5M-E injectors not firing

[demios]

We have a 5ME in an MA61 which won't start. A few days ago the engine started, running on only 3 cylinders, but died shortly afterwards. The three dead cylinders corresponded to one "block" of injectors, or half the dizzy - cylinders 1, 3 & 5. After that one last run none of the cylinders have fired, except very occasionally when the cold start injector fires.

We have spark, but the injectors aren't firing.

Some testing with the multimeter seems to show that that the relay, resistor block and related wiring up to the injectors is fine. Which left us assuming the fault was a wiring fault between the injectors and the ECU.

We rigged up leads from the resister block to the ECU pins corresponding to the injectors and put a noid light in between to test whether we could just rewire the EFI section of the harness, but it turned out the ECU wasn't closing the injector circuits at all.

So, it seems that the ECU isn't firing the injectors when we crank the engine over. After looking at this: http://www.autoshop101.com/forms/h25.pdf (page 8) we've decided that the problem is probably a lack of IGr signal from the igniter.

Does anyone have any alternative suggestions, or tips on what to do in this situation?

[thechuckster]

check that you have a spark when cranking (pull lead off centre of dizzi, put close to something metal, crank engine).

trace ignitor signal IGr back to ECU for continuity.

Have you loosened the ECU earth that bolts onto the intake manifold? No earth to ECU = no earth to injectors.

[demios]

We checked for spark first up, as well as compression on 1 and 6 (The previous owner said that the mechanic had told him that the valves were burnt). Compression seemed fine enough to run. We also checked for continuity between the ECU earth points and that seemed fine as well.

This is what led us to thinking that it's a lack of IGr signal, either a break in the wiring harness or the Ignitor itself.

The problem with that is that the car is 40 minutes drive away, but we may have it towed closer by the end of the day.

Are there any other signals that the ECU requires for the injector circuit? Or ways to diagnose the ECU itself?

[CrUZida]

If the IGr signal is dead, then the injectors will fire probably 3 times before giving up.

Do they fire at all when you first attempt to start?
Or are they completely dead?

[thechuckster]

i remember getting a 5me wiring diagram from wilbo and others ... finds it ... finds several ... from MX62 & MA61 but with variations like O2 sensor present/not and same for ISCV (suggesting they might also cover early 5mge).

ECU's sole source of timing data is the IG signal from the igniter - no signal from it, ECU doesn't know engine cranking speed and shouldn't fire injectors at al. Can't remember if 5ME gives a priming pulse to injectors.

5ME does no spark control in ECU (dizzi will have vacuum advance dashpot on it) - but does have electronic ignition (VR sensor in dizzi, 6-tooth wheel, external igniter)

MX62 (should have igniter in place of coil)

says MA61 (but has O2 sensor):
http://lh3.ggpht.com/_qRDJ1PwJbMA/TD...I%20Wiring.jpg

[demios]

Ooh!

Thankyou very much for the diagrams. We just got the vehicle towed to where we're staying so it's no longer the 40 minute one way trip between internet resources and the car.

We're not getting any injector pulsing when we crank the car over, so chances are it doesn't do the priming pulse.

The Hayes manual that we got with the car has somewhat vague (And American Market) diagrams, so a lot of our troubleshooting has been educated guesswork. Reminds me when I put in my 18R-GEU into my RA28, except it had a 22R-E ECU and an unknown, unlabeled wiring harness. Fun times...

[thechuckster]

actually, i don't think it does a primping pulse - as you start cranking it, enough air gets sucked thru the AFM to trigger the fuel pump switch and by the the time the engine catches, you've got proper pressure at the fuel rail.

If you're getting a spark, it's something between the igniter and the ECU or the ECU itself is not doing it;'s thing. If you need another 5ME ECU, I have an MA61 rotting away up at Conondale - will be up there on the weekend and can scab bits out of it if required.

[demios]

We'll check out the ignitor and associated wiring tomorrow and let you know if we need an ECU. We're in Brisvegas at the moment, too.

Cheers!

