stagger

[raz]

Phew! I just finished reading the 446-posts in the great ECU thread. For the third or fourth time, I think. Man, it's good reading.

 

What I fail to interpret is the word "stagger". What is that? I probably know it if you would tell me in Swedish but this time I can't imagine what the word translates to. So please anyone give a rough technical explanation.

 

Example:

I would look for stagger and/or ignition issues if O2 fell above .3%-.4% for large bores and 1%-1.1% for small bores after no more power was to be found by glogally adding or subtracting fuel.

 

Sorry for being, in a way, off topic.

[lavrgs]

Phew! I just finished reading the 446-posts in the great ECU thread. For the third or fourth time, I think. Man, it's good reading.

 

What I fail to interpret is the word "stagger". What is that? I probably know it if you would tell me in Swedish but this time I can't imagine what the word translates to. So please anyone give a rough technical explanation.

 

Example:

 

 

Sorry for being, in a way, off topic.

I interpret stagger used in the context to mean hesitation or poor throtte response. However it normally is used to describe my walk on Saturday nights...

[dlaing]

I interpreted it to be an imbalance between cylinders.

For example if you stuck an oxygen sensor and a CO sensor in the muffler of a two into one system, you would be reading both cylinders at the same time. If O2 and CO were both high, this would indicate a stagger problem because one cylinder is likely too lean and the other too rich.

Stagger is caused by many things like the timing of the 90

[Cliff]

Some imbalance would be inherit in the engine design but I think most will be due to the imbalance of the throttles. This would vary from tune to tune. The only way the ECU would adjust for this is to run closed loop on each cylinder independently.

 

I'm actually doing this on my Sport at the moment, just as a curiosity ( and to make sure MyECU works properly in this mode)

 

I'm finding that 5-10% difference is common at low throttle and seems to vary a bit depending on rpm and throttle. By about 1/8-1/4 throttle its evened out. This was after I had balanced the throttle.

[docc]

The manual states a specification for vacuum difference between cylinders (7 mbar or 0.5 cm Hg) and for CO (0.3%).

 

How could you adjust the CO "maximum unbalance" if it were out?

[Dan M]

QUOTE

I would look for stagger and/or ignition issues if O2 fell above .3%-.4% for large bores and 1%-1.1% for small bores after no more power was to be found by glogally adding or subtracting fuel.

 

 

Sorry for being, in a way, off topic.

 

I think the reference was to ignition timing variation at idle.

My question is, what the hell is GLOGALLY???

[Guest ratchethack]

What I fail to interpret is the word "stagger". What is that?

Raz, are you referring to "scatter", the tendency of the timing signal to "wander" around a given setting due to uncontrolled slop in the timing chain (as measured and discussed in the fairly recent timing chain thread)??

 

I've got no idea what "stagger" would be, but the two terms may've been confused in prior posts...?

[raz]

No wonder I didn't understand it, it seems it was pretty ambigous

My bet, in the mentioned context, is on dlaing. It fits best. There is some really good information in that thread once triple-distilled.

 

Thank you all

 

Edit: I now found another quote from moto and it confirms dlaing's interpretion. It's about tuning against O2 target (eg. MyECU closed-loop):

You can hit the [O2] target while having stagger and/or retarded ignition timing problems. In the case of a stagger problem, the ECU/tuner/autotuning software will add fuel, which will result in one cylinder being sort of in the ballpark and the other one being rich(...)

That statement is a good point but not valid when the sensor sits in one of the downpipes (unless too close to the crossover, where it could be influenced I guess).