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3.2 914-6 saga continues

Here is the latest on the project.
Well the main problem was I had no dme relay hooked up. I was told that the 6 pin connector by the altitude sensor was for test purpose only, not for a relay. Wrong!

I can get the beast to light up when I spray some starter fluid in the throttle. Sounds absolutley great. Definitley not a stealth machine by the exhaust rumble. But I can't get to stay running. I have gas running drown stream from the gas filter and I have some gas from the fuel rail to the return line.
Any ideas?
Old 12-21-2002, 07:18 AM
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Buck,
That DME relay controls your fuel pump. The 3.2 DME's have a safety feature that will energize the fuel pump only if the DME sees engine rotation via the crank sensor(s) (ie during start, or run). It's tough to hear whether the pump is working due to the noise of the engine cranking.

The fact that you can get the engine to fire only with starting fluid verifies you've got spark and timing, but it sounds like no fuel, ie no fuel pump. Try jumpering the fuel pump "always on" temporarily and see if your engine stays running. Just make sure you don't jumper your 12v to the ground side of the fuel pump !

I can post the wiring diagram I used if you need one.

BTW, for those of you keeping track of such things, "ss6" is a new shortened version of my former handle, "summersledsix".
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Old 12-21-2002, 07:59 AM
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Oh, yeah, one more thing- it's also very easy to wire your fuel pump backwards, which will give you false notion that stuff is working, when actually the fuel is being pushed in the wrong direction! Ask me how I know that...

Turns out my fuel pump had a tiny "+" and "-" next to the terminals, virtually invisible until I cleaned the top real good (uh, and put my bifocals on ).

Also, hope you are using the fuel pump that came with the six, and not your old 914 pump. The 914 pump may work, but might not crank the volume you need for your six headed beast when you get it "excited".
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Old 12-21-2002, 08:32 AM
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saga continues...

I actually got my wife out to crank the ignition (not an euthanism) while I disconnected the fuel filter from the fuel rail. I got gas pumping through at a good rate while turning ignition so I don't think it is the fuel pump. Could it be some sort of vaccuum problem in the fuel rail system?
Old 12-21-2002, 08:41 AM
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Ah, more information!

Doubt that you have any issues with the fuel rail, if you had air in the rail, it would have been pushed out eventually if you cranked the engine long enough, and you probably have by now.

Are you sure you have power to your injectors (yet another thing that goes through that d@mn DME relay). The DME relay provides +12 to all six injectors, and the DME box switches the ground side on/off to activate the injectors. Since you're not getting ANY fire except for the starting fluid, and you've verified fuel supply, sounds now like you're not getting fuel metering.

Are you using a complete 911 DME harness, or have you had to roll your own?
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Old 12-21-2002, 08:56 AM
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I assume it is a "complete" dme harness. There is a 4 pin female connection from the dme harness to a 6 pin male connector with 4 wires of the engine harness.
The dme harness has 4 wires
2 red wires
1 brown wire with blk stripe
1 white wire with black stripe

the engine harness has:
1 grey wire with brown stripe
1 grey wire with white stripe
1 red wire with white stripe
1 white wire with red stripe.

I have it hooked up like so

engine dme harness
grey w/brn stripe brown w/black stripe
grey w/wht stripe wht w/blk stripe
red w/wht stripe red wire
wht w/red stripe red wire


The dme harness did not have a connector with the 4 female wires so I took best guess to how they were to be connected.
Old 12-21-2002, 09:17 AM
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Getting closer...

The following stuff is from the "Bentley Manual", officially known as the "Porsche 911 Carrera Service Manual", published by, you guessed it, Bentley. This sucker is soooooooo much better than any 914 documentation, and since you are running a "hybrid", I strongly suggest you get one. I believe I got mine from Pelican, maybe your wife is looking for one last Christmas present for you...

Anyway, in text form, this is what the wiring diagram sez:

DME-14 ---(YLW)--- pin5-> <- pin5---(GRY/WHT)---Inj1,Inj2,Inj3

DME-15 ---(YLW)--- pin6-> <-pin6---(GRY/BRN)---Inj4,Inj5,Inj6

DME-18 ---(RD/YLW)---

DME-35 ---(RD/YLW)---
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Old 12-21-2002, 09:46 AM
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Though most likely fuel related, check for a huge vacuum leak, like the cap off the oil filler and a missing flow restricter in the oil breather tube.
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Old 12-21-2002, 09:57 AM
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I hit the send key by mistake, so here is the "complete" version.
Note that injectors 1,2,3 and 4,5,6 are indeed wired in parallel, and the "Inj. Connector" is that funky 6 position connector with only 4 pins in it. DME pins 18 and 35, which are the power input to the DME, are tied together (within the harness somewhere?) to those red wires that appear at your 6 position plug.