[demios]

If you're getting a spark, it's something between the igniter and the ECU or the ECU itself is not doing it;'s thing. If you need another 5ME ECU, I have an MA61 rotting away up at Conondale - will be up there on the weekend and can scab bits out of it if required.

Yeah, we double checked and we have spark. We have continuity between the igniter and the ecu. Did a dodgy check with the multimeter and it looks like the signal is being sent from the igniter to the ECU.

So it's probably the ECU. Might be keen to get that ECU off you if at all possible.

Thanks.

[demios]

Argh. It's probably not the ECU. We picked up a replacement 5M-E computer at a wreckers and still have the same issues.

[demios]

Does anyone have any advice for properly testing the igniter? That seems to be the current best suspect.

[CrUZida]

Yeah, replace with a known working spare.

[thechuckster]

22RE (RA65 Celica?) or MX62 5ME would be useful donor

diagnosing EFI system (ignore bits about diagnostic codes and shorting diagnostic port to get 10degree BTC timing - your ECU doesn't do ESA aka electronic spark advance)
http://www.cygnusx1.net/Supra/Librar...aspx?S=FI&P=11

[demios]

Are you sure the 22RE Ignitors are the same? I've got one in the RA28 we could pull out from when I upgraded to the electronic Dizzy.

[thechuckster]

i think so but compare the number of connectors on it. If the 22RE you sourced had mechanical/vacuum advance on the dizzi it should be good to use.

(edited as it's too confusing - found pic of mine, will post shortly when i put notes on it)

Takai recently pulled his 5ME out to replace it with a 2JZGE - he might remember the wiring at the coil.

edit: pics of MA61 igniter:



(full res imags at bottom of this page.

[demios]

The saga continues..

The 22R igniter was too important to be out of commission for any length of time so we haven't dropped in a new igniter to diagnose.

Instead we pulled half the wiring harness out and cut out all the injector stuff, bypassing any potential shorts in the dodgy wiring- found two injectors with broken wires going in and a short between ground and resistor/power on one bank of injectors, also found that 4 or 5 out of 6 injectors were running off one bank / side of the resistor block. Ugh...

This looked like it might be the problem, but sadly cutting all that stuff out and simply hooking a noid light between the resister and the ecu still gets us no pulse, as before, so despite fixing up some really bad wiring we still haven't found the fault.

Tomorrow we might go to the wreckers again and get the igniter off the cressy we got the spare ecu out of.

Can we just confirm that the igniter signal goes to the pin on the ECU labeled "IG"?

Thanks for all the help so far guys, we really appreciate it.

[wilbo666]

Is it possible that you have damaged both ECU injector drives given the wiring issues you had?

Take the ECU apart and check the injector driver transistor would be my suggestion

Cheers
Wilbo

[RA35GT]

Diagram for you.

[thechuckster]

i extracted the ECU out of my old MA61 and fwiw, there's only one injector driver. SO even tho there's two pin-outs, they come from the same large 3pin driver.

Also, yes, the igniter signal goes to the IG pins and the tacho

Anyway, if interested, I have my ECU, dizzi, coil & igniter with me in Toowoomba.


7M-GTE MX73's Picture:
http://img697.imageshack.us/img697/8339/5mewiring11.jpg

edit: holy crap - that image is huge, changed it to a link

edit 2: fwiw, when i un-butchered the wiring in my MA61, i replaced the injector plugs with connectors pilfered from a V6 commode - unlike the denso plug, they're not brittle and they have a simple push-to-unlock thing.

[demios]

Well we opened up the ECUs and had a look inside. On the underside of the board around the large transistor bolted to the ECU case there is some obvious brown discolouration, presumably from overheating or something. Worse on the older ECU but still present on the more recently acquired one.

I guess the ECUs are probably fried?

We just received an engine today, 5M-GE, with an igniter bundled with it.. was going to try dropping that in and a new resistor pack to see if it makes a difference, but I'm starting to think we've already killed both ECUs. Does that sound likely to you guys?

Thanks.