IRCM Woes

[BaySHO Performance]

1990 SHO, having trouble starting and running. May have a code 14 (PIP) with the WP leaking on to the CPS.

Trouble is, often when I turn the ignition on (engine off), the IRCM clicks like crazy, as do the injectors, with spark at the plug wires. I tried another IRCM, clicking went away, reconnected original IRCM, no more clicking. I originally thought that the IRCM connector was loose. No pushed out terminals in the connector.

Started the car today and it idled for 4 minutes before dying. Went to try a restart, and the IRCM is clicking again. Does the same with 2 other IRCMS. So not a loose connector after all.

Pull codes KOEO with the IRCM still clicking. Fan didn’t come on.

On Demand:

66 MAF circuit below minimum voltage. OK, may be a problem with the MAF, but that’s not going to cause the clicking.

98 EPC (Electronic Pressure Control) driver failure in processor. Doing some digging, the EPC is part of an automatic transmission, so has to be a bogus code.

It wouldn’t put out the stored codes.

Anyone had this problem before? The only thing I can think of before tearing into the circuits is to try a replacement ECU.

TIA

Nick

 

[sperold]

Your hunch on the ECU is a good one. That is your best bet.

 

[sperold]

Only 5 wires between the two components, so maybe look at these wires near the components. The list will look like this - the first terminal # will be the EEC, then the wire # and the colour, and the last terminal # will be Integrated control module (IRCM or CCRM):
1 - 37 yellow - 8
41 - 926 light blue/orange - 11
54 = 331 red - 22
56 - 197 Tan/Orange -14
19 - 787 pink/black - 5

Another list to name the duty of the wires in the same order as above;
12V power
EEC Module
Wide open throttle AC cutout switch
Coolant temp switch to control relay
Fuel pump safety switch

Hope that helps.

Also, people absolutely swear you can get more codes out of a Gen I with the paperclip method as apposed to a code reader.
http://web.archive.org/web/20070518111620/http://www.shophoenixproject.com/eec/eec.htm

And... dry out that crank position sensor completely as that injector noise and spark could be the sensor thinking the little shutter wheel is telling it something, and trying to fire, to accomodate it.
Might account for it running for awhile, then dying.

 

[rubydist]

I would check over all the grounds carefully - to the pcm and ccrm both.

 

[sperold]

This ^^^^^^
Some interesting facts / coincidences:
The ICM (pins 3, 4, 15) and the electric cooling fan shares a ground
The mass airflow sensor and the EEC (pins 40 & 60) share a ground (the battery in this case)
The crank position sensor and the EEC (pin 49) as well as the shielding for the
EEC, DIS, Crank Position Sensor, share a ground

The cooling fan, the maf and the crank position sensor all have odd performances in your car in the start-up phase.

The fuel injectors have a lot to do with pin 24 on the ICM and show up on pins 58, 59, 12, 13, 14, 15 (cylinders 1 to 6) at the EEC, but this is not a ground issue directly.

 

[luigisho]

A computer swap is quick so you can do that and see what happens but the funky codes and general bad behavior of several components usually is electrical. I've noticed a lot more of these issues pop up in last few years. The age of the wiring and ground connections are looking to be a problem after 25 +- yrs

 

[cali+Mocasho+]

ran out of gas last night. couldnt start the car for 20 min after refueling. today the car died on me and wouldnt start back up. it cranks and spudders. think i killed the fuel pump?

 

[luigisho]

Check for pump priming at startup and pressure at the fuel rail. I would check codes.

 

[luigisho]

Nick,

Any progress on this???

 

[cali+Mocasho+]

Check for pump priming at startup and pressure at the fuel rail. I would check codes.

im thinking the computer glitched, i drover it 6 miles today and it died turning into the parking lot. i parked it unhooked the battery for half an hour and it started back up. hopefully it dose not die on me anymore. when i get home ill pull codes. thanks!
quite an old post.

 

[sperold]

Actually, you are hyjacking a new post that was started on Tuesday.

You will get more help and answers if you start a new post that has a title that highlights your problem.

It could go in the emergency section since it is, in this case, if you want to keep driving.

 

[cali+Mocasho+]

sorry about the hijack i misread the date.

 

[BaySHO Performance]

Nick,

Any progress on this???

I discovered that if I bumped the crank a few degrees, the clicking stopped. No prob with the IRCM. The WP had been leaking on to the CPS. Replaced both, but the clicking persisted. Replaced the computer, the clicking went away. My guess is that the compromised CPS fried the computer.

 

[SHOtimer]

My guess is that the compromised CPS fried the computer.

Interesting theory. With as many CPS's that have gone out over the years in SHO's you'd think if their was this type of connection it would be a bit more common.

 

[sperold]

My experience with SHOs is that a lot of things can go wrong at once, sometimes related to each other, sometimes not.

What about the idea that some sort of "water- wetter" or other chemical additive played a role in the electrical activity?

 

[BaySHO Performance]

Interesting theory. With as many CPS's that have gone out over the years in SHO's you'd think if their was this type of connection it would be a bit more common.

Well, I've never come across this clicking before, having owned nothing but SHOs for the last 24 years, and having worked on over 250 of them over the last 15 years.

Computers can go bad, and how that manifests itself can be all over the map if the software gets compromised. For instance I have a couple of B9C1's that throw a false code 19 for the camshaft sensor.

 

[SHOtimer]

Well, I've never come across this clicking before, having owned nothing but SHOs for the last 24 years, and having worked on over 250 of them over the last 15 years.

Computers can go bad, and how that manifests itself can be all over the map if the software gets compromised. For instance I have a couple of B9C1's that throw a false code 19 for the camshaft sensor.

Maybe you took my post wrong, I'm not waving the BS flag at you. I was just more or less thinking out loud.

I'm also not arguing with how many SHO's you've owned or worked on. I know you own a business that keeps these cars on the road, and for that I am grateful. I spent most of my life in Salinas (just south of you), but managed to keep mine going without making a trip up there. I agree that computers do go bad, and can manifest themselves in different, weird, ways. As my post indicated, I thought it was an interesting theory - not claiming it was wrong or right. These cars do make us theoreticians after all!

But, as luigisho commented I think as the electronics in these cars age, they start to present all sorts of odd issues which will become more difficult to solve.

 

[BaySHO Performance]

I know you weren't waving a BS flag. No worries on that score. And yes, it's only a theory. But if software gets corrupted it can lead to all sorts of weird results as you say, as was this case. Back in the sixties I was a Fortran programmer. I had a program that would crash at a different point every time I ran it. Turns out I had overwritten the value of one.