Randy V

Started up this morning and got the failed ignition bank problem. Gas smell and running on half the cylinders.

Where to start to isolate the problem?

Thanks.

DR

Hi Randy,

Hope you are going great!

The most common issue is gonna be the EGT Sensors for the Ignition Monitor System. 99% of the time the sensor is just dirty and needs to be cleaned. In the old days we would swap them side to side to verify the issue. The most common side is the drivers side, but you can find out for yourself by pulling back the carpet from the Fuse Relay Panel and look to the far lower right of the panel Large Clear Device (see 1st pic below) with a Green or Red Light Glowing.. Red = Left side, Green = Right Side.

If cleaning doesn't work, or you just want to replace with a new one and move on, the part number is 928.606.155.02

Hope that helps ole buddy,

Dave

SeanR

DR

Good point Sean, Thanks!

Randy, check those lights with engine running in half cylinder mode, if you have none, then for sure Sean is dead on!

Happy Friday night to you both,

Dave

DR

Hi Randy,

I found your LH Failure thread back in 2014, part of the discussion was about Bypassing the Ignition Monitor Relay and Rob showed you some pics of how to bypass it, you next reply was :

So did you make that jumper and bypass the system?

FWIW, If I owned a GTS I would reinstate and repair that system. IIRC you have already had one fire... that raw gas you could smell from just standing there, think about how much fuel was being pumped out at road speeds?? Anywho, I know lots of people here say to bypass those, but once I cleaned mine for example on a 100K+ mile 928, that you can bet never had them cleaned before, I never had an issue again. Obviously this shouldn't happen and whatever the other ignition issue might yield the same results even with the system intact. I would just feel better with it operating as designed on a darn nice car like that.

Have a great evening,

Dave

dr bob

^^^^ What Dave Said. ^^^

dr bob

Then grab your inductive timing light and figure out which ignion system isn't working. It's often Stupid Stuff like a coil wire loose.

Randy V

Much thanks, guys!

I did look at that module shown by DR, will check it again.

I don't see the lights referenced by DR. Anyone can tell me where they are seen in that clear module?

Incredible memory, DR! I barely recall that fix on my own car from four years ago!

When I looked at that module yesterday, the pins located on the bottom right of it were exposed, without a harness plugged into it. So guess my previous mechanic did bypass it as was previously recommended.

Will find that connector and see if removing the jumpers and reinstalling it corrects the problem.

DR

Hi Randy,

This might help you understand what this system does...


In other words the Ignition Circuit Monitor System lets you know there is an Ignition problem and which circuit (and cuts off the Fuel for that circuit for safety), BUT it does not fix (or break) anything.

Cheers,

Dave

Randy V

LOL

Where are the indicator light located within the module? I'm guessing they are obvious if they are illuminated?

DR

You would see them if they were on. But according to your statement in bold above, you ain't gonna see nothing with it unplugged.

AND, that is not the focus of your issue at the moment, you have an ignition problem that needs solving, the Monitor System can come later, although if functioning, it would only help you by a factor of 2(50/50 chance) in figuring out which Ignition Circuit of the 2 is the culprit.

When the time comes, this will help you understand and reinstate the Ignition Monitor System, special Thanks to Theo for the pdf.
http://jenniskens.livedsl.nl/technic...01989-1994.pdf

Happy Saturday,

Dave

DR

Hi Randy,

Wow, I spend the rest of the day outside supervising Jeannie doing some landscaping:-)...and nobody has helped you with the normal ignition troubleshooting.

Things to check:

Coil Wires from Distributor caps to Ignition Coils, remove and reinstall both ends to make sure they are seated good. While each side is disconnected trying starting it for a few seconds. If when one is disconnected and it starts (and runs 4 cyl mode), then you have found the bad side. If it doesn't start at all, you have the good side disconnected. Once you nail that you know which Circuit you need to focus on. Oh, the coil wires on the drivers side sometimes likes to "play" with the large power supply cable for the ABS. Make sure they are not touching each other or routed within an inch of each other.

Distributor Caps and/or rotors. Inspect for extreme wear or fractures in the cap. If you don't have records of new ones in the last 5 years, I would replace them

Coils, one could be bad. You could swap coils from side to side to see if your symptoms move. Again, if I don't have records of those being replaced in the last 10 years or less, I would replace them.

Final Output Stage Modules (less rare IME), these are the boxes with the rectangular plastic covers over them to the drivers side of the lower hood latch. Carefully remove those connectors and swape them side to side, see if the bad side changes to the other side or not. If it doesn't change anything, they are OK, if it does change, you have the culprit.

There are other things to check but I tried to put them in the order I feel you should try based on failures rates I have observed.

Happy Sunday Morning to you,

Dave

Randy V

Thanks for hanging with me, Dave!

That passenger side coil is a biotch to get to!

Will run the tests you recommended and report back.

Enjoy your Sunday - my best to to missus JR!

Randy V

OK, pulled and reinstalled the main wires to the coils. Isolated the problem to the right (pax) side.

I removed the jumper and reinstalled the connector on the IMS. I couldn't see either a green or red light illuminated in there, but now there is no raw gas smell when engine is stumbling along.

Where are the EGT sensors for the IMS located?

Speedtoys

Directly under the exhaust ports on the heads is where they plumb up into the exhaust ports.