Porsche 944 Turbo Microsquirted, only one issue now

[jlturpin]

I have been working on my 944 turbo for a few months off and on and am glad to report that I am 90+ % running full tilt. I have driven it 300+ miles in the last few days and have gotten my VE table and spark table dialed in for a base tune.

Problem first, since some may not make it to that if I tell all the good first. Under high load and boost in 2nd gear and above over 4k rpm I lean out really quickly under full throttle. It does not do this in 1st gear when it goes through that rpm range quickly and load is much less. See log around 468-470 seconds in log for good example. My target AFR is around 11.5 under higher boost (Higher Compression engine, 9.7:1). It goes to 11.5 or below as it should according to my MAP/VE table, and holds for a few seconds and shoots up. I have checked VE tables, and changed them to with no luck. I am wondering if my injectors characteristics are not setup properly under fuel in Megatune, They are 55#/hr Siemens injectors, see attached .msq file for configuration. Other thing that makes me wonder is spark, but it is way in the back of my mind since it seems to run great under all other conditions and changing dwell and duration seems to make no improvement.
Could the autotune function be causing this? EDIT
You should be able to right click and save the file below. It was too large to attach.
http://www.autocrossphoto.com/microsquirt/951072908.xls

Now on to the good.


I have made an adapter to allow me to use the factory harness and connectors, with exception of a 36-1 trigger wheel that I purchased to fit the 944 crank behind the ribbed pulley belt http://www.goingsuperfast.com/Trigger-wheels.html. I will run a shielded wire under the intake and disconnect one of the factory VR sensors and route it through the factory harness with the connector near the firewall in the factory harness. I made a sensor bracket, or sensor holder using an extra factory VR sensor holder and adapted it to fit on the Belt tensioner below the crank trigger. I was not able to use the factory pickup locations on the 944 due to the 132 teeth. I have reused a factory VR bosch sensor though. I could only turn a bit over 3K rpm prior to trigger loss with the factory ring gear being used as a trigger.

I will keep this updated as I sort out the lean issue under boost and any help would be appreciated.

Jonathan

[tinoi36]

Hi Jonathon,
Where did you mount the sensor to your wheel trigger and what coils did you use to ignite that awesome 944 engine. Also please advise, I am working on my 944 non turbo and would like to get ride of that aweful stock air flow sensor. Did you replace the air flow meter with an after market one. Lastly, please please send me pictures of your engine with all modifications you have done. Me and robH are trying to get our 944s started and I am at your mercy for some help.

Thanks in Advance,


Tino
956-333-2781

[dsmith1484]

I two would be interested. I sent you a PM. Any additional info on your install specifically on the EDIS trigger wheel and the sensor mounting would be great! I have my car running on an EDIS based ignition but it is cam triggered with a 72-2 wheel and the sensor from a FC RX7.

Many Thanks

Dean

[Matt Cramer]

I two would be interested. I sent you a PM. Any additional info on your install specifically on the EDIS trigger wheel and the sensor mounting would be great! I have my car running on an EDIS based ignition but it is cam triggered with a 72-2 wheel and the sensor from a FC RX7.

Many Thanks

Dean

I'd be interested in hearing some of the details of your installation, too. I've heard of people talking about putting a 72-1-1 wheel in a cam sensor, but you're the first one I've seen mention that they pulled it off successfully.

[dsmith1484]

Hi Matt!!!

I have not spoken to you in ages. (We talked about putting a MS in a MR2 ECU housing years back to go racing in SCCA IT class)

The answer is yes I have a 72-2 setup working on my 924s. In fact it is my Daley driver/Cone killer/HPDE/Time trial car. I just don't have the hart to gut it and fully cadge it to go wheel to wheel. By making this upgrade it brings the cars ignition out of the 1970's up to 1990's standards. It also gets rid of the $200 tune ups (cost of the cap and rotor). Now I just get ford parts. ignition parts are from a 1993 escort wagon and the wires are from a 1994 mustang V6 Total tune up cost less than $50!!!

