Hi guys, I'm pretty new to tuning Hondas and MAP based systems. I've tuned quite a bit of MAF based stuff through the years and OBDII with great logging software but this Honda is causing me to pull what little hair out that I have left!

The car is a 94 hatch with a Chipped P72, its on basic CROME (I know I know but I'm old, married and broke!) I've got a LC1 wideband installed and have the AFR's great everywhere except at tip-in to VERY light throttle ~1800rpm. It pegs my wideband at 21.8 and of course the car runs terrible here and makes it very hard to drive or take off smoothly.

The motor isn't really all that radical, ~11.8:1 compression Darton sleeved B18C at 84mm, Buddy Club Spec III camshafts, 99 Spec ITR PR3-3 head, Blox ITR IM, OEM ITR TB, 240cc OEM injectors. Nothing too far from damn stock Type R B18C5 setup. I've tried so many things and still have this lean spot. What am I missing? I know I need to be able to datalog and need better tuning software but that isn't an option at the moment. I just want to get the car on a safe basetune and go from there to a reputable tuner.

Help!!! I can post my tunes or share with anyone that wants to help.

 

Simple, add more fuel where it's lean.

In crome you got a chart.
So if your lean from 700rpm to 1800rpm and -21inhg to -18inhg vac.
Then add fuel there.

 

man I've tried that and it doesnt' seem to help! I've added upwards of 25% additional fuel from 500rpm to 1800rpm, all it does it make my idle very rich, then as soon as I lightly touch the pedal it goes off the scale lean.

 

I was thinking it was possibly a TPS failure, checked it out with my DVOM and it appears perfect. I'm at a loss...

 

You remove the check sum? And what base map are your using p30, 28 or 72?

The only time I had that problem was when using a p28 base.

When get to my laptop ill look and see if there is some settings for adjustin the tip in.
Also what's the ignition looking like?

 

Yes, Checksum removed and using P30 base. I've Tried P72 base with the same results (actually worse)

I seen some tip in settings in the advanced tab of the fuel tools. I went as high as 1.5 (not sure what the number is, multiplier or what) and it didn't seem to make a difference.

Ignition timing is basically stock P30 for now as I haven't gotten to street tune it yet due to this lean issue.

I did just get a code 14 yesterday so I think the IACV is shot, could that do it?? I'll be replacing it once I get back home next week.

 

yea having the iacv code could be a problem. Not sure if it would lean it out like that but its possible.

 

code 14 can also be from a vacuum leak, which would cause the uncontrollable leaning. the better question to ask before replacing your IACV is if you're idling well or not, so be sure to properly troubleshoot that first.
Otherwise the leaning might be false readings if you have a ground issue or improper wideband wiring, so be sure to verify you have good connections with minimal noise.
There's a crome tuning manual in my sig, I'd recommend reading through it completely.

 

Update: my P72 ecu was the culprit. It finally got to where it wouldn't start so on a hunch after trying everything else possible, I pulled the ecu and found leaking caps all over. Swapped in a good P28 and it runs so much better now! Off idle lean spot is completely gone!

 

Good to hear. Which cap was leaking? The fuel pump one ?

 

I have no idea, it was actually a couple of them...

 

Granted the ecu is old, but they shouldn't all go out like that unless it was getting wet or the ecu is running a higher current than usual. If there's a lot of corrosion in the P72 or yellow residue you may want to find where you're leaking water from and avoid burning up your new ecu. also just to be safe monitor your alternator current, clean the thermostat ground, and look over the main relay for bad solder joints.

 

Thanks john good points. I'll check it out.