Can you run a TII to lean at idle?
10-07-02, 10:54 PM
#1
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Can you run a TII to lean at idle?
Is there any danger to running to lean at idle? can it detonate at idle or will it just not hold a idle and die if its to lean? I am going in for my smog check this week and I want to tune this thing as lean as I safely can ... I gotta pass a dyno smog check 2 with a street ported motor. I have a A/F guage .. but you know how that goes.
10-07-02, 11:05 PM
#2
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I guess, in theory, you could run anything too lean and detonate, reguardless of RPM. I would think it to be a feat of *** for that to happen, but i guess its possible. I dont know.
Reted? Hailers?
Reted? Hailers?
10-07-02, 11:10 PM
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Originally posted by Scott 89t2
nah it just won't run....
FYI. leaning it out will lower one number, but raise the other....
nah it just won't run....
FYI. leaning it out will lower one number, but raise the other....
Do you know what number does what?
How much will my O2 sensor compensate? I just got a brand new NTK one installed.
I am going to go to a no pass no pay place... so if I know what number does what I can make adjustments and try it again and again
10-08-02, 01:02 AM
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My TII likes to idle nicely at about 13.7:1 AFR... Going richer than that doesn't help too much, and if you go any leaner than about 14.0:1 then it starts to misfire. When the engine misfires, it shoots a whole bunch of unburnt fuel (HC's) out the tail end of things, which would defeat your purpose . So, if i were you, i'd tune the car so that it runs as lean as possible at idle without missfiring!
Let us know how it turns out!
Manolis
PS. if that doesn't work, try adding denatured alcohol to the fuel tank. It reportedly burns cleaner than gasoline, and leaves fewer HC's... (i'm gonna be trying that)
. So, if i were you, i'd tune the car so that it runs as lean as possible at idle without missfiring!Let us know how it turns out!
Manolis
PS. if that doesn't work, try adding denatured alcohol to the fuel tank. It reportedly burns cleaner than gasoline, and leaves fewer HC's... (i'm gonna be trying that
)
10-08-02, 02:09 PM
#6
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Too lean at idle just kills the idle, as Scott 89T2 said.
There is really no danger of detonation - detonation implies under heavy load.  Since at idle, there is very little load, it doesn't really hurt anything.
The rotary really like a rich idle.
-Ted
There is really no danger of detonation - detonation implies under heavy load.  Since at idle, there is very little load, it doesn't really hurt anything.
The rotary really like a rich idle.
-Ted
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10-08-02, 06:59 PM
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reted, I've had a vehicle pinging with the throttle barely cracked open before, but that was a stuffed computer / timing issue, not air / fuel mix related...
as for running lean at idle, my stock t2 is at 14.7, idling fine, if marginally low.
Charlie
as for running lean at idle, my stock t2 is at 14.7, idling fine, if marginally low.
Charlie
Last edited by Blowtus; 10-08-02 at 07:07 PM.
10-08-02, 07:34 PM
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Well, truely messed ignition timing will cause all kinds of funny sounds. It's debatable if it does any damage, since the engine load is virtually non-existant; I'm surprised it cranked and started!  Usually if the ignition timing is bad enough to ping at idle, it will not crank over and catch...
-Ted
It's debatable if it does any damage, since the engine load is virtually non-existant; I'm surprised it cranked and started!  Usually if the ignition timing is bad enough to ping at idle, it will not crank over and catch...-Ted
Last edited by RETed; 10-08-02 at 07:37 PM.
10-08-02, 08:21 PM
#12
If you run too lean for a smog you will get a high nitrogen monoxide level and fail. Mazda's stragety for smogging the rotory was to run it quite rich and use an airpump and multiple catylitics and ehaust port air orfices to catylize the unburned hydrocarbons.
10-08-02, 08:29 PM
#13
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Correct me if I am wrong, but doesn't the exhaust gas temperature go up when the mixture becomes more lean? If the temperature goes up won't that over heat the turbo???
Ryan
Ryan
10-08-02, 08:31 PM
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Yes, the EGT's do rise, but the extreme AFR causes the engine to die.  So it's a matter if the rise in temps was hot enough to cause damage.  I get idle EGT's of 480C; the engine is fine (barring messed up ignition timing) up to 700C.  Leaning idle will not cause the idle EGT to shoot over 700C...
-Ted
-Ted
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