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 Post subject: Hard to start when hot
PostPosted: Fri Nov 17, 2017 7:46 pm 
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Hi Guys,

Been dealing with this issue for a little bit now, just wanted to hopefully get some insight. Rx-7 S4, Auto (4N71B) 13BT, ID1000's primary, bosch 1650cc secondaries, aftermarket fuel pump, adaptronic plug n play ECU, LS2 coils and RX-8 starter.

I'm fairly sure this issue has only arised after I put ID1000's in the primaries, I've done a lot of adjusting with the cranking fuel map, neither putting in fuel or taking out seems to help, I most of the time have to use the accelerator to get it to start hot, I'd say around 80% of the time.

Without the accelerator, it feels like it wants to fire up, but sits on around 300-500RPM just trying to catch, if I give it a bit of accelerator, it'll catch pretty much instantly. I've attempted to do a comp test with a piston tester, which netted 60psi on all rotors but found out it's leaking, so I will get a new one tomorrow to confirm compression.

Just wanted to see if anyone has dealt with this before or might have some information.

Cheers,


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 Post subject: Re: Hard to start when hot
PostPosted: Fri Nov 17, 2017 8:19 pm 
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my guess is fuel is hot and the map you are playing is only the initial shot
try and find an after start enrichment map and lift that a tad for hot start

however the tardy warm start is also symptomatic of a lowish comp engine ,usually not a problem till they all read under 80
but the simple act of adding air with the fuel on startup isnt such an issue worth busting a nut over.
just check the engine is ok and consistent and start it how it wants to be started

nothing like what the weber boys have to deal with

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 Post subject: Re: Hard to start when hot
PostPosted: Fri Nov 17, 2017 8:38 pm 
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The map i'm playing with is the cranking fuel map (temperature scaling), until the car reaches over 400RPM then it'll switch to the regular fuel map, once it's started, it's completely fine, idles happily.

Yeah that's what I thought, motor has been rebuilt recently and only seemed to arise when the ID1000's went in, might go back to the stock injectors for shits and giggles to see if that cures it. Haha yeah sometimes it feels like a bit of a carby the way I gotta use the throttle, I guess I'll just continue to do it unless it gets worse.

Cheers.


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 Post subject: Re: Hard to start when hot
PostPosted: Fri Nov 17, 2017 8:42 pm 
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i drop crank maps to 250 rpm thresholds too. give it a try

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 Post subject: Re: Hard to start when hot
PostPosted: Fri Nov 17, 2017 8:46 pm 
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I'll give it a whirl, the RX-8 starter makes it crank @ 290-300RPM. I've also got two options for cranking RPM, which one would you recommend the 250RM threshold?

Appreciate the advise.


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 Post subject: Re: Hard to start when hot
PostPosted: Fri Nov 17, 2017 11:02 pm 
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set min to 200 max to 300 . give it a whirl . it may well be no fuel is injected if the min threshold is too high

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 Post subject: Re: Hard to start when hot
PostPosted: Fri Nov 17, 2017 11:36 pm 
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I'll give it a try and let you know. Just found this on the adaptronic website if it helps out at all:

Min Run RPM = if the engine rpm falls below this level, the ECU will
revert to cranking fuel/ignition settings.
Max Crank RPM = once the rpm exceeds this level the ECU switches
from cranking setting to engine running fuel/ignition settings.


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 Post subject: Re: Hard to start when hot
PostPosted: Sun Nov 19, 2017 3:36 pm 
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So comp tested it again, 60psi on each face. Then put the Schroeder valve back in, max of 60psi, guess it's time to pull the motor out.

Any ideas on what could be causing it to be 60psi on each face, both rotors? Side seals/corner seals?

Thanks,


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 Post subject: Re: Hard to start when hot
PostPosted: Mon Nov 20, 2017 11:40 am 
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So let it sit in ATF overnight, fired it up to a nice smoke show, let it run for around 10-15 until the smoke mostly dissapaeared. Retested and got 70psi.

Could it possibly just be carbon?

Thanks,


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 Post subject: Re: Hard to start when hot
PostPosted: Tue Nov 21, 2017 10:47 am 
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i wouldnt trust the number absolutely unless i had a 3 face digital tester . you have them all even and that is a good sign . if it idles strong then that also is a good sign

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 Post subject: Re: Hard to start when hot
PostPosted: Tue Nov 21, 2017 3:25 pm 
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If it quacks like duck....


I’d go and ask the engine builder what the %#CK

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 Post subject: Re: Hard to start when hot
PostPosted: Thu Nov 23, 2017 8:40 am 
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Just a thought - I've experienced the same problem with 2 cars after putting in worked (piston) motors. It both cases turned out to be the battery leads, which I replaced with heavier duty items and the problem went away.

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 Post subject: Re: Hard to start when hot
PostPosted: Thu Nov 23, 2017 1:43 pm 
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I’ve tried using another car with jumper cables to rule out any voltage drops or anything weird like that, even went back to the 550cc factory injectors, same deal. (yes I adjusted the tune to suit)

Safe to say, the compression is low and the comp tester will be accurate. So time to pull the motor, I’m converting to manual anyway, so give it a freshen up while it’s out.

Thanks,


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