Q – My 928 caught fire. I pushed it out of the garage and saved the house but the car is a mess. Just before I pulled into the garage the engine started running rough and it was very down on power. I figured that I could limp it home but that was clearly a bad idea. Now I am told that the engine has two separate ignition systems, one for each bank, and that when one side of the engine shuts down, the fuel injectors keep spraying fuel into the hot catalytic convertors and that is what caused the fire! So now my car is burned and I feel burned as well. To make matters worse, my insurance company wants to total the car but I love it and I do not want to let it go. How could this happen and how can I make sure it never happens again? Pete
A – I am sorry to hear of your loss but I bet your wife appreciates that you were there when it went “poof” and saved the house. I was surprised that the ignition system is split but the fuel injection system is not. Failing to take that into account has caused a number of fires in this model and it would seem simple to engineer a way to shut the injectors down if half the engine was not firing. I will think about that and let you know what I find in another issue. Modern cars cannot flood the convertor with fuel since a cylinder misfire is detected by the computer and that shuts that cylinders injector down.
On the insurance problem, you should always have a vehicle you love insured to an agreed value, not a stated value. And be sure to set your limits high enough to not only replace the car, but to bring the replacement car up to the standard of your present car. Many people fail to do that and buy less insurance than they need. Face it, no one likes to pay for insurance but if you cheap out to save money, don’t complain when a catastrophe occurs.
There are many ways to get excellent coverage and a reasonable price. If you have a classic car, and you do, you should shop for classic car insurance and even consider historic plates as well. There are often restrictions with this kind of insurance as well as the historic plates but they serve a purpose at a very low price without compromising your coverage. MC
Q – How do you find a high speed shake driving the car around town? Do you take the car out on the freeway? Rick
A – As a professional, in the interest of science, I have to drive cars faster than most folks do. I have a spot where there is a mile of straight road, few entrances to that road, few homes on the road and very limited places for the authorities to hide. I go about a half mile down, there is a little rise in the road where I can see a half mile in both directions, when there is no traffic, I pull out and do full throttle red line acceleration tests then full braking, short of lock up, stops from triple digits. I brake down to the limit, accelerate back up and try a second stop from a high speed while holding the steering wheel with a light touch to check for pulling or vibration. MC
Q – That sounds dangerous. Do you ever get tickets? Rick
A – Sooner or later, odds are a ticket is likely but generally the local officers know what I am up to and they usually let me off with a warning. Once I was test driving a supercharged Miata and it was fast. I accelerated hard, stopped equally hard and pulled it to let it idle. He was right behind me. His comment was “do you know how fast you were going?”, to which I replied “no, I was watching traffic and paying more attention to the engine since we just finished this car”. I popped the hood and showed him the install and he was interested to see what was under the hood than in writing a ticket. I know a number of police officers who are motorheads too.
There is one circumstance that they have warned me about which will always result in a ticket. If I have a passenger, they have to ticket me. I remember one incident where one of our members wanted me to test drive his car and wanted to go with me. I got pulled over and got the ticket. He was very amused by that. I did not find it as funny. It could have been that he had been in a similar situation and also got a ticket. You could say that it was a memorable event for both of us and he would frequently remind me of it.
