A/F Ratio

[Adam3482P]

When downshifting should it go lean?

 

[KYREDP5]

How lean?

 

[Adam3482P]

hmmm well I'm sure of the exact ratio but when wot it goes all the way rich and when engine braking it goes all the way lean on the meter

 

[duMb KeoLa]

thats how its gonna be man, you got turbo? if so, you dont want it to go lean when youre bo0stin, i got that problem right now, anyone got a solution???? but yah, for regular driving, its gonna go lean when you get off the gas, coming to a stop, etc.

KeoLa

 

[Adam3482P]

thats what I thought. Mine goes rich when I'm bo0stin so thats good. Only thing now is I'm gonna get the dump tube off my wastegate put into my exhaust cause it sounds loud and goes tat tat tat tat tat tat tat tat

 

[duMb KeoLa]

ummm...that might not be a good tat tat man, check to see if you have an exhaust leak somewhere, try to retighten all the bolts on the manifold, turbo, etc, and yah, get the dump pipe made, should help out. how much you bo0stin by the way? mine goes tat tat tat too but sounds like an exhaust leak.

 

[herarety]

I think 19-20:1 is normal for compression braking.

 

[spoolinmp3]

When downshifting or at idle and cruise you will be lean since your intake is not pressurized and the FMU is not increasing fuel pressure. Under WOT however you should be rich. Running atleast a 12:1 fuel ratio. If you are not running a wideband an egt and the probe is mounted in the manifold you should be in the realm of 730-800c at WOT. And if the probe is in the downpipe you will get lower readings.

If you are running a narrow band meter and you see the a/f indicate lean immediatly lift off the throttle since this may indicate a very lean condition (remember however that these gauges are not to accurate for WOT and should be used primarily for partial throttle tuning.)

Keola I am unsure what fuel set up are you using and gauges so I can diagnose your problem more effectively.

As for the rattatata on the dumptube.
It is not all that load. So make sure that all your manifold/turbo and turbo/downpipe connections are secure. If you have a leak you will be able to feel hot exhaust coming out of it. Kinda sounds like a fart

 

[Little Beavis]

I'm thinking about getting my wastegate dump tube plumbed into the exhaust as well.

Never did like exhaust leak sounds and at WOT, that's exactly what we've got here. I guess we're all wussies or something. I just don't like my car sounding like a '79 Chevy Monza with a tin can keeping the exhaust together (my first car - POS!).

 

[Little Beavis]

By the way, Terry. I still am only in "yellow" on the rspeed A/F under boost (never goes orange or red). As soon as I lift off the gas, the lights go all the way to blue (max rich), then fall back.

Under partial throttle, I can get green and blue. I would guess the FMU is doing its job, but I'm worried about it. Should I be?

Kind of makes sense that it should be rich if the extra gas is being used with the "extra air". Am I still too lean or what? As I said, never goes below the yellow when I get a reading (not counting idle, or braking, or that sort of thing).

Am I worrying over nothing?

 

[LinuxRacr]

thats how its gonna be man, you got turbo? if so, you dont want it to go lean when youre bo0stin, i got that problem right now, anyone got a solution???? but yah, for regular driving, its gonna go lean when you get off the gas, coming to a stop, etc.

KeoLa

Are you experiencing all this at partial throttle? If so, do you have a voltage clamp, because if not, the ECU WILL pull back fuel under partial throttle, leaning you out!

 

[duMb KeoLa]

whats a voltage clamP?

 

[LinuxRacr]

The Voltage clamp is an item that Flyin' Protege sells that you hook to your O2 sensor wires to keeep the ECU from reading the rich condition when you hit boost. The ECU has the power to pull back 30% of the fuel when it sees the rich conditon at boost. This will lean you out at partial throttle, but at WOT, you enter open loop where pre-set variables take over, and you run rich anyway. My advice to you if you don't have the Voltage clamp is to only boost at WOT.

Here is the info on the Clamp I speak of:
http://www.flyinmiata.com/store/prodinfo.asp?number=07-46300&variation=&aitem=6&mitem=7

 

[spoolinmp3]

Yeah linux he is using the voltage clamp.
Beavis are you still getting this with your new FMU?
If so then this is a problem. You should be in solid rich at WOT and at partial throttle if you are in boost. PM me or call me on monday so we can figure out whats going on

 

[LinuxRacr]

Yeah linux he is using the voltage clamp.
Beavis are you still getting this with your new FMU?
If so then this is a problem. You should be in solid rich at WOT and at partial throttle if you are in boost. PM me or call me on monday so we can figure out whats going on

Until then, I would stay away from boost to be on the safe side!