CT5-V engine surge / "porpoising"

[jkg]

thanks for trying to help out. very nice of you. i'll see how it goes - if it happens more frequently, i will open a case with service department. meanwhile, i just racked up mile 499, so i need to find an excuse to drive 1 mile somewhere to let it all out

 

[Speed Racer 007]

i do not have PDR. i do have hptuners software scan tool, so if i can consistently reproduce it, i can record the event. It does feel like a manual bog - like when i try to drive my vintage mustang with a race engine - but when it happens on the CT5 BW, i downshifted from 3rd to 2nd gear to raise the rpms and it continued to do this surging for several more seconds. if it was a bog from "lugging" the engine, then it should have gone away with the downshift? also, i wasnt bogging it that badly at all. it has happened 3 times in the first 500 miles.
During the last "event," i first downshifted to 2nd, but it continued surging, then i upshifted to 4th, and it continued surging. then i put it in neutral and coasted for a few seconds, then it was gone. basically it happened on an on ramp to the GW bridge here in NY (which is 1 mile long), and it resolved by the middle of the bridge. i was traveling 15-25 mph i would estimate during the event.
I am a very experienced driver/tuner/mechanic (have restored many old cars; track both vintage and modern corvettes/mustang; have done a bit of tuning on previous CTS-Vs) - this was far out of the range of normal operation, is quite concerning for safety, and seems like it is coming from the electronics somehow. fuel tank was not near empty.

Hate to read this, especially going up that hill which I'm very familiar with. Hope you get this resolved ASAP

 

[jkg]

i'm optimistic for now. it's too awesome of a car to be anything less
did you have a similar problem?

Hate to read this, especially going up that hill which I'm very familiar with. Hope you get this resolved ASAP

 

[Speed Racer 007]

i'm optimistic for now. it's too awesome of a car to be anything less
did you have a similar problem?

I wish I had a 5bw to even moan about, still in 1100 hell...LOL

 

[jkg]

The engine surging/oscillation has gotten more noticeable to me. In these 2 videos from hp tuners scanner, i raise the engine from idle to an increased rpm and hold the throttle carefully constant. you can see how the rpms, the TPS and the spark advance all oscillate together. cant quite figure out what this means but cant be normal. @Mirza Grebovic maybe your engineers have some idea
i have not taken it to the dealership, because i cant imagine them sorting this out so easily, and i'd rather not have then keeping and driving my car for extended period of time.

 

[WONT TAP]

Does your car have a manual or automatic transmission? If automatic, are you able to log TCC Desired Slip and TCC Slip?

Also, are there any DTCs that might not be lighting the Check Engine Light?

Finally, when this occurs, can you make the problem go away by giving it a bit more throttle?

 

[jkg]

Manual. No engine codes when I use scanner. If u look in the video, in addition to spark advance and TPS surging, fuel pressure is also but not sure which is the problem and which is just symptom.

 

[WONT TAP]

Sounds like a possible Driver Demand table issue. What happens if you switch to a different driving mode (i.e. Sport or Snow/Ice)? If you can circumvent the problem by selecting an alternate driving mode, that may confirm it's related to the Driver Demand settings.

 

[Mirza Grebovic]

The engine surging/oscillation has gotten more noticeable to me. In these 2 videos from hp tuners scanner, i raise the engine from idle to an increased rpm and hold the throttle carefully constant. you can see how the rpms, the TPS and the spark advance all oscillate together. cant quite figure out what this means but cant be normal. @Mirza Grebovic maybe your engineers have some idea
i have not taken it to the dealership, because i cant imagine them sorting this out so easily, and i'd rather not have then keeping and driving my car for extended period of time.

I would suggest you open a TAC case with dealer and ask for engineering support but from what I see those RPMs are way too low and it seems the ECM is trying to compensate like WONT tap suggested. Does it do it if you keep it around 2k?

 

[jkg]

The video is in neutral with me revving engine. The surging is visible here close to 2000 rpm. When driving on the road the surging is most noticeable around 2000 rpm. But the momentum of moving along dampens it sometimes. Other times the bucking is really bad.

 

[jkg]

I am holding the throttle pedal constant when it is surging in the video. But the throttle reading on the scanning software shows the throttle is moving up and down. But I’m not sure if that is the throttle position sensor or more likely the software in the engine management system

 

[jkg]

i tried running the engine in different modes - my mode, sport, track, and snow/ice the engine does the same oscillation/surging in all modes equally. it does not seem to do it when engine temp cold, but does do it well before engine temp reaches normal operating temp

 

[burn813]

I have had this happen about 3 times in the exact same place (location), in 3rd gear at about 2K rpm. I currently have over 4000 miles, I am not sure it is something at this point that can be reproduced consistently.

 

[jkg]

Sounds identical to my problem. You should try holding the throttle part way to keep the rpms Constant between1500 and 2000, when the engine water temperature is around 130 or 150° before it fully warmed up. On my car, you can see and hear the idle isolating back-and-forth about 100 or 200 RPMs.

 

[BlackwingDuck]

Sounds identical to my problem. You should try holding the throttle part way to keep the rpms Constant between1500 and 2000, when the engine water temperature is around 130 or 150° before it fully warmed up. On my car, you can see and hear the idle isolating back-and-forth about 100 or 200 RPMs.

@jkg this sounds exactly like my ‘09 F-150. It ended up being a bad camshaft phaser assembly. They’re not too hard to replace on these GM small block engines

 

[jkg]

Well, i had my car in for service for 2 days to change out something for this problem. Not sure if the problem is fixed yet- will forward more info when I have had a chance to drive it, but i have to say, that 2 days in a loaner chevy traverse (which is a fine car i guess), makes me really miss the blackwing. In my opinion, nothing beats a loud obnoxious, poorly behaved V8 with a manual trans. While we can debate whether electric cars or turbo 4 cylinders as being better for the environment (i'm not convinced yet), and maybe mini-vans are more practical, and maybe the media and government will shove those things down our throats, but i'll be the last one holding on to my V8 and manual trans. Like someone once said about another controversial issue, you can have my open exhaust V8 when you pry it from my cold, dead fingers...

 

[burn813]

Well, i had my car in for service for 2 days to change out something for this problem. Not sure if the problem is fixed yet- will forward more info when I have had a chance to drive it, but i have to say, that 2 days in a loaner chevy traverse (which is a fine car i guess), makes me really miss the blackwing. In my opinion, nothing beats a loud obnoxious, poorly behaved V8 with a manual trans. While we can debate whether electric cars or turbo 4 cylinders as being better for the environment (i'm not convinced yet), and maybe mini-vans are more practical, and maybe the media and government will shove those things down our throats, but i'll be the last one holding on to my V8 and manual trans. Like someone once said about another controversial issue, you can have my open exhaust V8 when you pry it from my cold, dead fingers...

Do you know what they are changing out? I would have thought this was a tuning issue, not a hard part issue

 

[jkg]

I’ll give a full report probably over the weekend.

 

[GTANotch88]

I'd be interested with hearing your experience with the service department. I assume you went to the same dealer you bought it from. I'm getting my 5BW from the same place.

 

[jkg]

that dealer told me they are expecting a blackwing order for a customer sometime very soon - they told me in transit. must be yours! so far, service department has been very nice. they have one service guy who appears to work on the vettes and my blackwing. much nicer experience than i had at last cadillac dealer in westchester when i bought my 2004 V. my 2013 V wagon never had to go in for service ever.