Early 944 Microsquirt DIYPNP...sort of

[badassdubs]

Originally Posted by RC924

Must echo the other replies, COOL PROJECT.

Thanks. I am running a fuel rail from a 924S which has the original porsche fpr. I will check the pressures and everything else you suggested. The learning curve is huge on this, trying not to destroy it in the mean time. I was running a 25k resistor in line with the VR+ as suggested by Matt but I have read that this can cause problems. I was losing the tach signal around 1700rpm. It would drop to 0 and then come back but wouldn't rev any higher. I read where someone used a 100 ohm resistor so I tried that and now it will rev to 3000rpm but still loses the signal. Tried a 10K resistor and it dropped down to 2000rpm before losing the signal. Matt suggested I get an oscilliscope and find out why it is dropping out. So now I am going to buy one.

I did have to move the turbo forward about 4 1/2 inches to put a resonator on it. It was just too loud and a little raspy. I had a 944S resonator laying around so I used that. Gave it a nice mellow sound and made the neighbors happy. Once I get it to where I'm happy with everything and the turbo size is going to work out, I will take it all out, clean it up and ceramic coat everything.

[cauzomb]

I like the pipe work up to the throttle body, good work on eliminating that stock j-tube. You might want to section the hard pipe with a couple rubber joints to aid in flexibility due to torque events/engine movement... that is, unless it's already flexible enough due to the length of the tube and the new rubber connection..

Keep an eye on the drive axle/cv boot for heat cracking once you get it going..

I'm looking at a set of universal silicone cv boots, they run anywhere from 25-35 bucks each, but should fair better in the long run. My inner CV boot sits a bit closer to the exhaust, due to my exhaust being 3" from the 951 down tube back it's LR 3" and custom 3" from cat back.. the larger diameter tube doesn't have alot of air space around the pan or up over the CV boots, I had to wrap up a section of the pipe near the inner cv but it didn't help much.

On your setup, since the hot side of the exhaust up to your turbo is going to see more back pressure/heating, the ceramic coating is a good idea.. It will probly be enough to keep the heat in the pipes, but might still be much hotter under there than a standard exhaust/engine setup that isn't seeing as high egt's back there... Some creative heat sheilds, with attention to sheilding brake lines, fuel lines, other rubber parts and the ceramic coatings and even then, maybe the silicone boots, just to ensure those parts stay safe and reliable.

[badassdubs]

Thanks for the tips. The pipe has 3 flex joints so that won't be a problem.
I checked the temp at the exhaust pipe by the cv boot and it was at 97F without the ceramic coating.

As far as the fuel pressure goes, I checked it today and it was at 2.0 bar at idle and 2.5 at 2K rpm so unfortunately that isn't the problem.

[cauzomb]

I was reading a bit regarding the signal/sync issues at 2k-3k rpm that some other people were having with MS and found they suggested using about 470ohm load between vr+ and vr gnd to keep the signal voltage from rising too high, and to privide a dump to gnd, so that the signal wires loose voltage faster?

here's a link to the thread I got the info from Megasquirt Now an Option - Page 2 - NASIOC

[Dean924s]

Wait did you post up on th MSEXTRA board? I was reading about someone that was having the exact problem. if it dropes below 500 rpm the fuel was cutting out to really lean. Re start and it comes back to normal.

[Dean924s]

Tough time seeing what is up in the photo but I think the oil line should be going in the top and coming out the bottom. It looks like you are coming in the side. You may want to look in to this. I had to re index my TD04 because of this issue. This causes problems with the wast gate diagram mounting to I punted that unit and went to a KO4 form a mazda 6 as it was already indexed they way I needed and has also a better match to my motor.

[badassdubs]

I put a 470 ohm resister inline on the vr+ and it will now rev to 3676 rpm. Still cutting out.
Haven't posted this topic anywhere else Dean.
The oil feed line can go anywhere on a turbo. It is the oil drain line that is critical and must always be in the down position. I was able to keep the wastegate in the original position.

How do I post an msl file? Here is a snapshot.

[cauzomb]

Have a look through the last few posts on this one RPM signal loss with 60-2 + VR sensor ms2-extra - Page 3 - e30tech.com Forums

some other posts suggest that sync loss with reson 0 is indicating an issue that is hardware related, rather than an actual lean condition.

Ensure that all your splice joints soldered and no more than 1/4"-1/2" of exposed/unshielded center conductor for coaxial wires "total unshielded length for all connections".. Even at the ecu plug. If the wires are like network cables or scsi computer cables, twisted pair, no more than 1/2" un-twisted pair between all the connections.. The exposed main conductor not being shielded by the shielding/gnd wire acts as an antenna for ignition/ alternator noise.

Use solder and shrink tube or electric tape over the center conductor, then overlap the shield wire over the center wire conenction as best you can. You can add a spiral wrap of bare conductor wire around the shield wire solder joint then tape it all together to re-inforce the shielding, get the shielding wire to cover the center conductor as best you can..

You mentioned that you are using the falling edge, some people suggest using rising edge

I don't have any first hand experience, just want to get you pointed in the right direction on that... The internal components, and resitor/capacitor values seem to be dependant on the version of MS board and firmware but the common thing that people are suggesting is that with the 60-2 wheel "higher frequency" is a capacitor needs to be replaced on the MS board with one that has a value of .001uf and uncommon is the Vr+ inline or Vr+ to GND resistor, or the polarity of the VR sensor..

