3.2 running on 5 cylinders

pistolpete · 09-12-2021, 08:37 AM

I have a 1985 911 3.2.
Relatively new to me. Sat for many years. Went through the process of getting it started, going through fuel system and many other things. Got it started and seemed to run well. Found an oil leak between the number 6 cylinder and head not too bad. (never hit the floor). I changed the oil to brad penn 20w50 now I have leaks everywhere. I noticed that the car was not running right when cold. Only running on 5 cylinders. I found it was the number 6 so I pulled the plug and it was full of carbon. Cleaned the plug and reinstalled. Still running on 5. Any ideas where to turn? I do have spark at that plug.

cabmandone · cabmandone's Garage

Injector not firing. If you search the site you'll find threads where guys had stuck injectors after the engine had been sitting for a long period of time. I sent my injectors in to have them flow tested, cleaned, and resealed because I knew there was a possibility of issues due to the engine not being fired in several years.

pistolpete · 09-12-2021, 08:55 AM

Right, I did not think of that. Id does start to fire on all cylinders after it warms up. maybe 15 minutes

proporsche · proporsche's Garage

well you have to eliminate which cylinder it is.try this way.start it up an once it is on 5 unplug each spark plug connector at a time and see if the engine changes..running if not that is your culprit
You also do it with the injector connector but the plug is easier..

Ivan

pistolpete · 09-12-2021, 09:07 AM

I did that it is number 6

proporsche · proporsche's Garage

ok my bad overlooked it...as said above by Nick, your injector

Ivan

Joe Bob · Joe Bob's Garage

If that Brad Penn is a synthetic, air cooled engines don't like it....at least in my opinion.

I agree it may be a partially occluded fuel injector. There are online services that will clean them for you can try a bottle of Techron in the fuel. If you choose Seafoam it's recommended that an oil change should be done with 200-ish miles. Again, in my opinion.

Solamar · 09-12-2021, 09:51 AM

And if not the injector, another common problem is the intake gaskets dry/shrink/break causing large vac leaks which makes the cylinder too lean to fire.

If I was bringing back a 3.2 I'd pull the intake and re-fresh all intake gaskets, fuel lines, reference sensors and cyl head temp sensor. The above are responsible for 99% of the 'old 3.2 running bad' issues.

pistolpete · 09-12-2021, 10:00 AM

Thank you all for your help! I have some work to do.

dannobee · 09-12-2021, 10:21 AM

If you have a mechanic's stethoscope, put the metal rod part on each injector. Goods ones go "tink tink tink." Bad ones won't click or tink at all. With a little practice you can even here when one is plugged up as it won't have the distinctive "tink" sound but more of a dull thud.

pistolpete · 09-12-2021, 10:42 AM

Will the injector free up when it gets hot? Because it does fire after it gets hot.

fanaudical · fanaudical's Garage

I'm guessing that the fuel pressure may not be quite high enough when cold to open all the injectors if you have one waiting to open when warm. I recommend doing a CIS pressure test and determine both your warm and cold control pressures as well as system pressure.

If you haven't done it yet, a strong dose of Seafoam in the gas tank may help free things up a bit...

Joe Bob · Joe Bob's Garage

Ummm, an 85 Carrera 3.2 uses a DME system and not CIS. CIS stopped in '83 with the SC. I could be wrong....my ex says I is.....

fanaudical · fanaudical's Garage

DOH! Sorry - I missed the year in the first post and have my head wrapped up in CIS problems with my car...

Joe Bob · Joe Bob's Garage

I had an SC motor in my 914/6 and My SC.....can answer many stupid problems.

As to gauges....good idea to buy them or have a friend that has them .

GH85Carrera · GH85Carrera's Garage

Quote:

Originally Posted by Solamar

And if not the injector, another common problem is the intake gaskets dry/shrink/break causing large vac leaks which makes the cylinder too lean to fire.

If I was bringing back a 3.2 I'd pull the intake and re-fresh all intake gaskets, fuel lines, reference sensors and cyl head temp sensor. The above are responsible for 99% of the 'old 3.2 running bad' issues.

If the sensors are original, or 20+ years old I would for sure replace them. And the head temp sensor, plug wires, and the DME relay. They will fail soon if not already.

Nick Triesch · Nick Triesch's Garage

Yes!! I have had this problem but on number one cylinder. It turned out it was a bad intake gasket. Sucked part of it in. Replaced/ re torque. Head bolts come loose on the 3.2. They just do.