Help! 3.2L Conversion in '73 911T wont run!
 

So after being up on jack stands and in various stages of either sitting waiting on me to work on it or being worked on, my '73 911T with a Euro '85 3.2 engine failed to fire up and run for my test drive. I just put her back together after doing tons of work - new front suspension pan, rust repairs, electrical repair and other stuff for the past 2 years.

Maddeningly frustrating. Yesterday, while still up on jack stands right after I had the exhaust all bolted back up, on a whim - just to see what would happen - I turned the key. The starter turned for 3-4 seconds and WHAMMY - she fired right up! I let her run for about 30 seconds and then shut down as the new exhaust was gassing out (new ceramic coatings ) and I did not want it in the garage. So I am pretty happy, she fired right up so easy after 2 years in the garage.

So I re-install the carpet and seats, bleed brakes, tidy up some wiring with zip ties and get her all ready for the first test ride. Nothing. All set and ready to go - not even a peep of firing up. She turns over on the key just fine, but does not fire.

I did not do the 3.2 conversion on the car. I honestly don't know really where to start to track down what is wrong. I have gone back over the wiring that I tidied up and cannot find anything wrong. There are fair number of dead and loose wires in the engine bay, but most I have identified as things no longer necessary with the conversion.

With the ignition key ON - I have no voltage showing at the coil. Should I? Seems I should.

I have been reading a number of threads on the 3.2 conversion into an early car - '73 included. I have tried to review all the details and compare to my car but it seems to be causing more questions rather than leading to any answers. I really don't want to have to completely re-do the entire conversion.

Any guidance or suggestions on what to try and how to be diagnose and correct this would be greatly appreciated.

First thing to do on a non starting 3.2, is to replace the DME Relay.

That sounds like an expensive guess. Just pop for a new DME Relay and hope for the best?

Surely there must be a means of diagnosing a bad DME Relay?


Terry

I hope that you are confusing DME Relay with the DME itself... Because a DME relay is about $30 and is the least money you will spend on your car :D

A DME relay is about $30 to $40 depending which one you buy and $90 if you want a Porsche one :rolleyes::rolleyes::rolleyes:.

You should not ride a 3.2 without a spare one in the glove box.

Pelican Parts - Product Information: 911-618-154-01-M252

Help this man please!

dme relay
 

I would test the relay first with a multimeter and jump it out. I thought I had dme relay problem on my targa that sat for years with the PO and had several people in it. The dme tested out fine. Spend the 15-20 jumping out the relay and testing it and save the money. Did you mess with the cht wiring? What about the reference sensors. The easy test was to flip flop them. It fired up right after that. Check the fuel pump relay just in case. Start with the easy stuff first.

I understand your frustration. I am planning a very similar project putting a 3.2 into a 71. it will be a 1-2 year project.

I have a similar transplant in a '74 with a 3.2 with all the ECU goodies on it. I don't have my Bentley handy to check if there should be voltage on the coil like traditional kettering ignitions, but the troubleshooting section is great, and may apply to your installation. One thing I can suggest is to not assume anything, and start with the basics.

• Is there spark at all? Perhaps try checking for spark while having a helper crank the engine over.
• Is there any fuel? Pull a plug and check for any dampness or fuel small.

If I remember when I get off work I'll take a look in the bentley and see if I can answer the coil voltage question.

Try to jumper the DME relay. On a real 3.2, the relay is under the driver's seat. Don't know where it might be on your swap.

Start at post #23:

http://forums.pelicanparts.com/6619164-post23.html

Will it run if you jumper power to coil?

Don't fool around. Carry a spare DME relay. Order it and while waiting for it to arrive, hook a timing light to the coil wire and see if it flashes while cranking (there is no voltage at the coil with the ignition on).

It sounds like it ran before the seats went in - double check the ECU and DME under the driver's seat.

Do you have spark? pull a plug wire, and connect an extra plug with a jumper wire to ground the case of the extra plug, turn the engine over - the plug should spark.

Do you have fuel pressure with the key on? There is a port at the rear of the left fuel rail, or you may be able to disconnect a fuel line and route it to a bucket.

It's hard to read the voltage pulse on the input side of the coil, unless you have an oscilloscope to see the pulse waveform from the ECU.

