Engine Problem - Could use some advice

[Mike Martz]

My BW5 (3000 miles) is having an engine issue. It is missing at high RPMs under full throttle. I just went out and recorded a few pulls with the PDR on and have been reviewing that using the GM version of the Cosworth Toolbox. I found it not to be very helpful but you can see the hesitation starting around 5k. I am also trying to learn the Cosworth Pi Light Toolbox which is much more powerful.

When I returned, I received an email from OnStar stating that my car has an issue with the emission system and I assume it is related to the miss. It frankly feels like the very old, old days when you fouled a plug. Full throttle at about 5k, it just starts stumbling and missing.

FYI - I ran with TC off and PTM set to Sport, 70 degrees. Also, I have 20" wheels with Michelin PS4 All Season tires for some low temp/winter use. At first I thought it might be the TC kicking in, that is why I ran with TC off plus it just felt different. Also worried that the 20" wheels might mess up some sensors but the overall circumference is very close to stock and it started a while after I put them on anyway.

I plan on taking it for its first visit to the dealership but wanted as much info from my informed friends as possible before making that journey. Has anyone had a similar experience and if so, what was the issue?
Thanks!

 

[Throat Yogurt]

First off, sorry you are having issues. If it sounds like a misfire, and you are getting emission system warnings, then it is almost certainly a misfire, and not related to TC/wheels/tires. Best guess would be a fouled plug, only way to know for sure is to pull codes and then pull the offending plug. Not worth doing it yourself since the car is under warranty.

Have you filled up at any sketchy gas stations?

 

[Berserker]

It frankly feels like the very old, old days when you fouled a plug.

In the Car and Driver Blew Up Their Car thread, a couple of guys reported broken plugs. One posted pics. linky

 

[Mike Martz]

First off, sorry you are having issues. If it sounds like a misfire, and you are getting emission system warnings, then it is almost certainly a misfire, and not related to TC/wheels/tires. Best guess would be a fouled plug, only way to know for sure is to pull codes and then pull the offending plug. Not worth doing it yourself since the car is under warranty.

Have you filled up at any sketchy gas stations?

Shell Top Tier only

 

[raptor5244]

In the Car and Driver Blew Up Their Car thread, a couple of guys reported broken plugs. One posted pics. linky

I had a cracked plug on a Corvette that caused this type of behavior before. I had HP Tuners logging at the time and could pinpoint the cylinder experiencing the high count of misfires. Swapped the plug and all was well.

 

[Speed Racer 007]

First off, sorry you are having issues. If it sounds like a misfire, and you are getting emission system warnings, then it is almost certainly a misfire, and not related to TC/wheels/tires. Best guess would be a fouled plug, only way to know for sure is to pull codes and then pull the offending plug. Not worth doing it yourself since the car is under warranty.

Have you filled up at any sketchy gas stations?

X2 . Seems to be a correlation

 

[Mike Martz]

Update - It is at the dealer and they cannot locate the cause. They checked the plugs, asked the gas question and are now talking to GM.
It is not creating any codes beyond the one emissions code that they said was too vague to be of any help.
The service people at Lockhart are being great and very helpful, they just don't know a lot about this engine.

 

[Nadnerb]

My BW5 (3000 miles) is having an engine issue. It is missing at high RPMs under full throttle. I just went out and recorded a few pulls with the PDR on and have been reviewing that using the GM version of the Cosworth Toolbox. I found it not to be very helpful but you can see the hesitation starting around 5k. I am also trying to learn the Cosworth Pi Light Toolbox which is much more powerful.

When I returned, I received an email from OnStar stating that my car has an issue with the emission system and I assume it is related to the miss. It frankly feels like the very old, old days when you fouled a plug. Full throttle at about 5k, it just starts stumbling and missing.

FYI - I ran with TC off and PTM set to Sport, 70 degrees. Also, I have 20" wheels with Michelin PS4 All Season tires for some low temp/winter use. At first I thought it might be the TC kicking in, that is why I ran with TC off plus it just felt different. Also worried that the 20" wheels might mess up some sensors but the overall circumference is very close to stock and it started a while after I put them on anyway.

I plan on taking it for its first visit to the dealership but wanted as much info from my informed friends as possible before making that journey. Has anyone had a similar experience and if so, what was the issue?
Thanks!

