Jrsc Euro ctr surging/fuel on closed throttle

[Corey872]

Thanks for the input,

To clear a couple of points-here in the uk we have the PRA narrowband ecu hence the afrcmd/afr.

Ah - that does explain it, then. Though given that fact, there seem to be a few other curiosities about your tune. Admittedly, I'm not well versed with the narrowband tuning, but it would seem having "WOT Compensation Fixed Lambda 0.85" checked, and values other than "14.7" in the Target Lamba tables might cause confusing issues for the ECU - though maybe checking the "Narrow band primary oxygen sensor" causes these values to be ignored.

I have today ordered another new thermostat in a quest to get the ECT to the 180-190 that hondata seem to favour. It's seems the opening temp is rated at 172 alledegally so my 'warmed up temp does seem a little low. I think the relevance of the ECT relates to the fuel compensation tables as it needs to be over 172 in order to not compensate any value.

Good point - not really sure if those values would also be ignored with the "Narrowband" option. I guess you could always make them "14.7" to make sure they are equivalent across the board.

The calibration was done by a pro tuner here, so I have no idea why the cut off values are what they are. Your logic regarding these does make a lot of sense, and it is something I would be happy to play with.

Might not hurt...should be quick and easy to bump them up and see what happens...or put them back if it seems to cause additional issues.

Regarding the cut off values though- I am under the impression that surely if the tps value is 0 then injectors should be shut off by that value alone anyhow? Maybe I'm mistaken though.

I don't believe a TPS value of 0 necessarily makes the injectors cut off...otherwise the engine could never idle. I also know when coasting down in gear, the injectors are cut off, but when you hit the "Overrun cutoff min rpm" they do start to fire again, even with TPS being 0.

Also, just to be clear, the cutoff table is in KPa - manifold pressure, not TPS percent, so the number could easily be up in the 20's to low 30s' to give a good cut-off.

Thanks

Good Luck!

[Lewvr6]

Thermostat changed and cooling system gone through again, still sits at a steady 172-174. The thermostat o.e from Honda is rated at 172, therefore it is running bang on Honda spec. Without blocking up radiators and other such bodge up methods, it's never going to run much hotter with the o.e Honda cooling system.

I have read various posts on this forums and others, it seems around 2004 that Honda superseded original thermostat with 172 rated ones (suggesting that early/original stats were higher perhaps)

I have tried playing with the overrun cutoff values, moved up and down-none of which has helped.

Has anyone got any more ideas? As I understand it spunkster is referring to ECT, as the ECT compensation tables do not zero out until 177?

What I'm failing to get my head around is the fact that this is a closed throttle/coasting problem only and I do not know which values/tables are wrong and being referred to by the ecu whilst in this condition? I would make more sense of it if was happening on acceleration or at wot.

[whoknows?]

do you have any logs of it doing it more than once ? i noticed your high speed fuel column 1 first three cells are 0 i dont think there should be any zeros may not help but still should be corrected

[Lewvr6]

Update,

Yesterday I changed the overrun cut offs to 15,10,10,36 on both tables (note: on my cut off tables the boxes on the right are 8000rpm-as opposed to 3000rpm that are in most calibrations I've seen)

My thinking behind the high number at the end (36kpa at 8000rpm) is to try and get the graph line to hit a normal value at 3000 (where most calibration have a last input for cut off).

The car feels much smoother over all and have not experienced the surge since uploading, and is not present in datalogs.

At the same time as changing those values I adjust the idle valve slider (as was rev hanging slightly), and also put values into into the 3 cells in high speed fuel that were previous at zero(as noted in above post).

Are these cut off values acceptable? I would like to have the normal cut off tables rpm range ideally-and do not know why mine ranges up to 8k? However this is not possible to edit the rpm, only the kpa values?

[Corey872]

The 10's still seem low to me. I never saw your pressure fall much below high teens / 20's in the datalog you put up. For comparison, my values on the low cam:

KPa RPM
21 906
22 1093
32 1406 (1875)
36 1875 (8000)

(your RPMs are a bit different as shown in () )

One thing to keep in mind, I have the 'overrun cut-off min. RPM' at 1200-1300, and you have it at 1300 across the board, so the lowest two RPM slots are never active anyway...falling below 1300 rpm turns fuel on, so you never have a fuel cut at 1093 / 906 RPM. So you mention 15, 10, 10, 36 - the first 15 and 10 are never active, it's really the 10 and 36 we're looking at.

Overall, I would just datalog a coastdown from ~4000RPM to below 1300 when the injectors kick back on and set the pressures just a bit higher than that curve to insure the injectors are cut off.