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Warm start issue


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Hi guys

Edit: I am also having another issue where once warm/hot the car will not start if i leave it for more than a few minutes. Starts and restarts cold and warm every time if not left for long (when warm can turn it off and restart repeatedly) but when up to 90degrees ect and left to heat soak when the IAT is around 40-60 degrees the car will just crank continuously but not start. As soon as the IAT cools down to 20degrees it starts fine with no throttle. If i hold 100% throttle it will rumble into life after 10 seconds or so. Do i need adjustments to my warm crank enrichment and add or remove fuel? Or my IAT compensation table at the 40-60 degree range at 0% TPS? (Does the IAT compenstaion table affect starting fuel as not rpm based?)Not sure if i need to add or remove i fuel as it will not burp or anything when this hot and part throttle doesnt help, and wideband only up after 30 seconds so not much help. 

How do my current crank enrichment and IAT comp tables look?





I have been playing around with my idle settings over the last few days. I have gotten the warm up and cold start sorted and once the car gets into idle the idle is stable at 14.7AFR and my target of 950RPM when warm. The car has also been dyno tuned by my tuner in regards to the rest of the ecu. It is on my toyota altezza with 9.0:1 compression, stock cams just uprated valve springs. It is running a hypertune manual throttle body with a 2 wire NZefi idle control valve(set at 120Hz as this is what was recomended on the idle valve info sheet)(is this correct as all link and others say 200-300Hz). With the idle control turned off it idles around 500-600rpm on the throttle plate but will stall eventually if the throttle is stabbed and the rpms are not controlled coming back down.

The problem I am having is every so often when coming to a stop clutch in at traffic lights etc the rpm will drop quickly and sometimes head to around 500-600rpm, before shooting up to 1500rpm and then does this over a few times before finally settling into idle, or sometimes it will not settle and oscillate between the low and high rpms and I need to give it tiny throttle input to settle it. I have also set up the idle ignition control. The log attached the drive actually went pretty well except the last few stops right at the end where the 600rpm happens (gets close to stalling but never does). 

Is someone able to look over my tune and give me their thoughts on my settings? I had noticed the ignition values on the main table jump around from 18-12-16 around the idle zone if that may not be helping) but thinking it may be to do with my idle settings. Fan step, AC and startup etc are all ok. 

Ideally I would like the rpms to drop and then hold above the RPM target and then slowly come down to it, rather than dropping below/through the rpm idle range it and having to catch the stall and bounce up and then drop again.


Note running an innovate wideband that comes online 30 seconds after car is started


Base fuel pressure was set at 43.5psi by tuner on my 1050X ID injectors. I also noticed that the injector size does not say 1060cc at 43.5psi  like the data sheet said that came with all the other injector values (currently reads 900cc at rated fuel pressure?)





300kW Cold start, Idle sorted final.pclr

log testing idle coming to a stop.llg

Edited by Brendon001
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I have only had a chance for a very brief look, but my initial feeling is the speed lockout for idle ignition control is too low.  It is currently locked out above 2kmh so it is not taking any action when you are moving.  Try it at around 10kmh looks like it would capture those situations better.

Can you also update to the latest firmware as it looks like the speed lockout for the idle valve control is not honouring the setting either (unless you changed that after the log was taken).  Im pretty sure that normally works.

BTW, 120Hz is about right for the ford valves.

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Hope I'm not treading on your toes Adam, I was just replying too....... :-)

The RPM lockout for Idle Ignition Control is set to 1200, perhaps set this higher so that the ignition idle table comes into play and bring the RPM down.

The Idle Ignition Table at zero error should be 16 (not 12) to help with a smooth transition between tables (maybe add 4 to all values as a starting point).

The Overrun Deactivation Table looks to have rather low values (at normal operating) temperature, which may cause the RPM undershoot (as it goes lean on the approach to target idle RPM).  You could even turn this off until you're happy with the idle.

The Overrun Ignition Trim (linked to the above) also causes the ignition timing to be retarded (by 10 degrees) on the approach to target idle, further causing RPM undershoot.

It may be useful to switch Idle Speed Control to Open Loop to carry out the above tweaks.  Then once the idle is a good as you can get it, switch it back to Closed Loop.

I have been through this process a few times and had great success with this approach :-) 

Re your comment "Ideally I would like the rpms to drop and then hold above the RPM target and then slowly come down to it" I agree, but can't see an elegant way of doing this.

Hope that helps...

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Thanks guys pretty much sorted now! Updated the firmware, raised the idle ignition  rmp lockout, raised the idle ignition value to 16 at 0 error and adjusted all the upper and lower error rpm columns, and updates the overrun rpm ect activation table at the warm temperatures. 

This gave the idle setup more chance to catch the rpm and now it will drop to around 650-700rpm, raise to around 1000 then settle to idle pretty quickly with no bouncing. Just need to fine tune the idle dc settings on the solenoid and will be sorted! 



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Hi Brendon,

With regards to the hot-start issue, in my opinion, this will be trial and error and I guess you need more fuel to get it started (assuming it doesn't already smell rich on cranking?).

You could try increasing the values in Pre-Crank Prime table (since it's not even starting).  If the 'hot-start' problem is repeatable, you should soon find out if you're improving the situation.  



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Hi timmy. 


Tried the above suggestion and would work with increased values when IAT sensor was around 50-60 degrees but then when at 90degrees ECT and normal 20degrees IAT engine would flood and foul plugs. 

Ended up leaving those settings and doing similiar to the HP academy 350z tune and put positive values in the 0%TPS row from 40degrees to 80degrees IAT on the IAT compensation table, starts perfect any temperature now and even when the sensor heat soaks  after 10-30 minutes the positive values give the extra fuel required :)

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