288 Miles and an engine failure

‘‘Twas a rough night last night. Cruising down the freeway at about 70 miles an hour and all of the sudden I hear metallic squeaking from the engine bay. Pretty sure the bearings went on it. 288 miles on the dash and my caddy dealership thinks it’ll probably need a new motor. Hoping it’s...

www.cadillacvnet.com

I had a similar hesitation on my motor but I was even just at the lower RPMs cruising. Turned out to be the motor spinning a rod bearing. Hopefully my new one wont have that issue

 

[Slick Blackwings]

Update - It is at the dealer and they cannot locate the cause. They checked the plugs, asked the gas question and are now talking to GM.
It is not creating any codes beyond the one emissions code that they said was too vague to be of any help.
The service people at Lockhart are being great and very helpful, they just don't know a lot about this engine.

You say they checked plugs how? if somebody is just looking at them i would say thats useless. I’ve had plugs all look good but one of them bad, impossible to tell with the naked eye hopefully they replace them with new ones to determine that they were good.
Sorry to hear of these issues.

 

[Mike Martz]

Update - They saw a misfire in cylinder 6 and replaced the plug, ignition pack and wire. Didn't fix it. They have now had it for over a week and are still talking to GM. Now think it might be an injector and waiting for GM to tell them the next step. I don't think they have worked on many LT4 engines and I am sure dealing with GM can be frustrating but I want my car fixed.
The people at the dealership have been great and I even took the lead tech on a drive to show them what it was doing. He has spent time at the V Academy and knows the cars and he is just as frustrated but.....

 

[Mike Martz]

FYI - Crystal DID NOT build the engine.

 

[Speed Racer 007]

FYI - Crystal DID NOT build the engine.

I don't even know who built mine, don't really care. If it pops, warranty will assist.

 

[Nadnerb]

Takes about 27 days and one Buick encore loaner, give or take a few days for a new motor

 

[Snowwolfe]

Interesting that engine issues are being seen so early and so often. Same basic motor went in the current ZL1 as well as the last Z06.

 

[Nadnerb]

Interesting that engine issues are being seen so early and so often. Same basic motor went in the current ZL1 as well as the last Z06.

From what I’ve learned on my kerfuffle is that it’s not the same motor and the hand building process sets it apart. The RO for my motor replacement came out to around 50k and the long block was about 25 of that

 

[Snowwolfe]

From what I’ve learned on my kerfuffle is that it’s not the same motor and the hand building process sets it apart. The RO for my motor replacement came out to around 50k and the long block was about 25 of that

C8 Z06’s came with hand built motors as well as a few ZL1’s.

 

[Nadnerb]

C8 Z06’s came with hand built motors as well as a few ZL1’s.

C7 Z06 I think you meant to put. The ZL1 was a different supercharger slapped onto an LT4. The Z06 I don’t believe ever had hand built motors with the titanium valvetrain like the blackwings

 

[Exia]

Te

C7 Z06 I think you meant to put. The ZL1 was a different supercharger slapped onto an LT4. The Z06 I don’t believe ever had hand built motors with the titanium valvetrain like the blackwings

The Z06 LT4 was hand built and have plaques (mine does). The LT4 in the ZL1 also started receiving plaques after 2019 I believe. The ZL1 LT4 is the same as the Z06 LT4 minus the dry sump. They have the same supercharger. The Escalade V is running the LT5 2.65L blower on its LT4 but the Blackwing (again without dry sump) uses the same engine as the ZL1 and Z06 with some slight revisions to exhaust, induction and a taller lid which gives it the 18hp over a Z06 or ZL1.

 

[Speed Racer 007]

Takes about 27 days and one Buick encore loaner, give or take a few days for a new motor

I was waiting for this remark...LOL

 

[raptor5244]

My ZL1 LT4 was hand built by Mr. Zach Lamb on the build plate. They were hand built when they could keep up with demand. It is cheaper to build them by hand for low production vehicles vs. retooling.

Z06 article.

All Corvette Z06 LT4 Engines are Now Hand Built in Bowling Green - Corvette: Sales, News & Lifestyle

Starting May 1st, every 650-hp LT4 engine that goes inside the Corvette Z06 will be hand-assembled by the Performance Build Center.

www.corvetteblogger.com