I'm lost, anyone have a clue what's going on?

[USMARINE1108]

I've put about 4000 miles on my 02 Z28 since I put the heads and cam in with no problems at all. A few weeks ago it started acting stupid.

When I'm driving, this is what happens. The ABS INOP light, Service light, TRAC light, BRAKE light all come on at the same time, and when accelerating the motor sounds/feels like it's missing on a cyl, like it's jerking. When braking, it feels like the ABS is kicking in and the pedal kicks back at you, when its just a normal stop. Every once in a while, the tach and gas needles go all the way to zero for a few seconds. Also, the ASR light flashes.

I'm confused, there is no check engine light so no codes. It only is like that half the time, the other half it's totaly fine. Motor runs strong and brakes work great. All of the issues happen at the same time, and will just go away by themselves.

I thought it was just bad gas, but I've been through 3 tanks now. I changed the fuel filter, pulled 2 plugs and they looked great, pulled and cleaned the ABS sensors on the rear, and checked the electrical connections on the motor. Anyone have any clue what's going on?

[Mr. Brett]

I've put about 4000 miles on my 02 Z28 since I put the heads and cam in with no problems at all. A few weeks ago it started acting stupid.

When I'm driving, this is what happens. The ABS INOP light, Service light, TRAC light, BRAKE light all come on at the same time, and when accelerating the motor sounds/feels like it's missing on a cyl, like it's jerking. When braking, it feels like the ABS is kicking in and the pedal kicks back at you, when its just a normal stop. Every once in a while, the tach and gas needles go all the way to zero for a few seconds. Also, the ASR light flashes.

I'm confused, there is no check engine light so no codes. It only is like that half the time, the other half it's totaly fine. Motor runs strong and brakes work great. All of the issues happen at the same time, and will just go away by themselves.

I thought it was just bad gas, but I've been through 3 tanks now. I changed the fuel filter, pulled 2 plugs and they looked great, pulled and cleaned the ABS sensors on the rear, and checked the electrical connections on the motor. Anyone have any clue what's going on?

Bad wheel speed sensor maybe?

[Yooformula]

is this an A4? possible tq management issues? have you dynoed recently? I once had similar issues because they forgot to plug the abs sensors back in.

[BAD LS1]

Problem with one or more of the 3 ground wires on the back of the driver side head. Its inadvertantly causing the TCS to activate and causing the miss.

The fluctuating gauges area dead give away of a ground problem.

[95 TA - The Beast]

As Tom mentioned, it is most definitly a grounding issue...

Also check the ground points on the fenders... LT1s also flake out like that when that gound point there is loose...

[USMARINE1108]

I checked the ground on the head and it's on there good. I'll check it again. Are there any other grounds? Where are the grounds in the fenders? Front or rear? And thanks for helping me out.

[BAD LS1]

As a side note, there is only one ground from the engine to the chassis. Its a bare copper ground strap that goes from the block, just above the alternator to the frame rail on the driver side. make sure the connections there are fresh. The other grounds i think Dennis is reffering to, are studs threaded into the strut towers, at the front of them, which havea couple ground wires on both sides of the car that run to them. Its straight back from the fuse block on the DS, and back from the batt on the pass side.

If you have all 3 of the grounds on the back of the head on ONE bolt, that WILL NOT work. They have to be all mounted by their own bolt on the back of the head, its that way stock for a reason... but i know its happened where they got all 3 on one because its a PITA to attach all 3 sepratley.

Pull them 3 wires off, emery cloth the eyelets and the head as well around the bolt hole, im sure they have a protective clear coat on them thay could be now raising hell... or the least bit if moisture/corrosion broke the small connection it made when you assembled it.

[MT98Z]

As a side note,
If you have all 3 of the grounds on the back of the head on ONE bolt, that WILL NOT work. They have to be all mounted by their own bolt on the back of the head, its that way stock for a reason... but i know its happened where they got all 3 on one because its a PITA to attach all 3 sepratley..
Tom is right,of the 3 grounds on the back of the left head 2 went to 1 bolt and 1 went to a diff. bolt.If you put all 3 together its causing your problems,I burnt out my traction controll by putting all 3 together.You need to check that and compare it to another car so you know you got the 3 grounds back on the way you found them.

[BadAzzGTA89]

Get a friggin 1 Ott wire for the ground!

[USMARINE1108]

Well I checked the grounds on the back of the head again, and they were on there pretty good. So I looked at all the other grounds and found that the neg on the batt is stripped out. So, it's time for a new terminal. Hope this fixes it.

[BAD LS1]

Well I checked the grounds on the back of the head again, and they were on there pretty good. So I looked at all the other grounds and found that the neg on the batt is stripped out. So, it's time for a new terminal. Hope this fixes it.

But are the grounds on the back of the head on their own sperate bolts? and have you removed them and emery clothed them?

That secondary batt ground is not the issue, those ground wires on the head specifically ground the gauges and the ASR.

[USMARINE1108]

But are the grounds on the back of the head on their own sperate bolts? and have you removed them and emery clothed them?

That secondary batt ground is not the issue, those ground wires on the head specifically ground the gauges and the ASR.

Makes sence. What's the best way of going about getting back there, short of pulling the head off? From the bottom maybe? Or just from the top? And thanks again.

[BAD LS1]

Pull the coil pack rack off the valve cover, pull the brake booster hose right out the booster and bend it out of the way then you will be able to get back there with an open end 15mm to take care of them... If your hands/arms are small enough to fit back there.

[USMARINE1108]

Well, I just cleaned the bolts, terminal lugs and holes. Put all 3 grounds in their own hole and it didn't fix it. Any more ideas?

[BAD LS1]

W/o being there to look at things my self, cant say for sure.... Its dealer time.

[USMARINE1108]

It's one of the rear ABS sensors. Disconnect them and the car drives and brakes fine.

[BAD LS1]

With it going so catywompass im still convinced its some sort of ground issue somewhere, or worst case an BCM or ABSCM.