richard_ha

You can see on the graph here the AFRs bouncing from 11 to 13.

Any idea what could be causing this?

bryantaylor

iTrader: (5)

looks like you have your O2 turned on in boost too

richard_ha

O2 turned on in boost?

richyvrlimited

iTrader: (1)

running closed loop when in boost.

generally not a great idea as the response time of a WB sensor isn't as quick as a NB.

can be compensated for in the software iirc, but it still won't be perfect.

hustler

iTrader: (6)

change your open-loop switch point to whatever (60-90kpa) or you have o2 sensor noise.

richard_ha

It is set to 90kPa already, isnt it?

richard_ha

I'm wondering if I've got a sticky injector or something. Look how rich this went (right to 8.9) after I did a 1/4 mile, even though the PW was 0

richard_ha

OK, think I've figured it. The noise on the MAP is causing the acceleration and deceleration flags to get lit so it must be dumping fuel in for the acceleration enrichment. Looks like I'll need a TPS.

cjernigan

iTrader: (13)

Where is your MAP line connected?
If you have it on the nipple by the throttle body you should try Ting it off the FPR line instead.

richard_ha

cjernigan

iTrader: (13)

yes
The port near the throttlebody is known to be noisy. It causes issues like you're seeing sometimes. Ting off the FPR port is supposed to cure that.

richard_ha

Cool, I also had a "no buzz" t piece so I've used that.

richard_ha

What a difference T'ing in there and using a no buzz T piece has made, look how smooth this MAP is now...

Sleeper_MX5

just wondering what is a no buzz?

richard_ha

Its like a normal t piece but the spout that comes off only has a small hole in it to prevent too much fluctuation.

cjernigan

iTrader: (13)

You can buy a restrictor for the map line at any advanced autoparts store. AKA No buzz.

Glad that fixed it.

richard_ha

Are you sure? Looks like its set to 90kPa to me, unless I'm missing something.

240_to_miata

iTrader: (2)

What does this restrictor look like?

Also.. is the vaccuum source next to the throttle body you guys talk about the one on the 1.8 manifold on the top by the fuel rail?

cjernigan

iTrader: (13)

The restrictor looks like a little plastic tube with a tiny hole in it.
Do not use the one near the throttle body by the fuel rail.
Tee off of the line going to the fuel pressure regulator, it is a much better signal location.

240_to_miata

iTrader: (2)

yeah i was gunna make a thread about my jumpy MAP values. It always fluctuates about 5-10 kpa real fast no matter how steady i hold my foot. Ill try it out and hopefully get a better reading