VEMS
03-08-2020, 04:44 PM
#1
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Thread Starter
VEMS
I'm really curious about VEMS. What are the benefits? I see that it eliminates the AFM. I think mine is "questionable", so that would pay for a bout 30% of the cost of a VEMS right off, and I'd get rid of the AFM. Does it also eliminate the TPS? Are there any drawbacks? Does it provide data, like you find on a modern car? That alone would come close to getting me to try it. It looks really interesting.
03-08-2020, 06:28 PM
#2
Rennlist Member
It does look like a good idea, but I don't think they have OBD2-like functionality, though you can certainly live-stream data to a laptop. The main drawback based on what I've seen is that they are not really plug-and-play. You get a base map, and then you have to figure it out from there. Why it is you can install a DME from most any 944 of the same generation and engine, from anywhere in the world and expect it to work fine, but these aftermarket ECUs always require fiddling/dyno-tuning I'll never know.
03-08-2020, 10:31 PM
#4
Rainman
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Rennlist Member
search this forum for VEMS info.
has been covered many times with all the info you're looking for.
i've had VEMS for 5 years and it's the single best mod you can do to a 944 NA.
has been covered many times with all the info you're looking for.
i've had VEMS for 5 years and it's the single best mod you can do to a 944 NA.
03-09-2020, 12:36 AM
#5
Rennlist Member
03-09-2020, 10:44 AM
#6
You're able to drive the car right away with the base maps.
The reason they all take some 'fiddling' is that each car has different 'needs' to achieve maximum output. The stock ecus all go for like 95% max, hence some cars perform better out of factory then others. The aftermarket ecu's allow you to eek out the final 5% by tinkering for your specific setup. The base map you get with the VEMS kit gets you to the same 95% as the stock computer. -Note this in a generalization, %s are not accurate.
I went a different route from VEMS (Link ECU) but the end results were the same. It took me a month or so to get my AFR's where I want them, but my setup did not come with a base map, so it took a little longer.
The reason they all take some 'fiddling' is that each car has different 'needs' to achieve maximum output. The stock ecus all go for like 95% max, hence some cars perform better out of factory then others. The aftermarket ecu's allow you to eek out the final 5% by tinkering for your specific setup. The base map you get with the VEMS kit gets you to the same 95% as the stock computer. -Note this in a generalization, %s are not accurate.
I went a different route from VEMS (Link ECU) but the end results were the same. It took me a month or so to get my AFR's where I want them, but my setup did not come with a base map, so it took a little longer.
03-09-2020, 11:54 AM
#7
Rainman
Rennlist Member
Rennlist Member
the car was ready to drive and running well within a few hours.
then go out and try to do steady-state load conditions (certain RPM with certain throttle position, going up hills vs going down hill etc) with the auto-tune function going to dial it in.
it gets more complicated (longer setup time) when you deviate further from "stock" that the base map is made for.
right now i'm adapting a 2.5L 9.5 compression pump gas stock tune to run my new, 2.9L, 12.5 compression E85 engine.
amazingly, to get it to start up and idle all i had to do was adjust the "reqfuel" to match my bigger injectors and E85 extra fuel requirements - everything else (timing, AFR, etc) still worked, but i am tweaking other parts still.
then go out and try to do steady-state load conditions (certain RPM with certain throttle position, going up hills vs going down hill etc) with the auto-tune function going to dial it in.
it gets more complicated (longer setup time) when you deviate further from "stock" that the base map is made for.
right now i'm adapting a 2.5L 9.5 compression pump gas stock tune to run my new, 2.9L, 12.5 compression E85 engine.
amazingly, to get it to start up and idle all i had to do was adjust the "reqfuel" to match my bigger injectors and E85 extra fuel requirements - everything else (timing, AFR, etc) still worked, but i am tweaking other parts still.
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03-09-2020, 02:50 PM
#8
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Thread Starter
Thanks for the input. It's definitely something I'll consider. If I do install one I'll post my experience. It's a big step, for me anyway, and I always appreciate the advice I get on here. Especially considering the fact that I am in no way a qualified mechanic.
03-09-2020, 04:40 PM
#9
Rainman
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read my initial thoughts here from 2016. 4 years i guess, not 5.
https://rennlist.com/forums/924-931-...tml?styleid=25
https://rennlist.com/forums/924-931-...tml?styleid=25
03-10-2020, 11:13 PM
#13
Rainman
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You can make it run at whatever AFR you desire, within reason.
VEMS has 100% tune-ability of any parameter you can think of.
That said I don't see the point going below ~12.8 or so on an NA car but I go off Lambda which is .87 or thereabouts. So that's where I set high-load/WOT AFR.
Cruising and idling range up to stoich.
With that in mind you should have no problem passing functional emissions with VEMS if you set the tune to be emissions oriented (stoich). You would just have to disguise it well to pass the CA visual check.
There's a guy on here who I won't name who passed CA smog visual and functional with his VEMS-equipped 944 turbo.
VEMS has 100% tune-ability of any parameter you can think of.
That said I don't see the point going below ~12.8 or so on an NA car but I go off Lambda which is .87 or thereabouts. So that's where I set high-load/WOT AFR.
Cruising and idling range up to stoich.
With that in mind you should have no problem passing functional emissions with VEMS if you set the tune to be emissions oriented (stoich). You would just have to disguise it well to pass the CA visual check.
There's a guy on here who I won't name who passed CA smog visual and functional with his VEMS-equipped 944 turbo.
03-11-2020, 02:12 AM
#14
Rennlist Member
You can make it run at whatever AFR you desire, within reason.
VEMS has 100% tune-ability of any parameter you can think of.
That said I don't see the point going below ~12.8 or so on an NA car but I go off Lambda which is .87 or thereabouts. So that's where I set high-load/WOT AFR.
Cruising and idling range up to stoich.
With that in mind you should have no problem passing functional emissions with VEMS if you set the tune to be emissions oriented (stoich). You would just have to disguise it well to pass the CA
visual check.
There's a guy on here who I won't name who passed CA smog visual and functional with his VEMS-equipped 944 turbo.
VEMS has 100% tune-ability of any parameter you can think of.
That said I don't see the point going below ~12.8 or so on an NA car but I go off Lambda which is .87 or thereabouts. So that's where I set high-load/WOT AFR.
Cruising and idling range up to stoich.
With that in mind you should have no problem passing functional emissions with VEMS if you set the tune to be emissions oriented (stoich). You would just have to disguise it well to pass the CA
visual check.
There's a guy on here who I won't name who passed CA smog visual and functional with his VEMS-equipped 944 turbo.
03-11-2020, 11:44 AM
#15
That's around the lambda I'm using too. I'd like to get it on a dyno though to see what I'm leaving on the table. I used an app "Virtual Dyno" which takes log files, and the data about your car to convert them to estimated dynos, Best I could get was ~ 190whp so I think there is room for improvement.