Engine Problems, help is on the way

Now that I have your attention. I have read a lot of posts on the board regarding engine problems. One of the things I noticed is that as soon as a problem occurs, the first thing Porsche owners want to do is start replacing parts. Although not eveyone does this, it is not the correct way to diagnose problems.

I don't claim to be an expert on Porsche engines, but I can say for sure if you have a Air conditioning problem I can probably solve it.

Problem solving is the same weather it's working on a/c units, cars, or any type of problem.

First you must understand the basics. You have to understand what each part does and how it interacts with other parts. Next, you have to have the proper tools to diagnose the problem. That does not mean you have to go out and spend thousands of dollars on high tech equipment. You just can't do that with the newer cars - they must go to a garage. But, a good multimeter is a start, and for injection systems you need a good injection gauge with hoses to troubleshoot.

Last but not least, you must ask the question "what is supposed to be doing, but it not." What I mean by this, is if all plugs are supposed to be firing and the engine is backfiring, what's causing the problem. You have to work back from the problem.

Ask the question "what would cause this problem?" What other components interact with this component to make it work? Again this all goes back to understanding your engine. If the engine is backfiring through the carburator, what would cause this. Why doesn't it backfire out of both the carburator and exhaust at the same time. Why does it have to be one or the other. Be curious.

It takes time to evaluate probelms, so you can't get into a hurry. Again, don't hesitate to ask questions. If you don't ask questions, you won't know and you won't learn.

As an example I recently found out that small reciprocating refrigerant compressors are used for air in dental offices. Would have never known, but when I was picking up a compressor, I was asking questions about it. You always learn something.

Be persistant and eventually you will find the answer. Hope this info helps.

Steve

Hey Steve, good job with the explanation that the solution to any problem requires a diagnosis! Part changers are a nightmare in our business.LOL! However, I need your help. I am also an hvacr tech. and I have a problem with my Porsche's a/c system. Here's the situation: a/c switch and t-stat work, compressor runs, condensor gets warm to hot, sight glass ball DOES NOT FLOAT OR MOVE, system was converted to 134a-I do not have the guages to check this system. A mechanic put guages on it and thought it was low on 134a-he proceeded to add refrigerant and then stopped immediately saying that the pressures were not responding to his adding refrigerant and he would need to investigate further. I have a feeling the expansion valve is stuck but I do not know how to access it or the evaporator. A second tech. said, without looking at it, that it could be system contamination due to "compressor guts" and would probably need a new compressor, clean-out, txv, and recharge. I would like to empty the 134a and return it back to r12(I have about 180 pounds of it in stock), put a vacuum pump on it for the night and change the expansion valve. What do you think? I would be a "part changer" if I do this but the expansion valve would only cost about $30 or so-worth the risk to me. The guages are expensive as I'm sure you know and I wouldn't really need them except for this which is why I'm hesitant to buy them and SEE the real story.

Steve, just noticed you are from norcross. Maybe you could help me - I'm in Roswell!

Well, without not knowing what his gauge readings were, it's possible that the problem could be either expansion valve or the filter dryer. If the compressor was running and refrigerant was entering the system, than the compressor was doing its job.

I recently changed my compressor and found the filter/dryer was blocked.

If the system is set up for 134a, than in all likelyhood the expansion has been changed. Not sure what your year is, but the expansion valve in mine (1978 911 SC Targa) was located in the front, under the door.

Steve

I'd only add two things to this. First, for me, I have to track back to see what the last thing I did to the car was, and how does that figure in the current problem.

Second thing is keeping a record of your work in a usable format. I used Excel to list out all the records, EVERYTHING that had been done to the car from the history I was given by the PO. Then I gave the Excel sheet to the PO and he pointed out the additional things that were not recorded.

The headings for each column are Date/Mileage; Shop; Complains of...; Work Performed; New parts installed; Comments. I include my own work at home, such as the rotors or clutch cable/pedal box rebuild, etc. I keep oil changes for all our cars on a whiteboard in the garage: date and mileage, filter and oil grade. Easy to do.

It's very handy and gives a nice top-down look at the car. A mechanic might find it useful as well should the car go in. Finally, I am sure it would be a useful tool should I sell the SC and move to another Pcar (of course!).

A bit anal retentive, but useful.

Jw