Musante944

Hi Guys, I have a brand new rebuilt hybrid stroker 8V 951 engine.

I am using Peep's VEMS PnP kit which I bought secondhand. I am having some issues with getting the car running and idling. The car fires up and runs perfectly with Motronic DME and KLR. Everything on the engine is brand new and the engine harness has been refurbished and all new connectors. I am running 80lb Siemens Deka injectors, and a 3.0 bar FPR. The engine harness has been also outfitted with the refurbished LR speed/ref sensor and injector/knock harnesses. I am using stock ignition distributor, new plugs and plug wires. I am using an aluminum SPEC flywheel (non-scalloped), with brand new sensors gapped at .030".

I have confirmed continuity on all wires to the Motronic-VEMS adapter harness. I also had Marc at EFI Express in NH inspect the ECU, and claims both injector drivers to be in good shape.

I have tried multiple configurations in Vemstune with no avail:
-Stock 951 configuration (injector settings corrected)= the car does not start, and only "farts" a little bit while cranking.
-Configuration made for 80LB injectors from Marcel Wolf= the car starts and idles, however it runs VERY RICH and ONLY on cylinders 2&3!
-Previous owner's configuration= car does not start and only "farts" while cranking.

I am at wit's end with this, and have utilized the knowledge of a couple guys within Vemstune making tweaks here and there. I am available to share my configs and answer any questions you may have. I really appreciate the help!!

V2Rocket

Post your config for review please

Musante944

I am unable to attach my configuration files as they are 'invalid' but please feel free to email me for them mcmusante@gmail.com.

I have attached a Motronic-to-VEMS pin out sheet I made per my actual harness adapter. All wires have continuity and pins are in good shape.
PLEASE NOTE: I have tested the injector batch groups in Vemstune using a noid light and have concluded that Injectors 1&2 are in Group 0 and Injectors 3&4 are in Group 1.
**With Marcel's config file, the car only would run on cylinders 2&3 (and very rich). Even though the injector group table is correct as 1/7 and 2/19, when I switched the table to 1/7 and 6/18, the car still did only run on 2 cylinders, but it changed to cylinders 1&2. Could this be an ignition issue?

V2Rocket

Easiest way here is to "ZIP" the config and then upload it.

Musante944

ZIP files attached.

Musante944

A few new notes to point out:
-With a "stock config" tweaked to my injector settings, the car cranks, and only farts a few times--nothing more. This config is correct; it has been compared to two other 951s and Peep's base tune.
-Both injector pairs "click on" in testing mode.
-I am running a SPEC aluminum flywheel (sensor gap at .030")

I read in another thread that guys with this flywheel were instructed by Peep to gap their sensors at 1.1 mm. I think there has got to be a way to get this to work without regapping the sensors. I also have a stock flywheel which COULD be a fix, but I would MUCH rather not have to change the flywheel....

I have 2 trigger logs from my start attempts (injectors enabled/disabled). I will attach them to this post.

GPA951s

Just an observation and I am no expert at this stuff, but I do know a VERY good tuner. I build it, and bring it to him and he makes it run like a purring kitten... never and issue.. Anyhow, he steers me away from HUGE injectors all the time if I want the car to idle properly due to the fact that as the injector gets bigger the min duty cycle changes to a higher rate, so even at its lowest DC it dumps too much fuel in.. Just verify that the injectors you have can actually "Idle" ..

Good Luck..

Droops83

This is a good point.

However, I have what might be the same Siemens-Deka 80# injectors and VEMS, and I can achieve a smooth idle at 900 RPM, even with the stock batch-fired configuration, and even passed the CA tailpipe smog test! The idle injector pulsewidth is at 1.7 milliseconds at that RPM, so these injectors must be at the very bottom threshold of being able to open/close properly.

I can't look at the config on this computer (Mac), but I'd be willing to bet something in the VEMS base setup is wrong if only two injectors are activating with VEMS but all are working with the stock DME---but you got the stock DME to start the engine using these same injectors? With batch-fired injection, the injector firing actual order is not super critical, but they all do need to work!

Also, hopefully a lesson has been learned about the pitfalls of trying to save a few bucks by buying this setup used----think of all the time and money you have spent trying to get this right. If you had bought it new, the warranty and support would be much more readily available!

Musante944

Yes, the engine runs 100% on the 80 lb Dekas and 3.0 bar FPR with the DME/KLR. For some reason, the engine was running out of fuel with the stock injectors (had to spray brake kleen in the AFM to keep it idling).

I understand your point, however I paid top dollar for the VEMS unit. The previous owner ran it for about 1 year and offered a full purchase buy back if there was anything wrong with it. Everything seems to be in functional order--it is simply a matter of a configuration change at this point (I think). I am soon receiving a new VEMS unit and adapter to test with. I have spent too much time on the VEMS group and now am going to utilize the knowledge and advice of my dad and his tuner at Musante Motorsports to figure out the rest. I am sure there has got to be a way to configure this to work with the standard 0.8 mm sensor gap with ANY flywheel.

V2Rocket

Ok I've seen a few things that raise an eyebrow. At least in comparison to my NA config which does run fine.
Maybe look into these numbers and play around?

There are significant differences in the primary trigger settings despite the 2 extra teeth on the 951 FW.


Same with the prime/start/crank settings.



Also I note your injector dead times are way off the published numbers at 3 bar.
https://www.ms4x.net/index.php?title...Fmin_80lb.2Fhr

Siemens DEKA FI114991 (110324) 875cc/min 80lb/hr

http://www.siemensdeka.com/product/8...scar-fi114991/

43.5PSI / 300kPa:

Minimum injection time: 0.600ms
ip_ti_add_dly__vb
V.......ms (taken from the above link and trimmed to be relevant for VEMS)
8.0...1.777
10.0...1.288
12.0...1.017
14.0...0.801
16.0...0.639

mdnt08

NA and Turbo flywheels are toothed differently.

mdnt08

There should definitely be some adv during crank tho. And it would not hurt to lower the crank threshold rpm to exclude that as aa factor.

DLS

I'm no expert but i compaired your config files to mine and what i noticed was different in some of your files was:
Reference tooth, related to ignition
mine is
0 6
3 0
2 6
1 0

Injector firing
mine is
Divider 1
Number of primary injectors 4

Angular width of tooth
mine is
30 degrees

And in one of your configs you had your injectors set to low impedance.

V2Rocket

Yes that's why I spelled out the tooth difference

But if they added only 2 teeth going to 951 why would the TDC mark be ~22 degrees further away than on the NA?
I am questioning the numbers in his settings for tooth count, size, angles, and TDC position.

I seem to recall recent discussion on this board saying the 951 is right around 60 (58.7 or some weird number maybe) degrees for the TDC marker.

Droops83

Yup, my Primary Trigger Settings are all exactly the same as Michael's except for angular width of tooth being 30 degrees.

My "injector firing" settings in the injector settings menu are also divider=1 and number of primary injectors=4; if yours are off, the could explain some of the injectors not firing.

As for the priming, starting, and after cranking menu, my "prime pulse" splits the difference at 6.0 ms, and the other settings are abut the same as Spencer's. I agree with @mdnt08 , change these settings to match Spencer's to lower the cranking threshold and get some advance while cranking.

Sorry I can't post my config, but make sure your injector impedance and dead time settings are correct!