924Board.org

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Hi guys!
After the weather changed to more humid conditions, CIS began acting weird and since I'm tired of this CIS stuff already, on friday I decided to convert my fiancees 924 to EFI. VEMS specifically.

Hardest part was fuel rail obviously. Since the one I purchased from endwrenh is going to one nice Latvian GULF coloured race-924, I had to get around this problem somehow. Solution was the one from my '86 Alfa Romeo 90 2.0 (125 hp) that had engine problems and I jeep it only as a body part car for my Alfa 90 V6. It has 190 cc hose ended Low-Z Bosch injectors and the fact that they're connected to fuel rail via hose, allows a little play with the cylinder spacing (4mm to be exact).
Nice surprise was that when I tried to fire up for the first time, it ocurred that the hoses were cracked of age and needed to be replaced that took me additional 2 hours

TPS is from GM one from Opel Vectra and fitting it was easy: I just welded a little D-shaped extension to the big-bore TB lower side and fabricated supports. Rotation is suitable for 924 TB.
Now CLT and IAT sensors. IAT is a generic NTC resistor type that I bought from VEMS webshop (1 euro) and installed in a suitable threaded casing. Coolant sensor is new, just went to auto-parts store and searched the catalogs for fitment to 924 thermo-time switch location. Cost 9 Euros.
Wiring was pre-made at home couple of months before.
As for vacuum hose, I destroyed cold start valve and glued a small diam. pipe into it with a cemic metal.

And please ignore all the mess regarding the wiring, I haven't done any cleanup yet

Crank trigger is simple: Honeywell 1GT101 Hall sensor and two welded notches on the crank pulley 180 degrees apart.

Fuel rail and injectors. BTW, I used all new connectors on sensors, coils and injectors.

As for ignition, I went COP (coil-on-plug) route. Why? Because they're damn easy to mount and configure, they cost little (24 euros a piece new) and NO MORE plug wires!!!

Coils are active type: they need only +5v logic level triggering. They're from VW.

LCD display that shows all engine parameters (when PS2 keyboard is connected you can scroll the screens and tune the car also).

And here's the VEMS itself. Again, ignore the mess, lot's of work ahead.

Car is running very well after couple of hours tuning but I have some problems (not with EFI though).
After throwing all the old ignition stuff away and changing the original fuel pump relay to usual relay, I can't stop the engine with a key!?!?!
I took the realy trigger +12v from the relay board where I have taken it for CD-player etc. And it shuts off, when I remove the main VEMS relay.
At first I thought it is main ign. switch but the engine didn't stop when I removed the connector from the ign- switch.

Is this "no-stop" problem somehow related to the original fuel pump relay? It had couple of wires that are not necessary with EFI.
Any ideas?
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Min

Min · Posted: Mon Nov 13, 2006 5:21 am Post subject:

Forgot to mention, nice work! ... even with the messy wiring.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

John Brown · Joined: 07 Nov 2002 Posts: 903 Location: Leesburg VA

Very nice. Wonder, do you have any concern about the coils holding up to the heat laying as they must right between the exhausts?
_________________
John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

I thought about that also before install and decided to wait and inspect the temp of the coils with EGT probe. So far (after a day of tuning and driving) nothing dramatic.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Smoothie · Posted: Mon Nov 13, 2006 6:02 am Post subject:

The FP relays' trigger is powered by circuit #15 (one of the horizontal lines at top of the wiring diagrams) and #15 should only be showing 12v+ with the key at either run or start. -So my first guess is something's been done with the wiring that's causing #15 to show 12v+ when the key is switched off and removed. Circuit #30 is 12v+ always (even with key removed), so I'd suspect circuits 15 and 30 got wired together somewhere.

Same thought here on the "COP's" - something's telling me it'll be too hot there for them.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Min · Posted: Mon Nov 13, 2006 6:18 am Post subject:

If #15 and #30 are crossed, wouldn't #15 have power all the time? .. in my case its only stays powered till the car stalls. once it stalls. No more #15 power. I'm just assuming raceboy's situation is similiar.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Yes, the usual "switched" +12v is not switching off in the entire car before the engine is not stalling.
But, could it be related to starter motor with it's 3rd wire? IIRC it is connected somehow to the FP relay?

And as for heat and coils. If I see temp. exceeding 120 degrees C on the coil, I'm going to fabricate new stainless steel heat shield in place of the OEM one, which is kinda "worn out"

.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

I had trouble with mine shutting off too, and I also had to crank the starter within a few seconds of twisting the ignition into the 'on' position to get the car to run.

My trouble ended up being: I ran the +12v power to the ignition off of the +12v to the fuel pump. The fuel pump ran through a new relay. The relay was powered for the first ~10secs of key 'on' by the MS to prime the pump, then it gets powered again when the MS gets a tach signal showing that the engine is running.

I changed the ignition +12v to the same +12v that switches on the MS and problem solved.

Maybe some of this is applicable to your troubles?

Anyway, nice work on the quick install!
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

Smoothie · Posted: Mon Nov 13, 2006 6:36 am Post subject:

Ok, clearly not a hard-wired direct connection between 15 and 30..
Next thought would be to look for something in the altered wiring and new ignition and/or fuel injection that's keeping #15 powered as long as the engine is running.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

Weird. I had the same problem with mine but it was 3+ years ago and I don't remember what I did to fix it. I do know It had to do with pulling the stock FP relay and using that as an ignition\crank +12V source.

Pretty quick install! You shouldn't have any problem diagnosing this little problem.

Todd
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

Min · Posted: Mon Nov 13, 2006 12:05 pm Post subject:

In my case, I don't even have a fuel pump relay wired, I just have a switch that is in place were the relay used to be.

I also don't have the 3rd wire on the starter hooked up.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Lizard · Posted: Tue Nov 14, 2006 10:10 am Post subject:

is there a possibility that the switched wire on the VEMS/MS is remaining charged, or that the EDIS/COP setup is still getting power when off?
_________________
3 928s,

Min · Posted: Tue Nov 14, 2006 11:56 am Post subject:

I put a multimeter on the ignition circuit. It shows 13.5 volts during running. THen when I turn it off and it continues to run, it shows 4.5 volts. Enough to power my main power relay for the ECU and the coil packs.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Lizard · Posted: Tue Nov 14, 2006 12:02 pm Post subject:

Just found this out from Min on MSN, and I think I know what the issue is, I have told him to unplug one wire and check again, will report back if my suspision is correct.
_________________
3 928s,