Tom M'Guinn

Wish I could be of more help, but never tried the VEMS/MS set up. So consider the source! But, based on what you're saying, I'd be inclined to verify some of the numbers that system is reporting. If you haven't already, I'd mark the front pulley and belt cover and see how the actual ignition timing compares to what your system is reporting. The discussion around ref sensor offset, etc. in VEMS always left me confused, as does needing 20 degrees just to idle.... I'd do the same with the injector pulses -- find a Fluke or other meter that will tell you how long they are really pulsing. With so many moving parts (system config, maps, physical engine realities, etc.), I'd want to start with what I know for sure and work backwards. Also are you sure about the deadtime? And that the injectors are clean and flowing right? An IR temp gun on each exhaust flange might show if your lambda is the result of one sticky/leaky injector?

Droops83

This is a good video that explains idle ignition timing, and at the end he talks about running larger injectors for E85 and how to get a smooth idle. Andy was was founder of Adaptronic in Australia, and they were recently bought by Haltech. He is a really smart guy and has made a lot of great videos over the last ~8-10 years that have helped me to understand aftermarket EFI tuning much better:

V2Rocket

Thanks, but timing isn't a concern right now.
just the bonkers AFR.

Pulled plugs today, characteristically black like rich running with the ground strap slightly more grey. Definitely not fouling anything, it does run well at all RPM, just wanting to nail down why so rich in the settings or tune.

unplugging injectors one at a time makes it run rough predictably but could not discern a difference between cylinders. It's got to be a "global" problem, not just a leaky injector.

Droops83

I agree that something is off with those VE/pulsewidth numbers . . . .but as a quick sanity check, have you tried dialing back your ignition timing to say, 10 degrees at idle, and then with idle control disabled, use the throttle bypass screw to allow extra air in and raise the idle speed back to your target, and see if the extra air matches the injected fuel and improves the idle AFR?

sm

RS Barn has a client who has a VEMS system on his 968. They had to do some investigation during the install and might have some ideas for you. Give him a call - great guy who is willing to help.

Superfx

Hello,
I´m sorta new here, been watching this thread for a long time. I´ve had my 1990 952 since 2006 but haven´t used it for 10+ years...
Got it on the road again few yrs ago & the turbine seal snapped due to corrosion (probably too much idling !!). Few yrs later, new 27/8, valve seats, cleaned up ports & manifold, arp studs, 3 bar fpr deka 80lb inj, wasted spark, oil temp & fuel pressure monitoring (vems), 3in dp & exhaust (diy) k&n cold air inlet (diy) and.....vems from Peep.
I wanted a pnp standalone. I understand they will all need `some tweaking´ and dont mind doing or learning that. I wanted to see whats been done & why, thats why i never liked chip tuning & never invested in it.
Anyway, after many problems with my PnP (lol) vems i was wondering if anyone has a config file i could either use or look at to compare with what i´ve got as its not running right & Peep has agreed that `it will not work properly´ but as yet has not sent another config... , also i´m wondering what firmware version of vems people are using ?

Thanks in advance for any assistance.

SamGrant951

Hi,
I could send you my file, its been tuned and runs pretty well. Similar injector size, I have a to4e/57, 3" exhaust/no cat. Mine is not on wasted spark though....pm me your email.

Superfx

Havin some trouble getting that pm to send.
I´ll get it sorted soon.
Thanks !

SamGrant951

You might have to have a certain number of posts to send pms? not sure, just send me an email at sngrant AT gmail DOT com

Droops83

Do you have any more details about what your problems and symptoms are?

I could also send you a config, my 951 is running wasted spark and runs great, and I have the same injectors and a similar exhaust and turbo setup. The only part that isn't sorted is idle control, the engine idles high with it turned on, haven't spent much time investigating that, otherwise drives great in traffic or on the open road or track.

Superfx

Thanks for the responses, i´ll have to get back to you with more info soon but have an urgent job os & have to fly.now.
Sam i´ll send you na email.
Thanks !

trivgar

I'll jump in here now... I'm expecting my Vems to show up from Peep pretty soon. I've got an 86 951, LR Super 65 turbo, 72# injectors, etc etc. Going wasted spark as well. Will be using GSF trigger wheel and sensor due to my LR Spec push type clutch and scalloped flywheel. Looking forward to install!

V2Rocket

Tried this the other day, gradually backing off timing a few degrees at a time and it cut out when I got to 10.
I have it set to 18 static in the idle region now and the idle control is able to subtract 3-4 degrees at idle speed (so net ~14-15 degrees timing) and it runs happy.
Did not affect AFR though.

However, I am going to move on with my life and call my idle AFR issue resolved, though I might have cheated a bit...by fitting injectors the next size down, but still large enough to support max power on this engine.

I swapped my green 42's for some white 36's and did a little VE/deadtime tweaking and now it idles around 0.95 happily and the VE table is back to making sense and being "smooth". Just need to add some VE at higher MAP values to make up for it.

The old 42s have some deposits around the holes, maybe they were getting clogged and not closing fully? Dunno.
Not going to worry anymore, this engine has been sold and is coming out soon for a swap...just wanted to get it running properly for the next guy.

Droops83

That is a great result, but odd because I am able to achieve stable idle AFRs of 1.0 Lambda @ ~ 1.7 ms with 80# Siemens-Deka injectors on my otherwise stock and tired 2.5 liter 951 engine, which shouldn't have drastically different airflow rates at idle than does your 2.9L NA with cam.

At this point we can only speculate about what that may be, but I wish you success in your engine swap, and if it is the one I think I is, I hope to be able to do that same at some point

V2Rocket

It really is perplexing, but I've messed with every setting and calibration and tried getting support from multiple VEMS gurus (though I must say I have not received much help from the PnP vendor on this) and things they have suggested either don't make a difference or the car won't run.

Like I said before I always had this issue back to day 1 of running VEMS on a totally stock 2.5 NA engine and had to have a wacky VE table to make it run decent. I had a Rogue MAF and tuner before VEMS and I was running 55lb injectors on that without any issue (back in the "i'm going to supercharge it" days).

I think it is a hardware mystery of some kind at the ECU, harness or those green injectors but I've run out of patience to deal with it.