Dennis Szeremet, our dear departed 928 fanatic, loved doing burn outs in his Gold Weissach Edition 928. He always left my establishment in a memorable way by leaving two long, ten inch wide, black rubber stripes on the parking lot. He knew he would not get a ticket on private property when he had the owner’s permission. MC
Q – Do you test drive cars that you service? I have taken my car in for service, gotten it back, and it still had the problem that I took it in for. That is so frustrating. One time I picked my car up, drove about 3 miles and one of the rear wheels came loose! Shouldn’t test driving cars be part of the process? Don
A – Years ago, I was a bit lax about test driving cars, but now, I or someone I trust, test drives every car. Some times it might be a trip around the block, occasionally twenty miles or so, and for a few cars, with very knotty problems, we may drive it a hundred or more miles. Tricky problems need extensive test drives, such as when I am told: “it only acts up after I get off the freeway after a 25 mile cruise”. Those are the tricky ones. MC
Q –My 1978 928 is driving me nuts! It has been unreliable and I have really had a tough time getting someone to work on it who knows what to do. It starts then dies and it does this repeatedly. I took it to a local mechanic who I trust and he is pretty good but when I got it back, it was no better than when I took it in. When I can manage to get it started and running, it will go about two or three miles then performance deteriorates, it misfires and sometimes stalls and won’t restart until it cools off. I don’t know how it could have even been test driven. –Bill
A – Mid-70s cars with Bosch K-Jetronic fuel injection can be challenging, especially since that technology originated in the 50’s. To find someone who can diagnose it, you have to find a shop that was in business when these cars were new. The next criteria should be that they have techs that were trained by Bosch to service these cars. That part is tough since the majority of techs that I know who can diagnose these cars are retired! Finally, ask around and see who has done work for other club members. Diagnosing an old car is like peeling the layers of an onion. You just start at the outside and work your way in. If you have ever peeled an onion you know that you should expect some tears. As far as test driving the car, the shop that you choose should be unafraid to drive your car long enough to be utterly certain that the car will be reliable—20 to 100 miles should be expected. –MC
Q—Last month you mentioned air brush touch up but you did not tell us who can do it. –Bill
A – A club member, Bill Kreager, has been doing custom painting and air brush as a hobby for many years. Now that he is retired, he is taking on more of this kind of work and he is very good at it. I know of another source but to get that name you will have to contact me since that individual has a day job and cannot take calls. –MC
Q—My 2003 Carrera Cabrio sunvisor fell off the car while I was loading groceries into the back seat. I cannot see how it attaches or what holds it in place. –Mike
A – The visor fits into the latch bracket on the header bow and to figure out what happened, you will have to remove the bracket. It is held in place by two allen bolts which are secured by Loctite. When you remove them, be very careful not to tilt the bracket because you will find the clips, washer and spring sitting inside the bracket if you are lucky.
Once you have all the pieces you will notice that the clips were deformed when you knocked the visor off. These can sometimes be straightened and reused but be careful. They are brittle and easy to lose. Once you have straightened them, you can hold the visor arm in a vise and place the bracket onto the arm then assemble the spring, washer and clips by pushing down on the clips with a 6mm socket. Following the reassembly, remember to reapply Loctite to the threads of those two bolts. Screw them back in, torque them down and you are all set. –MC
Q –My 1987 Carrera Targa was running just fine and then one morning it would not start. I went on line and learned about the possibility of a failed DME relay, fuel pump relay, fuel pump, computer and so on. I ordered in some parts. I plugged in the DME relay and nothing happened. I then tried the fuel pump relay but when I pulled it out, the female terminal pulled out with the relay! Naturally I got excited and figured that I found it but when I jumped direct power to the fuel pump, the car still would not start. When I ordered I got Uro brand parts. What do you know about them and what should I do next. –Steve
A – It sounds like you picked all the “low hanging fruit” so you were on the right track. The DME relay is a good bet and you are wise to have a spare even thought it did not fix the problem. Now that you know about the plug for the fuel pump, you can order that from Porsche and you might be surprised at how proud they are of that part. It is not cheap! To replace it you must splice it in.
This requires some expertise, so if you are not good with soldering or solderless terminals, leave it for a pro. That still might not get your car started. The next test is for spark and for that you have to be careful. The system can stop your heart if you do not take precautions. This too should probably be left to a pro. Things that I have seen which will stop your car cold include a failed temp sensor ground circuit caused by age and corrosion. If your car still has a “single terminal temp sensor,” replace it. If it already has been replaced, do not worry about it.
The next test I would perform would involve the crankshaft speed and reference sensors. That test requires an oscilloscope since simple resistance tests of those sensors yields far too little information. With a scope test of the sensors you should see a strong and consistent signal from both sensors. If one or the other fails, they often do on starting rather than running. Perhaps an engineer can explain this to me, but my theory is that during starting available voltage (11 to 12 volts) is lower than charging voltage (13.8 to 14.2). Finally, if the scope test of the sensors passes both, you could have a problem with the DME which is located under your seat.
