pilotgore
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So this last weekend while on track, I experienced an odd intermittent power reduction that I can’t explain, and I’m hoping someone will be able to chime in and give me some insight.
Ambient temps this weekend ranged from 75 degrees, up to 93 degrees on both Saturday and Sunday. Saturday was a normal track day, no issues whatsoever.
I have a ‘19 350, and typically run stock cup 2’s (which I did on Saturday all day.) For Sunday I switched over to a set of 305/30 cup 2’s, and holy hell the grip was noticeably better. For the first time at my home track, I was now having to contend with hitting the rev limiter at the end of two different straights. Partially because my exit speeds were higher coming out of turns, and partially because of the reduction in tire height.
Let me explain the power reduction first. There were no check engine lights or outward indicators of any kind. I’d go from full power and torque, down to having good power and torque at 5,000rpms and below only. Above 5,000 rpms was non existent. 30 seconds after onset of the power reduction, id get full power and torque back. This was very consistent. It seems like the majority of the time, it occurred in the last half of the session (so maybe heat related?)
All of my sessions I had plenty of gas, and I’ve experienced power reduction due to a low tank and sloshing, so I’m eliminating that as a possibility.
During the first session, I only experienced the issue once. It happened after turn 1, which is the highest speed turn on the track after the highest speed straight where I could now just hit the rev limiter a half second before the braking zone. I noticed I didn’t have full power exiting turn one, going from maintenance throttle to full throttle. 3 seconds prior in the braking zone prior to turn 1, the engine had no problem blipping up to 7-8k rpms as I downshifted.
Second session started out normal, but then I was having the power reduction every other lap on average. Sometimes twice a lap. During the session, I thought maybe hitting the curbing during apex or exit curbing, and that was causing the issue. But, then I noticed it was happening even if I didn’t touch the curbing at all.
After the second session I hypothesized that maybe I was hitting the rev limiter, and that was sending the car into a pseudo limp mode until it made sure the car wasn’t in danger, then gave me full power back. I’ve been in limp mode in the 350, and this is something different.
For the third session I adjusted my shift light slightly lower, and took care not to hit the rev limiter a single time. That session, I maybe experienced the issue twice (totally manageable but inconvenient.)
Forth session was horrible, I had the power reduction happen a 15-20 times. I actually got good at noticing the reduction and would immediately upshift to stay under my 5k rpm cap.
Fifth session, more of the same, maybe slightly better.
Sixth session, I switched back to the 35 series tires and ran with the heat on for the whole session. I was sweating like a pig before turning the heat on…. It was miserable but the car was acting normal again.
On the drive home I got a P0013 code and the car started running like crap. This is my third run-in with VCT stuff. The first time was the dreaded pigtail/wiring harness failure (thanks for your help diagnosing that one Kevin, the second time the brackets broke loose from both intake vct solenoids which caused the system to freak out and go into limp mode until clearing the code (pic attached), and now I’m waiting on my dealership appointment to find out the current cause.
I checked for codes after every session, including the advanced diagnostic codes on the pcm. I had P0219 (engine over speed), but after clearing the code and staying away from the rev limiter the rest of the day, this one never came back.
I left the track as I usually leave the track… happy, but with multiple codes to fix before the next event. Ohh yeah, on Sunday the starter also broke, the tpms system became inop, and I intermittently have a red brake annunciation. Fun stuff.
So…. After reading this novel, does anyone have any thoughts? @honeybadger , I totally see why you went with the VCT lockouts now. My friend Florian who runs lockouts on his modified Boss 302s says hello by the way.
Thanks everyone.
Ambient temps this weekend ranged from 75 degrees, up to 93 degrees on both Saturday and Sunday. Saturday was a normal track day, no issues whatsoever.
I have a ‘19 350, and typically run stock cup 2’s (which I did on Saturday all day.) For Sunday I switched over to a set of 305/30 cup 2’s, and holy hell the grip was noticeably better. For the first time at my home track, I was now having to contend with hitting the rev limiter at the end of two different straights. Partially because my exit speeds were higher coming out of turns, and partially because of the reduction in tire height.
Let me explain the power reduction first. There were no check engine lights or outward indicators of any kind. I’d go from full power and torque, down to having good power and torque at 5,000rpms and below only. Above 5,000 rpms was non existent. 30 seconds after onset of the power reduction, id get full power and torque back. This was very consistent. It seems like the majority of the time, it occurred in the last half of the session (so maybe heat related?)
All of my sessions I had plenty of gas, and I’ve experienced power reduction due to a low tank and sloshing, so I’m eliminating that as a possibility.
During the first session, I only experienced the issue once. It happened after turn 1, which is the highest speed turn on the track after the highest speed straight where I could now just hit the rev limiter a half second before the braking zone. I noticed I didn’t have full power exiting turn one, going from maintenance throttle to full throttle. 3 seconds prior in the braking zone prior to turn 1, the engine had no problem blipping up to 7-8k rpms as I downshifted.
Second session started out normal, but then I was having the power reduction every other lap on average. Sometimes twice a lap. During the session, I thought maybe hitting the curbing during apex or exit curbing, and that was causing the issue. But, then I noticed it was happening even if I didn’t touch the curbing at all.
After the second session I hypothesized that maybe I was hitting the rev limiter, and that was sending the car into a pseudo limp mode until it made sure the car wasn’t in danger, then gave me full power back. I’ve been in limp mode in the 350, and this is something different.
For the third session I adjusted my shift light slightly lower, and took care not to hit the rev limiter a single time. That session, I maybe experienced the issue twice (totally manageable but inconvenient.)
Forth session was horrible, I had the power reduction happen a 15-20 times. I actually got good at noticing the reduction and would immediately upshift to stay under my 5k rpm cap.
Fifth session, more of the same, maybe slightly better.
Sixth session, I switched back to the 35 series tires and ran with the heat on for the whole session. I was sweating like a pig before turning the heat on…. It was miserable but the car was acting normal again.
On the drive home I got a P0013 code and the car started running like crap. This is my third run-in with VCT stuff. The first time was the dreaded pigtail/wiring harness failure (thanks for your help diagnosing that one Kevin, the second time the brackets broke loose from both intake vct solenoids which caused the system to freak out and go into limp mode until clearing the code (pic attached), and now I’m waiting on my dealership appointment to find out the current cause.
I checked for codes after every session, including the advanced diagnostic codes on the pcm. I had P0219 (engine over speed), but after clearing the code and staying away from the rev limiter the rest of the day, this one never came back.
I left the track as I usually leave the track… happy, but with multiple codes to fix before the next event. Ohh yeah, on Sunday the starter also broke, the tpms system became inop, and I intermittently have a red brake annunciation. Fun stuff.
So…. After reading this novel, does anyone have any thoughts? @honeybadger , I totally see why you went with the VCT lockouts now. My friend Florian who runs lockouts on his modified Boss 302s says hello by the way.
Thanks everyone.
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. So I would suggest that you put it back together and then do those steps.