Getting closer...

The following stuff is from the "Bentley Manual", officially known as the "Porsche 911 Carrera Service Manual", published by, you guessed it, Bentley. This sucker is soooooooo much better than any 914 documentation, and since you are running a "hybrid", I strongly suggest you get one. I believe I got mine from Pelican, maybe your wife is looking for one last Christmas present for you...

Anyway, in text form, this is what the wiring diagram sez:

DME Box......................................Inj. Connector

DME-14---(YLW)-----------------pin5-><-pin5---(GRY/WHT)---Inj1,2,3

DME-15---(YLW)-----------------pin6-><-pin6---(GRY/BRN)---Inj4,5,6

DME-18---(RD/YLW)---+---(RD)---pin1-><---(RD/WHT)---Inj1,2,3
. |
DME-35 ---(RD/YLW)---+---(RD)--- pin2-><---(WHT/RD)---Inj4,5,6
. |
+---(RD)---[pin1 of DME relay connector]
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Last edited by ss6; 12-21-2002 at 10:05 AM..
Old 12-21-2002, 10:00 AM
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Thanks, John but...

John thanks for helping but I am a bit lost.

1) Can either of the red wires from my dme harness connect to either the red w/wht stripe wire or the white with red/stripe wire from the engine harness? Or do I have to trace down the correct red wire?

2) What becomes of the brown wire w/ black stripe and white wire with black stripe from the dme harness?

3) I don't see a yellow wire anywhere in the dme harness back by the engine compartment. I assume these yellow wires hook up to the engine's grey w\white stripe and grey w/brown stripe. I'll look up by the dme box.
Old 12-21-2002, 10:40 AM
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Something's weird with the color coding you described, at least according to Bentley.

You mentioned 2 red wires, a BRN/BLK and a WHT/BLK wire coming up to your injector connector.

Those red wires are the hot sides for your injectors, and you've got them connected where you want them, to the RD/WHT and WHT/RD wires (doesn't matter which to which).

What's weird is the BRN/BLK and WHT/BLK. Bentley shows a pair of YLW's for the 84/85 harnesses, and GRY/WHT (@DME14) and GRY/BRN (@DME15) for '86 to '89 harnesses, not the colors you mentioned. Your harness might have been repaired with different colors or something, I've found the Bentley diagrams to be quite accurate.

In any case, the bulletproof way to troubleshoot this is to disconnect your DME box and use an ohmmeter or continuity checker to verify connections between:

DME connector pin 14 and (the GRY/WHT side of ) injector1,2,or 3 connector;

DME connector pin 15 and (the GRY/BRN side of) injector 4,5, or 6 connector.

You don't have to know which side of the injector connector is the GRY/WHT or GRY/BRN side, just try both pins, and if you get continuity on one of them, you're a happy camper! DME14 does have to go to cyls 1,2,3 though.
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Last edited by ss6; 12-21-2002 at 10:47 AM..
Old 12-21-2002, 10:40 AM
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Thanks John but..

John just took off the dme box. Could you tell me how to deterimine dme 14 and 15. One row is a bit offset toward the cable then the other row. Where is "1" and where is "2"
By the way Thanks a whole lot!
Old 12-21-2002, 11:17 AM
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Attached is a diagram of your DME connector. Pin 1 is closest to the side of the connector where the harness exits.

Hope this gets you closer to the sweet sound of a successful 3.2 engine transplant! (Also hope it ain't snowing out there in God's country when you do...)
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Old 12-21-2002, 11:45 AM
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Hey Jim Smolka -
Spotted your reply here where you mentioned a "flow restrictor in the oil breather line". I don't think I have one of those, what does it look like, and where would it be hiding?

I'm pretty sure I transferred all of the big chunks when I did my swap, but this thing might have wound up in the "curiosity bin". Could this omission explain an occasionally rough idle?
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Old 12-21-2002, 12:00 PM
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Thanks, but.

