Fuel distributor blues

[kokenm]

82 911 SC targa

I have removed the fuel distributor while the engine was out and changed out a really bad gasket that may have been a large problem with setting the mixture.

Now that I have everything back in it appears that the I have a new problem.

I was running down the road running a little rich and the rain struck. The car ran incredibly rich all of a sudden. after much searching I have found that if I rev the engine it stutters very badly like it is running on 3 cylinders and then a black poof of smoke comes out and most of the time a backfire is associated with this.

way to rich!!! ok so I am back in the engine compartment with the air filter off and I reach in and push down on the Control Lever which is moving the air flow sensor plate. runs much smoother and revving the engine does not miss a beat.

Let go and we are back to a pain in the arse.

Am I missing something? I was thinking this thing was weight and gravity seated.

but it does not seem to be sitting correctly.

Any Help would be appreciated as it have been more in the garage than out

[Scott R]

Sounds like ignition, you stop getting the correct amount of fire and it appears to run rich due to a few missing cylinders. Maybe water or moisture in the plug boots, distributor cap? By pushing down on the lever you're just reducing the amount of fuel. This is just a guess BTW.

[kokenm]

All ready replaced plug wires and I guess that I will be replacing cap and rotor next. It has been in the garage for the past week without a drop of rain outside and still has the same problem.

Hope to get this cleared up today.

Mike

[al lkosmal]

If you had to pull down on the lever that actuates the air flow plate, it may be that you're fuel distributor plunger is stuck. (typically the air flow plate/lever arm..rest in the down position. When you push it up..the plunger moves up and distributes fuel to the injectors, etc. If it's stuck in the up position, that could result in rich running, i believe) The fuel plunger and the mating surfaces are machined to a very smooth finish and very tight tolerances. If, while the fuel distributor was out, any dirt got in the plunger area...or the plunger came out and was re-installed, it is possible that it is not working properly. It's a PITA if you have to remove the fuel distributor again, but I'd check for smooth lever arm/air plate/distributor pin movement.

[kokenm]

Thanks Al,

I am in the process of removing the fuel lines on the distributer so that I can remove the distributer and lube adjust and so on.

I rechecked timing and spark as scott talked about earlier with no change and believe that there is something inhibiting the sensor plate.

Will give a bit more information when I know more.

Mike

[kokenm]

I went throug and looked at the bottom of the fuel distributor and found that everything looked good. I going to wait on cap and rotor to replace and get that out of the way before searching for a ghost.

mike

[kokenm]

Cap and Rotor have been replaced but I am still seeing the same issues.

car starts and runs upon revving the engine it bogs down at about 3000 rpm like it is not getting enouth gas or too much. If I baby it a bit and get the rpms up there is a large amount of blackish smoke which tells me that it is running extrememly rich. I am wondering about the coil and the CDI...

Stumped.!!!!!!

[kokenm]

by the way:

So far I have replaced plugs, rotor, cap and wires. purchased the magnecore wires.

[kokenm]

I think that the cap and rotor were the culprit however there was a slight adjustment that I made to the mixture sensor plate that I had to readjust again so that things worked well. I know that this is a dangerous place to be when I am adjusting things that have loctite on them but it appears that I may have it ironed out.

I thought for sure it was a lot more indepth but I think that it comes down to water in the distributor causeing fouling of the distributer cap and rotor and screwing the fire timing up.

will drive ALOT Tomorrow and find out how that did the trick.

also there was an extreme dead spot at 3500 rpm when reving the engine that appears to no longer be there today. could be mixture and could be something that the guy in another post should look into. I sent a message~

Mike

[Alan L]

You can check your fuel piston is not sticking. Engine off, lift airplate up gently full way. Should be dead smooth. Then finger away and let it drop. It should vitually follow you down to a dead stop - clunk. If it does not clunk, pull on it and see if any more travel. Should not be,
Alan

[Alan L]

I would be interested to know where you got the gasket from.
Alan

[kokenm]

Alan,

Of course I picked it up from our sponsor "Pelican Parts"
I did have some difficutly finding it and ended up looking in the parts diagram.
I searched on the number from the parts diagram and viola it was there.

Also, It appears that my mixture adjustments are a bit more true since I replaced this gasket.

Mike

[Alan L]

Are you talking about the rubber fuel head gasket or the throttle body/airbox gasket?
I can imagine the latter causing mixture problems.
Changing the idle screw does affect your mix to an extent - particularly at idle. You generally need to re tweek the mixture screw if your idle speed adjust is changed much. The idle screw is an internal air bleed screw that lets more air into the throttle body, without going past the airplate (I think).
Alan

[kokenm]

Alan,

The throttle body/airbox gasket. it was in tough shape. I did look at the bentley manual and it showed where the sensor plate was suppose to be. mine was close to that but I adjusted it a bit. I am currently running on the lean side so it is surging a little as I drive down the road without a load.

The new gasket appeared to be some kind of foam gasket which had some stickum on one side.

It is running and I am thrilled. now it is time to dial in the mixture and start to really enjoy the car again. Also I am adding some silicone to the rim of the cap to keep out the water during the rainy season as this is what I attribute to this entire problem.

Mike

[Alan L]

OK. I would have been interested to find a source of the fuel head gaskets.
Alan

[T77911S]

wow.
if you are moving the air sensor plate and making it run better, that is a sign the mixture is off. i dont think the plunger is stuck if you moved the plate and things changed. but, to check the plunger, gentley push up on the plate with the pump/ or key on, and engine not running, and you should imediately feel resistance and you should be able to raise it all the way up. remember you are dumping fuel in the engine as you do this so do it quickly. if there is any "free" play, like when the key is off, the plunger is not returning to its off position. you can always pull all 6 injectors and put them in a jars to do this, then you can check spray patterns and fuel quantities for each injector. i found a bad injector line this way. i was only getting half the fuel to one injector.

if it is surging, it is too rich, not too lean. backfiring into the exhaust is also rich, lean backfires into the intake, and blows the airbox.

what adjustments did you make that you should not have? when at rest, the plate should be centered in the AFM when looking down at it and centered in the smallest opening when looking at it from the side. hard to explain but it is in the bosch book.

if the gasket under the AFM is leaking, i dont think that effects the mixture, the air is just bypassing the air filter at that point. same with the one under the FD. otherwise unmetered air would be coming in the mixture adjustment hole. i will look at the one i have off when i get home to verify.

the things you need to look into are the O2 sensor, the throttle switch, advance, frequncy valve.
my first choice is the throttle switch circuit.

if you are trying to adjust the mixture with the O2 connected, you are fighting a losing battle. the O2 compensates for your tweeking.

[kokenm]

T77911s,

I have gone through the usual mixture routine and the sensor plate is in the correct position as per the Bentley Manual.
The mixture may be a little lean now as the power is a little lacking.

I am extremely happy to be back on the road as it has been a little while.

The o2 sensor is bad and needs to be replaced but I will do that soon.

Thanks all for the support to everyone.

Mike