angela_itr

Setup: Built B18C6 running Hondata, 255 walbro, 750cc injectors, tuned by Mase 7k miles ago @16psi

AFRs have always been spot on, idling at 14.7, 12-13 as going into boost and low 11s when well in boost.

In the last few weeks, the car has started to idle really lean, like around 16-18 tho sometimes flicking down to 14-15. Sometimes I've seen 19 on idle
At 5-10in/vac, its still only reading 15-16. Once in boost it reads 12-13, and still drops to 11s on full boost.

Nothing has been changed on the car at all. The only 3 things I can think of are:
1. the weather is now slightly colder than when it was tuned in the summer, tho its not drastically different
2. i sometimes get a CEL for the o2 sensor. Am using the stock o2 sensor, and a second sensor for the PLX wideband
3. wondering whether the exhaust might be blowing a little from somewhere, as its using a little more fuel than usual and sounds a tiny bit raspy (tho could be my imagination)

Also possibly relevant - when I come to a stop and dip the clutch, the revs drop real low and sometimes it dies as it doesn't 'catch' the revs in time. This has also been happening for the last few weeks.

Help, any ideas?

underpressure02

is your fuel pressure the same? Is your fpr starting to take a ****? Is the o2 sensor going bad?

boostedcivicsir

i think you may have nailed it on the weather change.

angela_itr

I'm using a stock fpr. O2 sensor could be on its way out, its throwing a CEL every so often. I guess an option is to connect the wideband o2 sensor into the ecu and get rid of the stock one?

I did wonder about the weather, but it wasn't exactly scorching when Mase tuned it, and the weather's not that cold now. But am I right in thinking much colder, denser air would make it run leaner?

What about the revs dropping when I dip the clutch? Unrelated?

underpressure02

It has gotten *** cold here in pa in the past few weeks and I did not see that much of a change in my a/f

What throttle body are you running? Is it aftermarket? I Know on my new car it has an aftermarket tb and until it warms up it is a bitch to keep it idleing.

angela_itr

Stock throttle body.... and the car has been idling fine since it was tuned 4 months ago, nothing has been changed on the car at all lately

underpressure02

iacv maybe going bad. Just a guess

igy

A small exhaust leak before the wideband will show lean at idle and will not skew the readings very much while driving. It may also cause the low idle and raspy symptoms you speak of. I know if my vband flanges on my exhaust aren't perfectly aligned, I have very similar probs.

D@nnY

exhaust leak most likely at the downpipe where it meets the turbo.... open the hood and rev the motor a little to find it....

the o2 code is a hondata problem...mine did the same

boosted k20

to get rid of the O2 code, just plug back in the O2 sensor (but keep the car in open loop) so it feeds a signal to pin D14 in the ecu. or just feed a 1volt signal to D14.

for the lean condition, when the temp gets colder the car will need more fuel. just turn up the fuel pressure by 5psi and it should be good. when summer rolls around just bump the fuel pressure down 5psi so it wont run too rich

kyle h.

any exhaust leaks? sounds too me like it's a closed loop problem, since open loop afrs havn't changed. Check o2 sensor and exhaust leaks

this has nothing to do with weather change, cold air = more dense than hot air = more fuel needed. The IAT sensor will compensate for this.

if anything you are going to "run" richer in colder weather.

gnar kill

I bet it is a vacuum leak

0mtber

iTrader: (2)

Check your downpipe bolts.
I have seen several downpipes come loose & cause this

D@nnY

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mtber &raquo;</TD></TR><TR><TD CLASS="quote">Check your downpipe bolts.
I have seen several downpipes come loose & cause this </TD></TR></TABLE>

adseguy

If the car isn't bucking or hesitating you can run as lean as you want for light partial throttle and idle. If this is the case I agree that a small exhaust leak is contaminating you r wideband readings as it did for me

seen4ever

the hondata CEL normally only happens with you have closed loop disabled. in that case it would appear that your car may not be using the stock 02 sensor anyways. either way, that CEL is nothing to worry about, its a bug that hondata refuses to address. version 3.5 didn't have it but the current. 3.5.1.35.3.34.6.34.43.4 has it for some reason.


