Explosion, now no start.

[cre]

No, you don't need to make any changes to the ignition system because you're running a colder or hotter plug. The thermal transfer characteristics of a plug have little effect on the spark. Why are you running a colder plug? Preignition problems, damaged spark plugs or high EGT?

[vikenabm]

Yeah, I thought about that after I posted: plug gap should be the overriding determinant of spark. I'm running colder based on various postings on plug choices. I haven't run the engine enough to know where my EGT's will be in various conditions, but that's an obvious and interesting way to select plugs. I'm surprised I haven't noticed that approach posted.

So it's down to the ignitor or coils. And ignitor makes more sense to me. Clearly my spark is inconsistent, and it sure seems like the ignitor fires inconsistently in the TSRM transistor test, no matter how carefully I clean the probe and terminals> I have a replacement from a running motor to test when the weather allows. Thanks.

[cre]

I don't see that you've mentioned running an extreme amount of boost. It doesn't matter much. It won't hurt anything, they'll just foul frequently if they're too cool.

There's a thread in the FAQ, I believe, about a known grounding problem with the igniters (it's an internal issue). See if you can find it and see if the fix listed works for you.

[vikenabm]

Originally Posted by cre

I don't see that you've mentioned running an extreme amount of boost. It doesn't matter much. It won't hurt anything, they'll just foul frequently if they're too cool.

There's a thread in the FAQ, I believe, about a known grounding problem with the igniters (it's an internal issue). See if you can find it and see if the fix listed works for you.

Thanks. I already had the ground mod in place. I replaced the ignitor and it is not much different. WIth all the injectors unplugged it behaves EXACTLY THE SAME as with them plugged in. I believe it is sputtering a bit and firing into the intake runner due to fuel from the cold start injector. It sputters a bit more consistently maybe with the new ignitor, but no real change. Also no different with plug to injector resistor connected or not.

So without the injectors making a difference, and good fuel pressure, is it fair to conclude that I'm down to injectors not opening as my problem? If so, i've already tested the injector resistor with an ohmmeter, simple device. So now am I to check wiring continuity to the ECU, repeat the voltmeter tests at the ECU from the TSRM, and then swap ecu if those check out normal?
I am out of other ideas at this point.

[cre]

Are the injector's grounded at the correct location and is the ground clean and sound?

I've had issues like this on a couple MKIIIs and it's always something different. Wiring harness, CPS drive gear installed 180? out after a rebuild or on a new (reman) unit, igniter and coil pack grounds were the issue in all of those cases.

You can measure the timing of the injectors against the crank pulley with a timing light. If you don't have an adjustable it's just a light show and you have to guess what the timing is but nonetheless if the injectors aren't getting power or don't have a good ground you shouldn't see anything. You just connect the pickup to the injector's wiring clip, shine the light on the markings on the balancer and while someone cranks you watch for a consistent pattern. I think you'll be looking around the 50? range but I'm not positive, I haven't done this on a 7M. The timing isn't important though, this SHOULD show if the injectors have a solid signal.

[vikenabm]

Originally Posted by cre

You can measure the timing of the injectors against the crank pulley with a timing light.

This is a great tip! Thanks, I will try it.

[cre]

Thanks for the generous donation! Made my day. I think some people think this is my site and the advertising dollars come to me... it's not and sadly, they don't. I'm just a volunteer. Thanks again.

One more thing you might want to check is that the ECU is getting a signal of >11v+ at the STA input when the starter is cranking.

[vikenabm]

OK, had a spare ECU for an automatic transmission, same grey plugs. I have a M/T with a converted A/T harness, so I swapped the ecu anyway and it cranks fine. STA actually not checked once it cranked ok. Other voltmeter tests for the ECU and the "ignition on" were all correct, including all 3 injector channels, KSU signal, MREL, and ISC1-4.

Now the symptoms are back to before the explosion: With injector resistor connected I'm getting something. It chugs for a second and sputters, seems like it will almost go, but won't start all the way. When it was doing this before I managed to get it barely running a a few times and that's when it exploded and stopped, so I'm afraid to keep trying to start it without a clearer idea of what is wrong. Timing is set approximately according to the TSRM instructions for installing the CPS, which usually is enough to get it started.

Timing light didn't work in the injector wire. I put the magnetic pickup that normally goes on a plug wire over one of the two wires going to injector 1. Didn't trigger the light with old or new ECU.

Timing light does flash on plug wire #1, maybe not perfectly regularly, but better with the new ignitor than with the old ignitor, I think. STill not sure the spark is 100% regular. checked coil resistances - all ok. Plug wires (MSD) checked a month ago - some were close to 20K ohm, which is in spec but barely. I have some old stock plug wires left, as well as stock injectors and stock AFM, and an extra coil pack.

