with a loose connector and not a wire.

Of course, this could all be coincidence, I don't know if I prefer that or not, because finding the location of the exact fault is going to be very difficult, whereas isolating the problem to a sensor or damaged connector at a sensor would be much easier to solve.

But I've replaced practically every sensor on this car.

Note that moving around the wires closest to the CID connector and disconnecting and re-connecting the connector itself did not solve the problem.

I have to try to solve this problem because running outside the care, lifting the hood, and messing with a wire harness when I stall at a red light is not an option. Also there is no guarantee that this will keep solving the problem but just might exacerbate it and will someday no longer work.

If anyone has any suggestions let me know.

Thanks.

 

[93rev2sev]

I've been sorta following this for a while now and I'd strongly suggest you do some cranking compression tests...while the engine is cold, warm...hot...do a bunch of em.

My 93MTX exhibited the same symptoms of intermittant cold start harshness and stalling for a long time before the condition became permanant. The problem was (is) that it had a sticking exhaust valve. The valve would stick open and the engine would shake until the head got warm and the valve started moving...finally, it spit a shim and the engine has been declared dead.

 

[Marccus]

I've been sorta following this for a while now and I'd strongly suggest you do some cranking compression tests...while the engine is cold, warm...hot...do a bunch of em. ...

Well, I HAD planned on doing that, but then I ran across this. But if compression is a problem, why would moving the harness affect the performance of the engine?

Latest info ....

if I picked up the harness on the the passenger side of the firewall, the engine would start to die, if I let it down it would return to normal, ... pick it up and starts to die ... lower it and returns to normal.

So I moved to the driver's side and picked the harness up near the speedometer cable, the engine sped up and when I lowered the harness it returned to normal ... picked it up and the engine sped up ... lowered it and it returned to normal

Then I pulled up a little and twisted each connector on each the harness. Now the engine isn't affected by anything I do to the harness.

I think what you suggest to do is good anyway. I am going to visit Nick Chrimes tomorrow and have him look at it. I've never had a compression test done and it would be a good idea to know what it is with so many miles on the engine. The cost is minimal compared to the consequences of not knowing.

I was also thinking of a leak down test. Good idea too?

I don't have the ability to work on my car in my current living situation or I would "try" to do the compression and leak down test myself and learn how to do it.

Thanks for the suggestion.

 

[gmorrell]

One of the connectors on the "connector christmas tree" between the rear surge tank and the firewall is a round 4-pin unit that has only two or 3 wires in it, but two of the wires supply Vign (switched +12V from the IRCM) to all of the sensors and actuators on the engine. (Crank and cam sensors, ISCBPA, IMRC, fuel injectors, coil pack, etc.) I've seen this connector go wacky, and when it does, nothing works.

Long ago and far away in Gen 1 SHO history there was a harness chafing issue in the same area - caused intermittent poor running, stalling, and no re-start issues. There was a TSB about it, but I'll be damned if remember the number.

 

[elarm1]

Have you looked at the spark plugs lately? Try giving threm a look and tell us what you see

 

[ViPER1313]

One of the connectors on the "connector christmas tree" between the rear surge tank and the firewall is a round 4-pin unit that has only two or 3 wires in it, but two of the wires supply Vign (switched +12V from the IRCM) to all of the sensors and actuators on the engine. (Crank and cam sensors, ISCBPA, IMRC, fuel injectors, coil pack, etc.) I've seen this connector go wacky, and when it does, nothing works.

Long ago and far away in Gen 1 SHO history there was a harness chafing issue in the same area - caused intermittent poor running, stalling, and no re-start issues. There was a TSB about it, but I'll be damned if remember the number.

My friend had an 89 SHO with a chafing issue on that rear harness - a previous owner did not re-install the bracket that the harness sits on. The loom rubbed back and forth on a body seam until it wore through the wire loom and partly into one of the cam position sensor wires. It caused random stalling (especially while turning) and stuttering, especially when the motor got warm. Never had any codes initially until one day it threw a cam position sensor code (which I had already replaced to no effect.) Once I found the chafing and repaired it with 2 cents worth of electrical tape, the car ran perfectly (and continued to run perfectly for the next 10k miles.)