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Old 08-09-2011, 01:19 AM   #1
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Default 99 DIYPNP IAT Issue

I can't seem to get the IAT (Manifold Air Temperature) to work in TS.

I wired a GM IAT to the stock IAT wires. I have verified that I have resistance between 3B and 4F/4C (~1500 ohms). I have the same resistance between SG and IAT on the DIYPNP main board.

I have calibrated the sensor in TS several times.

Coolant sensor works fine. O2 sensor works fine. The car starts and runs.

Need some ideas quick, please. I have a date with Church tomorrow, and it is the last time I can get in before this car goes to the track on Friday.

Thanks,

John
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Old 08-09-2011, 11:05 AM   #2
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The pin on the microsquirt module for the IAT sensor is #9. Please continuity check between pin 9 on the module and the IAT pin on the DIYPNP main board. Then check resistance between pin 9 and ground and report results.
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Old 08-09-2011, 01:43 PM   #3
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That was it. Cold solder joint on pin 9. Thanks!
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Old 08-09-2011, 02:18 PM   #4
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Good deal.
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Old 08-10-2011, 10:21 PM   #5
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This just got interesting...

We had a good day at the dyno. Made good power, ran for a couple of hours, did many pulls. After we let it cool off, it would only run on 2 cylinders. A quick pull of the coil plugs (COP conversion) showed that it was missing on cylinders 2 and 4. Since we have sequential injection, I suspected a problem with that mod card.

When we went to work on it today, it wouldn't start at all. It would not communicate with our computers. I had to reflash the firmware to get it talking, but it still won't start. I can get the car to run with the old Adaptronic ECU but nada with the Megasquirt.

Is it possible to have damaged the injector drivers, and is there a way to bench test them?

Just started it on 2 cylinders. Pulling the seq mod card has no effect on the way it runs.

Last edited by Satisaii; 08-10-2011 at 10:51 PM. Reason: More info
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Old 08-10-2011, 11:59 PM   #6
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Quote:
Originally Posted by Satisaii View Post
Is it possible to have damaged the injector drivers, and is there a way to bench test them?
Yes, but it's a fair bit of work if you don't have an oscilloscope or don't already have an injector flowbench or similar.

The fuel injection timing is fairly non-critical. If you can swap the wiring around such that the 1/3 drivers are connected to the 2/4 cylinders, and then the engine runs on those two instead, then it narrows the field considerably.

I assume that you have a good spark on all four? (Easy enough to confirm visually.)
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Old 08-11-2011, 03:21 AM   #7
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I just did a 100 mile round trip to pick up a spare Seq Mod card. It still is missing. So I hooked it up as batch fire. Still misses. Plug Adaptronic in, runs fine. Verified continuity between boards/pins.

And in the end....

The tuner had changed it from wasted spark to COP. While running. Spent hours tuning it. Turned it off. And then it would not restart. Finally, we figured it had to be somewhere in the tune. Put in a base map, car would start. Change to the tuned map, runs like crap on 2 cylinders... but we can change it while running with no problems.
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Old 08-11-2011, 08:32 AM   #8
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Because the car needs to power cycled before the MS actually implements the change.

are you going from wasted COP to seq. COP. Or wasted to COP? cause if it's the later, I don't see how you can manage that without rewiring your harness...
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Old 08-11-2011, 10:23 AM   #9
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Sounds like you or the tuner made some bad settings choices causing a config error. The config error doesn't appear until after a power cycle.

Removing the sequential card will make the car run on 2 cylinders as sequential vs batch requires a wiring change.
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Old 08-12-2011, 12:10 AM   #10
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As part of the diagnosis, I rewired it for batch fire. The puzzler was in that pulling the Seq Mod card did not change the way it ran... therefore it HAD to be that card. But the same symptoms would arise from a 720 deg ignition firing vs 360 deg. It was just hard to think that the ignition would be an issue since it was clear that 2/4 were missing. If it was 1/4 or 2/3...

We did the Toyota COP conversion keeping the wasted spark. If would be advantageous to use sequential COP in a 25 hour race, I will make the changes needed to do it.

We did a test day today. Car ran great. The driver reported that the drivability and throttle response are improved. It also does better on hot starts, which was the main reason we wanted to try something new.
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