I never touch the gas pedal when starting mine, because I have flooded mine, and it would turn over but not start. The next day it would start OK.

Mike

The coil should have power when the key is in run and start position. You cannot check it across the 2 coil leads. The green lead on the coil is the DME trigger ground. It works like the points opening and closing to trigger the spark. You have to check the black lead to a good chassis ground.
Without knowing how the conversion wiring was done or any pictures makes it very difficult. Which fuel pump was used, where is the fuel pump located and how was it wired. If using the original pump feed it would run when the key is turned on. If the R/Gr wire from the DME relay was used it will only run when the key is turned to start, and then the DME keeps it running when its sensors see rotation. Removing the DME relay and putting in a jumper wire will make the pump run if the relay is bad. Even if it isn't, a spare relay is a must. The relay can be opened and resoldered to eliminate one of the main problems that cause the relay to fail.

Ok - THANK YOU for all the replies and help so far, lots of good info.

I have done some more testing and fiddling with it. No obvious problem discovered. It is baffling that it fired up first thing - really surprising me - when I still had it up on jack stands and not tidied up. Then next go - nothing. Still nothing.

Here is what I have learned so far -

1. Using a spare spark plug, I attached a spark plug lead to it and then grounded the plug body to the chassis and attempted to start. Engine turns over normally but no spark shown at the spark plug at all. So I assume the issue is spark and not fuel.

2. The fuel pump comes on with the key. It turns on and off immediately with the key and does not appear to be associated with the DME relay at all. I jumped #30 and #87 on the relay plug and it did not cause the fuel pump to run. The fuel pump runs continuously if the ignition key is on. So it seems the fuel pump is still wired as per original 1973 and not tied into the DME Relay.

3. I am getting 12V at the coil. I attached the positive lead from my multimeter to the black wire on the coil and the negative lead to ground. With the ignition key on I get 11.9V at the black coil terminal.

4. DME Relay - testing here... Relay plug terminal 30 is always hot. That would seem correct. Relay plug 86 shows 12V when the ignition key is on which also seems correct. Relay plug 85 is grounded. When the ignition key is switched on, I can feel two distinct relay actions taking place inside the relay - one when the key is turned on and another when the starter is engaged. The car does not fire.

I am shooting some pictures of the wiring and some question areas, will post those in just a bit. I am at a loss as to what to test or try next. Seems very strange to have run and then quit.

Reference and position sensors hooked up with good connections? Did you knock off a wire when installing seats?

It sounds like the fuel pump is definitely using the CIS connection still, so the fuel supply should be good.
I have read in the past where the electrical connector for the injectors on the drivers side by the rear shock tower came apart. Check to see all the harness connections are good.

Still working to try and track this down. Below are some photos to wiring questions and possible issues.

http://forums.pelicanparts.com/uploa...1376848264.jpg

http://forums.pelicanparts.com/uploa...1376848287.jpg


http://forums.pelicanparts.com/uploa...1376848300.jpg

http://forums.pelicanparts.com/uploa...1376848314.jpg

http://forums.pelicanparts.com/uploa...1376848328.jpg

http://forums.pelicanparts.com/uploa...1376848459.jpg

http://forums.pelicanparts.com/uploa...1376848473.jpg

http://forums.pelicanparts.com/uploa...1376848489.jpg

Thanks for the help, this one is baffling!

Here is a diagram of the wiring that goes to the coil. Most of it is not used. IS this correct?

http://forums.pelicanparts.com/uploa...1376849818.jpg

I don't have time right now, and will look over it later.
The 2 brown wires by the DME should be left disconnected. It is only for emmissions in California.
Last picture of Cylinder head temp sensor, it is the old single wire. Newer type is 2 wire and performs better. Would still run, but mixture would be off.

A quick reference diagram for you.
http://forums.pelicanparts.com/uploa...1376855561.jpg

E Sully - really appreciate your help and thoughts on this. I can replace the cylinder head temp sensor. I can also order a DME Relay but I dont think that is the problem.

