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

[Dj Buttchug]

will post all my settings in engine constants and warm up enrichments asap

[Good & Tight]

What are your injectors set at to squirt? how many squirts and are they alternating or simultaneous.?

[nando]

Yes :)

I believe the only startup curve you have to adjust is maybe cranking pulse, but I don't remember exactly - it's whichever one is set to a %. double that curve, and your VE tables, and you're set.

[wazzu70]

Yes :)

[Dj Buttchug]

you also have to adjust your startup curves when you adjust REQ_FUEL, the ones that are set to a % are multiplied by the REQ_FUEL value. so when you cut your REQ_FUEL by half, your startup curves that use it also got cut in half.

and yes, having a correct REQ_FUEL is important, because it affects everything - this is the base PW that every trim/correction, including VE, starts from!

so I should use my calculated req fuel setting of 3.4 and then adjust all my tables ?

[nando]

you also have to adjust your startup curves when you adjust REQ_FUEL, the ones that are set to a % are multiplied by the REQ_FUEL value. so when you cut your REQ_FUEL by half, your startup curves that use it also got cut in half.

and yes, having a correct REQ_FUEL is important, because it affects everything - this is the base PW that every trim/correction, including VE, starts from!

I've never seen a case where REQ_FUEL wasn't close. if you go from 6.8 to 3.4, all you need to do is multiply your VE tables by 2, and effectively it's the same.

[wazzu70]

It depends which option is best to take. Personally I would go with req_fuel values that make sense so your VE numbers are more comparable to other peoples. At the end of the day though VE and req_fuel are just numbers and the only thing that matters is the amount of fuel the injectors are giving.

Having incorrect req_fuel values may make others helping you difficult as the help generally assumes you have settings correct.

If you just reduce req_fuel without multiplying the VE table your engine will run like butt since you essentially just cut the fuel in half!

[Dj Buttchug]

I would change the req_fuel to the correct number, then multiply the whole VE map by (old number/new number).

You will also have to change the value for all cells that reference VE or req_fuel values.

Can you link an MS expert to the thread so they can give feedback on which cells might be impacted? Get Nando in here??

okay so heres an update. I adjusted the req fuel down to 3.4 like the mega manual says, but the car was even HARDER to start and when it was running it ran like shit.

So i up'ed the req fuel back up to six and then increased to 7 and tapered off till my idle deteriorated. final setting now is 6.8 req fuel.

Mega manual states that the req fuel calculator will get in you in the ballpark on 99% of engines.... so im wondering if i fall in the 1%

With my req fuel setting at 6.8 the car idles AMAZING. its JUST like stock motronic.

Tomorrow morning I will see how it starts cold from here. The higher req fuel seems to be giving me better AFRs into boost as well.... im seein low 12s into high 11s now.


my question is this: Is running an abnormally high req fuel terrible? does it have any downfalls? Should I run a lower req fuel and multiply my tables accordingly? Obviously the engine efficiency is effected...


lol


im way in over my head. i can build an engine but i cant even tune it.


fuck

[wazzu70]

I would change the req_fuel to the correct number, then multiply the whole VE map by (old number/new number).

You will also have to change the value for all cells that reference VE or req_fuel values.

Can you link an MS expert to the thread so they can give feedback on which cells might be impacted? Get Nando in here??

[Dj Buttchug]

my injectors are 970cc

If im using the req fuel calculator correctly it breaks down like this

engine size 1900 cc
4 cylinders
injector flow 970cc
afr 14.7

which yields a 3.4 required fuel calculation. this is no where close to 6.0 which was my original starting point

what do i do wazzu??

[wazzu70]

I thought your VE numbers looked low. If the req_fuel is off it will really screw with everything as its the main variable used in the calculations!

What size injectors do you have?

[Dj Buttchug]

thanks for the tips guys. Im not running an icv. My req fuel settings also raise other questions.

When I use the req fuel calculator and enter the engine specifics I get a value of 3.3 ms (open injector time)

My original tune was 6.0 ms.

Hoping to have the idle and start up dialed in today. thats the first step, Ive created like 3 different versions of my tune all with minor changes so ill burn those in and test them out. If things go south I can always load my original tune back.

[MF DOOM]

Here's my map for a m42 turbo,

107% load = 22psi
100% load = 20psi
i think 42% = 0psi

these are old maps which i have since changed a fair bit

Ill load mine tonight. I know i have a datalog somewhere of my idle settings. Are you using an icv? Im not running one on mine and it idles smooth as can be at 500rpm. Cold starts are perfect. Hot starts have issues because of what e30guy mentioned. Needs more enrichment. but anyways, heres theses. hopefully theyre useful

[e30guydownunder]

For you startup issue it just looks like not enough enrichment. Admititly I am on E85 so it is a bit but at 10-20 degrees Celcius I am running up to 200% enrichment. Generally it will be linear.

For sure I would be running richer. We tuned for a flat 12.0 AFR on my thing when on boost. I also think that your ignition values look quite high when on boost. But this really needs to be done on a dyno to know exactly what is going on.

[Dj Buttchug]

interesting. Im going to start making changes to the timing and fuel but i want to focus just on the start up and idle first before I move further.