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Hot start issue


scotty
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Hi guys, hoping you can help me out here.

Its one of those problems that's hard to nail down, as I only get a short time to try stuff and it doesn't always happen.

When I try to restart my  ba xr8 after driving it for a while all it does is wind over and won't fire. The only way I can then get it to start is to force start it on lpg.

This only happens if I try to restart it within about 10 mins of turning it off, but it will restart fine if its only a short trip.

At first I was suspecting my aftermarket fpr may of being getting heat soak and affecting fuel pressure but I checked that today and fuel pressure is fine.

I was then starting to suspect heat soak in my billet fuel rails causing it to vaporize and they were pretty hot to the touch, so I tried cycling the fuel pump to cool them to

see if that would resolve the issue but no such luck. The reason I believe its fuel related is that it will start on lpg after a few winds. The next thing I'm thinking could

be an issue is vapour lock at the injectors but I'm not sure how to check that. Fuel trims all look good, within 3%, so any ideas would be a great help.

Thanks Scotty

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Figure out exactly what coolant temp it is at when you do a hot start. Then massively enrichen that part of the cranking lambda table. If it still doesn't start then you have a mechanical fueling related issue.

The PCM already takes into account a heat soaked fuel rail and compensates for it on startup.

You could also try pulling your fuel rail out and checking it is spraying when hot.

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  • 5 months later...

Thank you BeerTurbo.  Appreciate it.  Will advise after changes.  I notice yesterday, the commanded hot start spark advance was about 5.5.  After some work with the tables especially AUF222 where the table was halved resulted in excellent hot start.

 image.png.13a2f9e1951529e3790c30d99390d171.png

 

We are working throught the wider implications of this table on the main spark request during running an WOT.  These values were also used in my vehicle which has massive cams and has resulted in good startup.  

PLease confirm Auf0181 to be like:

image.png.13f3375d94a77e8cbd37fd073e110af5.png

 

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after reading Roland's thread id take a different route.

the Auf0181 from the ba v8 file i have is basically 1's, but if you compare it to a turbo terry there a big difference. .5 might be a bit drastic...but it might be ok to testing.

perhaps you can start of the file at 1.2 in the first two rows then go to 0.8 in the third col (16) and test that, at least then it wont run to rich right of the button.

see TT file attached.

image.png.3cc7252bd7b3364352d33e0f413a3119.png

 

auF0180 for your commanded lambda during cranking at the temp you mentioned is 1 - so you can change it here or in the other table.

 

Edited by BeerTurbo
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It's the reverse, larger numbers are richer, smaller numbers are leaner. 

Eg in the e85 thread everyone ends up with big numbers. The multiplier is actually a divider for lambda so larger numbers is richer. We had it wrong in the thread initially, I've updated the early posts in case people are not reading the whole thread. 

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  • 2 weeks later...
2 hours ago, BeerTurbo said:

hi mate, how did you go?

Hey there.  We did not have to touch this table.  I found the spark advance was at 5deg on crank.  Modified the spark tables to get zero and worked like a charm.  Two cranks and it was started at 95deg ect which normally took 10 cranks. 

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