You say 1973 model, what intake? CIS is slightly different than earlier.
Cyl head temp sensor is tough to get to and needs slotted socket to clear attached wire, old and new style are different sizes. I'd hold off till it is running to see if it is a problem.
Yellow/Bk and Brown Aux. engine fan, not used if heat is backdated and fan eliminated.
Green wire, A/C or O2 sensor? My harness was a hacked euro so some can be difficult, mine was not set up for O2, which I added later.

First connector by DME, do you have the altitude correction sensor?
http://forums.pelicanparts.com/uploa...1376860704.jpg

I do not have that altitude correction sensor - not that I know of. It is not present near the DME itself on the drivers side floor.

The engine is a Euro '85 model 3.2. It has backdated heat exchangers and a Steve Wong euro model chip.

Even the Row had the Alt correction sensor. It is typically mounted near the dme. As far as a special socket, go to Auto zone and buy a cheap one and cut it. It works fine. Cut the wire for taking it out and use the other socket for installing. Check the resistance is in spec on the cht sensor first.

The Gry/W is not used.
The twisted and capped red wire would have been the feed to the CDI box.
The R/W, R/Bk are the rear defroster.
Brn/Bk, not needed.

The altitude correction module is open below 3000 feet, so having the wires disconnected should not be an issue in Georgia.

The green wire at the coil should be pin 1 of the 35 pin connector at the ECU.

Pin 5, 16, 17 of the ECU connector is ground. The ECU gets it's ground in the group of wires at the left rear of the motor intake rail, which means that the tranny ground strap must be connected.

Pin 13 is CHT sensor. (the top of the 3 motor connectors)

Pin 27 of ECU is speed sensor. (I think the middle of the 3 motor connectors)

Pin 25 & 26 is reference mark.(I think the bottom of the 3 motor connectors)

When I had bad solder joints at the ECU, I have been able to start the car by tapping on the ECU and DME when turning the key.

Mike

The Bl/Y and Brn/W wires are for Sportmatic and not needed.
As Mike wrote, altitude sensor won't keep it from running.
Interesting that it started once and now nothing. Heres a trouble shooting chart.
http://forums.pelicanparts.com/uploa...1376930226.jpg

Thanks for the graph for testing.... tough to use some of it because I do not know where the noted sensor is located.

Which items would prevent spark? The coil shows battery voltage, but a test spark plug confirms that the car is getting no spark. So - what specifically could be wrong that would prevent spark?

My father and I both have been digging into this - we went through all of the tests in table F that E Sully posted and found no problems. The only test we could not complete was the one for the ignition coil because my volt meter cannot show a "pulse voltage signal".

We definitely have no spark. I took the DME out and apart again and checked everything, no issues noted. The DME relay appears to be working fine. I cannot find anything that would prevent the car from running - but there is definitely no spark.

I am at a loss. I guess its off to a Porsche shop and a big bill. :( Totally infuriating given that it ran the first time I turned the switch and then refused.

I am wondering if the coil went bad? How can I determine if there is an internal failure in the coil that is causing this?

Bentley says the coil should read ~0 ohms across the + and - screw terminals, and 5000 to 8700 ohms from the screw + to the high voltage connector that goes to the cap.

Mike

PS - the speed (DG) and reference (BG) sensors can read good, but not be set correctly. If the reference isn't seeing TDC, the ECU won't know when to fire the plug. Both sensors should be set to 0.031" from the teeth.

I will test the coil, thanks for the help on how and what to look for.

Can those sensors be adjusted with the engine in the car? Where are they located and how best to reach if it is possible?

Thanks!

Terry

http://forums.pelicanparts.com/uploa...1376962584.jpg

There's some threads about this. I think I loosened the 2 bracket bolts, put some shim stock under the sensors, shoved the bracket down, (with engine at TDC), and tightened the bolts. It's not easy to get to - removing the rear left wheel helps.

Mike

Mike - In that photo, it appears that measuring the actual gap so you can adjust it to spec would not be possible with the engine in the car nor with the transmission attached to the engine. It appears that the engine is out of the car and the transmission is detached. I cannot see how one would be able to use a feeler gauge to set that gap correctly with the engine in the car, but I will jack her up again and check it out later today.

I also cannot see how that setting could be the issue given that the car ran and then quit, but at this point I cannot come up with anything that makes any sense.

