Starts but will not run in drive

[desertspirit]

na

[stepson]

Check the connection to the MAF. If it's connected, check to see if the MAF is in spec. (or find someone close and swap your MAF into his car to see if the problems follow the MAF.

Nice looking car on the outside BTW

[Danglerb]

After sitting five years you put in a battery and it started, so sounds like the previous owner parked it for some other reason.

Give the car a full inspection by someone expert in the 928. It will likely need a timing belt and water pump, plus a full top end service with replacement of all the vacuum lines and rubber couplings in the intake. All the fluids should be changed, and all the ground connections cleaned.

Car looks pretty low mileage, but the 928 has one of the least reliable odometers ever made, it likely has a lot more miles on it from the interior condition.

Good to put your rough location in your profile and the model year in your sig.

[MPDano]

You can easily google MAF and come up with it's definition. Also search here as there are also fixes to the MAF wiper, etc.

I looked to see if I took pics when i did mine but nada. Nice ride. I agree with Mike (DanglerB), if it was just a battery, the PO would have been driving it.

[MPDano]

Originally Posted by desertspirit

Thanks. I was under the impression this was a forum for 928 owners to help eaach other.

I thought I was when I took the time to look for pics of my MAF fix for you. So you think it's wasn't fair for me to ask you to use google to look up an acronym?

[MPDano]

That's possible. Did you drain all the fuel from the tank of all that 5 year old gas? Lot's of things downstream can clog once the molasses at the bottom of the tank starts moving through the fuel system. Look at my $900 Porsche thread and that might have pics of me cleaning the contact points of the wiper system in the MAF. I also believe I flipped the board around or something to that affect.

Water will just make your car stumble while it making it's way through the system but will eventually burn out.

[stepson]

Originally Posted by desertspirit

In fact, I did some research and did consider the mass air flow, but also the speed sensor.

1986 928S/Automatic

Here's why I said MAF :If the MAF is out of spec, the car will start fine and idle reasonably well. As soon as you attempt to accelerate, the engine will stumble and die. You are obviously inside the car attempting to start and drive the car. It is human nature to move your foot to the accelerator pedal after shifting the car into drive.

This is why I don't believe it's the crank position sensor (what I think you are calling the speed sensor): There can be many symptoms when the CPS is bad or going bad, but the most common is a lack of spark. You have stated that the engine will start right back up after dying. That would indicate that you don't have a lack of spark.

Wild card guess: There is probably more than just a single issue causing this problem. You do have five year old gas in it and five years worth of varnish that could dislodge and create all sorts of havoc within the fuel delivery system. The MAF connector could not be seated well, or it may have a burnt wire from the POs stereo fiasco.

If it was my car, I would flush the fuel system before attempting to start the car again.

[uBoat Commander]

What you are describing is almost exactly what my situation is - it ran, but now, after a while, it only starts then dies after a few seconds.

I cleaned the tank thoroughly, replaced fuel pump & filter, but did not clear out the hoses or clean the screens on the fuel distribution or WUR. It ran, but now, after a while, it only starts then dies after a few seconds.

I can smell stale gas, even though I drained everything.

Whatever you do - If you have a choice of paying $85 an hour for a Master General Mechanic, or $175 an hour for a guy on the street who knows 928s, go for the $175/hour choice.

Me, I'd set the car on fire before paying a mechanic.

[DougM]

Pull the MAF and send it to be checked and rebuilt. Years ago i had similar symptoms with an '87. Would run fine and then just die the next time started when giving it throttle. MAF was rebuilt and all was fine.

[neil30076]

Originally Posted by uBoat Commander

What you are describing is almost exactly what my situation is - it ran, but now, after a while, it only starts then dies after a few seconds.

I cleaned the tank thoroughly, replaced fuel pump & filter, but did not clear out the hoses or clean the screens on the fuel distribution or WUR. It ran, but now, after a while, it only starts then dies after a few seconds.

I can smell stale gas, even though I drained everything.

Whatever you do - If you have a choice of paying $85 an hour for a Master General Mechanic, or $175 an hour for a guy on the street who knows 928s, go for the $175/hour choice.

Me, I'd set the car on fire before paying a mechanic.

