warmed up starting prob(FAST)

[quickstrike]

I searched alot of the old threads first, but cant find the answer there.

Eng is a 331ci, with 83lb inj. At initial startup with cold CTS reading, all is ok. After eng reaches 180 or so, car does not want to restart without alout of pedal pushing. I have read through the manual,(excellent help manual by the way,answered damn near every question so far) and understand that I can adjust both the Starting IAC position and the Cranking fuel pulse width. I have tried various things to an extreme without much success. I understand that by looking at the BPW at a warmed up idle and then add 50% more inj puls width to that and ramping it down from there should work. Does this mean if my BPW is 2.5 at idle, that I need to set the Cranking fuel to around 3.75 and ramp it down to a warmed engine from there? Beacuse the only way the car wants to start is around 25 ms of PW and ramping it down from that point. Although the car still doesnt want to start when warm even with that. I have tried opening up the IAC at startup to 255(max) and still I have to pedal it to start it.

By the way setup paramaters have my inj delay at 1.0ms. car runs and idles pretty good except for this problem. I am new and learning quickly though. My 2 best sources of info are this site which is great, obviously some very intelligent tuners here, and also the FAST manual which was certainly careful written to answer most of the basic questions to get you up and running.
Please help a FORD man out, I promise I wont tell a sole! Thanks in advance for any help you may offer.

P.S. base timing is 10 deg(checked with light).

Randy

 

[TurboTR]

Well for starters, with the FAST you only really need concern yourself with raw inj pw in the crank pw table And of course wot duty cycle

With 84 lb inj, warmed up engine, 25 ms sounds WAY off to me. Assuming I understand what you've written. Maybe 25-30 ms at full cold, tapering down to about 2-3 ms full hot in the cranking fuel table. If you currently have 25 ms at 180 deg then I bet what it's doing is over fueling at cranking, then that load of fuel is serving as some after start enrichment, at least until it goes away after a few moments. So it probably catches quickly when you crank it, but then dies away with out enough after start enrichment. OR you could have too much after start enrichment too of course. Best way to find out which direction to go is to log the a/f ratio during starting.

Related to that, spark timing during cranking oughta be about 10 deg or so.

You didn't mention the after start enrichment table. Some related tables are the after start decay rate and the revs until adfter start enrichment tables.

TurboTR

 

[Craig Smith]

You won't be able to log a/f ratio during cranking. Not enough airflow across the O2 sensor to get any sort of reading. The O2 sensor also won't really become operative until the ECU switches to run mode.

I agree that 25 mS is a TON of cranking fuel out of an 83 lb/hr injector. On my last engine, I had about 15 mS with my 55 lb/hr injectors and so much gas ran right out the exhaust before the engine was able to start that the heater element in the O2 sensor started a fire inside my header!

 

[quickstrike]

I figured I wouldnt be able to log a startup. I thought about trying the after start enrichment tables, but the way it sounds I dont think it is realy getting that far. I dont believe it has switched into run mode while it is trying to fire up. I actually have it at about 25ms and ramping down to about 3-4ms at 180 deg. This will fire the car ok when it is cold, but doesnt want to fire when it is warm. In the instructions it speaks of adding 50% more to the inj BPW as observed from a warmed up idle. If I do this it would only be about 3-4ms at cold CTS and ramp down from there. The car wont start like that at any temp. are the instructions incorrect or is my car just way out from ordinary?

Maybe I am approaching this the wrong way, Maybe I should be leaving the fuel alone and messing more with the start IAC value. I did this for a while and didnt have much luck. Ikept taking it up and up untill I reached 255 and it didnt help much. I still have to pedal the gas alot to get it to fire. Its possible it is going to take the exact combination of the TWO tables to get it to work and I just havent had them both correct at the same time.

Randy
I cant wait to get real good with this thing. Total control of motor changes from now on!!

 

[TurboTR]

Well FWIW I was logging startup pretty well yesterday with a new supercharged Honda. At least with a warmed up engine... I was able to see the results of changes to the enrichment pretty well IMO.

But whatever works for you quickstrike.

TurboTR

 

[quickstrike]

Sorry I didnt mean it to sound that way, I just had remembered reading a previous post about it not working untill enough airflow was moving across it.

Randy

 

[quickstrike]

So in the spark advance table is it looking at these numbers for startup? In other words at around 200 rpms should I have the timing around 10 or so for cranking purposes? and then back to 30 or so after it starts at around 800 rpm? Maybe this is my problem . If it doesnt use that table during startup, then where does it look for timing for crank?

Randy