mark928gt

Ok, so I can see from doing a search that this topic has been beaten, a bit, maybe not to death so here I go.

IMS relay trips intermittently sending the car into 4 cylinder mode.
Green light comes on indicating there is trouble with ignition circuit #2.

Here is what I have done. The intermittent tripping of the relay remains and never has switched from ignition circuit #2.

New plug and coil wires. Just finished my rebuild and all of this is new.
Swapped coils from one side to other. Problem remains w/circuit #2.
Swapped coil to distributor wire with my old one (that worked fine).
Checked all grounds. All tight and no corrosion.
Checked 4 wires coming off battery. Tight with no corrosion.
Checked temp sensors:
Idle between E1 and E2 on IMS relay is 3.2mv
2000 rpm between E1 and E2 is 1.6mv
This appears to be in tolerance of 2.5mv acceptable range.
Checked IMS relay:
12.3V at terminals A1, A2, 15, 87 with key on.
12.3V at terminal AL with engine running.
14.1V at terminal 61 with engine running.
2.77V at terminals E1 and E2 with key on.
Ground at terminal 31 and AL when key is off.
Rotated the temp sensor for ignition circuit #2 just for fun.

All checks seem to be in order. Any thoughts on where to go next?

soontobered84

When I changed plug and coil wires on the GTS, the IMS was kicking off half the engine. What I found was the plastic cover on the driver's side coil was interfering with the coil wire connection at the coil. If you shoved the coil wire in until it clicked in place, the plastic cover would kick it back loose. I removed the coil cover and haven't had an issue since.

docmirror

First and most important, how far are you from the Crystal Peak turnoff in Florissant? I go up there regularly, next time we can have a meet in the T-bird.

Next to the TC troubleshooting.

Swap the thermocouples left and right and note which lamp comes on. You may have a bad TC. Oh, and clean the connectors on the TC leads when you swap them.

James Bailey

since you have an 89....you might follow the tech Bulletin and move the sensors to cylinders 3 and 7 if they are still on 4 and 8. Recommended because of problems with false signals...And standard location for all 1990 >

mark928gt

I just went out and pressed on the coil wire connection. It was pretty solid and did not seem to be kicked back. It did make one small click but i noticed it makes four or five clicks when you press it on once it is off. I'm thinking I was ok with that but may try to run it with the cover off just to make sure. Thanks.

I will swap the TCs tomorrow, clean the connections and move them to 3 and 7 as James suggested. I assume I have ports there to move them to.

I live near CR31 and HWY 24. A couple of miles west of Florissant. Are you a part-timer in this area?

Thanks for the quick replies guys!

worf928

Have you considered that you might have a cylinder with an intermittent misfire?

James Bailey

yes you have the ports......

mark928gt

Dave C.

I had not considered an intermittent misfire. The car runs smooth up until the time the relay kicks in. How might I detect an intermittent misfire and better yet, tell which cylinder it would be?

worf928

When all else fails, do a search for Misfire in thread titles. There's more food for thought in those threads than I could summarize in a day of trying.

In particular, though, this one has advice/suggestions from Wally and Malcolm that is apropos to your specific situation:

https://rennlist.com/forums/928-foru...hlight=Misfire

Mrmerlin

before turning the Thermo Couples,
just take the connectors apart and put deoxit 100 on the pins

Mrmerlin

before messing with the TC ,
I would swap the distributor caps.
NOTE run the engine for atleast 20 mins to heat soak the engine,
we found a bad new cap that would fail two cylinders once it got hot

docmirror

Might as well swap while you are under there. BTW he already 'turned'(rotated) one. Next is left to right and right to left. If it stays on the green side, then investigate the ignition.

dr bob

Since the thermocouples measure the differences in exhaust manifold temp, consider testing for even exhaust manifold temp with your IR heat gun. Shoot the same cylinder ports that your thermocouples sit under, to start with. You want to do this before the IMS relay is triggered, of course.

mark928gt

Tonight I tried a few things.

1. I swapped the distributors as Stan had suggested. This made no difference and I still got the same ignition circuit #2 failure with the IMS relay.

2. I pulled the TCs and inspected the connections. All were very clean with no visible dirt or corrosion.

3. I swapped the TCs side to side and moved them to the #3 and #7 ports. Voila! No more IMS relay activation! At least not during my short 7 mile jaunt. I was only making it about a half mile from the house before the IMS relay activated with all of the other things I had tried.

The only thing I didn't like about moving the TCs was that the wires are too short to clip into their holders on the back of the head. The newer TCs must have just a bit longer wire.

Thanks for all the help, once again, everyone. I'll post to to this thread again if the issue returns.

Matchmaker

Hello

I have a problem with Ignition System Monitoring Relay.
After standing few weeks it runs normal but if I start accelerating 4 cylinders a shutdown.
Stop and start again it work again normal.

Then when car stay with hot engine 2-3 hours all problem disappear. And I can drive all day normaly.
I used relay bypass but it didn’t help.
Wires and coils are new.
Now I want to check temp sensors, but I can’t find them, where they installed?