slant911

Been "out of commission" for a while. Work has had me traveling all over the damn place. Anyway, I am back and glad to be here on this great site again.

I now have a peculiar issue with my 1990 C4. Probably because I've neglected her for so long :0)

It starts fine, but, runs like sh** until the temp guage gets to about the 8:00 location then runs fine. I had a similar problem a while back in that whenever you put any kind of eletrical load on the car (i.e. A/C lights, stereo cranked up, etc...) it would run bad. I "thought" I had that worked out as that happened all the time (regardless of temp). I had traced a schaffed wire at the engine bay that I replaced and all seemed fine before my extended leave. It now Hot starts fine. COld starts fine. Just lacks guts, sometimes hiccups and backfires, and stalls pretty easily when cold. Then when warm runs like nothing is wrong in the world.

Any quick fix ideas???

Thanks all. You are a great group.

Is Randall still here BTW?

Kevin

Slant;

We've wondered where you've been and have wondered if you have fixed your nagging problem... You should list what parts you have replaced to date... O2 sensor.... Did you put the hammer on it...

Bill Wagner

I think when you compare your current problem with your previous problem, you're talking about two different things (at least it sounds like it). If I recall correctly, your problems before really didn't start to occur until the car was warmed up and it ran fine until the car got warm (if I'm not remembering correctly, correct me).

There are a ton of possibilities that could be causing the problem. It would be helpful if you could give some more details regarding your current problem and if and how they differ from the previous problems, or for those new to the list provide a link to the original discussion.

If the car sat in the cold for a while (in summer??? Maybe in Alaska ) you might have picked up some condensation in the fuel system, but I would think a problem like that would be more constant, not temperature dependent. You may also want to check your grounds for corrosion (was the car sitting out in the rain for a long time) and you may also want to check the charge on your battery.

Aside from that you might have some problems with the engine temp sensor or the DME relay, and those suggestions are just shots in the dark as far as I'm concerned.

Good Luck,

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

PS: Which wire was causing all your original problems?

Arjan B.

Hi Slant,

This time of year, you have a nice outside temp. in Las Vegas as far as I know.
We visited your city last June, way too much [113] heat!

I think you have a parameter problem.

A problem with one of the sensors for temp. so the DME thinks your engine has a different temp then it is for real, so your fuel is injected to much or to less, may be the airflow meter [on top of your engine, silver coloured with a black top, 10 x 10cm.]is the one who plays the wrong game.

DID SOMEBODY REMOVE THE BLACK TOP AND ADJUSTED THE SPRING FROM THE METER?? IF YES, THE YOU HAVE TO PUT THE SPRING I ORIGINAL POSITION!!!!


A other problem could be that the oil ventilation system did put far too much oil dirt in your throttle housing.
Clean it with carburettor cleaner.
Your car can't breath enough.

Have fun,

Arjan
964 C2 1992 Black

slant911

O.K. let me try and recap (if I can remember) what has gone on:

Around January of this year I had a strange problem in that the car would spit and sputter anytime you put a big electrical load on the car (i.e. A/C, lights on high beams, stereo way up, etc...) I found that if I disconnected the O2 sensor it went away. So I thought it must be the sensor. New sensor in - no change. I put in a new DME relay - no change. Just before my extended leave I found a wire in the main looom that appeared to be schaffed. I replaced it and all "seemed" well. The response from the engine is VERY similar in it's performance. The conditions are different though under which it does it.. (Did I explain that right?)

Arjan, yes the temp is pretty toasty here in the summer, although, right now we are in a cold snap (only 95 degrees outside)

I hope I covered everything. Let me know if more info is needed.

Thanks.

John

slant911

Anyone??

horst

Funny- a friend of mine just called- Sx= engine often dies when coming to a stop, poor idle, and a "flat spot" mid range in rpms. We know the O2 sensor is good. it has been replaced not too long ago. after much speculation, we pulled 2 codes out of the check engine light- 113- full load contact to ground and 114, ENGINE TEMP SENSOR! I am 95% certain that when we replace the head temp sensor his problems will go away. In your case, I remember we never got the check engine light to work, so I suggest you have it Hammered. Head temp sensor is a common problem, and the old ones have been upgraded by a newer version. Good luck.

slant911

Horst - You are correct in your memory. I never did get the check engine light to spit out any codes (1990 model year). Is there any test the garage mechanic can do to check the engine temp sensor? Obviously, without a hammer.

I'll check my shop manuals and see if there is a listed procedure.

Adrian

Dear Slant,
There is a resiatnce check for the head temp sensor. If you have a set of factory manuals which are revised (very important) go to Vol 7. In the front you should find the air flow sensor connector repair. There is an inspection to be carried out as well. Combine this repair with the later repair shown below. This may help fix this puppy once and for all.
Ciao,
Adrian
911C4

Air Flow Meter Cover Causing Erratic Idle, Loss of Power
90porsche08
May 15, 1990
Subject: Engine, Inconsistent Performance
Model Group

911 C2/911 C4 2

Part Identifier Number

24../9750 9005
ATTENTION: Service Manager/Service Technician

This bulletin replaces Technical Bulletin Group 2, Number 9005, dated April 6, 1990.

