4 Degree Offset Key Install Questions

[v2rocket_aka944]

note: you might need to close the idle bypass screw on the side of the TB after installing the MAF.
the engine breathes a lot easier with the AFM out of the way, so doesn't need as much bypass. that was my experience 10 years ago.

[AJT944]

Originally Posted by v2rocket_aka944

note: you might need to close the idle bypass screw on the side of the TB after installing the MAF.
the engine breathes a lot easier with the AFM out of the way, so doesn't need as much bypass. that was my experience 10 years ago.

Thanks for the heads up. Parts arrive later this week, so I'll keep everyone updated.

[Monkey Wrench]

it will be interesting to find out if the coil solves the issue. there was a good previous post where the owner used a scope to check the pulse from the DME and found an issue with the powerstage transistor, between the coil and the DME. I haven't had many coils fail myself, I did have one that got rusty terminals, It just needed the threads to be cleaned up, It did cause a no start issue.

Where can I find one of these 4 degree offset keys?

[Monkey Wrench]

I remember having a lawnmower and every time I hit a rock it would break the offset key on the crank, holding the flywheel. I think they were designed to break and made of pot metal, similar to a shear pin on a boat motor. eventually I put locktite on the tapered crank and it stopped breaking the key.

Maybe it isn't really a weak point , it will be a steel key, but can it break and cause an engine crash? I'm wondering if it may be a good idea to apply a locking compound or install a pin or something to make sure it can't spin? maybe it's unlikely to see enough torque on the gear to break it. I did find a post on another forum where the guy said he did break one , maybe in a race application. He might have had heavy valve springs? I assume its important to torque the nut properly. The key itself is weaker than OEM, being offset, but it still may not be a particularly weak point.

[v2rocket_aka944]

The offset keys are an OE Mercedes Benz part so they aren't likely to fail on you.

You can get them from 928motorsports.com

[Monkey Wrench]

Thank you V2 rocket. some research showed they are in Wisconsen. funny they don't put contact info at all on their own website.

after viewing it I think I could simply make one as I have access to a milling machine. The grade of metal may be important though, maybe best just to mail order it. If it's just standard keystock, that's easy to machine and I have a bunch of different sizes onhand. It might be hardened steel. Maybe ordering it is safer.

[Autobreza]

Originally Posted by v2rocket_aka944

The offset keys are an OE Mercedes Benz part so they aren't likely to fail on you.

You can get them from 928motorsports.com

While the offset key sold by 928motorsports has the same specs as a Mercedes, the offset key I got from them was decidedly NOT a Mercedes branded part. It was a machined part patterned either off the 928 key or a Mercedes key.

As received, it was not dimensionally correct and did not fit into the keyway properly (I did let them know about the issue). I carefully and minimally filed the key to fit into the keyway.

It has performed without issue and the engine feels a bit stronger on the bottom end. Four degrees of cam advance (especially without the use of a degree wheel) won't make a huge difference, but every little bit helps IMHO.

If you know a machinist, or have access to a mill, you can easily make the appropriate offset key. I think 4 degrees is the limit as the offset is about 50% of the key.

[AJT944]

Quick Update:

Still no start. Tried playing around with the MAF tune chip on different DME with no success. Replaced the coil and it seems to start nicer/easier - but will die after a second or idling. Still need to turn the idle control screw shut and try that. Might wire the MAF directly to the battery (With an inline blade fuse) and try that? Fuel pressure still good, electrical seems to be good. Maybe there's a vacuum leak I missed? Maybe I need to play with the fuel quality screw on the DME? I'm a bit baffled right now. Trying a few more things tonight, hopefully with some success. So close - it WANTS to run...

[Monkey Wrench]

If you could file the key its not hardened steel. probably the same as most of those keys , you can usually file them. I assume the original is a metric square key is it about 5x 5 mm? I might try making one, I have a milling machine I can use. looks like if the offset is about half the width of the key slot I'll be in the ballpark. I can likely just start with a larger piece of square key-stock and use that.

I just pulled the cam gear off my volvo over the weekend since I'm doing the head gasket and that one didn't seem like anything super special. It should fit nicely so there isn't any backlash in there. I think if it fits nicely then when the bolt is tight there probably isn't a ton of stress on it. if there was a loose bolt and some wiggle room that can amount to a hammering action.

another method might be to turn the toothed sprocket thing, to a different position and a new keyway can be cut with a key broach then it would need a new timing mark and fit with the cogs in the correct place for the "upgrade" the old slot would still be there and do nothing, the key could then be the original. then the "teeth" could be positioned as required. maybe the old slot could be filled with half a key or something, or just left empty. I have some keyway broaches here but they are so old I'm sure they will be standard dimensions.

im not sure how to do an internal cut like that with a square bottom on the milling machine. if it were to be left off with rounded bottom then I guess one might file it square from that point. a broach can cut through the bore of the hole leaving a square bottom in the cut. , I dont think a "normal" milling cutter can fit into the bore otherwise. to use a keyway broach it would be using a mandril press. I have access to one but perhaps not to a metric keyway broach. They aren't a super common tool. the keyway broach cuts a precision slot to the width it was intended for. the setup ( or rotation point) would also be critical and need to be accurate.

with that method the key wouldn't be a weak point but it would have a second slot that was unused, maybe it could be filled with braising rod or similar. make a half key to fit and solder it in there to fill the void perhaps. the offset key might be less complicated.
the other option is the adjustable belt tooth sprocket. Its a bit more money and I don't know if there is a different one needed for different engines but then you can probably change the offset without taking it all apart.

