Cold Starts are totally screwed.

Hey guys. I don't really even know where to begin. What I'm giving you is my 50% scaled tune out of my Silverado. It's MAF only, big cam, ID1000 injectors, Big Kenne Bell supercharger, LS3 TB, etc. Displacement is 415 C.I.

I recently got Chris's throttle body relearn procedure added to the scanner so that I could reset the ECM's previously learned airflow values to make the truck idle as commanded. However as soon as I did that procedure and set my base running airflow tables correctly for warm idle the cold starts went totally AWAL. Dunno what I've done or why it's doing this but here's a log and my tune. I've never seen this before but hopefully you guys have.

It starts, runs for about 1-2 seconds perfectly, then the Injector duty cycle goes crazy and it floods the truck with fuel, essentially killing it. It takes 5 more seconds of cranking to get it to clear, cough and start, then it does it again! But the warm starts are fantastic! WTF?

Thanks for looking at this, any help and/or suggestions would be greatly appreciated.

-Robbie.

Haven't looked at the tune, I will in a little while, but quick question. Have you tried reducing the fuel in the OL EQ table vs IVT? Sounds like an injector issue, not t-body. But again, haven't looked at anything yet.

There does seem to be some kind of strange anomaly there as the Commanded AFR isn't changing drastically when the PCM goes ahead and commands unrealistic InjPWs not in accordance with your MAF measured airmass and CommAFR.

If you still have an older beta or 2.22 (if it supports) I would try re-writing with a known good version as something is definitiely amiss there and perhaps highlight this to support if nothing else jumps out. I certainly cannot see any reason for the ridiculous Comm InjPWs.

Why out of interest do you zero out ECT/IAT Bias? Is it becuase you are MAF only? And have you considered tuning the VE Coefficients for at least the idle region if you don't want to do the entire operating as I have found that this helps startup using a blend of VE/MAF; setting the dynamic disable at say 400/350 so you get the benefit of SD for the cranking at least. I know that's not the issue here, but just food for thought.

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Originally Posted by edcmat-l1

Haven't looked at the tune, I will in a little while, but quick question. Have you tried reducing the fuel in the OL EQ table vs IVT? Sounds like an injector issue, not t-body. But again, haven't looked at anything yet.

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Yeah buddy. I've tried all sorts of different settings, and finally I got fed up and converted the Zr1 EQ Ratio over to the OL settings. No dice. The T-Body was the issue as commanded idle was around 800 and it'd let it drop off to 650 because of the airflow calculations stored in the ECM over the TB for coking. Got that fixed and now the starts went to hell. :(

Cranking VE is set at 40 right now too, still no help.

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Originally Posted by SSUte01

There does seem to be some kind of strange anomaly there as the Commanded AFR isn't changing drastically when the PCM goes ahead and commands unrealistic InjPWs not in accordance with your MAF measured airmass and CommAFR.

If you still have an older beta or 2.22 (if it supports) I would try re-writing with a known good version as something is definitiely amiss there and perhaps highlight this to support if nothing else jumps out. I certainly cannot see any reason for the ridiculous Comm InjPWs.

Why out of interest do you zero out ECT/IAT Bias? Is it becuase you are MAF only? And have you considered tuning the VE Coefficients for at least the idle region if you don't want to do the entire operating as I have found that this helps startup using a blend of VE/MAF; setting the dynamic disable at say 400/350 so you get the benefit of SD for the cranking at least. I know that's not the issue here, but just food for thought.

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I have the newest version of the beta. :( And because the tune is scaled by 50%. Even with Speed Density startup enabled it's the same thing :/

Notice it starts and idles then goes crazy.

Yeah, OK, something's seriously wrong with that thing LOL. Wow that's some IDC right there!

I will add this. I have seen some real strange shit just from changing one wrong table, or even combinations of tables. Maybe flash it back to stock, and start out with only changing the injector data, and see if it will run. Then start dialing it in slowly using fuel trims. Then just make one change at a time and see what happens.