The green wire that is shown in the wiring diagram I made and posted - noted as being a strange wire with an insulated wire running inside another insulated wire - that wire has continuity with the green wire at the coil. No idea what it was intended for.

Btw - car was CIS originally.

Yes this is a pic with the engine/trans separated, but you can access the sensors with the engine in.

If you study the picture, you'll see the two sensors sit in an bracket, and it's the adjustment of this bracket that sets the gap. Once the bracket is in the right place, the sensors can be removed without disturbing the bracket.

To reset the gap with the engine installed, the trick is to remove the sensor bracket with sensors, and glue pieces of paper to the sensor tips. Reinstall and press them against the flywheel, the paper will give you your gap. Once the engine starts the paper will tear away. The glue or paper residue if any remains will not affect the sensors.

HTH,
Chuck.H
'89 TurboLookTarga, 361k miles

Chuck.H
Good idea about gluing paper to the sensor.

Tspringer
I may have given you poor instructions about the reference sensor - You set the sensor gap when the TDC pin is at the sensor (see pic), the engine may NOT be at TDC.

http://forums.pelicanparts.com/uploa...1377005159.jpg

I agree that this doesn't make sense, because the car ran before the seat went in. If the bracket that holds the sensors is tight, I'd look elsewhere for the cause. I've had the same symptoms with bad solder joints on the ECU - it will run, then not. My thinking keep going back to the DME and ECU under the seat. The green wire at the coil should be pin 1 of the ECU connector under the seat.

Mike

I tested the coil as per instructions - the coil itself does not have any + or - markings on it for the terminals. Across the two screw terminals there are 0 ohms. With a lead on the high voltage output connection and the other lead on the black wire terminal I get about 7100 ohms. BUT - across the high voltage output lead and the green wire terminal I get about 6900 ohms.

Is this correct? Should I get a reading from either terminal and the high voltage output?

I do have continuity between the green coil wire and terminal 1 at the DME plug and also continuity between the black coil wire and DME relay plug. I also tried jumpering the DME relay as linked in the other thread and that made no difference.

Seems its either a bad DME or bad coil.

I checked my spare coil, and it reads ~6k ohms from either screw terminal to the high voltage connection, just like yours.

It sounds like you have the correct wires at the coil. If you have completed Sully's troubleshooting chart, my guess is the ECU (ECM).

Mike

Ok - maximum frustration.... no progress. Grrrrrrrrr

I took the DME apart checking for any arcing marks or breaks in the circuit board or anything I could identify as a problem - found nothing, it looks perfect.

With the GREEN wire disconnected from the coil and an old needle style volt meter attached to the green wire, when the car is turning over attempting to start I DO NOT have any pulse signal indicated. I see voltage - but no pulsing at all. This would seem to indicate that the DME is not sending a signal to the coil for it to pulse/fire spark plugs.

There is no arcing or other problems with the plug wires or distributor cap.

I see nothing wrong with the connections going to the reference sensors. Given that the car did initially run, I cannot think of any reason why something relative to these sensors could have changed.

??? If something is not correct relative to the reference sensors - would that cause the DME to NOT send a fire signal to the coil?

What other defective sensors or engine connections would cause the DME to not trigger the coil?

Is there any way to figure out whether the issue is something other than the DME without sending the DME out for testing? IF it has to go out for testing - who is cheapest / best / fastest ?

I just cannot get over why did it run and then refuse??? Just makes no sense. The car was sitting for 2 years... but then it fired right up? Second attempt - nothing and no spark since.

Any suggestions or ideas are greatly appreciated!

I had a similar problem with my DME when I did my swap. Mine was a no start from the beginning though. I was fortunate that the local Porsche shop was good enough to test my DME in a running car they had at the shop. Mine was a no start in their car, so I knew I had to send it for repairs, and an upgrade to the later style chip while it was being done.

E Sully - where did you send it for repairs and upgrade?

I am going to do more testing this weekend, but really don't know what to look for at this point. I do not know if a bad injector connection or such would cause no spark? All I really know for sure is that there is no pulse signal going to the coil and thus there is no spark.

I will try calling around to local shops on Monday to see if they have any 3.2 Carrera's in that they would test my DME in. What years 3.2 with DME would work to test this?