Help, Hot starts
04-18-2010, 06:24 AM
#1
Help, Hot starts
I am having an issue when I take a short trip about 7 miles or so and get out of the car for about 5-10 min. It will not restart. It just cranks over and over and nothing. If you let it set for some time it will start. I have check for codes and there are not any.
Any Ideas?
Injectors: Deatschwerks 600cc
Fuel Pump: Walbro 255
EM: Osiris. Currently running GTM Spec Base Tune
S/c: HKS GT Supercharger (GMT Stage 4, 10 PSI)
Thanks,
Any Ideas?
Injectors: Deatschwerks 600cc
Fuel Pump: Walbro 255
EM: Osiris. Currently running GTM Spec Base Tune
S/c: HKS GT Supercharger (GMT Stage 4, 10 PSI)
Thanks,
04-18-2010, 08:29 AM
#3
Classic hot start issue with bigger injectors...I didn't have it with my 440cc but it started showing up when I switched to 650cc and up...
Pumping/stepping on the gas pedal while starting the car solves it for me....kinda irritating but it get the job done...
And I'd like to say that a reflash will help, but not necessarily...I have Osiris and I still have the issue; maybe its because my tuner focuses on the tune and not as much on the starts...I'll have my tuner re-do the starts in the future and see if it improves anything...
And in your setup, its possible the GTM base tune might still be setup for stock injectors; you should ask Sam to verify this...
Pumping/stepping on the gas pedal while starting the car solves it for me....kinda irritating but it get the job done...
And I'd like to say that a reflash will help, but not necessarily...I have Osiris and I still have the issue; maybe its because my tuner focuses on the tune and not as much on the starts...I'll have my tuner re-do the starts in the future and see if it improves anything...
And in your setup, its possible the GTM base tune might still be setup for stock injectors; you should ask Sam to verify this...
I am having an issue when I take a short trip about 7 miles or so and get out of the car for about 5-10 min. It will not restart. It just cranks over and over and nothing. If you let it set for some time it will start. I have check for codes and there are not any.
Any Ideas?
Injectors: Deatschwerks 600cc
Fuel Pump: Walbro 255
EM: Osiris. Currently running GTM Spec Base Tune
S/c: HKS GT Supercharger (GMT Stage 4, 10 PSI)
Thanks,
Any Ideas?
Injectors: Deatschwerks 600cc
Fuel Pump: Walbro 255
EM: Osiris. Currently running GTM Spec Base Tune
S/c: HKS GT Supercharger (GMT Stage 4, 10 PSI)
Thanks,
Last edited by 350z006; 04-18-2010 at 08:31 AM.
04-18-2010, 08:59 AM
#4
Hot start issues are usually do to excess fuel in my limited experience. You have a Osiris cable so you can adjust it but you would have to get either Sam's help or UpRev's to get a reflash reworked and sent out to you. I'm not sure what arrangement they have for support. I would give Sam a call on Monday.
04-27-2010, 03:49 PM
#6
Today I was looking through my Osiris Rom editor and came across this Starting Enrichment.
Old Rom File. This is not currently whats in my Rom:
I wonder if adjusting these values down from the 60c mark to the 100c mark would help?
I am thinking at:
60c = 46%
80c = 36%
100c = 26%
?
Old Rom File. This is not currently whats in my Rom:
I wonder if adjusting these values down from the 60c mark to the 100c mark would help?
I am thinking at:
60c = 46%
80c = 36%
100c = 26%
?
04-27-2010, 06:01 PM
#7
The hot start problem when using larger injectors is not always caused by too much fuel.
It may well be the opposite, not enough fuel.
As you are using a re-flashed OE ECU & OE O2 sensor feedback, the motor under light load & idle situations only requires the same or similar amounts of fuel as a stock motor.
With the much larger injectors the lambda feedback to the ECU will be showing a rich mixture & the ECU will now compensate by shortening the injector pulse width.
The short term memory trim learns this and depending on how much bigger the new injectors are its quite possible that the opening times of the larger injectors has closed down so much to achieve the correct AF ratio that there is not enough fuel being injected on cranking when the motor is hot when more fuel is needed to start.
To confirm wether you motor is too rich or too lean at hot start cranking, get someone to stand behind the car to see if there is a lot of black smoke from the exhaust when the motor finally starts. If there is, your motor is defiantly too rich at hot start.
If on the other hand if you squirt a little gas or aerosol engine start fluid through the little capped pipe that's located at the front of the upper plenum
( the one that is often used as the source for a map sensor in FI )
and the motor immediately starts, then the motor is too lean at hot start crank
It may well be the opposite, not enough fuel.
As you are using a re-flashed OE ECU & OE O2 sensor feedback, the motor under light load & idle situations only requires the same or similar amounts of fuel as a stock motor.
With the much larger injectors the lambda feedback to the ECU will be showing a rich mixture & the ECU will now compensate by shortening the injector pulse width.
The short term memory trim learns this and depending on how much bigger the new injectors are its quite possible that the opening times of the larger injectors has closed down so much to achieve the correct AF ratio that there is not enough fuel being injected on cranking when the motor is hot when more fuel is needed to start.
