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Hot Start Issue

Hanaldo

By Hanaldo,
in Engines & Forced Induction

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Hanaldo Grand Master

Hanaldo

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Ok just checked the cranking voltage on the fully charge battery, it only dropped to 9.9 at it's lowest. So a little bit low still but not as bad as 7.8.

And once started, both battery and turbo timer were reading around 14.4v.

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DVS JEZ Grand Master

DVS JEZ

Posted
Posted

Waaay to many long posts to read.

With the nistune and bigger injectors. Nistunes dont seem to recalculate the cranking tables when doing a injector resize. Sir rb's car was my first nistune and from his hot start issues and an rb20 i did last week i noticed they both required a fair bit of fuel to be removed on hit start.

Hanaldo. Drop the numbers from 35 or what ever it was down atleast 5-10 and try. Rememer to write to ecu after changine the settings and try.turn it off straight away. Rinse lather repeat

Hanaldo Grand Master

Hanaldo

Posted
  • Author
Posted (edited)

Waaay to many long posts to read.

With the nistune and bigger injectors. Nistunes dont seem to recalculate the cranking tables when doing a injector resize. Sir rb's car was my first nistune and from his hot start issues and an rb20 i did last week i noticed they both required a fair bit of fuel to be removed on hit start.

Hanaldo. Drop the numbers from 35 or what ever it was down atleast 5-10 and try. Rememer to write to ecu after changine the settings and try.turn it off straight away. Rinse lather repeat

Thanks Jez, I'll give that a go. Is this on the Crank Enrich table? What about the crank enrich offset tables, do they need to be changed as well? The enrichment value on the Crank Enrich table is only at 8% from 50 degrees on-wards, I'll try lowering it slowly.

Edited by Hanaldo
Hanaldo Grand Master

Hanaldo

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Mmm didn't achieve much there. Tried changing the Crank Enrich table values (set at 8 normally) as high as 30 to as low 2. Didn't affect anything. Also tried changing the Crank Enrich Offset tables, but that didn't do anything either. I did notice the ECU was giving a code about the Throttle Motor Sensor? Likely related??

In any case, I think I've tried all I can. Need to take it back to my tuner. *sigh* more money :(

joeyta22 Enthusiast

joeyta22

Posted
Posted

I'm another one having hot start issues with my r32gtr, it's not as bad as the guys in previous posts, it's taken maybe max 3 or 4 attempts before spluttering into life. I'm running a PFC with a reasonabley tame engine setup although some tomei drop in cams have been installed and not tuned with them, so could partially have to do with that (but cranks over first time everytime when cold).

Interested to see what the problem turns out to be. Goodluck guys.

Room42 Proficient

Room42

Posted
Posted

Waaay to many long posts to read.

With the nistune and bigger injectors. Nistunes dont seem to recalculate the cranking tables when doing a injector resize. Sir rb's car was my first nistune and from his hot start issues and an rb20 i did last week i noticed they both required a fair bit of fuel to be removed on hit start.

Hanaldo. Drop the numbers from 35 or what ever it was down atleast 5-10 and try. Rememer to write to ecu after changine the settings and try.turn it off straight away. Rinse lather repeat

Gotta read them long boring posts otherwise you wont know what people are on about. It was my car that I tried 35 ms. Hanaldo's ms figures are at 8 and 10. We have tried pulling fuel out and adding fuel.

Hanaldo don't even think about paying to get it looked at. We will get it worked out.

Room42 Proficient

Room42

Posted
Posted

Try crimping the return fuel line when starting see if that helps at all.

Yep try it. That will rule out the fuel reg. I spoke to a bloke the other day and he reckoned that with bigger injectors, when you try to start the car they dont actually open for long enough to let fuel out. But both our cars start fine when cold and not when hot. Where are the common links here? I'm going to try crimping the fuel line tomorrow and see if that helps.

rob82 Mentor

rob82

Posted
Posted

To me it still sounds like an injector issue or battery voltage issue to the injector.

I've had issues with some sard injectors not turning on around 8-9 volts with 4bar base pressure. We had to drop it down to 3bar to get it to start.

Its time to scope the injector pattern at crank and compare good vs bad. More specifically check the peak inductive ring voltage from good to bad and see if the the injector is properly saturating.

Either that or you could try patching another known good battery onto the injector harness.

Room42 Proficient

Room42

Posted
Posted

I ran a chart for inj duty cycle with my datalogit when I was cranking. No matter what I did the injectors opened slowly from 0 rpm to idle. Even adding more cranking ms there was a spike after it started but still had the same initial slope. The injectors are definitely not working according to the tune at cranking rpm. Maybe that is what you get for buying cheap injectors?

Lithium Grand Master

Lithium

Posted
Posted

I ran a chart for inj duty cycle with my datalogit when I was cranking. No matter what I did the injectors opened slowly from 0 rpm to idle. Even adding more cranking ms there was a spike after it started but still had the same initial slope. The injectors are definitely not working according to the tune at cranking rpm. Maybe that is what you get for buying cheap injectors?

You mean you logged IDC with the Datalogit? If so, you aren't logging what the injectors are doing - you're logging what the PFC is telling them to do.

Randon_I_Am Veteran

Randon_I_Am

Posted
Posted

Don't rule out the battery!

I had the exact same thing, with nistune, bigger injectors... I would get stuck in all sorts of places, then I changed the battery and got a trickle charger that sits on it every night, and the problem hasn't happened at all since then :)

Are the cables you used to relocate the battery big enough?

Hanaldo Grand Master

Hanaldo

Posted
  • Author
Posted

Yes but I've already tried a new battery? If a 720cca battery isn't going to make any difference then it doesnt seem likely that it's the battery. I used 00 gauge cable, it's plenty big :)

Room42 Proficient

Room42

Posted
Posted

You mean you logged IDC with the Datalogit? If so, you aren't logging what the injectors are doing - you're logging what the PFC is telling them to do.

Are you sure that is how it logs? Why would the power fc tell the injectors to spray bugger all fuel at the start of cranking then more after it starts once I added a larger ms time? It 'should' be telling the injectors to open for 'x' amount of time immediately. If the injectors aren't doing what the pfc or in Hanaldo's case nistune, then it seems that the injectors are crap. What is your take on the whole hot start thing Lithium?

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