TT Oversteer

I haven't owned this car very long and I'm just beginning to get a feel for its oil usage rate. it appears to have used one quart in the last 500mi. It went from the full mark to midway between the two marks on the dipstick in just 500mi. I understand this correlates to about one quart used or 2qt/1000mi. which is about twice normal?

Here are the numbers:

Test 1) 15mph: CO2 14.5, O2 .7, HC 181, CO .51, NO 1814
25mph: 14.4 .9 268 .37 1435

Test 2) 15mph: CO2 13.3, O2 1.3, HC 274, CO .44, NO 1498
25mph: 13.2 1.3 277 .64 1208

So.......after all of the above changes, O2 is higher, HC is higher, CO higher at 25mph, NO slightly lower.

Something is obviously seriously wrong and the only thing that correlates with the high hydrocarbon numbers seems to be high oil consumption. By the way, compression is 150 to 155 across all six cylinders. I'm also noticing a slight miss at idle and some slight back-firing out the exhaust while driving with the throttle closed and just above idle. i.e. overrun going down hill.

Peter Zimmermann

I respectfully suggest (TT) that you have a second shop look at the car. With all that's been said/done I don't think that your high hydrocarbons are caused by something "hiding" in the grass. You changed out the plugs, did you not see anything strange with them? What replacements did you use, and what gap? Do you use the same gas station every time - I know someone who just had an awful time with a car, turns out the owner kept filling up at the same station, getting one bad tank of gas after the other. Just thinking out loud...

Yeah, Randy, I wish they would secede, join up with France, and get it over with!

TT Oversteer

Peter, I'm not sure I follow you on the "hiding in the grass" comment. The old plugs look surprisingly good: dry with no carbon or oil deposits. New plugs are Bosch super plus copper set to .8mm. As far as fuel goes, I'm running 91 octane from any station that's convenient, I'm not using avgas or race gas or anything like that. When you allude to "monkeying with the motor" what are you suggesting? perhaps the cam timing was advanced? I could check that without too much trouble. These numbers are two to three times the maximum allowable value for hydrocarbons and NOx. If the compression is good, mixture is set properly, O2 sensor is doing its thing with lambda, what else could it be? I thought large amounts of oil in the combustion chambers could be the only answer but it doesn't smoke hardly at all and you are leading me to believe perhaps it's something else? What are your thoughts on how cam timing could affect this problem?

KeithC2Turto

A couple of thoughts.

If somone went to the trouble to put a 3.2 in an earlyer car they may have chipped it. Unbolt the Motronic brain, lift it up, and look to see of the tabs underneath are unmolested. If there are scratches around them, someone was in there and there may be an aftermarket chip.

There is a fuel quality switch on the Motronic brain. Go to 911chips.com to see how to play with it and see if it is set to stock. Also, there is a brown jumper wire at the brain with a conicter in the middle of it. Make sure it is pluged into its self as this is enables the California emmissions setting.

Check the cat. Again if some put a big motor in an early car thay may have gutted it or it just might be dead or pluged. Might try putting a lazer temp gauge on it to see if it is hotter out than it.

Somtimes the O2 can be lazy or bad. May concider replacing it.

I run Tectron through my car's a tank before I smog, replace plugs, replace air filter, make sure the car is hot, the day is cool and do it on a Sunday morning if they are open (they wont be worried you are a BAR agent and they will not know anything about a Porsche.

Good luck.

Peter Zimmermann

Basically I was thinking that the combo of clean plugs and decent oil consumption, the source of your high HC was something other than what a teardown would fix (a valve guide or ring issue "hiding" from you).

I was just agreeing with Randy, with engine swaps there is just no way to be sure what has really happened. Keith's comments are also good, on its face your ECU might look fine, but if it's got some off the wall chip in it all bets are off.

Your emission results really do point to the cat, but I think that you said that the engine has a new (or maybe only "new" to the car) cat. Regarding cam timing, I'm at a loss on that one, I don't think that I ever ran across a 3.2 with the cams set up wrong. Now, if they're some kind of weird re-grind, I can see that messing with your numbers.

