Hondata

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

I have not checked pressure recently.

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

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

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.

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.

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

Well, well - thanks to CV19, I'm finally able to spend some time on the car.

Still no changes. Idles great at first, warms up great, all is good until it gets some throttle and all comes crashing down, LOL.

Is there any recommended folks out there that I could get in touch with to attempt to remotely troubleshoot the issues?

I am of course willing to pay, just don't know of any local resources to help with this. I'm located in south Louisiana - if anyone happens to know a good guy in the area, let me know.

Great news.

Car is running very well.

I reached out to Jeff Evans at Evans performance - https://www.evans-tuning.com/

He helped me out in no time, remotely.
The issue was simply a bad tune I believe.
After about a week of back and forth with datalogs and tune revisions, the car runs flawlessly - including idle.

I hope I don't get in trouble for promoting him here, not sure of the rules - but wanted to share my experience.

I'd recommend his services.