Just so we don't send the 'desertspirit' down a wild path, an 86 does not have screens on the fuel distribution or a WUR. I would also go for the MAF first. Assuming it is a 32v engine, this diagram may help MAF is item 11. Check all the vacuum lines as well. Ignore the highlite on item 12.

[stepson]

Please do not pay $85 per hour to someone to learn how to fix your car.

As a matter of fact, don't pay any money whatsoever to someone to learn how to fix your car. Do not let somebody baffle you with their BS. Ask for references. Talk to people who have had their 928 worked on by this person. Make sure that the 928 mechanic that worked on 928s in a particular shop is still there.

Do not just hire a Porsche mechanic*

Do not hire an all-Euro mechanic (WTF is an all-Euro car anyway?)

If you are going to hire someone else to work on your car, only hire a 928 mechanic.
*Remember that a Porsche mechanic may not be a 928 mechanic.

I am sure that either someone from the Central Fla area will be willing to help, OR at least recommend a 928 mechanic

Subliminally:Hire a 928 mechanicHire a 928 mechanicHire a 928 mechanicHire a 928 mechanicHire a 928 mechanicHire a 928 mechanicHire a 928 mechanicHire a 928 mechanic

[stepson]

BTW, How far are you from Sarasota? Looks like a big to-do this weekend there. Meet up with those guys and share knowledge with them

[DougM]

That's in Europe. There are a few in the US. Search here or Rennlist and you can find them.

Originally Posted by desertspirit

Thanks for the suggestion. Do you have a recommendation for having the MAF checked?

I did find JDS Porsche MAF Airflow Calibration & Repair


Thanks again.



1986 928 AUTOMATIC

[JK McDonald]

Hey Desertspirit - This is a good site for lots of good friendly advice on the meaning of life and the ownership of 928's in general .... You might check the fuel pressure at the fuel rail before you go too much farther. Since you have cleaned out the gas tank, installed a new fuel pump and replaced the filter - the fuel pressure is probably not the culprit - but eliminate the easy stuff first. There is a plug/cap test point at the end of the right hand fuel rail. I don't guess your air filter got completely saturated with the rain water you mentioned earlier and is smothering the engine ? Perhaps you could remove it for a moment or two and try reving the throttle. If you pull the spark plugs, you can determine if they are carboned up or if they are burning clean.

There is also a temperature sensor (Temp Switch II) is located in the front center of the engine just to the right of the fuel pressure damper. It signals the computer at what point the engine has warmed up. I have seen where a poor electrical connection was giving some issues.

The approximate Ohms/temp =
32 F: 4 - 6 k-ohm
85F: 1 to 4 k-ohm
100 F: 1 k-ohm
150 F: .5 k ohm
180 F: .3 k ohm

The Mass Air Flow Sensor is one of the "Hot Wire Air Flow" type which is critical in the calculation on fuel injector pulse width. One other thought - With the possibility of rain getting into the intake - does anyone think that the MAF sensor could have been zapped by the rain or that the hot wire portion failed ?

Keep us posted and good luck, Michael

[neil30076]

Please check your private messages for a suggestion...

[Fredfox]

Low fuel pressure can also cause your problem.
I believe there are pressure regulators that could be bad.

[Danglerb]

The nice thing about Porsche owners groups, nobody expects any social skills, just thick skins and a willingness to ignore anything we don't like. For some reason we all seem to get along pretty well, and the tech is indeed here.

[Danglerb]

Both of the good sources for rebuilt MAF's I think will check them free prior to rebuilding.

Every so many starts the hot wire inside the maf does a burn off cycle to clean itself, but it also fries off a little each to so eventually needs to be replaced.

[stepson]

Originally Posted by desertspirit

Hey John,

So I finally got around to removing the MAF and unplugging it, and the car started right up. In fact, I can even drive it. It revs to 4-5000 rpm without any hesitation. I am assuming this means the MAF is bad? Thanks for your feedback.

That's the direction I would lean. But it would be really nice if you could put your MAF into someone's car just to test before you sent it.

I do think that the MAF repair folks test before they tear into the MAF, but really, I wonder how many are sent back having checked out okay.

[neil30076]

Don't send your MAF out yet, Please check your pm for additional info
Neil