After a recent super charger installation, the car is presenting two issues:

#1. At 1500 RPM while not in gear (in park) the engine is surging. The attached video show the condition. I am just holding the accelerator; the engine is surging as shown. This only happens in park, and I cannot reproduce this at any other RPM or when the car is in gear, or under load. It may be present, but I cannot see it.

#2 When coming to a stop or at idle, the car lunges forward then the transmission seems to disengage. On an incline (lift ramp, driveway) the car will roll backwards. Once the RPM's are increased the trans will re-engage and perform normally. The data log indicates the engine is trying to stall when this happens.

The car performs normal under load and WOT. There are no codes and trans shift normal with no noticeable problem. Installer is telling me it is a trans issue. They have replaced the TCM with no change to the problems. I am way out my wheel house but, it seems like a vacuum issue since it only happens at low RPM's. Car was perfect prior to install.

Attached is the data log I captured before shipping the car back to the installer to facilitate the repair. Any help or ideas would be greatly appreciated. Car as been at installer approx. two weeks. I am not beating up the installer, I understand things can happen. I just have a sick car, and I am trying to get a second opinion (just like I would do if I were sick) from some of you who have the knowledge and experience to help.

I had previously posted this in tech, but realized that was probably not the best place to look for help.

 

Maybe something simple like the TB gasket

 

I am being told that during the data log it was determined that there is no vacuum leak found. That would rule out a simple gasket leak.

 

Who's tuning it?

 

PM sent

 

BTW, do you have other mods, headers, catback? etc

 

No sir, this is the only mod.

 

Sounds like it’s hunting idle bad. ProCharger? Magnuson?

 

It does seem like that. It is throwing fuel then taking it away to try to prevent stalling. A little update, and this make no sense to me (and I know nothing). It was determined that the TCM was not communicating with ECM. This was causing the transmission to disengage at idle. The problem was the radar detector mirror tap. I have had that radar detector installed since February of 2024 with no issues, so that makes no sense, but that is what I am being told. Surging has not been resolved.

 

If it helps I have had a mirror tap installed for 4+ years and never had an issue, I don't see how the mirror connector has any relation to the TCM. The TCM might need a software update, I remember early on there were occasional false TCM codes stored and the fix was to update the TCM. The surging issue is something else though.

 

My common sense says the same thing. I installed the tap March of 2024. The car had zero issues before the install. The installer did put a new TCM in prior to the tap diagnosis. Chevrolet diagnosed the tap, not the installer. Now I am waiting on the surge issue to be repaired. My last, update was "we are getting close". what ever that means. 30 days at their facility This not a mom and pop shop. I am at the point of pulling their system off, and sending back the car. If this is the level of service at time of install, imagine what it will be like in the future.

 

where? I await install update after dropping deposit and hopefully no issues after putting the Magnusson and headers on my C8 in a few weeks? Thanks david

 

PM sent

 

It is my understanding a third party comes in and completes the tune. I will know today since this seems to be coming to an end.

 

Hey Randy!

I would have your tuner review the data log as they are going to have the best resolution! Can't say we have seen a surging issue like this before a SC application! Hope you find a resolution!

~Ryan

 

Idle torque/ spark/air....maybe MAF as well.

 

Lots of possibilities. transmission disengaging is still a mystery. This install is a nightmare.

 

its all in the tune,,trust me..i had that and worst symptoms....one call and tunning by the experts at ELITETUNNED fixed it all...trust me on this one..and ive had 7 vettes...elite does great work...they even have a college to teach ppl how to tune cars...

 

I tend to agree. The problem is, once you change the tune it blurs the warranty . Nobody wants to share their "secret sauce" or work with anybody in regards to the tune..

 

factory warranty was out the door the minute you decided to supercharge. They may consider warranty for other components but seriously doubt it if you blow up your engine. . . Mine showed extreme lean condition at 6000 rpm. I had to add aux low fuel pump and c7 z06 hp fuel pump and bigger injectors. Now its perfect reving to 6900 rpm with 80 psi of fuel. Dont mess with fuel
man. Itl burn up pistons in a second. Get it tuned right for your application. Call elitetunned today