Giovanni

Anyone has a pic of its location? I have the bypass relay but I don't know where it goes
I went to visit a client today, got back in the car about 5 minutes later and no start. The Fuel pressure with ignition on is 35 psi. At cranking it jumped to 39 psi and then settles back to 35 psi.

I had someone drop me at the business 4 hours later and car started like always. Got back home, let it sit for 10 seconds and it barely started after 5-8 secs off cranking. Let it sit for 5 minutes and no start.

I am guessing the ignition monitor relay or the ignition sensor(s) is going bad. It got new coils, plugs, wires, and temp 2 sensor.

Please help!

Giovanni

That was it. Car started right up with the bypass relay. Put the old relay and no start. Pics coming up.

Giovanni

picture of IMS relay

9x8

I've got some weird question: what does it mean if the car runs without any relay or bridge there? Installing either doesnt make any difference.

It's '89 catless euro GT btw, temp sensors seem to be present, so it looks like the system is there.

9x8

I'll clarify myself a bit:
Is the car supposed to run (or even start) without any relay (either IMS or bypass one) connected?

Alan

No - someone bypassed it already...

Alan

9x8

Alan, thanks for your reply!

The (not so) fun part is that the system seems to work even without the IMS relay in there. Car seems to run just fine for a while and then at some point it just dies, with symptoms looking very similar to ignition monitoring system activating. For example, yesterday we burned rubber for a good 30-40 mins, with car pulling really strong as it should, and then had it idle for a while - and it died twice within 15 mins of idling (10 mins of idle, then it goes into really rough idle and stops, we wait 10 more mins, restart it, and it dies again in 5 mins). We had 87, A1 and A2 pins in the relay connector shorted at the time (should be exactly the same thing that bypass "relay" does?).

If we put the IMS relay in place, it seems to flash green light when this "shutdown" mode happens (I do know that green one means ignition circuit 2: cyl. 2-3-5-8 - are shut down, we'll try to change that coil tonight, might be the coil overheating at idle and failing?).

P.S. Name of a friend of mine who owns this car is Alan as well.

Giovanni

I think the IMS itself goes bad after time and cost a few hundred buck to buy a new one. As long as you bypass the IMS and the car runs fine, then you are good. But if you bypass it and it still has the same symptoms than the IMS is not faulty and you need to find the reason its kicking in.

9x8

Yea, the thing is: the car starts and even runs good most of the time without anything plugged in (which, as Alan suggested, is probably an indication of the whole system being bypassed somewhere deeper in the wiring). But when this "emergency shutdown" thing occurs, and IF the IMS relay is plugged in, it flashes a green light. The whole problem looks really weird to me, because most of the time the car runs just fine. It also doesnt have cats, so there is actually no point of having the system there.

WallyP

If the car had cats from the factory, and someone bypassed the monitoring system after removing the cats, my first guess is that their bypass has an intermittent problem.

9x8

Also, is the car supposed to ask for diagnostic connector when IMS kicks in?

worf928

The LH ECU will store fault codes if the IMS triggers on either set of four injectors. I have no idea what the ECU does when no IMS is present.

I have seen "creative" bypasses of the fuel pump relay to work-around a failing/failed LH ECU. I don't know if the IMS relay could be the subject of such creativity. However, if your LH ECU hasn't been rebuilt then your symptoms might be an early warning sign. It will cost you only shipping to have it tested by JDSPorsche.

9x8

Thought so as well at first, tried with different ECU - didnt solve the problem.

worf928

OK. Good. Then I concur with Wally that Ockham's Razor applies: the simplest explanation is that this creative IMS bypass is what is causing the problem.

Should be a lot of "fun" to find and correct and that's convolved with the unknowable reason of why the IMS was bypassed in the first place.

worf928

Actually, if the IMS bypass was done to work-around a failing LH, then using a known-good LH doesn't rule out the original LH as a culprit since the suspected intermittent IMS bypass would be working around a problem that doesn't exist with the known-good LH.

A failing LH is probably not the original problem that triggered the IMS bypass. But, keep the LH in mind once you get the bypass figured out and the IMS corrected back to factory spec.