Was -30* F this morning, went out to start the car, and it fired on the second revolution, and instantly died.

Must have something to do with this "afterstart fuel" which I can't find to save my life.

Anyone know where to find the afterstart fueling parameters in the $6E bin???



*update*

Went out to start it again right now -15* F 2:30 pm. Cranked over two revolutions fired, died. Let the fuel pump prime again, cranked it over and it tried to start, gave it just a little bit of throttle, and it fired over, and went to about 1050 and just went vrump vrump vrump vrump really fast. really rough, and it smelt like a boat.

Not sure if it has to do with excess fuel on the plugs, or what.

Any ideas on this afterstart fueling any1???

 

Have you tried the clear fooded engine routine, where you hold the throttle wide open while cranking? Could be you have a leaking inj. Look at the table called Crank Fuel PW vs TPS. The two upper table entries should be zeroed out. That allows you to clear a flooded condition while cranking. Then release the throttle while your still cranking and it should help to get the engine started. If your inj test ok then the table to adjust for after start enrichment should be labled Startup Enrichment vs Coolant.

 

Starts without doing the "clear flood" mode. It just dies instantly after initial fire from either 1 revolution or 2 revolutions only when it's frigidly cold out, like the last two days, -20 F and -30 F

Priming the pump it holds pressure for atleast 15 minutes after key off. I doubt it's a leaky injector.

Here are some tables that I have so far.








Looking at what Redngold86z said in a different thread, he was talking about needing a big initial pulse and then 75% and then 75% again. Maybe it isn't addressed in the pw vs ref pulse, but the startup enrich vs coolant? I'll have to try that and see what results.

 

Startup IS afterstart enrichment, just named differently by different people making XDFs.
Startup is NOT used during cranking. Only used when RPMs are above 400.

Having a failed start and then re-starting will ALWAYs make it much richer than a 'dry' or 'true' cold start. The fuel is already built up on the walls, and if it fired at all, the piston/chamber is already starting to warm up which richens the mixture quite readily, which is why reducing the fuel by 25% is needed for each cycle.

The initial failed start might be from the Crank Fuel PW Mult vs Ref Pulse table. I would try .75 x8, then .5 x8, then .35 x8. There's also a multiplier available for Ref Pulses greater than 17, but you weren't getting that far before it stalled I think.

-30F starts are VERY difficult to get reliable. I use a wideband powered by a spare battery to get them dialed in. Otherwise, it's shooting in the dark.

Vrump vrump vrump vrump usually means it's rich (and may have some brown exhaust). Vrump vrump poop stall, is usually lean.

 

I completly forgot to mention, that I am using 24# Svo injectors, and I was just wondering if maybe there was some scaling that had to be done to the values for startup enrichment/afterstart enrichment??

Or does the injector constant take care of all that??

Thanks again!!

-Tyler

*that bin made a lot more sense than the one I was currently using*

Made some changes, going to go out now and try it, it's -20* F and it's sat since noon today. Maybe i'll shoot some video.

 

Changed the values for the ref pulses to .75 .5 .35 x8 each.

Went out, about -25* F now, and it did what it did this morning again.

Not sure what belt squeeked but it's prob the a/c compressor belt, I had to get it a little tight to fit the tall valve covers, and it probably did that because it's freakin cold outside. I gave it about 1/4-1/2 throttle and then it fired up.

That's the instant die, and the idle surge i'm talking about. But when it's not really really cold out like this, just about maybe 5 below or 0, it'll still do the surge, but not the instant die. It'll almost instant die but catch itself.

 

Injector size changes -
It makes some difference to cranking fuel, afterstart, transients, and some to the open loop. The cranking and afterstart fuels are mostly wasted fuel that passes through the engine (some is to build the wall film, some is to maintain it, or else it would get robbed and make a lean mixture), so in theory it should be grams of fuel per injection, but it's calculated in percent of current injection (which changes with injector size). Transients are for wall wetting (and to compensate for sensor and transport lags), and also should be grams per injection, but that fuel is not wasted (so you could scale it down a little if you wanted a perfect match). Some of the open loop offset is continually wasted too, but some is meant for shifting the mixture richer - you'd have to use a wideband to correctly match it to the previous injectors' burn AFR.

Your injectors are 9% bigger. Making any adjustment to the cold calibration is darn hard without a wideband. But, Cranking fuel can typically be scaled directly. Afterstart may differ a little. Open loop may only need a very little change. Transients will be affected by any airflow improvement modifications that you've made, and are also affected by carbon build-up - so use a wideband.

Injector constant only takes care of the steady state main fueling that is burning, not wasted.

 

That's what I was afraid of, having to use a wideband. I was going to get one anyways for WOT tuning, but funds are a little short.

What do you think is causing the instant die on first fire?

I can live with a real rough idle on cold and surging, but not the instant die.

Thanks again!

-Tyler

 

Try opening up the Park IAC position steps at -40 from 125 to 135 then 145, and see if that helps.

 

Put in some more IAC park counts. Doesn't help.

It won't hold the start unless I give it 1/4 to 1/2 throttle.

Everytime it'll just fire and die.

But when I give it some throttle before i crank, it fires, and revs up and then it's fine.

I tried resetting minimum air, and re cleaned the IAC valve and passage and set the TPS to .54

Still doesn't start on the first try unless I hold the throttle open some.

What does that mean? Not enough air? Too much fuel?

 

I think it's just too much initial fuel.

I scaled back the crank pw mul. vs. ref pulse to .5 .35 .2 x8 each and it took longer to crank but it fired up and kinda stumbled but caught itself.

So I'm going to try to scale back the crank pw vs coolant temp and put the ref. pulses back up to .75 .5 .35 to see if I can still get the instant start but not instant die.

We'll see what happens.

 

Be sure to tell us how it went

 

Must have been just way too much fuel.

I kept pulling back the cranking pw vs coolant temp by 10% or 5% and finally ended up with pretty much half of stock ARAP crank pw.



Didn't start instantly, but it started within a second, 2-4 revolutions, no surging, no stumbling, went to commanded idle well. Didn't smell real strong either.

 

Are you using a different xdf? The original table entries you posted earlier show fractional numbers but now your showing hugh whole numbers in the fuel percentage multiplier table. No wonder you were flooding the engine.

 

Heh, yeah, RednGold86z provided me with a better xdf which has better wording, uses different units.

Here's using the previous xdf for comparasion. It's the same thing just a different format in the xdf




And before, with the instant start and die, flooding out.

 

It's my XDF. It's converted to 0-100% displayed, rather than 0-1.

These cranking fuels are only used during 0-400 RPM, then it quickly decays out. A fast decay can be hard for the idle stability to manage. The longer crank time is likely from being smaller.

The video, if I recall correctly, was showing the surge much later than what can be affected by cranking fuel.

Spark advance can really help in these situations.

 

After cutting the Crank PW in half, it now starts normally and doesn't surge. Must have been due to the 24 svo's providing way too much fuel for first crank? Didn't touch the SA.