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I was out doing some multi-gear pulls today and on one 2nd to 4th gear pull I shifted into 4th and the car felt like crap so I let out. It felt like the ignition system just went blehhhh but then I looked at the logs and saw this:
What on earth? Everything just goes all crazy zig-zag, TPS, Load, etc. I know it's not the log dropping out because other things that aren't related aren't all zig-zaggy (like APP, ethanol %, coolant, MAT, etc)
I think its a TCS event. Take a look at the tps and rpm signal behavior...looks like wheel slip control. Are you running a soft sidewall tire? Tire wind-up can appear to the brake controller as wheel slip with a soft tire. TCS slip thresholds tend to tighten up at higher speeds for stability.
I think its a TCS event. Take a look at the tps and rpm signal behavior...looks like wheel slip control. Are you running a soft sidewall tire? Tire wind-up can appear to the brake controller as wheel slip with a soft tire. TCS slip thresholds tend to tighten up at higher speeds for stability.
Was it raining or wet outside by chance? Mine does exact same in the rain but thats because water's misting onto the MAF sensor causing faulty load readings. I put on an intake airbox/cover/headshield and ever since that problem went away.
So possibility of CANBUS falling on its face, or failure of power delivery (voltage spike/dip).
Vehicles also like to **** themselves when you have EMI in the canbus (twisted pairs be damned)
Edit: if its a vehicle that has alot of custom wiring added into the harness, check those connections as well?
Had this problem happen once again but this time on track at over 120mph. I thought I lost a spark plug again but after looking through the logs it's the same issue I had above! What the heck is going on?
Note APP is still WOT (because I was), while TPS and others are doing the zig zags.
Here's my thinking on this, if the problem was happening at the CAN layer you wouldn't be logging anything because the can packets would be corrupted and dropped. So that would lead me to believe this is happening higher level in the ECU. Because its a combination of sensors and not just one, its probably not an analog problem with just one of the sensors. Like in the other thread I would suggest checking / tightening the chassis grounds and make sure all the harness connectors are plugged in good and snug, Because in my experience, gremlins like this are usually ground loop issues within the circuit. I would point to the logging hardware too, but you said you felt something happening in reality so it can't just be faulty logging.
So... guess what happened again? Damn car fritzed out again and lost power. Car was solid all day long and in the 2nd lap of my fourth session, every time I shifted to 4th under WOT the car would fritz out and loose all power, just like before. However this time it was repeatable and not just a one time thing. It was more dangerous this time as well because I almost had a C63 run into the back of me going down the straight since I was hauling *** one second and then the next, nothing.
ONLY happened in 4th gear and after doing that four times while trying WOT in 4th it all cleared up on it's own and I was able to go 100% the rest of the session. So odd that it just clears up on it's own. Now that I know it only does it in 4th, I'm going to start looking at any gear/speed related tables in the ECU.
Did you lift the throttle on that event you posted? TPS drops basically all the way down. If you had it WOT for that maybe somethings up with the pedal sensor.
NM I get it your shifting, throttle signal looks pretty weird though.
Last edited by Biggiesacks; Apr 18, 2018 at 09:36 AM.
Did you lift the throttle on that event you posted? TPS drops basically all the way down. If you had it WOT for that maybe somethings up with the pedal sensor.
NM I get it your shifting, throttle signal looks pretty weird though.
APP will show what I am requesting with my foot, TPS is actually what the throttle body is doing.
The part of the log I zoomed in on and linked above is showing WOT in 3rd, then shifting to 4th gear and getting back to WOT (APP), car feeling like crap so I let out, then I try to go WOT again, and it feels like crap again so I let out again. Later I go WOT in 3rd and all is fine again, then shift to 4th and a repeat of feeling like crap. So it's 4th gear only (or certain speed).
APP will show what I am requesting with my foot, TPS is actually what the throttle body is doing.
The part of the log I zoomed in on and linked above is showing WOT in 3rd, then shifting to 4th gear and getting back to WOT (APP), car feeling like crap so I let out, then I try to go WOT again, and it feels like crap again so I let out again. Later I go WOT in 3rd and all is fine again, then shift to 4th and a repeat of feeling like crap. So it's 4th gear only (or certain speed).
cool that context helps. If you look at APP to TPS you see you go WOT, but the TPS does not. So the ECU is definitely pulling some ****. They are not tracking at all in what you posted, when you go WOT again it doesn't even really respond. No wonder it felt like ***, throttle isn't even opening past 45% on that second blip.
This is what I'm talkin about (boxed in red). I don't really know anything about the CZ4A ecu so i couldn't really even speculate on what would cause it to do that. I figured everything else is pretty down stream of the TPS though so if thats doing weird things it would effect most everything.
Last edited by Biggiesacks; Apr 18, 2018 at 01:58 PM.
