GlenL

My '87 N/A does not run well when cold. Starts fine but won't take gas aroun 2500 rpm. Will belch a huge cloud of rich exhaust while bogging.

Have looked through the archive and:
Checked the AFM including the temp sensor.
Checked the blue temp sensor under the elbow.
Pulled the rotor cap and cleaned it up.
Looked for arcing on wires.
New plugs installed.
Checked for misses with timing light.

Everything looks OK, although I didn't heat the temp sensors.

One thing of interest is that I spliced in a new O2 sensor recently. Used the Ford 3-wire. Didn't notice the problem prior to that, but it's been cooling off with the season around here so hard to tell. Runs crappy when started below 60F.

Engine runs pretty good when warm. The belching diminishes with engine temp becoming a small bog and then disappearing. Does sound like the blue sensor to me.

Looking for other ideas or pointers to diagnostics.

Thanks!

GlenL

Let me add a bit of info and bump this.

The thing is stinky rich when warm. Runs OK, though.

Mike S

What is your vacuum at idle?

GlenL

Not sure about the actual vacuum.

I did check the vacuum lines. The small ones to the damnper and regulator were loose but I fixed that. The larger ones to the idle stabilizer look cracked.

One more thing: I did the mounts and rack along with the O2 sensor. Had to lift the engine, and lower the cross member, to get the mounts in. I'm concerned that something migh have gotten damaged in that operations.

GlenL

Dudes,

Figured someone would have a lazer-like perspective on this issue.

Maybe a vote:
Screwed up the O2 sensor.
The blue temp sensor is bad.
The wiring to the DME controller is ripped.
The FPR is shot

Hoping to avoid throwing Porsche $$$ parts at the thing and/or paying Porsche $$$ to have it diagnosed. Won't be storing it this winter so it needs to work below 60F, to say the least. This is Minnesota, ferchrisake!

RJB

Glen,

I am having the same problem with my '87. Here is what I have done in an attempt to correct it.
Replaced the FPR
Replaced the O2 sensor
Had fuel injectors rebuilt
Replaced rotor, distributor, and wires
Replaced spark plug
Tried a different AFM
Replaced temperature sensor in engine block under the air intake
Found that the vacuum lines were routed wrong - but corrected that

I am at an impasse as what to do next. I was going to check the wiring to the DME and make sure all of the sensors are connected correctly, but have not done this yet. Also, I have checked the compression on my cylinders and they are OK. Maybe someone can help both of us out with another suggestion.

Mongo

next options would be a bad ignition coil, DME, idle stabilizer valve, or auxiliary air regulator (under 85.5), I dunno if this would cause problems but it did on a 300E I used to own that totally screwed up my gas mileage and idle, the wiring harness.

hosrom_951

Measure the fuel pressure, that MAY show you why you run rich when warm.

COld 'hesitation' USUALLY indicate a failing/bad/dirty ISV since they are 'on' when cold and when the a/c is on, but im doubting this since you run rich when warm (suspecting bad FPR or FPD).

BTW, how do you know you are runich rich when warm? you said stinky, so you smell fuel? from inside the car, engine bay, accelerating/decelerating? any black smoke under hard acceleration?

GlenL

Checking a few posts and such, I've ordered a FPR and four intake gaskets. Then I can take the manifold off and get at all of the hoses.

The car smells of rich exhaust when warm on hard acceleration. I suppose the bad hatch latch (one side) lets in some exhaust.

What I'm afraid of is that there's a wiring problem after lifting the engine. As the car was neglected for nine years it's likely several things wrong at once.

Magown

The electronics rarely fail. Don't waist your time, checking and replacing components until you check for vac leaks. The best way to check is to pressurize the intake. It should be air tight from the afm all the way to the head. I've yet to see a 15 year old car that didn't have a leak.

How does your car run with the O2 unplugged?

Once you verify that the intake is leak free, I would do a compression test, since you have already tested most of the sensors.

Also you may consider having your injectors cleaned, if you run out of ideas.

GlenL

There's no difference with the O2 sensor unplugged. Or when connecting up the old one. Made me think the mixture was waay off and the sensor feedback couldn't fix it...or that the wiring was busted between the first plug and the DME.

RJB

In my case, I do not know how the exhaust smells because I am driving and cannot smell it. What I see is that at idle, everything is OK, but when I pull into the street and accelerate, at about 2500 to 3500 RPM, I get hesitation. If I push down on the accelerator hard, it blasts through it but I see a cloud of smoke from the tail pipe. It seems to be white and blue. One of the things that I have thought of - but do not know how to test - is that while the car is sitting and cooling down - maybe a small amount of oil gathers in the cylinders and has to be burned off before it runs well. This happens only once - or maybe twice - and then the car runs very well. As I said, I have checked the compression in all of the cylinders and they are fine. Also, the spark plugs have the normal gray look to them when I pull them. Boy is this frustrating.

I have not checked the vacuum yet. How is the best way to do this? One of the techniques I have tried is to spray all of the suspected areas with carb cleaner and listened to the engine at idle. I have not found any leaks doing this.

Magown

In the 944 Factory repair manual, it says to take a fuel fiter (I think from a 914) cut it in half, stick a schraider vale in the end, remove your AFM, stick the device in the boot, clamp and add pressure. IMHO, any other method is a waist of time. You can also add fog from a fog machine to make it easier to find.

JR Reed

Potentially it is that generic o2 meter. My early car is set up for california specs. When I replaced the o2 meter, i did not buy the califonia model but used a stock unit for other 944's. The difference was a o2 meter pre-heater. With out the 02 meter being heated the car now hates running in cold weather. After I push through and the engine warms up the o2 meter starts sending correct signals and the cars runs fine. Something to think about. I belive all later cars have a pre-heater requirment. Perhaps the genaric unit you used does not accomodate?

GlenL

The one I used is a three-wire that fits just right. (Bosch 13913)

Check out http://frwilk.com/early944/misc/oxygen.htm