[AJT944]

Update -

Finally got the MAF to work and the engine to run. @v2rocket_aka944 was right that the idle screw next to the throttle body needed to be turned way down. Also a few tweaks to fuel pressure regulator (Mine is adjustable), and I went to position number four on the ECU.

Didn't get a chance to take it out for a drive. The car has been sitting long enough, that I'd like to do an oil change, and a better bleed on the coolant before I take it for a good drive. Once I can knock those out, I'll post a review - and THEN I'll get to the 4 degree offset key.

Man, these cars really make you do one thing at a time. I'm nervous to do a whole bunch of stuff all at once and throw it all out of whack. Glad this whole thing helped me get a hopefully more reliably running 944, as well as identifying some of my fuel and coil problems along the way.

[OK-944]

Lindsey Racing also has an adjustable camshaft gear - better fine-tuning and (possibly?) potentially safer. Might be overkill though, and quite a bit pricier than the cam key.

[AJT944]

Originally Posted by OK-944

Lindsey Racing also has an adjustable camshaft gear - better fine-tuning and (possibly?) potentially safer. Might be overkill though, and quite a bit pricier than the cam key.

I did see that, and I'm interested, for sure. I already purchased the cam key (I think it was ~$40. I keep telling myself that after this cam key, I'm 100% done working on the car, and I plan on finally enjoying it (After 2 years of just getting it healthy). We all know how that goes...I would like a fancy new Dansk exhaust too...

[OK-944]

Yup, same here...my car had spent 18 months up on my low-rise lift - complete engine rebuild, PS system rebuild, Clutch, FOES, brakes, struts and rear shocks, front wheel bearings, CV's, fuel lines, ref. sensors, seat re-upholster, etc...all to a car that came with a complete (and great) history and did not really need all of this attention - and while it drives and feels great - I'm not done! (thinking rear wheel bearings, possibly torque-tube, re-bush rear suspension and rebuild control arms. Oh...and reupholster the dash) Am I obsessed? Could be!

[Stoneguy]

I find working on these cars," Therapeutic".
I too have gone through virtually every system on my 86 and have completed rebuilds, repairs and refurbishments on everything over the years. I do enjoy driving it but I don't as much as I'd like. Beware! Once everything is done, you will be sitting there, wondering, "What do I do now?"
Time to look for another 944???????

That is the question!

[Monkey Wrench]

I look upon any car as a rolling project and personally see very little fun in owning a trailer queen. I think I enjoy seeing them but not touching in a similar way to trophy wives ;-) A car I can actually drive is just more fun to me.

[AJT944]

May have spoken too soon. Car is back to starting and running for only a few seconds before dying. Fuel pressure is at 35psi, and a full 12 volts is getting to the MAF.

Starts and runs longer spraying some starter fluid into the filter. I put in some fuel stabilizer last fall and ran it a bit. Should I put some fuel system cleaner and octane booster in the system? Is it just bad/old gas?

Man - this MAF is giving me trouble. Might just do a chip and go back to the AFM if I can't get a reliable start.

Any ideas from anyone?

[Monkey Wrench]

easy enough to siphon your gas and refill, you can check the fuel delivery rate by extending a hose and put that in a gas can, run the pump to make sure you have enough flow. the rate is documented. you can observe the fuel injecting and that it shuts off from the injectors with fuel rail removed BUT be very careful, no one wants to prompt you do unsafe things. Know the risks, have appropriate extinguisher at the ready.( not a water hose) take the car outside..

I have a friend that drained gas tripped on a trouble light he created a serious fire ,lost his shop some nice cars and now his face is badly scarred and he has basically PTSD from that too.. No car is worth all that.


I think you can choose various fuel maps but Others can advise on that. You can read the plugs for wet gas or carboned up etc. see if one is bad.

at idle there is only so much air entering , if it can find way past the AMM into the engine by a loose cracked hose or manifold leak then the engine wont inject enough fuel because this air wasn't measured by the AMM.

the pulse from the computer gets amplified by the power stage ( amplifier or transistor) before the coil's primary winding. , maybe if that failed it could have a weakened or intermittent spark. I'd clean those connections and check grounding in that area too.

If you attempt to change multiple things at once and then have issues that can be confusing so maybe you can revert back , Not to call the whole thing a fail, but just to verify everything except the mod you are working on is functional and verify that you aren't off on some troubleshooting tangent due to some unrelated issue.

[AJT944]

Ended up giving up on the MAF. Just can't seem to get the car to run reliably. I re-installed the AFM (Using the F9Tech new ECU and their NATune chip, just to try it) and the car now runs beautifully. No idea why I couldn't get that MAF to work, and probably will never find out. One note on the new ECU is that my gauges don't bounce anymore, and are more dead set (Coolant, and oil pressure, notably). Not sure if that's just from the DME reading faster/easier, or something else all together.

Now to bleed the coolant system, change the oil, get some new tires mounted on my freshly refinished fuchs, and enjoy it is next on the list. This upcoming winter I'll likely get to this 4 degree offset key and one of those shiny Dansk mufflers. This whole experience has led me to discover that I should leave well enough alone and just replace things as necessary.

[Monkey Wrench]

electrostatic discharge, (like if you scrub your feet in the carpet and touch a ground and create an electrostatic shock) - This can wipe the E-prom out. bent pins can also cause trouble. I doubt if you could troubleshoot things like that if it happened without swapping for a known good one. Also hard to determine if that is the case. There is also a possibility that you may have gotten one that suffered from this issue previous to delivery. the problem with all that is it may affect the recognition of a warrantee on electronic parts. many vendors will have a clause about this, or a return charge.