Alan29
Active member
- Joined
- Jun 23, 2019
- Location
- Jax Adjacent, FL
Car in question is a b21ft running Microsquirt, DSM CAS, LS Coils. Engine itself is pretty much stock with a fresh rebuilt stock turbo, intercooler, T5 blue injectors, Spartan 2 wideband. This was a Kjet to MS swap I completed last year and, up until earlier this month, its been running great. Never lost sync while driving with the laptop in the car...aside from just needing some tuning refinement its been most excellent.
Few weeks ago I was having a little fun on some back roads when I blew the charge pipe off the turbo. Loud turbo noises, no power, but it was still running. About a minute later as I was pulling into a safe spot to address the pipe the car just died on me. So fixed the charge pipe, double checked everything was in place, and all was visually well. Car would not start. Sat for a bit figuring out my options to get home and tried one last time...car fired up and was running just fine.
Drove it another 15-20 minutes when it died on me yet again. Let it sit a while, car will start but only able to get it to drive maybe a couple minutes before it leaves me on the road. So I get a tow.
Get it home and take it out with my laptop to datalog to see whats going on. Thankfully I get it to die again. Look over the log with a friend and we see some very strange MAP spikes. So I get to probing around with my multimeter which led me to do the following:
- Found alternator ground cable melted. I was an idiot and used the old one when I did the Denso 80a swap. Looked good at the time, but yeah I'm a dumbass. Replaced the ground.
- Had alternator tested. Output and rectifier good.
- Went over all grounds in engine compartment. Found the newly purchased battery ground cable ring terminal was never crimped onto the cable. Fixed that. Inspected, recleaned, etc all other grounds.
- Pulled the intake manifold to inspect my MS wiring underneath to make sure all is good.
This is what I've found with diag both before and after all above was done:
- Key on not running my 5v reference and 12v power supply to ECU are good
- Key on with no sensors plugged in my 5v reference is good
- Key on not running 12v to CAS is good
- Tested CAS by rotating by hand with 12v supply to it and based on what I found online the output readings look good
- I'm averaging 13.6-13.8v at the battery and starter at idle
- With car at idle the 5v reference is measuring an average of 7v
- MAP output is all over the place and exceeding 12v in fluctuations at idle and when revving motor
- Backprobing 12v supply at the CAS at idle I am finding voltage exceeding 14v.
All the idle diag done above was with the car idling up to operating temp but not after the car had died. Seems maybe this is a heat related issue of some sort as the car will restart and run just fine for a short period of time after sitting a bit after it dies from driving.
At this point I'm getting beyond my knowledge and could really use some help/direction on where to go from here. Drive link below has my tune file and four logs if anyone would like to give them a gander. The new newer logs were from today and are considerably shorter than the others:
https://drive.google.com/drive/folders/1ab0P8letfjHofUqVCPQidJhoM2f8WUve?usp=sharing
Few weeks ago I was having a little fun on some back roads when I blew the charge pipe off the turbo. Loud turbo noises, no power, but it was still running. About a minute later as I was pulling into a safe spot to address the pipe the car just died on me. So fixed the charge pipe, double checked everything was in place, and all was visually well. Car would not start. Sat for a bit figuring out my options to get home and tried one last time...car fired up and was running just fine.
Drove it another 15-20 minutes when it died on me yet again. Let it sit a while, car will start but only able to get it to drive maybe a couple minutes before it leaves me on the road. So I get a tow.
Get it home and take it out with my laptop to datalog to see whats going on. Thankfully I get it to die again. Look over the log with a friend and we see some very strange MAP spikes. So I get to probing around with my multimeter which led me to do the following:
- Found alternator ground cable melted. I was an idiot and used the old one when I did the Denso 80a swap. Looked good at the time, but yeah I'm a dumbass. Replaced the ground.
- Had alternator tested. Output and rectifier good.
- Went over all grounds in engine compartment. Found the newly purchased battery ground cable ring terminal was never crimped onto the cable. Fixed that. Inspected, recleaned, etc all other grounds.
- Pulled the intake manifold to inspect my MS wiring underneath to make sure all is good.
This is what I've found with diag both before and after all above was done:
- Key on not running my 5v reference and 12v power supply to ECU are good
- Key on with no sensors plugged in my 5v reference is good
- Key on not running 12v to CAS is good
- Tested CAS by rotating by hand with 12v supply to it and based on what I found online the output readings look good
- I'm averaging 13.6-13.8v at the battery and starter at idle
- With car at idle the 5v reference is measuring an average of 7v
- MAP output is all over the place and exceeding 12v in fluctuations at idle and when revving motor
- Backprobing 12v supply at the CAS at idle I am finding voltage exceeding 14v.
All the idle diag done above was with the car idling up to operating temp but not after the car had died. Seems maybe this is a heat related issue of some sort as the car will restart and run just fine for a short period of time after sitting a bit after it dies from driving.
At this point I'm getting beyond my knowledge and could really use some help/direction on where to go from here. Drive link below has my tune file and four logs if anyone would like to give them a gander. The new newer logs were from today and are considerably shorter than the others:
https://drive.google.com/drive/folders/1ab0P8letfjHofUqVCPQidJhoM2f8WUve?usp=sharing
Last edited: