911 SC no start Perma Tune question
 

So I left work this evening and jumped in the car, turned the key and it fired but then died immediately and would not start afterwards.

It feels like an ignition problem as I lifted the plate in the injection with the ignition on and got the injectors to "scream".

The car does not try and fire at all, I had the same about 3 years ago and it turned out to be the bosch CD box, I replaced it wth a Perma Tune box and coil and have had no problem since until today.

When I get back to work tomorrow I will have my tools with me so I can do some more troubleshooting, first thing will be to see if I have a spark.

So the question I have is what experiance have people had with the newer Perma Tune boxes? I have researched the site and it seems there was new technology introduced a few years ago?

Permadoom strikes again....

Yea, that's what I am thinking.....

If you still have your Bosch unit...send it to 'ischmitz' 3.6@cox.net

I didn't know about the Permadoom problems and when my Bosch unit died, I got one. It too worked about three years. Fortunately, it went out intermittently and I was able to limp it to a local Porsche mechanic. He loaned me a "bench" unit and the car fired up and ran great. He found a Bosch core and sent it out for rebuild. He told me to never tell anyone how little he charged me for the core - Let's just say that he's a very nice guy. If I remember correctly the whole thing cost mid-$300's and I got to run around on his bench unit for a week while the core was being rebuilt. I could pull the receipt to refresh my memory on the cost, but I'll never go back to Permadoom now. Just have a Bosch core rebuilt and stick with it.

Thanks to the always helpful guys at Zims the Perma Tune has tested good........more work to do tomorrow!!

Let us know what up on the fix.....

Post your location, intake and model year....based on your post we all assumed the worst.

I'm sure Permacrap has been trying to live down the past.....

This is what I am using now. Retail $595 with coil. Has data logging, advance and retard curves built in.

http://forums.pelicanparts.com/uploa...1327630225.jpg

This is the coil


http://forums.pelicanparts.com/uploa...1327630261.jpg

I have not done it yet, but I can lock down the distributor advance and set an electronic curve with the computer software.

for more information: http://www.daytona-sensors.com/CD1.html

I'm in Dallas/Fort Worth, car is a 1983 911 SC.

In the Dallas area there is a really excellent mechanic that runs Dallas Eurocars. He really knows his stuff and is honest as the day is long. Ask for Jim:

Porsche-Lexus Mercedes-Bmw repair in Dallas Ft Worth Tx

Phone (972) 243-4911

Some of you guys are really quick to condemn my product before doing any investigation at all. As it turned out there was nothing wrong with the Perma-Tune.

Bosch makes a really good product too but it fails as well and none of you jump on Bosch like you do Perma-Tune. I do not understand why some of you have such a bad attitude especially given that the most vocal critics have never asked for my help.

Lonnie

631.909.1011

While your newer products may be more robust, the past haunts it......the potting didn't make them repairable.....just sayin'.....

Surface-mount technology - Wikipedia, the free encyclopedia

Modern electronics is, for the most part, SMT and is not easily repairable. Even for the most skilled and highly equipped technicians it is very difficult to troubleshoot and repair SMT circuit boards. In my experience, one repair begets another and is just not worth the effort in the long run.

Potting is required to eliminate vibration, moisture and corrosion damage to the electronics.

As for the past haunting me, I don't believe in ghosts.

I had a perma-tune fail immediately years ago and replaced it with an M&W which has been flawless.

I have since read that both the Bosch and perma-tune fail due to bad ground paths. Maybe the P-T is more sensitive to this, but if the Bosch fails because of this then the P-T will surely fail for the same reason.

I had mine fail as a new install, never had a Bosch, but I was quick to blame P-T at the time. They may do a better job now, but I was surprised that they didn't make a big deal out of checking grounds before installing. I think my grounds were good since I had just installed the engine, but who knows.

http://forums.pelicanparts.com/uploa...1327679420.jpg

I had a Perma Tune in a '77 911 and converted to MSD, one of the best things I ever did with that car. Improved idle, fuel economy and pulled like a train!

The Bosch design is very reliable which is not the case for the later Perma-Tunes.

The overwhelming Bosch failures result from external factors:
1. The tech shorts the coil with a screwdriver adjusting something.
2. The alternator overcharges.
3. The battery is reverse-jumped with the ignition 'on'.
4. The engine is not properly grounded to the chassis causing
the 6 pin Bosch unit to fail.
5. The tech uses bad troubleshooting techniques when analyzing
ignition problems inadvertently damaging the unit.