weather change does definately change things, but the easy way to check would be to examine your plugs, if they are ok, then plx sensor is going out or exhaust leak. if htey are lean, then car is in fact lean.

angela_itr

ok cool, thanks for the replies

Gonna check for exhaust leaks tomorrow, fingers crossed will find the cause and report back

blundar

*cough* IAT correction *cough*

seen4ever

LOL, like hondata would give us something like that without dropping 500 bucks.


although i still can't get cromepro to datalog, so i just assume i'm fucked either way.

stirnice

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by seen4ever &raquo;</TD></TR><TR><TD CLASS="quote">LOL, like hondata would give us something like that without dropping 500 bucks.


although i still can't get cromepro to datalog, so i just assume i'm fucked either way.</TD></TR></TABLE>

--------------------------------------------------------------------------------

IAT correction tables are found at 0x5516(low load); 0x5531(medium load); 0x554c(high load).

It follows a temperature, Correction(word, not byte), temperature, correction, temperature, correction....pattern.

Anyone with a little motivation, logic, and computer knowledge should be able to handle hex editing the ROM. Another big hint is to use whats available to you(download sManager, Crome, and Uberdata....should give you big hints, especially since uberdata and crome's scripts are able to be opened in word pad)

vtec.dc2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by angela_itr &raquo;</TD></TR><TR><TD CLASS="quote">Setup: Built B18C6 running Hondata, 255 walbro, 750cc injectors, tuned by Mase 7k miles ago @16psi

AFRs have always been spot on, idling at 14.7, 12-13 as going into boost and low 11s when well in boost.

In the last few weeks, the car has started to idle really lean, like around 16-18 tho sometimes flicking down to 14-15. Sometimes I've seen 19 on idle
At 5-10in/vac, its still only reading 15-16. Once in boost it reads 12-13, and still drops to 11s on full boost.

Nothing has been changed on the car at all. The only 3 things I can think of are:
1. the weather is now slightly colder than when it was tuned in the summer, tho its not drastically different
2. i sometimes get a CEL for the o2 sensor. Am using the stock o2 sensor, and a second sensor for the PLX wideband
3. wondering whether the exhaust might be blowing a little from somewhere, as its using a little more fuel than usual and sounds a tiny bit raspy (tho could be my imagination)

Also possibly relevant - when I come to a stop and dip the clutch, the revs drop real low and sometimes it dies as it doesn't 'catch' the revs in time. This has also been happening for the last few weeks.

Help, any ideas?</TD></TR></TABLE>

i had this **** happen and it was O2 sensor - everything leaned out by a lot, i ignored it for couple days and 2 weeks later #3 cylinder went..

seen4ever

stirnice, i'm an accountant by trade, while i used to understand C, C++ & VB those skills have vanished from me at this time. Although with seeing the locations, maybe i'll download a hex editor and see if i can make sense of things.

blundar

I was going to give them till the end of the year before releasing the "Hondata Migration Wizard" for Crome... Not only does it have 90% of the ROMeditor functions for S200, but it also adds editing of the stock IAT and ECT correction tables. Hopefully Hondata will show everyone what excellent customer service they have and add these functions to ROM Editor before me...

seen4ever

dave, if you can do that and make my moates datalogger work, i'd tattoo your name on my ***.

angela_itr

Found the problem.... my downpipe was split almost in two just under the turbo! Hence the strange o2 readings, raspy noise and eventually noticeable loss in power.

Seems its not a great idea to use exhaust wrap around a mild steel pipe in a wet country such as the UK... the whole pipe has rusted pretty badly in just a year. I got it welded up temporarily but I'll be getting a replacement soon.