Models Affected: 911 Carrera 2 and 911 Carrera 4, Model Years 1989 (K) and 1990 (L)

Concern: Inconsistent acceleration, erratic idle, loss of power or engine dies.

Possible Cause: The air flow meter wiring harness protective cover (Figure 1) contacts the engine ventilation hoses (Figure 2) causing current flow interruptions on the plug terminals.
Vehicle Information: The protective cover on the air flow meter wiring harness plug was discontinued from production date February 13, 1990.

VIN's 96 - LS 45 1659 Coupe 96 - LS 46 0409 Targa 96 - LS 47 1072 Cabriolet

Repair Information: 911 Carrera 2 model year 1990 and 911 Carrera 4 model years 1989 and 1990 prior to the above VIN's should be modified when the engine is removed or when working on the air flow meter, even if no engine performance problems are present.
Work Procedure: 1. Remove air filter housing cover and filter.
Figure 6


2. Push down locking spring on air flow meter wiring plug and disconnect plug (arrow in Figure 6).

3. To gain access to plug, pull wiring harness with plug between air flow meter and idle stabilizer towards rear of vehicle.
Figure 3


4. Pull back rubber boot and cut protective wire covering using side cutter or similar tool (arrow in Figure 3).
Figure 4


5. Heat protective wire covering with hot air blower to maximum 110~ C (230~ F). Pull off and discard protective wire covering (Figure 4).
Figure 5


6. Reinstall rubber boot on plug housing. Loop wiring harness along side of plug and tie wrap as shown in Figure 5.
Figure 6


7. Reconnect wiring plug. Make sure spring lock is engaged. Figure 6 shows wiring plug connected (engine removed).

Important: Do not use contact spray.
Figure 7



Work Procedure:
8. Check clearance between wiring harness and vent hoses. (continued) Distance should be at least 15 mm. If necessary, bend bracket on right shock absorber mounting slightly forward (arrow in Figure 7). Make sure vent hoses are properly installed on bracket at shock absorber mounting and on bracket in front of air flow meter. The small diameter hose must be routed below the large diameter hose,

9. Reinstall air filter and filter housing cover.

10. Mark air flow meter with a black paint dot as shown in Figure 8.
Parts Information: Tie wrap: PN 999 513 021 40

slant911

O.K. Here we go...

Adrian,

I found and followed the tech refernce in the manual for the air flow meter. It appeared that this had already been done either by previous owner or my wrench when they replaced the entire air flow meter and intake shroud last year. I have not tested the temp sensor yet, but, was curious about something. I put everything back together EXCEPT I left the air filter and cover off and started the engine. I COULD NOT GET THE THING TO FAIL. Didn't matter, hot, cold, any electrical loads all at once. It wouldn't fail. Now this could be that I fiddled with the wires and what not and made some difference in the distance as noted in the tech manual, but, it seems weird. I am going to let it cool off and try again cold tomorrow as that is when it surely fails. I'll keep you posted. Drilling the airbox is sounding better all the time <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

Adrian

Dear Slant,
Obviously this points to an air problem. I wonder if you have a leak in your system somewhere. Try putting the filter and cover back on and see what happens. Airfilter off an it is okay suggests a leak to me. By leaving the air filter off you are compensating for the loss elsewhere. Fiddling with wiring also has amazing affects.
Ciao,
Adrian
911C4

slant911

It seems strange that there would be an air leak in the system as that was the reason my wrench replaced EVERYTHING on the top side having to do with air intake. It was leaking like crazy. Supposed to hold like 7 pounds of pressure for 15 minutes (Please don't quote me on that). Mine wouldn't hold 1 pound of pressure for 30 seconds. So it was completely replaced as virtually every seal from the shafts were leaking. So if that is the problem I will be one unhappy camper. Gave them nearly $2000 to replace that whole thing. I'll put the air filter back on and see what happens later today.

Thanks.

John

slant911

I decided to try it again with NO filter in place and see if I could repeat last nights performance. Again it ran like a champ no matter the load, hot, cold, whatever. So now I'll try putting it back on tomorrow and start from cold again and see where that goes....

Thanks again.

John

slant911

Well I went at it last night again. Put the filter and cover back on and it ran great from cold for about 2-3 minutes then started to choke and cough. I quickly popped the lid open to fiddle with the wires and before I could even get back to the engine it stopped doing it's coughing. I fiddled with the wires to see if I could get it to go into "screwed-up" mode and it would not. So, now it is running fine, but, clearly something is up with the harness there.

John

slant911

Tried it one more time with everything together and it went crazy again. Kicked and sputtered. I tried to shake the wires and it didn't change a thing. I even took the air filter off to see if that would clear it up. Didn't work. Just kept coughing until the engine temp got to about the 7:00-7:30 position. Then it ran perfectly whether the filter was on or not. I am going to try and get some readings from the engine temp sensor tomorrow and see how that goes...

Until tomorrow......

<img src="confused.gif" border="0">