Edgy01

Go find a trashed 1975 911 in a junk yard. Spend abot 20 minutes with a torch and cut out the VIN numbers. Weld them into your car. Reregister your car under the new VIN.

TT Oversteer

Keith, some good points, thanks. I will take a close look at the computer and see if it appears to be tampered with, and also check the brown wire and "fuel quality switch". I guess the cat could also be suspect and bears further investigation. I never suspected the chip for two reasons: 1) why chip the car and keep the cat in place when it's not required (Idaho). I would personally lose the cat before adding a chip. 2) if Steve W's chips pass smog why would others cause such gross emission levels?

Pete, I'm encouraged that you think my problems are not caused by worn rings, guides or seals. my suspicion of non-stock cam timing comes from the fact that service records for my car state the timing chains and rails were replaced during an engine reseal. Maybe someone got the bright idea to "enhance" the cam timing at that time. I never stated that the cat was replaced or new, only that the engine itself supposedly has around 75k miles on it. I didn't focus on the cat due to its alleged low mileage and also because another poster here stated that his car passed CA emission levels with a cat bypass installed. Again, I am at levels 3 to 4 times allowed for HC and NOx.

Dan, I like the way you think. I usually save the cutting torch as a last resort but, who knows, I may have to get MIDEVIL on this car at some point!

I realize I may have made to many "assumptions" here and we all know where that leads. I will continue to eliminate the easy stuff BEFORE tearing into the motor. Thanks all for your good ideas and I'll post what I find out.

porsche4us

Sorry to butt into the conversation here, but I thought it would be appropriate to ask my question in this thread. I believe my car is from California, and was wondering what makes a California emissions car different that a federal emissions car?

Edgy01

It used to be a bigger difference. Today there is no difference. It had to do with the state of the tune and what was allowed (emissions, wise).

Peter Zimmermann

Oops! I misread/misinterpreted your comment "a stock cat is installed", post #24, as something that you had done. Sorry about that! Better check it out and make sure that it's not gutted!

Brett San Diego

I believe it was 1980 that the 911 became 48-state emissions compliant (no more special California emissions package). For 1978 (my 911 model), I think the only difference for CA emissions was an EGR system installed in the CA cars, but there could be more.

Brett

porsche4us

Well it's a '87 911 and it is equipped as a California emissions car. It passed emissions requirements with extremely low numbers. I'm just curious to know what other things are present in a California emissions car.

Steve Weiner-Rennsport Systems

JMHO, but if your oil consumption is 1qt/500 miles, no amount of fiddling-tuning-adjustment-tuneup parts will make up for those high levels of HC's.

One should be performing leakdown tests and removing the lower valve covers to measure guide wear.

Peter Zimmermann

I would prefer to see the consumption test done the way that I had my customers do it. (1) Track the oil level until it's down to the minimum mark, (2) add one quart, (3) record mileage, and (4) track consumption until the oil level is once again at the "min" line, and record mileage. No insult intended - all oil level checks done with the dipstick, car on a level floor, engine idling, front cooler hot to the touch. My experience was that we serviced a fairly large number of 3.2 cars that were in the 500-700 mile per quart consumption range and had no difficulty with HC during emission testing.

TT Oversteer

and here's what I found:

1) This is not a virgin box; I could see obvious scratch marks around the tabs indicating it has been opened previously.

2) The "fuel quality switch" was in the stock (full counterclockwise) position.

3) I tested continuity of the altitude pressure switch and it is open at my ambient altitude of 1800 feet which is the correct position.

4) The pin 10 brown wire jumper connector was disconncted creating an open circuit. When connected this apparently retards timing 3 degrees and leans the mixture at part throttle settings for California and Japan cars.

5) It is indeed a US spec DME part # 0 261 200 082

6) The chip appears stock however it has been marked on with a blue inkpen. Could this indicate a reflash perhaps? Or has anyone seen this pen marking on other stock factory chips?

I was encouraged when I found evidence of tampering and hoped to find some kind of funky aftermarket chip. Now I'm once again scratching my head as the chip appears stock. How would I know if it's been reflashed?