drake

Hello All- I am having some intermittent issues with my car that I have not been able to diagnose myself. I have recently swapped my entire running and driving drivetrain into a 96 model car. The drivetrain in question is from a 92 model car. To keep this as simple as I could, I retained the 96 wiring harness and bought a known good second-hand MS2 9697. Since the firmware is the same, I have loaded my tune onto this ecu and am running into issues under WOT. The car is set up to run only of the CAS as the NA crank sensor is not present and only detects misfires.

The issue feels like a boost cut and sometimes on the data log, looks like a boost cut as well. Other times I am losing sync to the ecu(lost sync 39 CAS) and the ecu is cutting RPM, Fuel and Spark. I have triple checked all the grounds, changed main power harness, tried multiple CAS, tried different coils and COP set ups, Ive changed the ignition switch and seem to be running into the same issue. Sometimes when I data log, I do not lose sync at all with the ecu but still hit a cut under boost.

I will attach and label my logs the best that I can. I have 3 composite logs from different days and different CAS as well and I will leave my current tune for anyone to peer at.

Any help at all is much appreciated, this set up ran fine on 30 year old 1.6 wiring harness and a 9093 MS2.

1996 Shell and Wiring Harness - Dash, Inj harness etc
MS2PNP 9697
1.6 Engine with 1.8 throttle body sensors(coolant temp, TPS and idle valve)
Toyota COP set up
550cc RX7 Injectors
External 3-bar MAP
Independent Fuel Pump Relay

curly

iTrader: (25)

I feel like you've got a lot going on, your TPS signal is also wild, and it does seem to coincide with sync loss, not that the TPS is causing it, but perhaps what ever is causing the sync loss is also causing other issues. Sync loss in "offline 5 times 2 cuts" goes from 0 to 3 at the same time TPS goes from 22.5 to 0, RPM goes from 4100 to 3000, and MAP goes from 138 to 19. Can't tell if that's an interrupt in the log or not, is your TPS signal stable?

What are your spark plugs gapped to? Seems to correlate with boost levels, its possible you're just dealing with a misfire. Try around .020" gap with some fresh BRK7Es and see if it changes.

drake

Curly - Thanks for taking a look for me. The TPS signal is strong KOEO 0%-100% and I recorded a log for you sitting still at idle just stabbing the throttle. In this log, I noticed that on one single occasion, the TPS did not pick up at all. I do not see any disconnections on this log like the others.

As far as plugs, I run R5671s .25 gap. Will try your recommendation but I still am unsure why I keep seeing so many disconnections and discrepancies in the logs.

curly

iTrader: (25)

I've had bad luck with "racing" plugs, they need to be scalding hot to have marginal gains over a BKR7E, which usually can't be replicated on the street. They can also cause excessive electrical noise if I'm not mistaken. I'm not saying it'll solve all your problems, but it's worth a shot. If that's not the magical fix, I would say you have an electrical problem, although without hands on diagnostics, I couldn't tell you what. MAP and TPS are both 5v ref, you can't unplug the MAP and run it well without significantly changing your tune, but beyond some throttle hesitation, you can unplug TPS and see if the issue goes away. Again, I'd change plugs first though.

If I'm not mistaken, your MAP didn't change with the 5th throttle blip either.

Looking at that 5th blip, you went from 1034rpm to 2575rpm in .073 seconds, the log trips out trying to play it, but if you do, it's like RPM is on a switch or something. Unless this is a motorcycle, I highly doubt it's actually doing that.

drake

I tried some brand new 7e's with .020 gap, no luck.

On this newest log the ecu lost sync with RPM and Duty Cycle completely.

On the previous log the lost sync counter goes up when the car cut out however, the ecu did NOT lose RPM and Duty Cycle.

I have taken this ecu out of my car and installed it on a friends car. The final tune and log here is from the same exact ecu but in a different car. You can tell the tunes apart from the engine size, my car is a 1.6, my friends car is a 1.8. As you can see, this car runs great and I seem to be down to wiring issue/electronic issues.

Any advice on where to start? Tracing CAS wires to ECU?

oreo

This certainly is strange.

I did notice in the file "New COP lost RPM Completely" file, at 167.6 ADC7 drops to 0 just prior to the RPM dropping out.
What are you using ADC7 for? (it is not used in standard setups) Is your friends car also using/connecting to this signal?

Any other inputs/outputs your car is using that your friends car is not?

drake

Update- No luck yet, still working in tearing through the wiring harness. I noticed today that my fuel pump was making noise when i have no battery or ecu installed. Weirdest issue I have ever had with any car.

thanks for the insight curly and oreo. My brain is fried at this point and i plan on taking a break from the car for a week or so.

will continue to update my findings. Wish me luck

curly

iTrader: (25)

If RPM goes to 0, duty cycle will too, so the duty cycle and even RPM at 0 is a side affect of the sync loss.

If I had to blame anything, it would be the COPs, but that's without seeing the car in person, you might have a giant rust pile with exposed wires everywhere, I don't know. Your friend's log does indeed look much better, although in need of a tune.

I'll agree with the break from the car, you've got a gremlin and those can be frustrating and difficult to find.

drake

Spent some time looking through the car again today. I will post some pictures soon, I dont have the nicest miata in the world but it is no rust bucket. I actually swapped to this new chassis because my old one was well over 300k miles and had seen enough.

I noticed that the noise i am hearing KOEO is definitely coming from the fuel pump. I have the battery and ecu out, sounds like the fuel pump is priming by itself. I have a fuel pump relay kit wired in, might try to remove and return to stock see what happens.

I took you all’s advice and removed my Boost Control and External MAP from the options port(same as my friends car). I believe that ADC7 reading was boost control but am unsure.

I also found some wires at the ecu connectors that looked questionable. Repaired those and tried to connect to the ecu, TS is now telling me the firmware is wrong and that the cominstruction failed to communicate 5 times in a row.

That being said I have not been able to drive the car with these changes yet. Will delete and reinstall TS, check for updates and report back.

Thank you all so much for the input. This car has been killing me lately and Im trying hard to stay motivated.

I am still considering just swapping the entire harness back to 1.6. I just really like the 1.8 harness because those cars seem to work better in many ways.

For anyone wondering,

1.6 Kraken Garrett G 25-550
Rx7 550cc Injectors
6-Speed
3.33 Rear Gear
Destroy or Die Drop Knuckles

Pics of the old car prior to swap for my soul and motivation:

mmmjesse

what happens if you use taylors tune as a test? Adjust the constants to match your car though.

As Curly said previously, the TPS and MAP in the beginning of the one log look terrible. If it was a hardware issue, I would think it is related to the 5v supply that the ecu provides the tps and map sensor. I am assuming that the MS uses the same 5v for both. The ground for the TPS also goes to the coolant temp sensor and it seems to be functioning as expected.

However, you just swapped it back into Taylors car and it doesn't exhibit the issue.

I dont see any fuel cut codes? does ms2 not use any?