[RC924]

Agree with and second the advice given in the above post. Have personally used a pro quality (125*C) dual shielded audio type cable from the sensor connector right to the MS connector. These VR sensors are not a critical design component. All work on the same principle, only output voltage will vary between different types/makes. Theoretically at least, as long as a sensor generates the minimum voltage it is usable. Higher outputs can easily be attenuated by a voltage divider, which incidentally is the preferred option to a single series or parallel resistor.

The polarity is critical however for a clean AC signal with correct zero crossing point. Relative timing will change with RPM also, although not much with a 60 tooth wheel. A scope will quickly show polarity but unless you already have one it is not necessary. An analogue meter can be used here too. Easiest & quickest though to simply reverse the wires and try for better or worse.

Originally Posted by badassdubs

I am also using the original 944 vr sensor.

Surprised that no one picked up on that. The stock 944 sensor is the top candidate for the most unreliable, intermittent, misdiagnosed, yet most often discussed problem part on these cars. Just try a good known one first and there is an excellent chance that this whole issue will be resolved. It doesn`t need to be an overpriced Porsche one either. Just about any VR sensor that physically fits is fine. Aim for around 0.010" clearance to teeth.

Originally Posted by badassdubs

Right now the stock injectors. If need be I will upgrade.

Can also see definite fuel issues with a stock 2.5 bar FPR, injectors and boost. You will need to upgrade, no question. In fact, your RPM limited problem is probably a blessing in disguise. May have saved you going lean at even low boost.

Originally Posted by badassdubs

How do I post an msl file?

For a shot of the MLV graph, go to MLV/file/save graph as ...

Have posted shots of my settings for a basic idea. I`m running 36-1 on the cam, and a GM or Saab sensor, selected purely on size / dimensions/ connector availability. Has no probs with a Ford one either, no resistor on either. Check or play around with "rising edge" and "going high or low"settings. These may mask or reverse the VR polarity input.

[Dean924s]

Look up sensors from a 87 535 BMW. I think they are the direct fit replacement with a shorter cable that makes for less spaghetti by the motor. They are about half the price of a OME unit. Many suppliers are now selling the non OE ones at around $75 last time I looked.

[badassdubs]

OK folks. Well it has been two years and the problem is finally solved. I just had to walk away from it and work on other projects. I have been through about everything with this setup and finally hit the sweet spot. I even tried a prototype board from Matt to no avail. Hall sender too. I decided to put a ford escort 36-1 wheel on it along with the ford vr sensor and it now revs cleanly to my 6300 rpm rev limit. The car is 95% finished. I have pulled the front end off of it at least ten times trying to get the trigger wheel issue resolved. So here are a couple pics. The sensor mount is just temporary. I will build a real one now that this is solved.



Oh and that vanagon in the background looks like this now. Complete with 996 cluster.

[Gawernator]

That's so awesome dude

[speedracing944]

Great to see you got the problem solved and the thread revived. I am looking forward to some video.

Speedy

[Dean924s]

I hate to say it but you could have just put a 72-2 trigger wheel on the cam replacing the stock cap and rotor and used the sensor from a FC mazda RX7. This is what I did when I converted my car to EDIS. It has gone over 100K with no issues using the EDIS ignition from a 1994 escort wagon and a MJLJr as the controller.

Much easier than trying to mount a trigger wheel on the crank. Car is running but the flash froze the action.

My solution to the problem of putting EDIS on a 944

Another that I took without a flash.

[badassdubs]

Thanks for the comments guys. I will get that vid once the turbo is sorted out.
Dean, I appreciate your input, but I was going for a clean look. I didn't want a bunch of wires and odd, out of place items everywhere. Thats why I went with the DIYPNP. What you are failing to realize here is that just any trigger wheel and sensor wouldn't work. Alot of guys are running mismatched trigger wheels and sensors and they work just fine, but for some reason this setup wouldn't rev past 3600rpm. It only took me five minutes to attach the 36-1 wheel to the pulley. Matt said this was one of his toughest cases to date. But I'm glad it's solved and it still looks clean.

[Dean924s]

The messy wiring is only due to my placement of the EDIS unit and me being lazy. The sensor and the trigger wheel are hidden under a cover I fab-ed that mounts where the distributor cap use to be. There is only "one" wire that runs from the trigger sensor to the EDIS box.

I really wanted to do the install like you did but getting at the crank in a Porsche is a real SOB with the fans and what not that are packed in there. So I took the easy way out and mounted things on the cam.

[badassdubs]

A little update here. I finally took it out for a drive today and all I can say is that
this thing hauls. There is no turbo lag to speak of unless 1 second is considered lag. Boost goes right up to 12 psi so I am definitely going to get a blow off valve and a waste gate. So my fears of not getting enough boost or major turbo lag were unfounded. BTW I ended up putting on a 944 turbo. Here is a pic but the placement of the filter and the oil pump has changed.

[Dean924s]

I like that !!!!!

[speedracing944]

What are you using for your oil pump?

Speedy

[badassdubs]

Thanks Dean.

The pump is a MOCAL. Purchased from here.

Pumps - Mocal Differential Cooler Pump