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Location: Fort Worth, TX
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Question 993ina914 conversion won't start

Well, I've tried and tried, but I can't figure it out. Maybe someone here can help. I've gone through all of the checks in the service manual, but everything that I can check, checks fine. It won't start the fuel pump when cranking and doesn't appear to be firing the injectors. I've hotwired the pump and cranked it and there is no gasoline smell in the exhaust as one would expect. I can hotwire across the pins on the DME connector as the service manual shows and the fuel pump will run, so I know that the DME relay is good and all of the fuel pump wiring is okay. I suspected the engine speed sensor, but checking AC voltage across pins 48 and 49 of the DME connector gives 3 to 4 volts AC. The pin to the DME that should have constant power does, even when cranking. The pin to the DME that should have switched power does, even when cranking. And the pin that should be grounded, is. I think these are like 24, 27, and 18. I don't have the diagram with me right now, it's in the floorboard.

Last weekend, I wired up a check engine light and the DME will never turn it on. I can ground pin 21 on the DME connector and the light works, but the DME won't turn it on. Do I have a bad DME? Or 2? I have two and neither will work. I even tried a Snap-On code reader that my grandfather has and it wouldn't connect to the DME at all, kept saying to check the connection.

It's a 95 993 engine in a 76 914. The engine, harness, and DME were all sourced separately because a I got a good deal on the engine. Right . . .

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Avery
76 914 (95 993 conversion in-work)
05 Caddie CTS-V
70 Pontiac GTO
Old 09-03-2007, 09:41 PM
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I assume you posted this on 914club.com?
Old 09-04-2007, 04:11 AM
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No, not yet. I may, but I would assume that there is a lot more knowledge on the 993 here. I'm pretty sure it's something wrong with the fuel injection system. All of the 914 systems seem to be working fine. There are a handful of people that have done 993 conversions there, though.
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Avery
76 914 (95 993 conversion in-work)
05 Caddie CTS-V
70 Pontiac GTO
Old 09-04-2007, 04:43 AM
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Have you checked the gap on the speed sensor? IIRC the fuel pump will only run once that speed sensor detects a certain RPM.

Have you bled the fuel rail - there is a small cover on the LH rail and if you remove that there is a bleed ball thingy you can press to let the air out, cover it with a cloth tho

What is the part number on the ECU? Is it 993.618.124.xx? If it is 124 and not 123 then it is drive blocked and will just kick but not run.

Hope this helps
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Old 09-18-2007, 02:47 PM
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Avery,

Hm, from what you are telling (good power to both the switched and the permanent +12V at the DME and good ground) it sounds like a bad DME. The reason I am saying that is that it should by all means turn on the CEL once the switched +12V gets power. The snap-on code reader won't do you much good. It requires OBD-II. The 993 non-varioram DME is OBD-I. I wonder how you connected it.... What you need is either a hammer (Bosch tester) or the self-made tool that is on Rennlist. Both need to connect to the K-line and L-line. This is how the Bosch 993 DME communicates.

I don't know what the chances are that you have two bad DME boxes but you never now. I would try and find a stock 993 car and put the DME in to see if they work. That way you can at least isolate the culprit. The next question is whether you fried the DME boxes on your conversion or whether they came broken.....

Keep us posted,
Ingo
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How about a NoBadDays DualChip for 964 or '95 993
Old 09-18-2007, 03:54 PM
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Based on the posted data, there are two possibilities:

1. No power to pin 27 (run - #15 power)
2. 2 damaged DMEs - check that DME unit internal grounds are all connected (14,19,24,30,48)

The CEL should come "on" once pins 18, 37, & 27 have power without ANY sensor
signals.
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Old 09-23-2007, 07:53 AM
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Well, I'm sorry to those who answered, but I quit checking this thread after a week or two. Then the responses came.

