When I let off the throttle my A/F goes threw the roof. It comes right back down to normal, but seems odd that motor would run that lean for sec...

Here is a log of what is going on when going to 2k RPM and letting off.



thanks,
platinum

 

Thats normal, also when you blip the throttle it does that.

 

So is the motor really runing that lean, or is it just cause the gas gets sucked out of the exhaust during lift?

platinum

 

Are you asking about when you're completely off the throttle? Off throttle the injectors are off...

 

I'm pretty sure it's ok to be lean at idle.

 

mine does the same thing i wouldnt worry about it.

 

The injectors shut off completely when your decelerating off the throttle completely. However if your at part throttle and its that lean then you have a problem.

 

No for sure not part throttle. A/F looks fine during throttle and boost.

I guess it's the injectors shuting off when decelerating.

Learn something everyday from you guys.

thank you,
platinum

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">The injectors shut off completely when your decelerating off the throttle completely. However if your at part throttle and its that lean then you have a problem.</TD></TR></TABLE>

hit the nail on the head

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by platinum00 &raquo;</TD></TR><TR><TD CLASS="quote">No for sure not part throttle. A/F looks fine during throttle and boost.

I guess it's the injectors shuting off when decelerating.

Learn something everyday from you guys.

thank you,
platinum</TD></TR></TABLE>

Thats it! I noticed when i let off my Wideband would go nuts!! Like -x38 past 1:100 AFR lol!

 

yea plx m300 just reads "air" when you let off the throttle.

totally normal.

 

fuel cut under decel. Aem has a couple parameters you can set.... its pretty dope. I had the decel function in my SDS unit as well.

 

thats normal man
that means the ecu cut off the duty cycle on the injectors to a point it will lean
the amount of fuel and air consumed by the engine is minimal and poses no threat to the engine
everytime i datalog my air fuels during shifts it also climbs up to 21 afr's and goes back to normal

 

That is why when you datalog, you set a min TPS, so you don't get those big spikes in the A/F.

 

can you elaborate on setting a minimum tps, what would you want to set it to?

sorry im a noob when it comes to this

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 &raquo;</TD></TR><TR><TD CLASS="quote">That is why when you datalog, you set a min TPS, so you don't get those big spikes in the A/F. </TD></TR></TABLE>

is this in the EMS software?

platinum

 

thats wierd, cause when I let go of the gas/shift my A/F goes rich. It will read rich for like 2-3 seconds THEN go lean. Its wierd cause when im driving, I shift from 2nd and the a/f goes rich then go into 3rd, if I shift fast the a/f is still rich and when I give it some gas in 3rd it'll make a small pop. It does this just about every time in every gear.

I'm running crome with the plx m300.

 

I was told by xercon that OBD1 injectors shut off until 1300RPM and then they turn back on to catch the idle.