The simple recipe for this is. Get a 72 tooth spur gear and modify it to mount to the end of the cam where the rotor was. You then mount the sensor to the cam gear housing and voila there you have it. Yes there is more to this but it is basically that simple. The things you have to overcome are:
1. The size of the death versus trigger wheel diameter this leads to #2
2. Having a sensor that can read the fine resolution
3. Because of the small teeth you have to get the wheel centered virtually perfectly so you can have very tight clearance between the sensor and the wheel. we are talking less than .020" .010" is best
4. Thickness of the trigger wheel as the sensor is quite wide versus weight of the wheel. I don't want to put undo stress on the cam bearings.

All this was eventually figured out and it works perfectly. The plus side is that it is much easier to install then down and the crank. The negative is that it is not a true crank fired system. You still have the "slop" of the timing belt in the system but at the moment it is light years better than the stock set up and I now can program it.

Video of it running the first try only on the EDIS. Note the hack job of mounting the sensor:
http://www.youtube.com/watch?v=ufkbAqUPiAQ

Second install with better trigger wheel and modified sensor to clear the larger wheel.
http://www.youtube.com/watch?v=-sDNVjqg4cM

Write Ups of what I did can be found here:

Long tale of my install 7 pages plus of trials and errors.
http://www.autosportlabs.org/viewtopic.php?t=2026

Me working on the sensor and trigger wheel.
http://www.autosportlabs.org/viewtopic.php?t=2164

A bunch of info on maps from the great people over at pelican. again my trial and tribulations as I revers maps. I eventually got it figured out.
http://forums.pelicanparts.com/showthread.php?t=443767

If you need more info let me know I will be glad to share.

Respectfuly

Dean

I two would be interested. I sent you a PM. Any additional info on your install specifically on the EDIS trigger wheel and the sensor mounting would be great! I have my car running on an EDIS based ignition but it is cam triggered with a 72-2 wheel and the sensor from a FC RX7.

Many Thanks

Dean

I'd be interested in hearing some of the details of your installation, too. I've heard of people talking about putting a 72-1-1 wheel in a cam sensor, but you're the first one I've seen mention that they pulled it off successfully.

[jlturpin]

Sorry for the delay in response. There is no need to run a trigger wheel on the 944 or 951, even easier on a 944S or S2 with the 60-1 factory wheel. I have run several thousand miles on the mS on the 951 using the factory wiring harness and factory speed and reference sensors. Check out the sticky at the top about the VR fix. A few mods are required to the mS, but works great to 7K and I am sure beyond. The mods cost a few bucks.

Jonathan

[dsmith1484]

That is great stuff!!! I will need to ponder the VR fix. The one thing I really want to do is get rid of the of the speed and reference sensors. They are expensive and tend to fail (these and DME relays are the bane of our existence). I also like the simplicity of the EDIS unit and the cost savings of never having to get another set of OE wires, cap and rotor (close to $200) where as the EDIS stuff is dirt cheep (1993 ford escort cheep! Being able to get tune up parts at any parts store over the counter versus having to order the stuff while the cars sits dead has been a huge determining factor in the planing of my project and a huge part of why I went with the EDIS in the first place.

Ultimately I would like to eliminate:
DME
DME relay
speed sensor
reference sensor
Cap
Rotor
Bosch / Porsche wires

This list is based on cost of replacement, reliability and availability.

[jlturpin]

That is great stuff!!! I will need to ponder the VR fix. The one thing I really want to do is get rid of the of the speed and reference sensors. They are expensive and tend to fail (these and DME relays are the bane of our existence). I also like the simplicity of the EDIS unit and the cost savings of never having to get another set of OE wires, cap and rotor (close to $200) where as the EDIS stuff is dirt cheep (1993 ford escort cheep! Being able to get tune up parts at any parts store over the counter versus having to order the stuff while the cars sits dead has been a huge determining factor in the planing of my project and a huge part of why I went with the EDIS in the first place.

