The 15 Y/O Turbo M42 Build Thread (Now Holley EFI Terminator X Controlled)

[Dj Buttchug]

I'll be honest, boost, tuning, and MS scare the shit out of me. All I ever read is horror stories about people trying to get their tune right.

true, but its been done and It can be done. Ive come to the conclusion that if I want my car to run properly im going to have to tune it myself. If you want something done right these days its really the only option (at least this is my experience with tuning so far)


Ive taken the car to be dyno'd TWICE, and it still idles poorly and wont start. It runs fine when driving and pulls like crazy under boost. It just seems like the guys that did my tune didnt really care about the fine details and I guess thats where I come in.

My target AFRs at idle are 13.4 ish. Either warm or cold it seems to want more fuel to idle smoothly, especially when I kick on an accessory and put extra load on the charging system (cooling fan or distilled mist)


If I give it more fuel it seems to have better throttle response too. I donno, ill wait for some tuning pros on here to chime in because Im well aware that I am NOT a professional at MS.

[wazzu70]

Tuning is not bad at all, you just need a desire to learn and a fundamental understanding of how an IC engine operates.

Many people would be smart to have a professional shop wire in and test the unit and set up the base configuration though!

[Lof8]

I'll be honest, boost, tuning, and MS scare the shit out of me. All I ever read is horror stories about people trying to get their tune right.

[Dj Buttchug]

and my target AFR table.

[Dj Buttchug]

Is your charging system working correctly? How many volts to the battery when running?

my volt meter reads 13.5 however when data logging it reads less. Something doesnt seem right here.

I have a datalog from a drive i took the other day. Im not sure how to show it here.

[wazzu70]

Is your charging system working correctly? How many volts to the battery when running?

[Dj Buttchug]

here is my startup enrichment table. It used to be much linear but I raised the enrichment around my startup temp to finally get it started.


Here are my symptoms.
1. shitty idle (hunts constantly)
2. Still will not start up cold (70-80 degrees)
3 Starts when hot but excessive cranking is needed.
4. When I jump the car battery it seems to start much easier, hot or cold. The battery in the car is brand new.

megasquirt gurus help me out

[Dj Buttchug]

for some reason my tuning PC will not upload my files correctly so here are screen shots of what I am working with

The numbers are red because I just changed them back. I was tweaking things a little


My cold start issue still persists. Ill post my startup enrichment as soon as the photo uploads.

[wazzu70]

Those dwell numbers sound much better!

I have the TDC tooth the 20th tooth after the gap. Thats the best way to explain it since all trigger settings for different system need different info.

The cam sensor is before TDC, so you shouldn't need to make any changes to that as most system place #1 cyl after the secondary trigger tooth. The early M42 has a VR sensor second trigger, at lower RPMs it does not generate a signal...on my setup at least. I want to change to a hall secondary for that reason :)

[e30guydownunder]

why not just do some screen shots?

[Dj Buttchug]

adjusted my dwell from 4ms down to 2.8 on startup. much better now. Also added some nice heat syncs under my new drivers.

Im trying to upload a few msq files of my tune so you guys can my numbers but im having issues attaching it to a post. who knows how?

[Dj Buttchug]

I think positioning the cam sensor different but rotating the cam wheel would help also.

BCPR7ES - had them left over from SR20 days but seem to work nicely

interesting. When does it miss? in my experience missing under load COULD be related to spark gap. I had issues choosing plugs and I ended up going with s2000 plugs.

[e30guydownunder]

I think positioning the cam sensor different but rotating the cam wheel would help also.

BCPR7ES - had them left over from SR20 days but seem to work nicely

[Dj Buttchug]

same here. There is a way to remedy it. You can run a gm style trigger wheel and sensor DIY autotune.

What spark plugs are you using?

[e30guydownunder]

my trigger signals are good, but just the relationship between them and tdc, have to do a few revolutions for it all the sync up nicely. Not sure what is causing my misfire though :(