1987 3.2 Carrera Backdate project - Sladeys hotrod

[Bruce M]

Pin10 is an input so nothing wrong there, alas.

[sladey]

I’ve gone through the software manual and there was a test to confirm that the crank sensors are both working. I ran that and it confirmed that they are


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[sladey]

Ok this morning I got a response from Canems! First he's suggested checking the boots under the injectors to make sure I haven't got a short. He's suggesting this on the basis that I've done a bit of work on the engine and they may have been touched/knocked. I didn't touch them or disturb then during the work so I doubt this is what's happened (I'm presuming one short wold stop them all from working?). Anyway I'll still follow his suggestion just to make sure.

He then said I could post it up to him and he'd have a look at it - whilst they don't make this model any more he should be able to repair it if it's damaged.

Fingers crossed again!!!

[rhd racer]

Sounds like good customer support


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[sladey]

Yes - he's been good to me in the past too. I've said that I'm going to drive up on Monday as I don't work Mondays - might be easier if I see him face to face. Even if he can't do it there and then at least I know he's got it and he appreciates the urgency

EDIT - now I've found he's on holiday next week. Getting tight! I've asked if he works Saturdays so I could pop it up in the morning

[Nige]

At least you haven't had to wait a long time for an email response.

[sladey]

Ok so he didn’t respond to that last email so I’m not going up today.

I’m going to post the ECU to him (after I’ve checked the injector boots for a short) and hope he can fix it and get it back to me on time.

With regard to checking the injector plugs for shorts, thinking about it I should be able achieve this by testing for continuity across the two pins shouldn’t I? Let me know if that isn’t logical but it makes sense to me.

This all reminds me of my tense deadline work 10 years ago to get the car ready for CLM. I honestly don’t invent these deadlines- when I started the AC install in December there was no way I wasn’t going to be ready for May! But the snapped stud changed everything.

So now the plan is to do the jobs I’d lined up for after it was running and hope that a. I get the ecu back in time and b. It is fixed and c. That was what was causing the problem.

Those other jobs are getting the AC gassed up, fixing the N/S indicator, and fitting the RS bonnet prop

[DustyM]

Mark, just a thought but can you still plug in a standard 3.2 ECU or is your car modified too much? I have a 3.2 ECU you could borrow.


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[sladey]

Thanks Jon - no it’s modified too much I think - not entirely sure though. The distributor has been replaced and it’s got a MAF instead of the barn door, and a new/different WOT switch

Just tested across the two pins in the injectors plugs and I’m getting continuity from each one.

Looking at the diagram this would happen in all of them if just one was shorting. I can’t see how else they would be connected

investigating further


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[Bootsy]

I’ll admit I don’t understand a lot of what’s being posted but I’m hooked.

Hoping for a prompt and positive outcome soon, fingers crossed for you Slothey

[Bruce M]

With the ECU plug disconnected, there shouldn’t be continuity between the injector plug pins.

The ECU injector driver probably links the injector signal wire to 12v via a resistor when not firing the injector (a “pull up” resistor) and a semiconductor will sink it to ground when the injector is open.

[sladey]

Not really sure on this continuity idea now. I’ve unplugged the injector loom and I get continuity between the two pins on every injector - even with the main injector loom unplugged. The only thing I can think of is that the two pins are connected somehow inside each plug - which I just don’t understand.

However, as advised I’ve broken into all of the rubber boots and stripped back the insulation looking for a short between the wires.

I found cracks in the wiring but nothing actually shorting out. I’ve taped up all the cracks. Further along the injector wiring there was a bit of insulation with a bit of a crease in it - I wondered if that could have split underneath and be getting short so I stripped that back but the wiring underneath was fine. I’ve taped all that back up again. Doesn’t look pretty but it is functional. At some stage I’d like to replace that wiring loom with something in better condition - but I don’t think that’s causing a problem at the moment.

Thinking it through, a short possibly wouldn’t have made sense when we could fire the injectors by earthing pins 14 or 15 in the ECU plug? Not sure on that.

So I’m still looking at the problem being inside the ECU

Currently hopefully got the AC gassing booked for Monday - waiting for a time from the guy


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[sladey]

With the ECU plug disconnected, there shouldn’t be continuity between the injector plug pins.

The ECU injector driver probably links the injector signal wire to 12v via a resistor when not firing the injector (a “pull up” resistor) and a semiconductor will sink it to ground when the injector is open.

OK only just seen this Bruce. I then disconnected the main ECU plug and I’m still getting continuity between the two pins on the injector plugs. Which I don’t understand. I’m getting it from everyone and also a clearly consistent beep - not an intermittent one consistent with a moving shorted wire


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[Bruce M]

Sorry, should have added that’s with the 3 injectors disconnected from their plugs on that bank. Each injector is electrically a simple coil.

[sladey]

Ah so I should disconnect all 3 of them and then test?

I’ll try that later.

I actually heard back from David at Canems late last night saying he’s away today but if I post it to him at home he’ll aim to get it back to me in time. Excellent service.