To confirm wether you motor is too rich or too lean at hot start cranking, get someone to stand behind the car to see if there is a lot of black smoke from the exhaust when the motor finally starts. If there is, your motor is defiantly too rich at hot start.
If on the other hand if you squirt a little gas or aerosol engine start fluid through the little capped pipe that's located at the front of the upper plenum
( the one that is often used as the source for a map sensor in FI )
and the motor immediately starts, then the motor is too lean at hot start crank
Last edited by Nathan; 04-27-2010 at 11:14 PM.
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04-27-2010, 06:37 PM
#9
The hot start problem when using larger injectors is not always caused by too much fuel.
It may well be the opposite, not enough fuel.
As you are using a re-flashed OE ECU & OE O2 sensor feedback, the motor under light load & idle situations only requires the same or similar amounts of fuel as a stock motor.
With the much larger injectors the lambda feedback to the ECU will be showing a rich mixture & the ECU will now compensate by shortening the injector pulse width.
The short term memory trim learns this and depending on how much bigger the new injectors are its quite possible that the opening times of the larger injectors has closed down so much to achieve the correct AF ratio that there is not enough fuel being injected on cranking when the motor is hot when more fuel is needed to start.
To confirm wether you motor is too rich or too lean at hot start cranking, get someone to stand behind the car to see if there is a lot of black smoke from the exhaust when the motor finally starts. If there is, your motor is defiantly too rich at hot start.
If on the other hand you squirt a little gas or aerosol engine start fluid through the little capped pipe that located at the front of the upper plenum
( the one that is often used as the source for a map sensor in FI )
and the motor immediately starts, then the motor is too lean at hot start crank
It may well be the opposite, not enough fuel.
As you are using a re-flashed OE ECU & OE O2 sensor feedback, the motor under light load & idle situations only requires the same or similar amounts of fuel as a stock motor.
With the much larger injectors the lambda feedback to the ECU will be showing a rich mixture & the ECU will now compensate by shortening the injector pulse width.
The short term memory trim learns this and depending on how much bigger the new injectors are its quite possible that the opening times of the larger injectors has closed down so much to achieve the correct AF ratio that there is not enough fuel being injected on cranking when the motor is hot when more fuel is needed to start.
To confirm wether you motor is too rich or too lean at hot start cranking, get someone to stand behind the car to see if there is a lot of black smoke from the exhaust when the motor finally starts. If there is, your motor is defiantly too rich at hot start.
If on the other hand you squirt a little gas or aerosol engine start fluid through the little capped pipe that located at the front of the upper plenum
( the one that is often used as the source for a map sensor in FI )
and the motor immediately starts, then the motor is too lean at hot start crank
05-10-2010, 09:39 AM
#10
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This is what mine finally looked like to get it to hot start with 800cc injectors.
Try cutting those numbers down further if you need to.
Trick is, if it gets worse when you lower them, then go the other way. You'll find out real fast that way if it is lean or rich. Mine was way too rich. Usually it will be rich with the larger injectors.
Try cutting those numbers down further if you need to.
Trick is, if it gets worse when you lower them, then go the other way. You'll find out real fast that way if it is lean or rich. Mine was way too rich. Usually it will be rich with the larger injectors.
05-14-2010, 05:28 PM
#11
This is what mine finally looked like to get it to hot start with 800cc injectors.
Try cutting those numbers down further if you need to.
Trick is, if it gets worse when you lower them, then go the other way. You'll find out real fast that way if it is lean or rich. Mine was way too rich. Usually it will be rich with the larger injectors.
Try cutting those numbers down further if you need to.
Trick is, if it gets worse when you lower them, then go the other way. You'll find out real fast that way if it is lean or rich. Mine was way too rich. Usually it will be rich with the larger injectors.
05-14-2010, 09:13 PM
#16
I've never had hot start issues (after warmed up or driving, it starts up perfect and idles normal) but I have had/sometimes have cold start issues (engine starts after a few cranks, but rpms would be very low/belts don't seem to be driven 100%, then after a few seconds, the idle jumps up to where it is supposed to be on a cold start and the belts are driven normally and the engine runs fine).
05-15-2010, 10:34 AM
#17
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I've never had hot start issues (after warmed up or driving, it starts up perfect and idles normal) but I have had/sometimes have cold start issues (engine starts after a few cranks, but rpms would be very low/belts don't seem to be driven 100%, then after a few seconds, the idle jumps up to where it is supposed to be on a cold start and the belts are driven normally and the engine runs fine).
Mine did that with osiris quite a bit, it would idle low for a little while before going to my set idle rpm for that coolant temp.
since i've switched to haltech i don't have this problem because it has so many more fields to adjust for warmup.
05-15-2010, 12:24 PM
#18
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Im runnin same injectors n fuel pump as OP on a boosted single turbo at 8psi with Haltech and have no hot-start problems. Gotta be the "base" tune hes using. Or was using...
05-15-2010, 01:24 PM
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