Jevvy - The speed sensor is the first thing I suspected. The gap is about .9mm right now. That gives about 5V AC while cranking, minimum is 3V. The service manual says to use an oscilliscope to look at the signal, but I don't have one handy. It puts out a nice signal, so that should be good enough. I bled the fuel rail checking for fuel pump operation. It works if I hotwire it, but thats all.

One ECU is a .124 and the other is a .123. I know about the .124 . . . now. I wouldn't think that the driveblock would prevent the CEL from functioning, but I really don't know anything about that system at all. I'm only worrying about the .123 ECU now, and it doesn't work either.
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Avery
76 914 (95 993 conversion in-work)
05 Caddie CTS-V
70 Pontiac GTO
Old 10-31-2007, 05:33 PM
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ischmitz - I didn't think the Snap-On tool would work, but it was worth a try. I have an OBD-II style port because I am using a Patrick Motorsports conversion harness between the factory DME harness and the 914 chassis. It includes the diagnosis port. It's the trapezoidal one with 10 or 12 pins, not the early round one. I'll probably invest in one of those tools later, but haven't yet. Nobody I know has a 95 993. It wouldn't work in the 96 I could maybe get my hands on. I kinda feel like I would need to be real good friends to ask that.
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Avery
76 914 (95 993 conversion in-work)
05 Caddie CTS-V
70 Pontiac GTO
Old 10-31-2007, 05:39 PM
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Lorenfb - I only get to work on the car on weekends because it's too far to my shop where it is currently, but I have the DME here. I checked all of the grounds for continuity with a voltmeter. Pins 2, 14, 19, 24, 26, 30, and 48 are all connected internally in the DME. Everything there makes sense to me except for pin #2. My diagram says "not used" for that one. Does that indicate something sinister? I checked pin 24 to 27 on Sunday for the umpteenth time, so I know that it is getting power there. I also checked 24 to 18 and it is fine as well. Those are tests 1a and 1b in the service manual, so I tried them pretty early.

A big thanks to everyone for their inputs. I'll watch this thread more closely, I promise.
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Avery
76 914 (95 993 conversion in-work)
05 Caddie CTS-V
70 Pontiac GTO
Old 10-31-2007, 05:47 PM
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Update: Good news, it runs!

Proof:
HTML Code:
http://www.youtube.com/watch?v=rYdwZYZT7D8
My Patrick adapter harness that connects the DME harness to DME relay, the fuse box etc. was mis-wired. Not by me, but by Patrick. The pin outs were wrong, so terminal 87 on the DME relay wasn't connected to pin 37 on the DME. As soon as I fixed that, it fired on the first crank. Not too happy that a purchased harness was messed up like that. Could have built my own at this point.

It's kinda loud. Sounds like a V-8 at idle, really. I'm curious what it sounds like on the road at rpm. Next weekend.
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Avery
76 914 (95 993 conversion in-work)
05 Caddie CTS-V
70 Pontiac GTO
Old 11-04-2007, 10:33 PM
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Thanks for that cool video. Why so smoky?
Old 11-27-2007, 06:17 PM
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Congratulations. I had a '72 914/6 (2.7S) and now a '95 993. The combination of this motor and that chassis would have been a riot.
Old 11-28-2007, 04:06 AM
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Thanks. It smoked a lot at first because it had been sitting for at least three years. That's how long I've owned it, I'm not sure before that. The rings aren't seated well, the cylinders are full of oil, whatever. Not unexpected. It smoked a lot more than that after it warmed up actually. Now, it doesn't smoke at all, not even a little on startup.

It's quite fun. I've really missed driving it while I was doing the conversion. I've been treating the engine like it's new, even though it's really not, so I haven't really rung it out yet, but the few times I've stood on it briefly, it's definitely pretty fast. I'll know more when I get it to an autocross or drive with some other 914s.

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Avery
76 914 (95 993 conversion in-work)
05 Caddie CTS-V
70 Pontiac GTO
Old 12-01-2007, 09:31 AM
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