I'm going to keep looking through it and see if anything seems strange.

It almost looks like something kicks in and multiplies the IPW by a factor of 100. Maybe there is something wrong in that reset procedure that has been added like a decimal point out of place. Like 100 instead of 1.00 Do you have an old file you could do a write entire from, then just copy the tables back over from your current tune?

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Originally Posted by IDRIVEAG8GT

I have the newest version of the beta. :( And because the tune is scaled by 50%. Even with Speed Density startup enabled it's the same thing :/

Notice it starts and idles then goes crazy.

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I was aware you had the latest beta with your reference to the throttle body re-learn that's why I thought that it *may* be related to that and if you had an older beta that you knew worked to try.

Yeah, I noticed that everything is alright and then for no apparent reason the funky chicken commences, everything else in the log seems consistent that is why I can only think something's gone wrong and the only variable that you pointed out was the new beta so if you can rule that out, you can move on.

As per what edcmat said I have seen some strange shit too, but the strangest one I found did the exact opposite - it was a decay multi of some sort from memory. But if you haven't changed the tune than other than trying what I said above or trying what edcmat suggested then I am not too sure.

Log injector flow rate, just for kicks... Also add dynamic airflow and dynamic cylinder airmass.

As soon as I get the old beta re-downloaded I'll continue on and see what it does. If not I suppose I'll start from scratch. Whoopee :(

I friggning love the terminnoligy in here !!

What year silverado, and what ECM? If it helps, I just did a 50% scaled tune (FIC1000) for my 2006 Trailblazer SS with the 6.0 in it (E40). It drives and runs great, just set a new PB time with it. Then the tranny puked.......sigh. PM if you want a copy of the tune.

I'm having some cold start issues with our Supercharged 08 as well, nothing this drastic though.

Keep us updated

Well, I did an entire rewrite back to stock, then rescaled for the injectors. This totally cured the cold start problem.....

However! Now whenever you hold the throttle steady the TB bounces back and forth between 26 and 33% making the rpm and entire truck surge like..... Like blower surge!

Not to mention I have a nasty oil leak to take care of. :(

Again I have no idea what caused that cold start problem at all. It just randomly did it.

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Originally Posted by gn2beatu

What year silverado, and what ECM? If it helps, I just did a 50% scaled tune (FIC1000) for my 2006 Trailblazer SS with the 6.0 in it (E40). It drives and runs great, just set a new PB time with it. Then the tranny puked.......sigh. PM if you want a copy of the tune.

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Thanks but this is E38 stuff here. No bueno.

I had startup issues on Vette with 2000 CC IDC Injectors. Then I remembered the Cranking % table.... Scaled to 20% and Voila! Starts nice every time now...

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Originally Posted by 383_Stroker

I'm having some cold start issues with our Supercharged 08 as well, nothing this drastic though.

Keep us updated

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What does your issue look like?

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Originally Posted by EC_Tune

I had startup issues on Vette with 2000 CC IDC Injectors. Then I remembered the Cranking % table.... Scaled to 20% and Voila! Starts nice every time now...

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In my tune, the cranking VE is set to 50%. Concerning the 50% scale of my tune :) I tried the data out of a 2007 Corvette Z06 for the TB and now it is doing much better. Cold starts right on. Warm starts just about flawless.

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Originally Posted by IDRIVEAG8GT

What does your issue look like?

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It's fine if you don't act stupid... lol.. However, my dad has a tendency to start the truck, back out of the driveway.. and blow the tires off immediately. When you do this and it's sub 40* outside, it goes off the charts rich, loads up, and dies.

I've actually been leaving it like this so he'll stop stressing me out by going wot on a cold motor... :D

Pretty sure i can level it out by adjusting on the ECT Multiplier..

Sounds like the perfect candidate for lowering the RPM limiter vs ERT vs ECT so he cannot rag on a old engine :)

To IDRIVEAG8GT did you confirm that the beta caused the issue, and if yes which version were you running? Glad youbgot the issue sorted though.