stranded please help
 

i'm stranded in roswell NM. my 86 951 will run perfectly cold; once warm, it will start and idle no problem, and rev if you pull the throttle by hand, BUT if you push the gas peddle under load it will hesitate then fire-- at first; after driving several minutes, it will simply drop down to idle and stay there; it will roll along top speed 20mph until cool again.

fuel pressure: 28 to 35 psi
air flow meter is working
throttle position sensor is working
amps at the battery ~13
new alternator
just replaced column switches
just fried 3.5 year old battery w/ plenty of electrlyte
cd player is malfunctioning
horn relay is very hot
turbo water pump is new and the relay works but it is not coming on

any ideas? thanks for reading

Was there a large, silent, shiny object above your car when all this happened??

The poor guy needs help!!! But that was funny. :)

as a matter of fact, this weekend is the 'anniversary' and the town is full of people even crazier than me.

OK... now some of you old timers that were born in your Porsches help this guy already! Ernest, one of the wiser ones will be here soon to help you. Sit tight till they get on here. :)

bad temp sender?
just a guess but as not running hot is major clue
try unplugging the sender

How old are the distributor cap, rotor, plugs and wires?

plugs are new, everything else 115K; do things go to hell right now if cap/rotor/wires wear out?

They were probably due for a change about 90K ago.

Two things to try.........

1. Check for a leak after your AFM and before throttle body....... Check for tears/loose connections on your hard pipes as well....... Easy for unmetered air to get in an create chaos.

2. Unplug the TPS. It will idle around 1500 rpm but it will run on partial maps. If it works .... just drive it home. You can go on boost.....just don't go crazy with too many WOT runs. TPS have been known to fail under heat related conditions.

Can you put the model and year in the signature line of your profile.
I see you only have 15 or so posts. Is this car new to you? When were the timing belts last changed? How about the fuel filter?

he has an 86 951.

86 951 w/ 115k miles, full records, service up to date, all neww hoses and belts at 95k. i was wrong about old disributor cap and rotor, replaced at 95k as well

Well, what about the fuel filter? Did you try what Alex suggested?

already done, checked all bolts and fittings AFM and replaced TPS, and tested AFM by unplugging.

i recently tried 87 octane plus octane booster to avoid running 90 octane supreme; any chance the octane booster fouled something?

probably not, but that crap is useless.

you should always run 91 in the car.

Did you remove the fuel filter yet? This really sounds like a fuel delivery issue to me. Possibly the fuel pump is getting hot, and not working well until it cools again.

once it gets hot, will it rev cleanly in neutral?

There should be no difference between it revving with your hand on the TB or with your foot actuating it. If there is, that's just weird.

when it's cold, does it run fine totally?

how long of a cooldown between "using" the caruntil it works fine again?

not true. the car was built for 87. some people claim that they think the car runs better with 91, but that doesnt change the fact that the car was built for 87.

running 91 accomplishes two things. 1) puts a bigger dent in your wallet. 2) you do get some benefit from the gasoline additives that clean as you drive.

unless, of course, the 951 is different than the 944 and does actually require 91... but I dont think that's true.. if it is, I apologize for the misinformation.

A month or so ago my sister had a similar problem with her Mustang. It's not a Porsche, but she had the same problems. Her starting and running were a little worse than yours. She is not one to maintain anything and I hate working on her car. Turns out she NEVER changed her fuel filter. The filter was clogged pretty good. This happened in the middle of a long road trip. I think she was about 10 hours into the drive. She ended up needing a new fuel filter, fuel pump, and fuel prssure regulator. After they were replaced the car ran well again.