cas sync problem rb25

[dalejr240]

HI im new to megasquirt I have a ms3 3.0v unit with ms extra and im having trouble trying to get spark to the engine. I cant seem to get the cas to sync and I have no rpm and no low res signal that I can see on the composite logger. I have read a lot of articals about my problem. I have wired it using the 330 ohm resister from tps to the low resolution and the high resolution for the 5v pull up in the harness. I can see the low res signal with my volt meter but the megasquirt acts as if it doesn't see it. I have tried everything I can think of and now im left with no more hair, so im open to any information that can help me. The engine is completely stock and im using all stock sensors eccept for the maf and I added the air temp sensor.

[Matt Cramer]

I would first try adjusting the trim pots for more sensitivity.

[dalejr240]

Thank you Matt for the info and I adjusted the Vr trim and now I have both the low and high resolution signal in the composite logger but I still have no rpm and no spark and no sync. GRRR Attached is the latest log file after getting both signals

[elutionsdesign]

What engine is this? I see in your tune file LS1 configuration for wheel decoding and cam signal turned off. Is this correct? You're not getting any spark because you have a constant sync error.

[dalejr240]

The engine is an RB25 det in a 87 Nissan 4x4 and I just double checked my tune file and it is showing me it is set to Nissan rb25 so im not sure what u r looking at or what im missing, and if was set to ls1 I t would give a constant sync error. Im new to this so im open to all.

[Matt Cramer]

You might want to change the high res tach polarity setting; does that do anything?

[dalejr240]

Matt I tried that to and no change

[sheek]

feel free to try a base map that is known to be driving

[dalejr240]

Thank you sheek for the base map and I did try it today and still no luck so im beginning to think that there is something wrong with the trim pots or the unit cause I have tried everything I can think of and then some and still cant get it to sync. Once I get passed this hurdle I will be ok just trying to get this to work has been a pain. Attached is the latest composite log file and im open to any suggestions.

[Matt Cramer]

Are you using PT4 or the cam input for the high res signal?

[dalejr240]

Hi Matt and yes im using pt4 for the high res signal using the 330 ohm resister from the tps for a 5v pull up. I set it up per the instructions on the diyautotune web site on how to megasquirt your rb25, that's why im so aggravated with this and I just don't know what Im doing wrong or what I might have over looked. And thank u to all who give me info and things to check.

[winstonusmc]

How is the tach sel set on the V3.0 board? It has to be set up as VR. I have been running an optical sensor for quite a while and use 330 ohm pull up to 5v. Mine is done inside on the project area and I dont have to use PT4, so Cam In is using the supplied pllup. Back when I had this on an RB25, I used a pullup to 5v as well.

[mxsteven]

Hi,

May i know what is the outcome? I had a similar problem here which making me crazy too. Any advise is highly appreciated!!

[Scottie-GNZ]

Any updates on this issue?

[mxsteven]

Hi Scottie, I had solved my issues! It seems like the pull up voltage using 330ohm resistor is too low where you will have to use 1k to 2.2k for the pull up voltage of the high and low res. I had also informed Matt and he had updated the tech webpage for RB25.

I would suggest you test it on the bench using Jimstim and jimstim X first. remove the tach jumper and take the CAS from the car and wire up on the bench where low res to pin24 and the high res to PT4 on the MS3X. Always remember to turn the CAS in the right direction during the bench test else you will end up chasing wild goose hahaha..

let me know if this helps.

[Scottie-GNZ]

Thanks for the update.

I just took on a project to replace the OEM ECU/harness/piggyback with MS3X in an RB25/240Z swap. The original swap was....I'll be kind and say a "hack" job and now won't start. Carefully trying to remove the current ECU/harness/piggyback.

Digging up as much reference material as I can and hope I can lean a little on those who have been there/done that. Have not had very good luck with VR setups on my 2JZ and current LS and hope this one will be the charm

I am assuming these swaps go speed density, eliminating the MAF.

[mxsteven]

Hi scottie, perhaps you need to verify the connections... Please go to the link below and check out my pinout setup, so far it works pretty fine...

http://www.msextra.com/forums/viewtopic ... 31&t=54452

[jsmcortina]

I updated the MS3 manual page on this yesterday and confirmed that it works with a CAS wired up on the bench and spun with a drill.

James

[winstonusmc]

I remember spinning an rb20/26 CAS with a drill, haha. Back when I was helping out with this. I noticed the noise from the drill was messing with the signal. Then I spun the CAS with a bike tire and took it to 19000 rpms before it lost sync, haha. I miss driving the RB26 on MS, couldnt street tune it in Okinawa because with 1.1 bar on td04b compressors, it had too much power to safely tune it ar over 6000rpm.

[gslender]

I updated the MS3 manual page on this yesterday and confirmed that it works with a CAS wired up on the bench and spun with a drill.

James

Which specific page did you update - still says a 330 ohm pull is fine/correct?
http://www.msextra.com/doc/ms3/nissancas.html

G