Frustrated-need advice

[Louie1411]

I have an 85.5 944 na with about 75K miles. Since I bought the car I made it into a little upgrade project. It stammers, stutters and seems to lose power a bit below 3000RPM. Above 3000 it goes like hell so runs much better if I keep the RPMs up. Since purchase I have installed new timing and balance belts, water pump, O2 sensor, plugs, wires, rotor, coil and wire, fuel pressure regulator and dampner,intake boot and air flow sensor, fuel filter. I bought but have not replaced TPS switch although it clicks at appropriate time. I checked electronics on injectors which seem ok and run a couple bottles of injector cleaners through system. I sprayed throttle body with brake cleaner. I have tried to find any vacuum leaks that were obvious but could locate none. What have I left out? Am ready to giive up and take it to local Porsche mechanic who will take literally weeks to get work done. Any suggestions?

[Lawrence Coppari]

Clean the unions where the TDC and rpm sensors come together. The sensors are on top of the clutch housing near the firewall. About a foot away are some unions where the remainder of the wires go elsewhere. The things get dirty on my car and screw up the idle )among other things).

Don't know if this will help but it can't hurt.

[todwic]

NTP II sensor (temp sensor, not for the gauge.)

[carsontc]

and clean/check connection for throttle position switch

how did you check for vacuum leaks?...

do you have a multimeter?...

[Louie1411]

Don't really have much of anything to work with-no manuals except haynes, no multimeter , no foolproof method of locating vacuum leaks, and a complete ignoramus when it comes to car repairs. Am not sure if I can even find the NTP II sensor. What kind of cleaner works best for electrical connections? That stuff they sell at Radio Shack in a spray can? Like I said, best head for mechanic. Not much satisfaction in that though......

[XJOSHX]

Originally posted by todwic
NTP II sensor (temp sensor, not for the gauge.)

Where is that thing hiding out?

[carsontc]

we all started like this...with nothing

anyone that owns one (or more) of these cars for very long has either waaayy too much money or likes the satisfaction from learning about them and doing most of the work themselves…not to mention saving a boat-load of cash and knowing it was done right

simply because these cars are old and rely a lot on electronics to run, the car’s electrical system is very often the route of many problems. but like life…it all comes down to your own attitude

before working on car repairs it’s recommended to always disconnect the negative battery terminal to prevent disasters…good advice…of course if you are only changing your oil, this step can be skipped (just don’t tell)

most will advise to clean the electrical connections with a small brush to get rid of the trouble causing corrosion/oxidation and, of course, dielectric tune-up grease - available from an auto parts store - nothing hard or expensive to do and yet fixes so many things

I wonder sometimes how many parts get ‘replaced’ at a repair shop when really all that happened was a good cleaning and sometimes fresh paint when they tell you they installed a ‘new’ part…often I’m afraid

and you should get a Haynes ‘Porsche 944 repair manual’. it will give you a ton a good info…and a little not so good information like referring to the ‘tempostat’ (cruise control) as the ‘thermostat’ in the wiring diagram!…nothing is perfect even the Porsche factory manuals have errors…but in time you may want these as well…tons more good information

Haynes will give you basic information on how to test components such as the coil, throttle position switch, air flow sensor, reference and speed sensors, temperature sensors, thermal switches, oil pressure sending units, idle control valve, relays & fuses, fuel injectors, fuel pressure, etc. etc AND where these things are located and what they look like.

it is SOOooo much cheaper then guessing ‘I think it’s the DME computer’ and replacing perfectly good parts with used parts (that you don’t know are good either)

and go to a ‘Radio Shack’ (the help there is better for this next item then an auto parts store) and get their cheap digital, auto-ranging multi-meter…it’s very simple to use but ask them to show you anyway…how to measure ‘voltage’ and ‘resistance’.

the training will only take a minute or so (though don’t ask them when they are busy with other customers) and get some alligator clips/wires too…you’ll need them.

then ask the forum any questions…(and listen to us ‘trash’ Haynes manuals!) ..but just use your common sense to figure out if we are trying to help you or just want to entertain the audience...the responders like to do both sometimes…often without good results if we are tired, or drunk, or stupid, or all three!

When we see a problem and know from experience what cleared ‘our’ problem…we make a suggestion or two

The DME computer is very good but relies on all these sensors and switches to do the right thing…as an example, if the temperature sensor is not working it may ‘tell’ the DME the engine is cold when it is not. The DME believes the sensor, so adjust the air/fuel mixture accordingly which may cause the symptoms you are having

[todwic]

Nicely done Tom! Yep I was exactly where you were almost 2 yrs ago to the month. It took only one $2000 repair bill to send me running to the Haynes manual. I'll trash it like anyone else, but I have two of them! And I have the pirate Fact. manual. I use them both when I have a taxing problem. and yes. get a multi meter if you plan on doing much DIY repairs. worth thier wieght in gold. I got min from Autozone $40.

[carsontc]

Originally posted by Louie1411
method of locating vacuum leaks?

all of that & missed his question !

tired, drunk, stupid

pick any 2

[Louie1411]

Disconnected O2 sensor in preparation to find vacuum leaks. Before I could start the process, got a phone call and had to leave but did not reconnect. Now the car runs great. Hesitation is gone, it pulls smoothly through whole RPM band. I am ecstatic but what gives? I am definitely leaving O2 sensor disconnected. Don't quite understand what happened here-it was new last fall.

[TSNAPCRACKLEPOP]

a girlfriend was a virgin last fall, but now, she............................do you think it was the porsche??????????/hehe

[Louie1411]

OK..let me restate- Is it all right to run without the O2 sensor plugged in? Performance is so much better.

[todwic]

I had "You have a bad 0₂ sensor" tattooed on my wiener last fall. I used the Ford # Bosch 'neric sensor for $40 instead of the $189 Porsche one. Works fine

[Louie1411]

But my question was.......Do I NEED to replace the O2 sensor? It runs great now.

[carsontc]

it will fail smog test