Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Honda s2000 tune

General Tuning Discussion

Forum Posts



Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads


I have a honda S2000

JDM motor (tiny bit higher compression)

Run on Shell V power UK 99 RON

TTS Rotrex SC - c11PSI max

one step colder plugs

800cc ASNU injectors

uprated fuel pump

4 bar MAP sensor


AEM Wideband

it is idling at 11 and failing emissions

if i drop the injector open time on my fuel map i can get it leaner but the revs are not stable, stumble and blip

at 3k rpm it's hitting mid 11 AFR so also rich

I'm new to the course so checking it. its never idled at 14.7 since i had it any ideas where i need to look are welcome :D


First, it's possible the wideband sensor reading is incorrect. If it's a gauge style unit I'd verify what's shown on the gauge face matches what's being logged in the ECU, since wiring between them and sensor ground offset can be an issue with analog units. Then perhaps the sensor is just old, fouled, and no longer trustworthy. Perhaps what it shows as 11 is really 14.

Beyond that, it sounds like you have a stock engine, so it should idle and cruise happily at 1 lambda as long as there are no issues present. Injection timing is one factor to consider. You could verify fuel pressure is proper. Injectors may need cleaned. A coil or spark plug, or multiple may have an issue. There are many potential causes which are mechanical or electrical so they should be checked in addition to calibration adjustment attempts.

I hope one of these suggestions helps you find the root cause. Please keep us posted.

Thanks Mike, i think you were right

i had the injectors cleaned and tested, they were not bad but the manifold seals were in terrible condition. The cat to exhaust gasket was the same. I replaced both, swapped the plugs too and new plug tube seals and it passed. The AFR is quite eratic so i will fit a new probe, i switched off AFR feedback for the test


That sounds like great progress. Well done!

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?