Hey there.

Being doing a lot of reading and haven't found anyone with this particular issue.

I recently finished a B18B turbo build in a 97 EK.

Important specs for this thread are -
- Stock 97 EK harness
- Hondata S300
- 255 Walbro pump
- RC550cc Injectors
- 92-95 Integra injector clips
- BKR7E plugs capped at 0.30"


I'm having quite an annoying issue while cruising or at idle when the car is warm.

I will start the car up, it will idle at 13 until it warms up and move to 14.5.

While driving with the car still cold, there are NO issues.

When the car is warm, I get a very bad hesitation / swinging AFR (between 11 and 16) when going from COASTING to the 1-5% throttle range. Soon as I give it more gas, or put the motor under load, the issue clears itself up and the car runs perfect.

Soon as the car hits a certain "lack" of load, it goes whacko.

I just got the car tuned on a dyno and am still talking to my tuner about this issue. He can't seem to figure out why my car is acting like this. He said a lot of the fixes that should make the car run lean, actually makes it run rich. We thought my wideband was not working right, except for the fact that during tuning, his 02 was showing the same issues (swinging).

I received an updated tune from him (we are 3 hours apart...) and tried it this morning. Now, the car will run rich ALL the time (idle at 12.5). but the issues seems to be less severe. Instead of swinging from 11 to 16 during low throttle, it will swing from 11 to 14.

In an attempt to see if I could fix idle, I changed my overall fuel trim from 0% to -10%. It brought my idle AFR to 13.9 but soon as it hit that, it began to swing from 11 - 16 again. The fuel trim was the ONLY setting I changed. It seems weird to have that drastic of an effect.

Putting the car into closed loop also makes the AFRs drop right to 11.

I have checked the injectors (getting 13 - 15Ω across all 4).
I have cleaned my IACV


Another weird thing, is during tuning, changing my timing had VERY little effect on my HP curve. My AFRs changed, everything changed, however the motor still produced the same HP / TQ.

Its currently sitting at 19 degrees in Hondata (Actual timing is 17).


The car runs amazing under load. Soon as that load disappears, the AFRs will begin to swing.

Any ideas? I DO NOT know much about tuning. But I'm pretty computer savvy so changing small things to my tune is pretty easy. I can also relay this info directly to my tuner to give him some ideas.

Thanks guys!

 

Sounds like a tuning issue.
Make sure your TPS is properly calibrated.

Without posting a calibration & log file you won't get much help.
It sounds like you have an issue which your tuner should resolve for you.

 

are you using the wideband for closed loop fueling or the stock narrowband?

 

I'm using the wideband. I don't have any stock 02's left lol

This is my first turbo build, so I'm still learning about making my own changes to the map and seeing how they work.

While I was in the car today, I did some Data-logging at idle and noticed something funny... Maybe... haha

Everything looks pretty smooth. I also double checked my TPS. HOWEVER, my Ignition timing is VERY erratic. I can post up the data-log tomorrow morning (PC computer is in my car, I'm in bed . I will tap the throttle (15%) and my Ignition timing will launch up and then fluctuate for a good 10 seconds till it calms down.

I also notice a slight miss at idle while its cold. I always thought this was from the plugs / gap I am running. It always runs Super smooth at idle once warm (as in no miss...)

Is my erratic Ignition timing the CAUSE of my swinging AFRs, or do my AFRs cause my erratic Ignition timing?

I will be checking my Cap and Rotor, as well as testing my Coil and ICM tomorrow. My distributor already makes some noise, so I'm REALLY hoping I find something corroded / wrong... Least its something to fix lol