Kpro - K24 Idle drop and instability, tried everything....

K-Series Programmable ECU installation questions / support issues
AREA876
Posts: 388
Joined: Tue Jun 15, 2010 6:14 am
Location: Jamaica

Re: Kpro - K24 Idle drop and instability, tried everything....

Post by AREA876 » Mon Dec 17, 2018 2:44 pm

Is your fuel pressure ok?
What's the pressure when this is happening

Geauxkart
Posts: 12
Joined: Thu Apr 26, 2018 6:02 pm

Re: Kpro - K24 Idle drop and instability, tried everything....

Post by Geauxkart » Mon Dec 17, 2018 3:41 pm

I have not checked pressure recently.

The pump was replaced during the build, walbro 255.
Dyno tuning the pressure stayed constant.

TTR
Posts: 34
Joined: Wed Mar 31, 2004 8:48 pm

Re: Kpro - K24 Idle drop and instability, tried everything....

Post by TTR » Tue Dec 18, 2018 3:59 pm

Gear Comp, tip in gear retard multiplier should be -100 in every gear

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Arno
Posts: 41
Joined: Sun Sep 02, 2012 8:41 am
Location: The Netherlands

Re: Kpro - K24 Idle drop and instability, tried everything....

Post by Arno » Wed Dec 19, 2018 12:05 am

Geauxkart wrote:
Mon Dec 17, 2018 9:36 am
Go for a little ride, and it starts missing and stumbling severely on throttle tip in. Get back home and it doesn't idle well at all again, hunting up and down. AFR all over the place. Floor it at idle and it will bog down and die. Gently ease into the throttle and it will rev fine.
Do a datalog and check your MAP and especially TPS values. Symptom like this often means either is not reading right or not responding correctly.

My bet is your TPS (or it's wiring) has a problem. If the ECU doesn't see the throttle closed off enough via the TPS then it won't go into idle mode and start the rpm control using ignition advance, so that would explain your idle issue.

It revving cleanly when slowly opening the throttle but dying on fast throttle also points to this as the ECU will adjust the fueling based on the MAP feedback but it's too slow to react for quick throttle openings and you need the acceleration enrichment to kick in.

However.. If your TPS signal to the ECU is bad then it likely doesn't 'see'/notice the throttle opening fast and as a result won't apply the acceleartion enrichment (as it has no clue the throttle was suddenly opened) so it spikes lean and dies on you or it stumbles bad until the MAP sensor 'catches up' and the ECU adjusts the mixture via that route.

On issues like this it's very important to do a datalog and then verify that all sensor values are at least 'sane' in their response and what you expect. Things like TPS sudden dropouts or spikes in the datalog would be very suspicious.

TPS units are known to break internally which can cause odd behaviour, but of course wiring/connector issues could also be present. The latter can sometimes be tested by letting the car idle (or at least trying to ;) ), pop the hood and then wiggle the wires and connectors around the TPS area. If it suddenly smooths out then you have a pointer to a potential problem area.

BYe, Arno.

fonzeka
Posts: 70
Joined: Thu Feb 11, 2016 4:15 am
Location: Sweden

Re: Kpro - K24 Idle drop and instability, tried everything....

Post by fonzeka » Wed Dec 19, 2018 8:50 am

It can also be very useful to datalog and check the TPS signal with just the ignition on.
That way you can really provoke it without worrying about the engine revving like crazy.

Geauxkart
Posts: 12
Joined: Thu Apr 26, 2018 6:02 pm

Re: Kpro - K24 Idle drop and instability, tried everything....

Post by Geauxkart » Wed Dec 19, 2018 8:58 am

Thanks for the tips guys. When I get some time, I will jump back into it and let you know what I find out.

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