[jeremyeliseo]

Originally Posted by Whatwarranty

And solved issue. While checking out my cars fine back side I discovered a 1” strip of mangled rubber. I took wheel off and found chewed up wires they were fuel pump wires. Fixed connections and rerouted the harness. All issues are now gone. Lowering the car I guess caused a slight rub.

Where is the location of this piece of mangled rubber you found?

[jeremyeliseo]

Originally Posted by Whatwarranty

And solved issue. While checking out my cars fine back side I discovered a 1” strip of mangled rubber. I took wheel off and found chewed up wires they were fuel pump wires. Fixed connections and rerouted the harness. All issues are now gone. Lowering the car I guess caused a slight rub.

Where exactly was the rubber piece you mentioned located?
Has the problem come back?

[Spedee]

My 2016 has been doing this also. Dealer checked all the grounds which now it seems to do it more frequently. Also the HUD is now bouncing. I'm out of warranty now so I hope someone finds the smoking gun to fix this issue.

[DorkMissile]

I will say I was experiencing this issue after rebuilding my engine over the winter, was a loose ground on the block, passenger side, just under the header

[blpadge2]

Originally Posted by iPODFAN11

Haveth a read below good sir.

Thanks for posting this. Took mine in to dealer today for another issue, and I quoted the TSB. Lo and behold tech supposedly found a painted ground. We shall see.

[Theme Song]

Originally Posted by Whatwarranty

Ok so I just purchased this car and put headers and full exhaust on it.when I’m driving the car and alternator is charging (hair over 14volts) I have no issues. Once alternator cuts off (12-13 volts) tach begins to jump on decel and around 3800 rpms. Now since it works when alternator is on I know it’s not a bad ground. My question is how can I make the alternator continuesly charge. Or what will resolve my issue?

Loose Tach cable.

[Sorange]

Old thread I know, but I had the issues with a bouncing tach and long crank before starting on my 18 ZLE. Got a CEL for P0340 and P0341 Camshaft position sensor. brought it in for warranty and the tech found that the harness had rubbed against something and rubbed through the insulation of a wire. They ended up replacing the Harness.

[cerino2000]

Bringing this back up. You guys that had problems, did you get a resolution? If so, what was it?

[cerino2000]

Bringing it up again hoping someone found a solid resolution.

[rcoe]

Mine was doing the same thing and I ran a new ground wire from the negative jump point in the front pass side to a solid spot on the engine. Can't remember where exactly I ran but it was close to a pulley under the evap cannister.

This 100% solved both problems of slow crank when hot and the tach jumping.

If you need I can get a picture of it tonight.

[SSDan]

Originally Posted by cerino2000

Bringing it up again hoping someone found a solid resolution.

Originally Posted by rcoe

Mine was doing the same thing and I ran a new ground wire from the negative jump point in the front pass side to a solid spot on the engine. Can't remember where exactly I ran but it was close to a pulley under the evap cannister.

This 100% solved both problems of slow crank when hot and the tach jumping.

If you need I can get a picture of it tonight.

Cerino - I shared this in the other post you made about this but in case you missed it - below is a link to my thread that backs up what rcoe shared. There are a lot of pictures and descriptions for where and how to install an additional ground cable.

https://www.camaro6.com/forums/showthread.php?t=586153

Good luck and report back.

[rcoe]

Originally Posted by SSDan

Cerino - I shared this in the other post you made about this but in case you missed it - below is a link to my thread that backs up what rcoe shared. There are a lot of pictures and descriptions for where and how to install an additional ground cable.

https://www.camaro6.com/forums/showthread.php?t=586153

Good luck and report back.

This is exactly what I did.

[cerino2000]

Originally Posted by SSDan

Cerino - I shared this in the other post you made about this but in case you missed it - below is a link to my thread that backs up what rcoe shared. There are a lot of pictures and descriptions for where and how to install an additional ground cable.

https://www.camaro6.com/forums/showthread.php?t=586153

Good luck and report back.

Ok. This problem is actually on a C7 Corvette. Since they share the same engine and same RPM tach issue, I am doubling my resources trying to find the resolution. I don’t have a slow start issue. In fact the only issue I have is the annoying tach bouncing issue. When I first bought the car it was doing it and someone of the Corvette forum mentioned a little pigtail that could be broken off the negative terminal. They were correct and that pigtail was broken. I fixed it and the problem went away….for a month. Then it came back out of the blue. I have checked every single ground. Rechecked the pigtail and it’s still good. I put a brand new battery in it to eliminate that as a variable. The tach signal actually comes from the cam sensor. I am thinking about replacing that to eliminate that as a variable next. I’ve inspected all of the wiring that I could get my hands/eyes on and all looks good. GM should have done the tach signal to the instrument panel the same way they did the RPM to the ECM and this problem wouldn’t exist. If I ever find the problem I’ll report back with the fix. I’ve got some other tricks up my sleeve.

[cerino2000]

Just to follow up: Today the car magically fixed itself. But what I mean by that is when I started it earlier the instrument panel actually had a short (but noticeable) delay before it came up. And then all of the sudden it was fine. Like perfectly fine. No more bouncing. I feel sure that it finally reset itself and in fact I could have probably got a dealer to do an update on the IPC and that would have cured it too. This all started after I hadn’t driven it for a while and the battery got low. It just took it this long (weeks) to straighten itself out. An amazing bunch of horseshit from GM in how they designed this particular system. Only problem I would have with the dealer reflashing the instrument cluster is I’m not crystal clear on whether they could do just the cluster without over-writing my tune. I THINK they could just from things I’ve seen but just don’t know as a matter of fact.