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Selecting drive on cold start

Practical Reflash Tuning

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Hello Everyone.

I have a L98 with a small cam and LSA blower fitted, running standard boost and standard LSA injectors and L98 throttle body.

when the car is warm, then engine runs and drives great, all AFR's are good and selecting drive and reverse is fine.

When starting cold, The engine starts and runs fine but when selecting Drive, it stalls, or the idle drops so low it nearly stalls and then revs right up again. It only does it first thing in the morning and then is fine, I have played around with the idle airlfow drive transition but nothing seems to make any difference, AFR when starting cold is around 1.00 lambda. what am i missing here as i have been struggling with this for about 12 months, as soon as we come into warmer weather i don't have a problem, Cold start temps are around 5-10 degrees Celsius.

I have added my tune in for reference.

Thanks

Hi Ben try adding your tune file again it hasnt attached

Hello.

Hopefully my tune is attached now.

thanks

Attached Files

here is a scan of me starting the car also if this helps

Attached Files

I typed up a post & must have missed the send button. I have an E38 computer in my car, not sure if yours is the same. My version of HPT is old, 2.24 so most likely I cannot view your files.

My guess is you need to head to the fuel tab, then go into "Open & Closed Loop" Upper left in my version is Open Loop. There you will see Gas(Gear) & Gas(P/N). Those tables reference Intake Valve Temp vs Engine Coolant Temp, that should increase your cold start warm up fuel.

Maybe check your temperature to Closed Loop Enable, make sure those temperature are high enough so you stay OL during warm up.

Hello Dale.

Thanks for that. i logged it again this morning and when starting cold is commands 12.5 afr but as soon as i select gear it drops to 6.5-1.

After reading you post I looked at those graphs and there are quite different. from in gear to P-N, as a start, should i just copy the P-N one into the gear table as it starts well and runs well at in park, it is just in gear that is the problem?

Thanks

I'm somewhat confused between your first post & your last one. Your first post states when starting cold your are seeing 1.0 lambda, the last post states cold 12.5 AFR p/n then 6.5AFR when you go into gear.

What is the stoich of your fuel?

When I suggested those tables, it was based on your 1.0 lambda comment....that would be lean for a cold start.

I would be curious your TPS position during cold start & when you go into gear.

Hello Dale.

My wideband is showing 14.7 but i think that is due to it hasn't warmed up yet.

the commanded AFR is 12.5-1 but when in gear it drops to 7.0-1 for the commanded AFR. The widband the entire time stays at 14.7.

For cold start you need the WB warmed & ready. Maybe a toggle for switched & unswitched power to the WB. Are you sure the WB is functioning & reading correctly?

If you have intake valve temp & ETC in your table when you turn the key on "not running" look @ those temps. Then you should be able to see in those tables I suggested what the targeted equiveillance ratio is. Compare the P/N where you say it runs correctly to the same cell in the Gear table.

Hello Dale.

i copied over the P/N table into the gear table and tried it this morning. It was perfect.

now i just need to fine tune the cold start and will have a perfect setup.

Thanks for you help!

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