Ultimately I would like to eliminate:
DME
DME relay
speed sensor
reference sensor
Cap
Rotor
Bosch / Porsche wires

This list is based on cost of replacement, reliability and availability.

Not to be a ball buster, but these are all things that are all good for 100+K miles. If they are original, they are 20 to almost 30 years old. Having the ability to tune with the mS is awesome and will be a great addition to the car allowing fueling options, ignition options, datalogging etc. I just don't want others to read my thread and think that a stand alone is the solution to a DME Relay issue, or maintenance items such as cap and rotor and is certainly not an upgrade option for everyone. This will be a great learning experience for those who want to go this route. Read through this forum if the car sitting is a concern, many of the success stories took many months of trial and error to get right.
Having one of these engines grenade on you while tuning, trying to decode the high tooth count wheel, would be much more costly, ask me how I know. BTW, I am running my mS setup using the factory harness, which retains all the above with exception of the DME.

[Matt Cramer]

Thanks for sharing. Most of the speculation I'd seen about this kind of setup involved whether the sensor could read teeth that small...

[dsmith1484]

Not to be a ball buster, but these are all things that are all good for 100+K miles. If they are original, they are 20 to almost 30 years old. Having the ability to tune with the mS is awesome and will be a great addition to the car allowing fueling options, ignition options, data logging etc. I just don't want others to read my thread and think that a stand alone is the solution to a DME Relay issue, or maintenance items such as cap and rotor and is certainly not an upgrade option for everyone. This will be a great learning experience for those who want to go this route. Read through this forum if the car sitting is a concern, many of the success stories took many months of trial and error to get right.
Having one of these engines grenade on you while tuning, trying to decode the high tooth count wheel, would be much more costly, ask me how I know. BTW, I am running my MS setup using the factory harness, which retains all the above with exception of the DME.

No. I concur completely with everything you have said. Microsquirt is not by its self solution to DME issues that place these cars. It is not cheaper the gop this rout. I have a plan for my car. It involves forced induction. The elimination of these various parts is something that I looked at as part of the bigger plan so I am doing it. It would be interesting to see that the total cost would be to strictly get the car running on Microsquirt and an EDIS based ignition.

The problem is that millage is not the killer of these parts it is age and as you pointed out most are now reaching the 20 year mark and that is what is really causing the issues that are cropping up with the DO's and the sensors. Heat under the hood and exposure to dust dirt and petroleum distillates all take there toll on things. They are just getting old and reaching the end of there service life. Getting a New DME or getting one repaired is not cheep. Replacing it with used is alot cheaper but it is still a 20 year old electrical car part. Replacement of the speed and reference sensors is at least $150 in parts and getting the old ones out can be a fun task. Relays and what not are $$$. The grounds in these cars are a known problem. If you have a car that has some of all of these issues the installation of a standalone engine management system can start to look pretty good. However as you pointed out there is the intangible of getting it running and the risks associated with that. Screw it up and as you noted it can get quite expensive.

The edis swap in my car has been hugely successful. Put of pocket I have spent less than the cost of a new cap, rotor and wires. But I bet I have more than 60 hours in research, fabrication, trial and error, Junkyard hunting, ebay hunting. Figuring out how to get the cam fired ignition to work researching stock maps for the car and then experimenting with maps to get it correct on my particular application took a ton of time. If you had to pay retail for all the parts and services to do what I did it would be well over 2K. So if anyone is thinking that this is a cost effective way to eliminate various stock components it is not. It is a really fun thing to do but by the $$$$$ it is much cheaper and much less risky to just swap out parts and get another 100K / 20 years.. . . Well except for the cap, rotor and wires those are more like every 30K or so.


jl turpin, You are not busting balls you are stating a fact! If others are thinking of going down this road they should think long and hard about it. This is after all all experimental.