Bought my 95 z m6 back in november. Love this car! However, today was on the Long Island Expresway doing about 85 in fifth and the car hiccuped big time. It was almost like it had a speed limiter on it. Car ran flawless otherwise. Then later on entering the highway in first with my foot most of the way down it did the same thing. I know the car wasnt really taken care of before me soil am going to throw a new filter in it. Anyone ever have these symptoms? Thanks

 

Sounds like an opti hiccup (though I hate to say it).

 

Not as much as I hate to hear it.

 

Is there any way to narrow it down?

 

Shobox has some tests you can do on his website.

Opti replacement is very easy to do and does not take much time at all. The horror stories you read are from people who are not very mechanically inclined. Not to mention, most of the time the opti is not even their problem. It is the first thing to be blamed whenever somebody posts about a problem pertaining to driveability. If you are not mechanically inclined yourself, do not fear, even for you it is a straight forward job that is hard to screw up.

I replaced my opti at 120k and it was still good. Use an OEM unit.

The only problem is the cost, not the job itself.

Once you replace the opti, it will last you another 150-200k miles (sometimes they die prematurely but I think that's less common).

 

Have you scanned it for codes? A problem with the optical cam position sensor can cause the hiccup, and that will set a code. Look for DTC 16 - shuts the fuel supply off, and if the problem is momentary, the shutoff will be momentary. And the code does not turn on the SES light.

 

I haven't scanned it in a while. Cel has always been on, but itmwasmfor the air pump. I will have a friend of mine scan with his snap on scanner and see what's going on.
I have done optis before, although both on impala ss. Not a bad job at all, especially with the room. I will check out the shoebox site, thanks for the help.

 

If you want to rule out the pump and filter, you need to run it with a fuel pressure gauge hooked up and watch it. Does it do it when your climbing in rpm's or cruising at high speeds? Any issues with the battery of electrical?

 

No electrical issues that I can tell. The 3 or 4 times that it happened I was really beating on the car. It felt exactly like my old Tahoe did when it reached 96 mph,lol.

 

As said, you NEED a fuel pressure gauge to test that system. Hook it up to the valve in the back of the engine, tape it to your windshield and pay attention to the pressure at WOT. IF it drops, you have a fuel issue. If not, then look elsewhere.

I would try the fuel filter first if there is an issue because it's the easiest/cheapest thing to do. Pulling the tank sucks.....so if that's your problem have fun lol.

I just did my friends 97 z28 when it was 30deg outside....that sucked.

 

If its the pump, get your tin snips/ saw ready to cut a trap door, takes 45 min to change the pump.

 

My issue sounds a lot like yours and I changed the alternator and injectors and it was fixed. The electrical is a free test at most auto parts stores and will easily rule that out. Fuel pressure tester are also something you can barrow for free there also and you will kill two birds with one stone. If fuel pressure is it, change the fuel filter and retest. Cut the trap door if that doesn't work.