Crank and after start enrichment suggestions

[Morris400]

looking for some ideas on my enrichments for my 94 Audi S4 AAN.  having trouble getting it to start, it takes 3 time before it will stay running and maitain idle. it starts up then dies the first 2 times, then the 3rd time its fine.

i cant upload my config file for some reason, im guessing i need to post more. 

Crank enrichment:
-30c (300)
   0c (200)
 20c (138)
 80c (125)

Afterstart Enrichment
-30c (200)
   0c (150)
  20c (125)
  80c (100)

Should i rasie these up or are they too high as is? 

Kenny

[MWfire]

you need around 500% crank at 0c and 600% at -20C

[Leonhard]

I made good results with these settings:

Crank enrichment:
-30c (400)
   0c (250)
 20c (138)
 70c (110)

Afterstart Enrichment
-30c (300)
   0c (163)
  20c (138)
  70c (100)

check also on the Afterstart settings (duration)

afterstart coldtime (-40°C)  256 cycles
afterstart warmtime (77°C)  32 cycles

warmup enrichment

-30  158
-20  150
-10  141
0     133
10   126
30   115
50   105
65   100
80   100
100  100

it differs with your hardware setup, like

type of spark-plugs (gap), coil ernergy, dwelltime, valvetiming, compressionratio, injector angle curve etc.

[msh]

PRJ in S2forum posted AAN stock cranking enrichment, from motronic tune:

-33C 1800%
-20C 838%
  0C 363%
 10C 238%
 40C 125%
 94C 100%

Although cold weather numbers should be taken with care.

As for "engine starts and then dies", there is apparently not enough enrichment - you probably have enough fuel to start the engine, but you don't have enough fuel to keep it running. I would suggest you to increase warm up enrichment first, afterstart enrichment could be enough or even too much.

I made good results with these settings:

Crank enrichment:
-30c (400)
   0c (250)
 20c (138)
70c (110)

This value suggests you have slightly too low Cranking VE, as you still need cranking enrichment even for warm engine...

[Leonhard]

This value suggests you have slightly too low Cranking VE, as you still need cranking enrichment even for warm engine...

No, this is on purpose. The engine would start with 100% @ 70°C CLT under perfect conditions, but 10% is added extra for safety and 
"cold weather" ambient conditions, not realized by VEMS via MAT e.g.
For a realy hot start you need even more cranking enrichment, another row @ 100°C could look like 115% again.
Yes, you could put this on top of cranking VE, but it's just my application strategy to "remember" the necessary safety extra 

[Morris400]

\Thanks for the replies guys,  i did manage to get it to fire up 1st start cold now.  i adjusted the CE to 500% @ -30 and 375% @0c. 

cold the car will start, idle and stay running.  after a hour drive or so i shut off that car and when i go to start it back up after 10 mins or so, it just cranks and cranks. i have to hold the throttle at 100% and that gets it to warm start. any ideas on this one? 

how do i attach my config file so you guys can see what i have so far? 

[msh]

What are your current "cold" temperatures? 500% @ -30 is clearly not enough - if you're puzzled by the fact that the curve can go up to max 600%, just make that point 600%, and after burning, the whole thing will be in different scale.

As for your warm start issues, this must be at fault - " 80c (125)" - you're simply flooding your engine, and that's why you're using "flood clear" function to start it. Set that point to 100%, and, if warm start still isn't fine, adjust cranking VE upwards or downwards, depending on engine behaviour - but keep in mind that changing cranking VE also affects the rest of the points.

[Morris400]

Right now when I go to start the car the coolant temp is 10c. Car starts and idles for 4 seconds...dies. on the second start it fires up and stays running. Would this be warm up en or afterstart en?

On warm start, the car floods right away. Just cranks. At that point the coolant is about 70c and MAT is 60c.  So today I changed the MAT/TPS en to 100 at 60c. No change.

Now one thing I looked at today was injector O rings  the ones on my Deka 630s measure ID 7.8mm and OD 14.3mm rhe stock measure 7.8mm ID and 14.9mm OD. Could the source of my problems be the .6mm smaller Orings?  They feel right in the rail and the IM. Stock feel tighter though.

[msh]

Warmup enrichment - afterstart enrichment is what keeps your engine alive for those 4 seconds and engine dies when it ends.

I doubt MAT/TPS fuel correction map has anything to do with cranking - it is used when engine is running.

[Morris400]

I'll ritchen rhe warmup en then in Hope's that keeps her running. I'm going to change the injector o rings to stock size before this.