I have the original "silver" permatune in my 77 Targa, with 110K miles, runs great. Talked with Permatune folks awhile ago, very helpful, knowlegeable folks. Would not hesitate to use PT products. They made a plug wire set awhile ago, looked very robust. Unfortunately, they don't make them anymore. Maybe I am just lucky with mine.

Yes, there are ground issues due to the way the car is built and we do make a big deal about checking for it. Every one of our ignitions has an instruction sheet that includes this check in the installation instructions. Too bad that most people do not read the instructions.
The entire drive line is on rubber mounts so the ground connection between the engine and the body is the only high current path for the starter and other electrical components on the engine. Since this wire is connected to the engine with a steel bolt through an aluminum alloy housing and a brass lug, dissimilar metals corrosion is common.
When this ground wire goes bad, current is diverted from the intended high current ground wire through the ignition circuit ground reference circuit. The ground reference wire is of course much smaller than the engine ground wire and cannot handle high current. This is what causes the problems. See below on how to trouble shoot this issue.
A tour of any Porsche junk yard will reveal cars with the engine compartment burned out. This is what happens when the engine ground is really bad. This can also happen after an engine swap if the ground wire is not reconnected.
Another issue is the crispy green wire on the distributor and corrosion in the 14 pin connector. When an aftermarket ignition is installed that requires re wiring the car these problems are often bypassed by the new wiring. In this case the engine appears to run better due to the new ignition module when in reality it is the new wiring that solved the problem.
MSD does make a good product and there are others out there that are good too, some not so good. We have done many dynamometer tests comparing ignition systems. I tried to paste one here but cannot figure out how to do it. I can email them to anyone who wants to see them.

From our web site:
Ground loop problems are very common on Porsche cars, especially on cars that do not get driven much. Symptoms of a ground loop problem are many, can affect the entire electrical system and are often intermittent in nature. Some indications of ground loop problems are: hard starts, poor engine performance, radio reception interference, weak engine ignition spark, false alternator failure light, repeated ignition box failures, repeated alternator failures, repeated tachometer failures, repeated relay failures, dim interior lights. Especially common on the 911SC are defective ground connections between the engine and chassis of the car. The defective ground connection diverts current from the starter though the ignition system. The higher the ground connection resistance, the more current will flow through the ignition system during cranking and the faster the ignition will be damaged.
There are many ways to troubleshoot ground connections, here is a fast way to do it on a 911SC. Use a digital Ohm meter set to its most sensitive setting, an analogue meter is not sensitive enough to use this technique. To reduce the chance of misdiagnosis, tug on the wire being tested while watching the meter and perform the test in the order as follows: Stab the black lead of the meter directly into the lead of the battery minus terminal and connect the red lead to the chassis of the car, do not connect the red lead to the battery ground connection. The resistance should read less than 0.5 Ohms, any more than that indicates a bad connection. Move to the back of the car and connect the black lead of the meter to the chassis of the car and the red lead to the engine case, again the meter should read less than 0.5 Ohms. Disconnect the harness connector from the ignition box. Connect the black lead of the meter to the engine case and the red lead to the ignition box ground wire, pin 1, of the cars’ harness connector. Refer to the Model 911SC902 connector diagram above. Again the meter should read less than 0.5 Ohms. Connect the black lead of the meter to the engine case and the red lead to the aluminum relay panel that the Perma-Tune is connected to. Again the meter should read less than 0.5 Ohms.
Defective ground connections at the alternator or fuel pump can also cause damage to the ignition box by diverting current through the ignition ground.
WARNING: To avoid the possibility of fire, do not install additional ground wires on the vehicle and replace defective ground wires using only wires of the same gauge.

"I have the original "silver" permatune"

That's NOT the original Perma-Tune, i.e. It was blue. The silver is the least reliable.
Hope you keep a second one in the car!

Loren, you are right about the external factors and these factors apply to the Perma-Tune as well as any other ignition system. This is basic electronic principal. However, I do not agree with your assessment of the Perma-Tune.

Interesting, didn't know that Lorenfb, learn something new everytime I get on line here. Guy I bought the car from was adament that everything was original. Na, won't carry another, I like to live on the edge...