I checked it out. I do have Grey wires after all on the dme harness. It was right where you said they would be. Dme 14 and 15 have continuity just like they should. The wires from the dme harness are a bit darker grey color but they do match up properly to the dme brain BUT it ain't starting yet. I do have the air box disconected so I could spray starter fluid down the 3.2's throat. Could this stop it from starting?

There are 3 connectors of the engine harness right above the fuel rail. One is colored orange the others are black. The dme harness has three cables that connect to them. One is labled od, one is marked bd, and the other is unmarked. Pehaps I got these connected wrong? By the way while I await your diagnosis I am going to see if I can get the bentley book from pp.
Buck
Old 12-21-2002, 12:12 PM
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Those three connectors you mentioned are the 2 pin cylinder head temp sensor (your "orange", was once white), the 3 pin "reference mark" sensor, and the 3 pin speed sensor. Not sure which one is OD and which one is BD, but if you look at the sensors (which are mounted on the passenger side of the engine, right at the engine/transmission joint), the reference sensor is the higher one, and the speed sensor is the lower one. You'll have to follow the wires back to those mystery connectors.

First, find which of the two 3 pinners back to the DME box has continuity with pin 8 or 27. That one should be connected to your speed sensor. That's 2 out of 3, you can do the rest of the math.

One more check you should do is just verify you're getting 12 volts on those RD/WHT & WHT/RD injector wires when you crank the engine, you still could be fighting that !@#$$% DME relay.

Oh, yeah - if you're trying to start the car with the air box off (what are you using for an air box, anyway?), make sure all those little connectors up there are connected. The sensors can be dangling, but they need to be connected, or the dme computer will be pissed.
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Last edited by ss6; 12-21-2002 at 12:44 PM..
Old 12-21-2002, 12:39 PM
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what should I be using for an airbox?

What would you suggest? I have a cone filter down stream from the air box.
By the way Thanks!
Old 12-21-2002, 01:07 PM
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checked for 12v

Checked the red wires and am getting 12v when ignition is turned on and when cranking. I am also getting 12v on the grey w/wht wire and grey w/brn wire. Checked the speed sensor and the other two and looks like it is in the right place. The orange 2 plug is orange on the engine side white on the dme harness side.
Any other ideas? Should I check the sensors down by the fly wheel?
Old 12-21-2002, 01:45 PM
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OK, so far we're pretty sure you have fuel pressure at the rail, and 12v at your injectors, and your injector cabling is correctly wired to your DME, and your crank sensors are in their right places.

I've assumed since you got the engine to "run" momentarily on the starting fluid, that you are getting spark at the right times to the cylinders. Are you sure your coil is firing and this isn't due to dieseling of the starting fluid?

Also, you've checked for 12v at your injectors, but we haven't verified they are actually firing. You might want to verify that the DME is getting 12 volts too, by checking for 12v on DME pins 18 and 35 when you crank the engine.

This is a long shot, because those DME's are pretty bulletproof, but the injector outputs could be toast. You can verify their health, but it's a little trickier, since the injectors fire in very short pulses that some meters won't "see". You can, however go to your local Radio Shack and ask them for an LED that is pre-wired to run on 12 volts, ie their p/n 276-270. Take the LED and hook up the plus wire to RD/WHT or WHT/RD any of you injector connectors, and the other wire to the other pin. Crank the engine, and you should see a very short flash of the LED. You may have to turn the lights off around you, the blink may be pretty faint.

Jim Smolka's earlier reply about massive vacuum leaks should not be ignored either. I've uttered more than a few "technical terms" in the process of discovering that the engine won't start if I leave the oil filler cap off, or a breather hose, or etc. There are two or three ports I had to seal on the engine ('cause the 914-6 oil tank didn't have all the teats the 911 tank had), I think there were two on the neck of the throttle body, and one on that copper tube thingy that connects at the back of the passenger side fuel rail. How do you have your oil tank hooked up, and how did you replace your air box? Got any pix? The air intake was the tightest fit I had to deal with during my swap (picture attached).

Finally, if you haven't found out by now, 914's are a lot like women in some respects (no disrespect intended). When they're mad at you , they're mad at you, and continued fondling will only make matters worse. Sometimes it's best to just back off for the night, grab a beer, and wait for a fresh morning. Sooner or later, they come around.
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Old 12-21-2002, 02:29 PM
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I'll send pics tomorrow

I'll take some pics and e-mail them.
Old 12-21-2002, 02:52 PM
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