I'm having a ****-show of a time getting my track car running correctly (at all) after trimming the OEM dash and body harness 18 months ago. I made a handful of weekends last summer with varying technical issues which degraded to the point that I can't even get it to run for a minute now. The quantity of variables are now embarrassing and I'm sure I've exacerbated at least a dozen minor problems 'fixing' and troubleshooting things. I'll never get all the facts in one post and I'm sure I have some incorrect AssUme-ptions so I don't want to steer the troubleshooting the wrong direction. Here are some basics of the car:
'04MSM motor and turbo
Gutted NA6 body and dash harness with toggles for basic functions
Toyota COPs running wasted spark
The other blah blah blah is in the build thread in my signature if anyone cares but this will hopefully get us started...
*Disclaimer - I've forgotten a lot of details over the last many months but I will do my best with the facts...
Last season, the performance degenerated to the point where the car wouldn't run at all. The car seemed to suffer from intermittent ignition cuts while at speed at at some point, I discovered the crank trigger wheel had come loose which certainly caused some issues. I fixed that but intermittent problems persisted. It came to a head as I was loading it on the trailer to leave for MRLS at the end of September. Some of you will remember the stock MSM street car dicing it up in the A group with the fast guys in race cars. 72 hours before the driver's meeting, I didn't have much choice!
Needless to say, I'd like to bring the right car this year not to mention 6 or 8 HPDE runs I was hoping to make this summer. I suspected a dead ECU and since so much of the harness was set up for the 420c (yes, I know I will probably end up needing something better), I sourced a used unit.
The new ECU started and ran which was a big improvement but it was still cutting out intermittently so I then suspected the adapter harness. Adaptronic doesn't support the 420c anymore so I bought a generic NBB adapter and soldered it to the early NB harness that came with the replacement ECU. The car started right up and then suffered from the 'sudden' shut down issue it had with the other combinations. At that point, I started trading out parts I had as spares anyway - different coils, different injectors, Cam and Crank sensors. I put in new plugs - the old ones were pretty black but uniform, For a while it would run (poorly) if I kept my foot on the throttle so I traded out the IACV. Water, MAT, MAP and TPS all pass sanity checks on the laptop so I didn't change any of them. Compression was checked and is fine.
As I type this, the car will barely fire. Different combinations of adapter harness and ECU have worked enough to start and idle the car so I'm hoping that there aren't two dead ECUs in the garage. If there are, something about the car is killing them, Today, I'm going wire by wire through both harnesses (the original Adaptronic piggyback harness and the one I built this winter) checking for continuity. Once that is confirmed, I'm continuing to the engine harness checking the same circuit (this is easier since I have just looked up the wire in the Adaptronic schematic and cross referenced it to the Mazda diagram and probed the pin on the mazda side). It is slow going but so far everything appears to be fine until I got to the coils...
Toyota COP Question:
I am running a basic Toyota COP ignition wired according to Brain's writeup here. Upgrading to Coil on Plugs (all years) COP writeup
, I was probing the trigger for one of the pairs when the probe touched the cam cover and the meter beeped. I figured something must have grounded out at the other end but the trigger was definitely continuous to ground. When I unplugged one of the two coils, the circuit was interrupted. I thought I might have found the issue but further checking shows that the same is true for the other coil on the 1-4 side and the same results happen on the 2-3 trigger wire with those coils. Two coils gives trigger to ground. One coil does not. The results are the same with spare coils in and out of the head,
I tried searching for that phenomenon but found nothing. That's when I decided to swallow my pride and say f*ck it - I'll post about the problem and see if some of the brighter minds can help. Yes, I know I almost certainly caused this by gutting the NA6 harness that was running most of the non-engine system previously. Yes, I know nobody runs a 420c anymore. Yes, I know I should start over with a new engine harness and a Megasquirt. I may do that, but I'd like to save the $1,000+ it would cost for parts and a new tune. As it is, I'm 'saving' $500/day on registration and consumables not driving so I guess I can afford it.
If something is cooking ECUs, I want to fix it before I put another victim into the mix. Like I said initially, I'm sure there are details missing so let me know if you have any ideas or questions. Thanks!