1)Should I focus on trying to get the timing more accurate by having someone crank while I check timing? Or do I need to double check anything else before going further. Not sure about these RC injectors, Lexus AFM, AFPR: haven't worked with this setup before.

2) Should I scrap the setup and go back to stock AFM, injectors, and plug wires just to test it? That's of course a couple of hours converting, and a couple more changing it all back later, but well worth it if I learn something from the exercise. Actually, I crimped the new injector pigtails and heat shrunk the connections, so I can't really go back to stock injectors very easily. I could make a adaptors of the old injector pigtails and some crimp on female terminals, I suppose. I'd do that if it would help.

3) should I go back to stock on just the plug wires, maybe swap the coil pack?

4) Should I continue with the A/T ECU? How much difference will it make?

At this point I don't want to shoot from the hip. I'd just be picking at random from the list.

Thanks.

[cre]

I would start with swapping the electronic part of the old AFM into the Lex AFM. The electronics are the same and you know the old one works I presume.

I don't understand your reply about the STA signal. This signal is important as it tells the ECU that the car is being started and despite the airflow being below the specified threshold for the emergency fuel cutoff that it should power the pump and injectors for a set period of time. At least this is my understanding of how it's applied in the 7M-GTE's case. The timing light on the injector wires is to ensure that they are getting a proper signal when cranking. If you know it's getting fuel then this probably doesn't matter.

As I reflect I feel that the explosion may have been either due to the ignition timing being wildly off from the mechanical timing OR the injectors are firing way out of order and fuel is pooling in the runners until that unfortunate spark lights one off. The injectors are low impedance right?

I wouldn't worry about keeping the other ECU in place. I don't think that's the issue... I could be wrong though.


I'll go back over this thread in its entirety tomorrow, think about it for a bit and try to see if I can think of anything specific which we've neglected. Have you verified that the injectors are connected in the proper order?

[vikenabm]

Originally Posted by cre

I would start with swapping the electronic part of the old AFM into the Lex AFM. The electronics are the same and you know the old one works I presume.

Yes, though the part number is different by one digit and might not be eletroncially identical. I have to supra part in the lexus body now, I will try that swap.

Originally Posted by cre

I don't understand your reply about the STA signal. This signal is important as it tells the ECU that the car is being started and despite the airflow being below the specified threshold for the emergency fuel cutoff that it should power the pump and injectors for a set period of time. At least this is my understanding of how it's applied in the 7M-GTE's case. The timing light on the injector wires is to ensure that they are getting a proper signal when cranking. If you know it's getting fuel then this probably doesn't matter.

Ok, I didn't understand the STA function. I will check it. My only proof that i'm getting fuel is that it almost starts when the injector resistor connector is connected and not otherwise. I believe this takes the injectors on and off line. With my lovely assistant, I will also verify that pressure is over 30psi WHEN cranking.

Originally Posted by cre

As I reflect I feel that the explosion may have been either due to the ignition timing being wildly off from the mechanical timing OR the injectors are firing way out of order and fuel is pooling in the runners until that unfortunate spark lights one off. The injectors are low impedance right?

both issues may have come to play, i think so. those are the two issues I considered: back fire or ignition timing. It sounded more like timing, too loud and crisp for a back fire, not a pop, but a boom. and a lot of protesting cranking, like the engine was kicking back at the starter. That isn't happening any more so I think the timing is at least better.

Originally Posted by cre

I wouldn't worry about keeping the other ECU in place. I don't think that's the issue... I could be wrong though.

I feel the symptoms are different with the new ECU: It definitely is much closer to starting now, chugs in it's own for a second, so I'm thinking the old ecu was damaged by jumping it incorrectly. there was smoke and an ozone smell in the passenger compartment... Just a matter of whether to buy a new M/T ecu. Plan was to wait until I get it running before worrying about that. I will take the old ECU apart and inspect just to see if the board is burned.

Originally Posted by cre

I'll go back over this thread in its entirety tomorrow, think about it for a bit and try to see if I can think of anything specific which we've neglected. Have you verified that the injectors are connected in the proper order?

I really appreciate your help. the injector plugs are long enough now that they could be connected out of order, but it would be pretty obvious. Only #5 and #6 are easy to mix up. I will verify continuity to the correct injector resistor pins per TEWD with a voltmeter. Also will verify that both leads to 1 and 4, 2 and 6, and 3 and 5 are in continuity with each other. Connection of each of the 3 circuits to the ECU was already verified with voltmeter yesterday.

FWIW - I wonder if air/fuel mixture could be way too rich. I have AFPR, A/F adjust screw on the AFM, and a bosch 'BOV' (recirculating discharge with stock plumbing). I have checked for boost leaks carefully, so I don't think that is a problem, but I might have been fixing boost leaks when the problem starting first occurred, before I screwed up the timing. Just another factor to consider.
Thanks again.