[Morris400]

I've made the changes to the enrichments which to me should correct my issues.

I changed the crank EN at 20c from 200% to 120% and at 80c from 150% to 100% to me this should solve my hot start flood issue, No?

Changed the warm up enrichment by adding 10-15% all over. I would think this should help the cold start issue when it starts fine and stalls 5 seconds later.

I kept the crank VE at 75% as the car does start cold...just does not stay running.

Does this all make sense or am I on the wrong path here.

Still going to check plugs to see the condition and change the fuel injector O rings to be safe.

[msh]

Cranking VE should be adjusted so that with cranking enrichment 100% @ 80c the engine would start nicely. I don't understand why you changed that cranking enrichment @ 20c point - it's clearly not enough, and you have problems with hot engine, not barely warm.

Warmup enrichment needs to be tuned, or, as a stop gap measure, added some enrichment in points where needed, NOT all over. How to tune warmup enrichment - enable your wideband oxygen sensor to start upon ECU startup - in case your oxygen sensor is being powered by fuel pump relay, not directly from ignition, some fiddling with output configuration would be needed, in order to keep fuel pump on to heat oxygen sensor and to keep it running afterwards - so you get your sensor hot and running with engine off, and open warm up enrichment curve - then start your engine and adjust the curve so that you would get target lambda at all temperatures till it's hot - of course, if VE table isn't really correct, that won't be very precise.

As a side note, this is how does both of these curves looks like for my engine, just for reference - no, I'm not experienced tuner, my level is only slightly above yours, and my engine is VW 2.0 8v [but the physics concerning these curves aren't much different between our engines], but car is my daily, with VEMS for more than year, and I live in colder climate than you [apparently] - warmup enrichment curve was tuned last winter, when there was -15c outside , although I'm going to retune it today, as the engine is now different - cranking enrichment curve, well, the 30c and 80c values are there for a long time, but -40c and 0c values I am upping slowly for a last month; I guess 0c will end up somerhwere around PRJ mentioned 330% or so.

[Morris400]

Msh:

Yhe reason I changed the EN on crank at 20c was based on the warm start. My coolant temp on warm starts was 68c. With my settings being 20c - 150% and the 80c - 125%, I figured on that warm start the ecu is using the 20c values as the temp is not at 80c yet.

For the warm up EN...I added a cut all across as I figure the stalling issue on cold start could be not enough warm up EN?

Also...I'm located in Canada...notmally we see -35c -40c but so far we have had a mild winter lol.

[msh]

When it comes to curves, ECU is extrapolating - it takes value from curve that corresponds to current temperature, in your case 63c - with 20c point being 120% and 80c being 100%, @ 60c you'll get ~107% crank enrichment or so - when you turn on ignition with PC connected, you can see in the curve where ECU currently is; the yellow cross indicates that. So yes, that temperature is affected by both points, but they should be chosen so that engine would start good enough all way between them, and 120% @ 20c is not enough for sure. You may want to move that @ 20c point to slightly higher temperature, say, 30c, that would make your curve more curvaceous and allow you to have less cranking enrichment towards warm temperatures, without decreasing it from temperatures towards 0c.

I understand your "all across" as "I increased all points of warm up enrichment curve 10% - 15%", am I right? You need to increase points of temperatures, where your engine is prone to stalling. You can use my warm up enrichment curve, posted previously as a rough reference.

P.S I toyed with vemstune to made up this composite image with paint [we have just four reference points, not six... ], using stock motronic values I posted earlier - apparently this is how crank enrichment curve should end up like...

[Morris400]

SUCCESS!

By raising my warmup enrichment that 10% I was able to get 5he car to start on 1 start and stay idle.

By lowering the crank enrichment at higher temps I got 1 start and kept idle when starting at 69c coolant. It was not a perfect start but after 3 seconds of cranking it caught. Going to try slightly raising (5%) at 70c and see if it catches sooner or takes longer. But for now I'm happy on the starting .

Idle is now a bit higher then I'd like. The idle is set to 950 warm. But hovers at the 1100 mark. Its steady there. It could be cause the heater is on.  I made some adjustments to the IAC Minmap from 36 to 34. Is about the same. Going to go through some old configs as I did have a better idle not long ago. And I've made next to 0 VE changes. The idle is bang on lambda @ 1100 mark though. Maybe timing is too low or too high? Currently at 15.00 @ 700 and 15.00@1200  in the idle area.