Datalogging Question: Ignition advance reading at idle

ben · Post by **ben** » Sun Apr 10, 2005 9:16 pm

I'm having a problem with a friend's RSX-S K20A2 with Kpro (RC750cc high-imp inj's). It's having misfiring issues at idle....sounds like it's lean misfiring, but the datalog AFR's are right around stoichiometric and nowhere near the typical 16.0:1 petro AFR for Honda motors to start lean misfiring.

Also, when you try to hold the rpm's steady at 2000rpm (0mph), the AFR's will be sky high (17.0:1+) and the engine will misfire and not be able to hold a steady 2000rpm. I've tried to compensate by adding fuel, but it never seems to be able to add enough even though I've added about 20% into the high vacuum and idle columns (up to 413mbar, column 4 I believe).

How much vacuum and ignition advance is the datalogging supposed to be reading on the datalogger?

I'm seeing around 20.9" and anywhere from -2 to 9 degrees BTDC on the datalog with the engine at operating temp.

The ignition timing cells at idle are set to 18.50 deg BTDC. Shouldn't the datalog read the same as the idle cells being highlighted by the map trace?

My guess is that the datalogged ignition advance values are reading correctly and that the retarded ignition timing is causing the misfiring and erratic idle.

Datalog files:
http://portfolio.iu.edu/bchang/HondataD ... 10_003.kdl
http://portfolio.iu.edu/bchang/HondataD ... 10_006.kdl

Thanks for whatever advice or insight anybody can provide.

Post by **Hondata** » Mon Apr 11, 2005 7:34 am

Welcome to Honda's ignition controlled idle speed. -2 to 10 degrees ignition timing is normal at idle - the main table is not used.

From the datalog you need to check the TPS and reset it so that it shows 0% at idle. Then check the plug type (make sure they are resistor plugs) and plug gap. The A/F is a little lean - are you running in closed loop? If so then reduce the idle target A/F ratio, otherwise add fuel.

ben · Post by **ben** » Mon Apr 11, 2005 11:06 am

Welcome to Honda's ignition controlled idle speed. -2 to 10 degrees ignition timing is normal at idle - the main table is not used.

That's quite a bit different from working with the S200/B-series stuff. Interesting.

Spark plugs are the original, stock ones. Plug gap is stock (probably 1.1mm just like the B-series plugs).

We started with the K20A2 GReddy map with 650cc injectors. I typed in 750 for the injector correction factor and then tried to compensate manually by adding fuel to get it to idle properly (to no avail).

Closed-loop was disabled.

I've had it idling down to as low as around 14.0:1 with the AFR's fluctuating up to as high as 14.9:1 (by adding about 20% fuel), and it still doesn't idle without significant misfiring. It'll misfire pop at least 5 times in 10 seconds. It's not a huge stumble, but it's a frequent enough miss to make it sound bad.

The idle AFR's probably shouldn't bounce around that much, should they?

I also don't think I should need to add that much fuel to get it to idle correctly, especially on a stock block motor with just a bolt-on GReddy kit.

Is the stock semi-wideband UEGO sensor accurate enough to rely upon? If nobody knows, then I'll have to check it against my wideband and get back with people.

DC5 · Post by **DC5** » Mon Apr 11, 2005 11:29 am

The oem plugs are in the car now, it also had NGK BKR8EIX plugs in it before and still misfired.

I have read somewhere that the oem o2 sensor is accurate from 11.4X-30.2X:1 which if thats true is pretty good. I wouldnt think we would need to go any more rich than 11.5 anyways right?

My a/fs are lean at idle, and even under part throttle acceleration it misfires...goes way lean and falls on its face.

I'd like to get it to the dyno to have it tuned but at this point im not sure if it will make it

TIA Hondata,
Tony

DC5 · Post by **DC5** » Mon Apr 11, 2005 12:09 pm

Ben also noted to me that my Short term fuel kept going up.

Could my o2 failing cause all of this?

DC5 · Post by **DC5** » Mon Apr 11, 2005 8:06 pm

Also,

I took the plugs out to observe their condition...

They were pitch black, not white. which tells me the car is running way rich.

ben · Post by **ben** » Tue Apr 12, 2005 3:13 pm

I think we should use my wideband the next time I'm there.

You might want to run a compression test to make sure none of the valves are burnt.

xactdyno · Post by **xactdyno** » Thu Apr 14, 2005 12:47 pm

did you get any further with this? i'm having troubles that are very similiar using the greddy/650cc kal included in the latest software update.

ares650 · Post by **ares650** » Fri Apr 22, 2005 6:46 am

you guys have stock motors with a greddy kit? cause my base map was the greddy one and I don't have an issue. I will post post my map to see if it help.....it runs fine on one of are cars but use it with caution.