smoke@high rpm, noise, 86 carrera

ok, interstate driving last week in 86 carrera...hard throttle accelerations from on ramp produce white/yellowish smoke above 5000 rpm, can't tell if from exhaust or not, with accompanying loud detonation-type noise. oil pressure and temp are fine, no excessive oil consumption. I read a similar post from July (without noise), diagnosing mixture problems. Any help from the gallery? btw, running 10w-40 syntec which was reading 5+ above 3000 rpm, and autothority chip.
(and thank you in advance)

Paul

What kind of gas are you running?

Any Additives?

Nick

just found this original post...just duplicated too. currently on pump texaco 93, but the problem happened with several tanks/brands of 93 oct as i drove. no additives. this was the coldest temps the car has been driven in (40 deg or so), so I don't know if that could have contributed.

thanks
P

I think the post you mentioned was about my car (1987 Carerra). The car would smoke a bit upon hard acceleration somewhere in the 5-6k rpm range (blk/grey). It would not smoke until reaching 5k.
It would also let out a burst of black/grey smoke after idling at a stop and then pulling away. No smoking at idle, but a big puff as I hit the gas.
Inspection revealed the plug on #6 was constantly fouling, leaving a damp black residue. Oil consumption had also increased. I was worried about valve seals and piston rings.
The consensus was that since the smoke was blackish and not white/blue, it was an over rich fuel mixture causing the smoke, and not just oil burning (interesting note: the black smoke increased while using techron). Since you say your smoke is more of a white/yellow I'd hesitate to say it's the same thing.
In trying to eliminate the smoke I replaced many things (one by one). Plugs, wires, cap, rotor, fuel filter, gas stations, and the injector on #6. The biggest change occured after changing the injector, and replacing the oil filter/oil. I did this immediately after running 2 bottles of techron through the system.
I think the injector may have been overspraying, letting an excess amount of fuel into #6. This resulted in a lot of unburned gas leaching into my oil. The contaminated oil was then more likely to burn; slowly increasing my oil consumption as the fuel was dilluted... causing more and more smoke.
After the oil change, consumption went down, the high RPM cloud dissappeared, and I think the idle-drive puff also vanished. I say "I think", because shortly after the final changes I put my car away for the winter. I suppose I'll discover the truth in the spring...
I think the first thing you need to do is to make sure the smoke is coming from the exaust. Also note the exact color of your smoke. Does the car smoke if you rev it by hand (parked, hood open, revving by hand)? I'm not sure about the "detonation" sound you describe. That worries me. Are you talking about popping, like a little backfire... or something else?

Dan Tolley
1987 911 Coupe

Pendelton,

Do you have chip installed on the computer?

Also I believe your '86 (3.2 with higher compression than '84 & '85) has a knock sensor to retard the timing when detonation occurs. This may be failing.

Good luck.
Nick
'85

the car does have an autothority chip...i think I'll try examining the plugs and injectors, with an oil change thrown in. before i noticed the problem, the car sat for 2 weeks and was only lightly revved for the 2 months prior to that. otherwise the car runs great. thanks again for all the help!

P