Under hard braking....check engine light comes on

[Vip-RT10]

I don't know if this is normal, but I have always noticed that when I lace into the brakes to make an agressive stop, the check engine lights up, then dissappears. I think it's because the oil gets spilled to the front of the oil pan, making the pump starved for oil. I may be wrong. It does use oil, like one quart every 300 miles (more or less). Anyone with the same observation? Any suggestions? I also notice that when I go WOT, there is a sudden cloud of darker smoke at the begining of the WOT. Anyone with suggestions? I'll do research now.....

[SteveBCloud9]

Dark cloud of smoke means the cars sits for too long and builds deposits. If this is NOT the case, then engine wear. As far as the light it can be related to many things. I believe if the brake pedal travels too far or hits the floor board it would go on indicating possibly worn rotors, vac. leak, master cylinder gaskets, etc. If the brake pedal is firm then look elsewhere.

[Vip-RT10]

Thanks Steve.....the car doesn't sit long it gets driven every 3 days or so now.

Brake pedal is firm too and no visible leaks anywhere....I'm bogled now....

[GTS Dean]

The "Check Engine" light and "Brake" lights warn separately.

1 quart per 300 miles of driving is what I would call excessive consumption. When I first read your problem concerning oil use, I figured you must have a 2000 creampuff with powdered cylinder liners. However, with a '93, I would guess it is stuck rings or missing valve guide seals (it's happened.) The Gen1s hold about 10 quarts of oil and tend not to be as finicky about supply as the '96-'99 Gen2s which have 7.5 quart sumps.

Could it be a temperature problem? My '93 used to have the engine light come on at the track or in the Texas summer heat.

[SapphireGTS]

Dont you love check engine lights? What the heck are they for. I think what would be equally useful is a general "Car Problem" Light.

Good luck

My experience with check engine lights coming on is just a malfunctioning check engine light.

With your symptons sounds like its getting starved for oil. TOo much at WOT and to little at hard braking.

[JonB - PartsRack]

Antonioioioioio......

If you want a new-but-aging set of MPPerformance/trap door baffled pan for a Gen-1, I have one. Authentic. Rare. Endangered. Sell at cost.

[Jeff Torrey]

My car does the same thing when it is low on oil. Another sign is that at idle the oil pressure will drop to 40 pounds.

Yes puff black smoke on accelleration after. Same thing.

Only mine uses 3 quarts every 500 miles.

Rings stuck, oil getting by. Burning off and expelled through the exhaust.

My car is going in for service over the winter months.

Good luck with your 93.

But I am not a mechanic. This is second hand information from Chuck Tator.

[Vip-RT10]

OK....Thanks for the info everyone

JonB...I'll call you tomorrow

BAKNBLK95RT...I'll reset the cables tomorrow.

Jeff Torrey...what do you have to do, change the valve guides?...seals and the works?

[Sniper]

Speaking of oil pressure, where should a 94's pressure be at? Mine is at a fraction over 30.

[Jeff Torrey]

Basically the engine has to be checked. Rings changed. Cylinder walls checked, polished - resleeved if damaged. Heads checked machined if warpted. New valve seals if needed.

New updated head gaskets.

Budget $ 2500 to $ 4000 if heads need to be done.

[GTS Dean]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Matt Kovac:
Speaking of oil pressure, where should a 94's pressure be at? Mine is at a fraction over 30.

<HR></BLOCKQUOTE>

What weight oil are you running? That sounds reasonable for a 0W-30, but maybe a tad low for 10W-40 and certainly low for 15W-50. The old rule of thumb for oil pressure is 10psi/1000rpm. There's almost no stress on an idling engine, so it doesn't have to be that high.

One thing I've noticed on mine since I do oil sampling and run extended drain intervals - fuel dilution (from blowby) eventually begins to lower the viscosity. However, this takes about a year under (my) normal driving. Addition of make-up oil between changes fights the viscosity drop.

[Doug Supercharged Vipers]

Antonio -
One way to determine if you have bad valve seals w/o removing them is to let the car sit overnight. In the morning cold start the engine and check to see if it blows smoke out of the exhaust on startup. Also, you can pull the spark plugs in the AM to see if there's any wet oil on them, but, the cold startup is usually the dead giveaway when it puffs smoke from the exhaust.
Valve seals can be replaced on the engine w/o removing the heads if necessary. The large puff of smoke on acceleration could be the plugs loading up with oil.

Another thing to remember, if your using that much oil you will have to keep the oil level up to par to eliminate the Check Engine Light during hard braking. Next time fill the crank case to the proper level on the dipstick and then do an aggressive stop to see if the light doesn't illuminate.

Good Luck and if you need some tech advice give me a call,
Doug

[Sniper]

Yes, I am using 10W-30. What does everybody use? I thought it was 10W-30.

[GTS Dean]

For street driven cars, the factory recommendation is entirely adequate and gets you slightly better fuel economy. Those of us who see track time with any degree of frequency typically go to the heavier grades for higher loads and temperatures.

[Sniper]

Thanks, Dean!!!!!!!!!

[Tom and Vipers]

My money is on the PCV orifice system sucking liquid oil into the intake when the oil pools up in the timing chain housing during heavy breaking.

Tom Sessions went a bunch of laps with me at Watkins Glen and my car would puff white smoke the instant the throttle was touched after heavy breaking. It could have been mistaken for black smoke.

At no time did the oil pressure deviate.

Our first thought was that the oil sump was sucking air, losing oil pressure, and collapsing a lifter because the engine make a substantial valve ticking noise when the smoke was generated.

There was a noticeable loass of power when the smoke was generated.

Tom called some contacts and the PCV problem was discussed.

When you suck that much oil into the intake, the engine detonates - hence the valve noise - it is acctually pinging.

Solution other people have is to plumb a reservoir into the PCV draw line so that there is always sufficient "gas" to draw thru the orifice.