Flormat

I've been having problems with my '86.5. It has been in storage while I have been living in a different state. When the water pump pulley bearing went bad 1.5 years ago I decided to replace several things while the car was down. New water pump, timing belt, updated cam chain tensioners, adjusted camshafts per factory manuals and Wally's write up, new MAF, fixed all vacuum leaks I could detect, new ignition rotors, new spark plugs. Now it fires right up but then runs poorly. If it will idle it idles low and rough and there is slight "popping" noise emitting from the airbox with the air filter and cover removed. If I give it some gas it will rev to redline and smooth out some but still doesn't feel quite as smooth as it used to. If I barely put any pressure on the accelerator it will stall. I rechecked everything, cam timing was spot on according to the dial indicator and the crank and cams line up just right. Coil grounds are both conected. I did not install new distributor caps or plug wires. I've done this type of work on 16 valve 944S's, 16 valve 928's, and 911's so I'm not completely unfamiliar with this sort of work. But this 32 valve engine has got me stumped even though it's very similar to the 944S.
I 've been working on it little by little over the past year and a half. It ran poor a year ago after belts and water pump but I was hoping with the new MAF it would run better. I have to leave again tomorrow but was hoping to get it fixed this time around. Any help is greatly appreciated.

JHowell37

This my sound stupid. Go back and check, then double check your spark plug wires. Poor, rough, idle with "popping" sound coming through the airbox suggests plug wires. Use the decals on the radiator and follow each one. It's one of those things that's so simple, we make a mistake because we feel no need to broker caution.

Flormat

Thanks I'll check it out. I've started taking things apart see a part with a small vacuum line not connected to it. It sits right next to the fuel damper and connects via a large diameter hose to the heater valve and has two small vacuum lines coming off of it, one going to the intake and the other???
I don't think this would give me the problem that I am having. It sounds like it's running lean. I guess after the plug wires I'll check cam timing again.

Flormat

Plugs are all on correctly. The cam timing on the drivers side is perfect. Then began to take apart the passenger side to do the same and found a small vacuum line going from the air pump valve to near the intake broken. Replaced it and still runs the same. When I rev the engine up black sooty smoke comes out the exaust which tells me it's rich. But when it idles, or tries to idle, it acts like it is lean with the popping intake and all. Also, when I removed the intake plenums there was a bit of fuel there. What would cause it to run lean at idle and rich at higher rpms? Tomorrow I'll check the passenger side cam timing.

WICruiser

Air / Fuel control is done via the electronics based on the O2 sensor. Check the wiring from the O2 sensor to see if it is disconnected or damaged. A bit of fuel or oil in the intakes is typical and probably not related to the problem.

Lizard928

the oil in the intake is normal as stated and mainly comes from the rear most cam cover vent on the passengers side.

Check the vacuum with a vacuum guage, it should be between 18-20 at idle, if it isnt you may have vacuum leaks, which normally causes it to run lean though.

It could also be that the MAF needs to be adjusted/calibrated.

Flormat

Thanks for the input. I knew oil was typical in the intake but I wasn't aware that fuel in there was normal as well. I'll check the O2 sensor first thing in the morning but I thought the O2 sensor signals were not used until the engine was at normal operating temp? And Lizard, wouldn't a rebuilt MAF already be calibrated? Lizard, I just read your post from back in '05 after you swapped an '86 engine into an '81 and had a similar problem. What turned out to be the problem? Thanks for your help everyone.

JHowell37

Fuel in the intake manifold is NOT normal and could create a dangerous situation. If you're getting black sooty smoke from the exhaust you can check the MAF as they sometimes don't get rebuilt properly. If the MAF checks out fine, there are two suggestions I have.
1.There's a service port on the front of the engine that has three terminals on it. It's under a cover(unless your cover is broken off) and it's next to the plug for the throttle position switch (the one that always breaks.) With the engine running, connect a jumper wire from the bottom terminal to the one above and to the right. If things are working properly, the RPM should change. If there is no change in engine speed, you need a rebuilt ECU.
2. Install an air/fuel meter. When properly installed, with a warm engine, the needle on the meter should move back and forth rapidly.

Lizard928

Flormat,
when the MAF is rebuilt and calibrated it is put to factory settings, however when you put it into the car you must set the CO level on your car, as every engine is alittle different.

The issue I had with my car ended up being the tach, I had tried to adapt the 81 tach to interface with the 86 wiring/instument cluster. I unplugged the instrument cluster and the car ran perfectly.
Before the car would NOT run. It was strange though as I would see the correct RPMs on the tach as it surged up and down.

HTH

Flormat

Ok guys, I'm going out to check this stuff. Can I adjust the CO level with that little adjustment screw looking thing the maf?

Lizard928

yes,

read the factory manuals for the info on setting the CO level,
it should be set to a 1% CO level at idle, I havent looked at the procedure for awhile but you may need to unplug the O2 sensor to adjust properly, and you will need to take the CO reading from the test tubes BEFORE the cats.

Flormat

I connected the wire to the two ports on the test terminal. Started it up and the engine held at 2k for several seconds longer and then stalled as opposed to w/o the wire connected. Then I unplugged the maf and it ran steady strong at 1800 rpm and never stalled, popped, or spat out black exhaust. So I think you're right about adjusting the maf. I'm going to take a look at the manuals about setting it at 1% CO although I imagine I need special equipment to do that which I don't have. Could I adjust the maf in 1/4 turn increments until it runs well and take it to a shop to fine tune it?
And as far as the O2 sensor is concerned, I'd say I need a new one. One of the wires lost it's insulation coming out of the sensor and it looks like it's been that way for a while.

Lizard928

just unplug the O2 sensor for now if that is the case.
yes you can turn the adjustment on the MAF to get it to run abit better to be able to get it to a shop, however before you do that maybe get some info from John Speake here on the board as to adjusting the MAF and checking its baseline.

Flormat

Ok, I'll try that first. Also where is the O2 sensor plug? I cannot see where the wires go out the sensor?

Lizard928

lift the lid to the fusebox area, then undo the 2 10mm nuts and remove the lower section of wood, you will see a large black rubber plug, this is the O2 sensor, there is close to it as well a 2 pin connector, this is the O2 heater, undo both of them.

you MAY not need to remove the lower wood piece, but most that I have seen it has been tucked under there, and unless you know exactly what you are feeling for it is just easier to remove the wood piece.