Hey guys,

I just picked up a 96 Z-28 M6 with 60K on the clock. The car is in great shape except for a couple of things. First, when the car is warmed up, the oil pressure at idle is only about 20-25psi, is this normal for these cars?

The other problem is that the car backfires. But it only backfires when I rev it in neutral. When driving it sounds perfect. What could possibly be causing this?

Finally the gear shift **** vibrates a good bit, is this a problem?

Besides that, it's a great car and I am enjoying it a lot so far.

Thanks,
-Max

 

Sounds about right.

 

Is it a aftermarket shifter? Does it have a short throw? If so, aftermarket shifters don't have any vibration dampeners on the shifter so its going to feel rougher over a stock. If its a stock shifter, a bad pilot bearing can cause that, but unless its shaking violently, I woudln't worry about it.

 

My oil pressure (at idle 20 - 25) (at 60 mph 50 - 55) this is since 48K miles looks Ok to me

backfiring mine will sometimes and sometimes when you have been a bit hard on it and let off, sounds normal to me with these cars do you have aftermarket exhaust??

Virbrating gear shift ****, that is all depending on your exhaust you will see more than the shifter **** vibrating,, is this at idle or on the road, either way vibrating stuff to some degree is pretty normal.

Enjoy your car as the minor inadequacies (it's not a Caddy) will be made up for during right foot pressure!!!

 

If the backfiring happens as it revs down that is normal. The shifter vibrations check your transmission mount it could be worn, factory rubber depleats quickly. If your oil pressure rises as you step on the gas you should be alright.

 

the vibration is most likely normal, they all do that a little bit. its the power *grunts*

 

Thanks for the replys guys,

The car is completely stock down to the air-filter, so nothing aftermarket is affecting its performance. The backfires only happen when the engine is slowing down, but it does not sound normal. I had an L98 GTA and it never did that. Could the car possibly need new plugs/wires or a fuel filter?

I am very happy to know that the oil presure is normal. When driving it usually stays right above the 40 mark, it's only when idling that it drops to 20.

Another problem is that when its totally cold, it takes 10 secs of cranking before it catches, what could cause this?

Well now that the important stuff is out of the way, does naybody know where I can get a good repair manual for these cars?

Thanks for the help,
-Max

 

you can get a haynes or chiltons manual from auto zone, advanced auto, napa, or any auto place probably. I would do an oil change, fuel filter change, check spark plugs and wires and possibly change, check all fluids, take off and clean your throttle body and idle air control (iac), coolant flush and refill.........then after all that and if it seems to be running strong...well my friend then you have to start modding away!!!

 

Its normal in the lt1s to get some rattle from tranny clutch and some vibes thru shifter.
Its normal for oil pressure to be lower at idle and as said as long as it increases when you rev it up thats good sign.

Its not normal to be slow starting.It shoud fire up instantly.
You might have bad battery..check that first.As said change fuel filter, plugs and wires they are big pain and can be pricey if you pay someone to change them so put in like good plugs that last a long time.
You could have bad optispark it can cause backfiring and think hard starting..they are pretty expensive to have fixed but not too bad if you are handy and have tools,jacks etc.

Anyway sure you will be happy with your car even if it needs a bit of work they are still big fun.

 

10 seconds of cranking to start sounds like fuel pressure problem, replace fuel filter, $10.00 well spent, if clogged fuel filter pump will give out soon trying to pump through clogged filter. Plugs and wires are only a problem if a miss-fire exhists which doesnt sound like you have a miss-fire.

Oil pressure at idle with engine at operating temperature 18-20 psi. normal.

Backfire or pop through exhaust when rev in neutral or when decelerating normal, most noticed when engine is cold but can happen a bit at operating temperature.

Vibration in shifter not uncommon.