Trouble Starting on Hot Days

[Black Nugget]

Mods :
Siemens 900cc Injectors
Inline Pro Turbo Kit with SC5865
Fully Built Engine 9:1 Compression
NGK 7446 Spark Plugs
18psi
Hondata FlashPro

As the weather started getting a bit warmer, my car began breaking up around 6k rpms. It didn't feel to be getting any slower, just loud popping out of the exhaust. After a lot of trial and error, I lowered the gap of the NGK 7446 Spark Plugs from .035' to .030'. That helped, quite a bit with the popping not starting until 7k rpms.
The next day I changed the gap down to .027'. The popping/breaking up was completely gone.

Now.. on hot days my car has trouble starting. It continues to attempt to crank, probably 5-7 seconds. Sometimes after that it will start, but immediately stall unless I smack the gas to rev it up right as it starts.
I've lowered Cranking Fuel Trim from 3% (original tune) to 0%. It will start up fine, but then after 1-2 days will go back to the problem of cranking for 5-7 seconds. I then lowered the Cranking Fuel Trim to -4% and had the same issue; fired fine first day or two, then goes back to taking 5-7 seconds..




Since then, I have spoken with members from S2Ki and we have assumed that it's my air temperature compensation values.

We have moved the Cranking Fuel Trim to 0%. Then we altered the three right most Air Temperature Compensation temperatures to 90', 125', and 155' with their value's being -1.5%, -3.2%, and -5%.

Working with my tuner to resolve it, but it's a pain since he's three hours away.

Any recommendations?

[Spunkster]

Please don't post screenshots. You have to post your calibration and a datalog showing the problem.

[Black Nugget]

Newest Datalog and Calibration

This is using the current calibration with air temperature compensation values being set at 90' = -1.5%, 125' = -3.2%, and 155' = -5%.
As well, Cranking Fuel Trim is set to 0% as seen in the calibration.

Car took 6 seconds of continuous cranking to start.

[Spunkster]

You should start by putting all your compensation tables back to stock and just try adjusting the cranking fuel table.. Try adding fuel instead of taking fuel away and see if it starts any easier.

[Black Nugget]

You should start by putting all your compensation tables back to stock and just try adjusting the cranking fuel table.. Try adding fuel instead of taking fuel away and see if it starts any easier.

Thank you! I'll go to my car in the next few minutes to give that a shot.

[Black Nugget]

First start attempt datalog.
Added 10% fuel into the cranking fuel table.



Approximately 3 hours since last time the car was started. Outside temperature gauge reading 93'.


As well, including the calibration that is being used now. Default compensation value's, as well as original calibrations 3% cranking fuel trim amount.

[Black Nugget]

Day 2 with +10 Cranking Fuel Map.



First start, 8am at 79' Outside. Took a little bit of cranking to start (4.5 seconds), but eventually started.

Second start, 12pm at 90' Outside. 8 seconds of attempting cranking before firing and immediately stalling.

Third start, moments after the second start. Took a little bit to start (4 seconds).



What does Hondata recommend?

[Black Nugget]

As cranking only got worse, I attempted the other direction.

Installed NGK 2668 Plugs gapped at 0.026'. 2-Heat Ranges Colder.

I uploaded my original calibration, editing the original +3% cranking fuel trim down to -10%.

Starting was better than it was when adding fuel; this start took 5.5 seconds.

Here is the newest used calibration and datalog.

[Black Nugget]

Decided to go a bit more aggressive on my most recent upload.

I have changed back to the original compensation value's and lowered the Cranking Fuel Trim to -30%.

Included is this new calibration.

The first start was at 88', approximately 1.5hrs since last time the car started.
The second start was at 78', approximately 12hrs since the last time the car started.
The third start was at 97', approximately 3hrs since last time the car was running.

The third datalog is much longer... as it shows the car cranking, then fire and immediately stall, then me pause and start cranking again.



Hondata, any recommendations? Even -30% isn't helping.

[Hondata]

I think it would be a good idea to measure the leakdown and do a compressure test.

Otherwise, wire the wastegate open, put the stock injectors in, reset the cranking trims and injector size to stock and then see what trim you need to get the car to start consistently.

[Black Nugget]

I think it would be a good idea to measure the leakdown and do a compressure test.

Otherwise, wire the wastegate open, put the stock injectors in, reset the cranking trims and injector size to stock and then see what trim you need to get the car to start consistently.

Thank you. I know of a friend that has the tools to do a compression test; he's checking to see if he has access to what's needed for a leakdown test.


If it does get to the latter and I have to replace my injectors with stock size for testing purposes, how much time should be given between tests to ensure that the start is accurate?

[Hondata]

how much time should be given between tests to ensure that the start is accurate?

At least 30 minutes.