More 3.2L problems (long)

kretzj · 10-18-2002, 11:51 AM

My engine has been slowly deteriorating because of lack of use. It was getting harder start and I found out I fouled all my plugs by not allowing the engine temps to rise. I just started the car preriodically and drove around the block. I change the copper plugs to Bosch Platinum and it started right up. I left the country for 6 weeks and upon my return, the car would not start. I found out my batteries (72 911) were both bad. I replaced the batteries today and the fuel filter and the car started. It sounded rough and the idle was really low. I backed it out of the garage and it drove ok in 1st gear but when I shifted to 2nd, it wanted to die. I could hear the intake of air from the mass flow but it was silent when I hit the gas. The car would die at this point and I had a hell of a time trying to get it started. I drove it home in 1st gear. Why would it die in second gear when I pressed the gas? I am thinking of going back to copper plugs. BTW, the engine is twin plugged.

Jon

Superman · 10-18-2002, 12:51 PM

Pretty mysterious. I think you should strip everything out of the car that is not necessary for it to drive around the block, then ship the car to my location with some cash, and I'll get it running nicely for you.

Seriously, many 3.2 folks have had good luch changing the DME relay. Other than that, I'd say return to basics. Spark first, then fuel/air. Copper plugs nearly always outperform platinum.

Rick Lee · Rick Lee's Garage

Sorry I can't help with the fix, but once you get it right again, take a lesson and drive the hell out of that car. I went to Germany for 3 wks. last Christmas and had Doug E babysit my car while I was gone because I never want it to go more than a week without a good hard drive. Last time I went to CA for a few days, I even took my 911 to long term parking (brought the car cover) at BWI Airport. That way I had a good long drive there and my baby was waiting for me on my return. Drive, drive, drive!

ChrisBennet · ChrisBennet's Garage

Could you supply a little more info on your engine? Is it a Motronic 3.2 that has been twin plugged using a splitter box?
-Chris

ChrisBennet · ChrisBennet's Garage

Could you supply a little more info on your engine?
Is it a Motronic 3.2 that has been twin plugged using a splitter box?
-Chris

kretzj · 10-18-2002, 02:49 PM

Info:

The engine is twin plugged using the Andial splitter to two coils and a C2 distributor. I installed a Carrera fuel tank, fuel pump, oil tank, transmission, suspension, and oil cooler. The engine was completely rebuilt from scratch with new euro P&C's, big bore throttle body, mass flow, new heads,valves, etc., SSI's, and a custom Autothority chip. I have <5 miles on the engine. I fouled the original plugs from starting the car when it is rich and never heating the engine up. I am almost fed up with this project and considering selling the whole thing.

Jon

kretzj · 10-18-2002, 02:53 PM

More pictures

kretzj · 10-18-2002, 02:57 PM

More

kretzj · 10-18-2002, 03:09 PM

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Steve W · Steve W's Garage

Could be anything, but is that a K&N filter on your mass flow or the white filter Pro-M recently replaced the K&N with? Reason is because Pro-M had problems from the oil of a K&N contaminating the hot wire inside the mass flow meter, and causing faulty readings. Since it cannot self clean, you should remove the sensor from the mass flow body and clean the hot wire element with some brake cleaner periodically, in order to restore full sensitivity.

Also, why is it running so rich when warmed up? You do have a O2 sensor connected right? If not, it will run way too rich. I have virtually the same setup you have, yet my engine runs very clean, I can't even smell any exhaust, and I don't have a cat. You should use a battery maintainer when you don't use your car consistently. A 911 will drain its battery at a rate of 3% daily, so after two weeks, you will have almost lost half its charge.

Your Autothority mass flow meter has a provision for adjusting the idle fuel mixture in the wiring harness for the meter. It is a little 15 turn 10k trim pot, which if you turn counterclockwise, will lean out your idle mixture, clockwise to richen. Disconnect your O2 sensor, attach a dvm to the output of the O2 sensor, and adjust so that voltage fluctuations center around 0.5 volts. 0.1 is too lean, and 0.8 is too rich.

kretzj · 10-18-2002, 03:50 PM

Steve,

I believe I have a K&N filter. It came with the MF. I thought the motronic starts rich and then leans itself out. I had new plugs and over time , these quick starts fouled all the plugs and created a coating on the tips preventing spark. This stuff would normally burn off after obtaining elevated engine temps. The car did run perfect after it was built and I routinely started it. Am I off base? All the sensors are new including the O2 three wire sensor.

Jon

Steve W · Steve W's Garage

Your filter will say K&N on the side stamped in the metal. Otherwise it will say Pro-M. Make sure to remove the hot wire element and clean it off first, then do the idle mixture adjustment, as it sounds like it is running too rich until it warms up and the O2 sensor takes over and tries to adjust it. With a ohm meter, the trim pot should be somewhere between 1.5k to 2.5k ohms. Rich running will foul your plugs. If this doesn't help your problems, then you have another problem.

kretzj · 10-18-2002, 07:07 PM

Please see my post about my spark plugs. This might be part of my problem.

Thanks,

Jon

Bobboloo · Bobboloo's Garage

Being the car is a 72'. Is the gas tank in good shape. i.e. Any rust in it? Also when cars sit for a long time it's a good idea to add gasoline stabilizer. Also check the fuel filter.

I know that those suggestions don't address plug fouling but you might have more than one issue.

Is all the engine electrical running through new wiring or is some of it running though your old harness. If so, then check the conditions of the connectors like the multi-pin in the engine compartment for corrosion.

Also make sure you have good grounding on the batteries and the motor. If there is any corrosion then clean it off. The computer can't tell the motor what to do if it doesn't have good juice so check it's grounding as well.

Bobby
P. S. That's going to be a great car when your done. If you do decide to bail please give me an email. I would die for a car like that.