Since you have a Targa, is it possible that it got wet? I know it may sound crazy but I know of one car that was left out in the rain and ended up with two inches of water on the floor. It wouldn’t start! After disconnecting the battery, removing the DME, removing the circuit board and drying it out with a hair dryer, the car started and ran! So if you think you have a bad DME there are a few options. Do you have a friend who owns a similar generation car as yours? If so, try your DME in his car and see if the problem follows the DME. If it does, Bingo! If it does not, then you will need to have it flat bedded to the expert of your choice.
As far as the Uro branded parts, most of them are made in China and I do not recommend Chinese parts for German cars. Now, having stated my general philosophy, several German companies are now sourcing their parts from China such as the original manufacturer of the fuel pump relays. Still, I would prefer German. Interestingly, the DME relays which are from an OEM manufacturer come from Hungary and many of the OEM parts from Porsche are sourced from many European countries other than Germany. –MC
Q – My midnight blue Carrera has some scratches in the right rear bumper skin that really bug me. I went to two body shops and they both wanted to repaint the whole skin at huge expense. I do not mind the expense as much as I do not want to risk devaluing the car by having it repainted. Craig
A – As an alternative, you might consider air brush touch up. A number of vendors can direct you to an artist that can perform minor miracles with your paint. MC
Q – My 944 Turbo has a very subtle whirring sound that I hear when I change lanes and load the car from left to right. I just started to notice it. Is there any danger or should I wait until it gets worse. Ed
A – I say trust your intuition. If you feel uncomfortable hearing or sensing anything your car is doing, drive it to you favorite tech and get a second opinion via test drive. If could be something as simple as a wheel bearing in the beginning stages of wearing out or a wheel with loose lug bolts. Trust your senses and play it safe. I associate whirring noises with wheel bearing failure and at first, when the symptom is slight, it may be hard to detect where it is coming from. On your car, even it your cannot hear it, any looseness in the bearings tells me that you have some wear issues. Your tech can usually check for loose bearings or wheels quickly and at little expense.
Q – My 2001 Boxster makes an odd whirring noise when I turn the AC on, I took it in and first thing the shop noticed was a loud idler pulley which they replaced, now they tell me that the AC compressor is the source of the noise. I am not sure I trust them since they “guessed” wrong the first time. What do you suggest? Pete
A – Serpentine belt drives can be tricky to diagnose. These belts operate at very high tension and noises from one location can be transmitted to another. Remember the “telephone that you made when you were a kit with two cans and a taut piece of string? This can fool well intentioned techs who simply call out the loudest noise location. One was to tell where the source of the noise is coming from is to remove the belt and (with the engine turned off) feel the idlers and bearings in the various components such as the alternator bearing, the alternator clutch, the water pump, the idler pulley(s) and the AC compressor. Unfortunately, when you are trying to detect a failing bearing by hand it is not being loaded and you are limited by that lack of tension. However, if a bearing feels rough or loose, it is a safe bet that it is not long for the world. A prudent approach would be to replace the obviously failing part first with the understanding that the sound could still be coming from one of the other components.
I would also suggest that you consider replacing the serpentine belt when you replace idlers since my opinion is that an old belt is far more likely to transmit noise than a new fresh belt. (Perhaps one of you engineers reading this can explain this to me) I have seen a new belt cure noise on numerous occasions when the belt shows no outward signs of distress. The added advantage of replacing the belt is labor overlap when doing the pulley. This saves the aggravation of getting back into that area later.
The fact that the noise is only noticed when the AC is operating tells me that the compressor is the most likely source of the noise but that does not mean that it is failing. It could just be low on refrigerant. I would recommend charging the system after eliminating the idlers. If the noise persists then I agree that a compressor may be the ultimate cure. Clearly the shop should have informed you about ALL the possibilities before hand. MC