quality adjuster

If I set my quantity adjuster from 4 to 2 I know my engine well stumble at idle what are the signs if I go to far the other way by being to lean .Thankx

Its quantity.

The numbers are inverse.

Too lean will cause harder starts but, you would have to adjust your quantity much higher to experience that...somewhere higher than 6-7 mg/str for a stock car.

You know, as I recall, this subject has been discussed in numerous Threads, but for the life of me, I just cannot accept the "fact" that the numbers are inverse of the numerical value.

When my engine is first fired-up, the quantity per stroke (whatever it's called) is a rather high number (5.0 or higher) and as it warms up the number settles down to 2.2 mg/str.

Doesn't a cold engine require more fuel and then leans out as it warms up? If so, why does the injection per stroke number drop as the engine warms up?

Rather another long discussion, if someone has a link that provides a good explanation as to why I cannot wrap my brain around this topic with clarity, please post.

selway said:

If I set my quality adjuster from 4 to 2 I know my engine well stumble at idle what are the signs if I go to far the other way by being to lean .Thankx

Click to expand...

Diesels cant run lean or rich in the seance that the term means for gas engines. you cant hurt a diesel going "lean or "rich, you either get less smoke or more smoke and fuel mileage suffers. You cant hurt anything, well unless you have a heavily modified injection, but thats another topic.

i have mine set at 1.2, thats ultra high. the values go from 0 to 9, 9 is lowest quantity injection and 0 being the highest. 3-5 is the usual place to set it to, but 2 ish is a fun zone, your fine at 2.0, if it goes a bit rough, bump it up to 2.4 or until it stops bucking at idle.

AndyBees said:

You know, as I recall, this subject has been discussed in numerous Threads, but for the life of me, I just cannot accept the "fact" that the numbers are inverse of the numerical value.

When my engine is first fired-up, the quantity per stroke (whatever it's called) is a rather high number (5.0 or higher) and as it warms up the number settles down to 2.2 mg/str.

Doesn't a cold engine require more fuel and then leans out as it warms up? If so, why does the injection per stroke number drop as the engine warms up?

Rather another long discussion, if someone has a link that provides a good explanation as to why I cannot wrap my brain around this topic with clarity, please post.

Click to expand...

Idle fuel is determined by what it takes to maintain 930ish RPM. It will be the same amount after hammering as before.

If you bang the QA over so it idles at 2.2 the ECM thinks the feedback it's getting from the pump is for 5ish; therefore off idle it provides more fuel.

The inverse thing only applies to before/after the hammer mod. While running 5.0 is always more fuel than 2.2.

Where would you set IQ for best miles per gallon . thankx

manual trans or auto?

manual transmission

Theoretically you would want to raise the number as high as you can without causing a stumble at idle. With that said, you are likely to have to push deeper on the throttle to leave a stoplight , so the whole thing kind of becomes a wash so-to-speak.
Here is a bit of thought: my engine is tuned (see my sig) and I was sure the tune I was running should provide better FE than I was getting currently even after I added all the new hardware. I went back to my original Stage 3 tune and I lowered my IQ from 4.4 to 2.4 and my FE increased, and here is why I believe it happened: my new turbo at the same shaft RPM as my previous turbo moves a lot more pounds of air, and I was at the lean edge of the power curve. By increasing my fueling I needed to push less on the throttle to get the same engine response, thereby increasing my FE. I know to most this sounds like backwards logic when referring to a diesel engine, but if this engine were gasoline powered no one would even think twice about this "more fuel, better FE" engine response.

selway said:

Where would you set IQ for best miles per gallon . thankx

Click to expand...

My 2000 Jetta (no tune or mods) has been at 2.2 mg/str at 903 RPM at idle (fully warmed up engine) since I've owned it (44,991 miles to almost 370k miles now). I have all the fuel data in an Excel spreadsheet. It has averaged over 50 mpg. Now, I very seldom exceed 70 mph and have only had it to 4000 RPMs a few times. I generally shift at 32-3600 RPMs ... depending on the circumstances.

Well I tried to go to 5 and my fuel consumption went to .7lh moving it back to 4 it said .5 lh is this what is being used at idle and what happens when i'm diving at 70 miles and hour with the settings at 4 or 5 . or will 4 give me more speed between points than 5 (better acceleration ) .more fuel used would 5 be slower between points and use less fuel .

What said .7lh? Liters per hour I assume?

If it's some sort of real time display it is probably using data from the QA which you have altered the calibration of by your adjusting the IQ.

It would only be accurate on a factory calibrated pump.

While driving, a higher number would be greater consumption than a lower number but comparing the numbers before and after moving the QA would be futile.

Although this "number" thing with Fueling Quantity is driving me nuts, Selway, here is a link with some good reading. I think it will answer your question(s).

http://www.myturbodiesel.com/wiki/injection-quantity-adjustment-fuel-pump-hammer-mod/

RATS! I opened this thread hoping someone really had found the quality adjuster.
-Jason

Thankx AndyBees

For (cold) starts the IP will advance. This might have more effect than IQ, for starting.

I realize this is a QA discussion, but since we are talking FE what about the static timing set at idle on a warm engine? In theory more timing advance (within reason) will provide more power and FE, but since the ECU controls the engine timing off-idle, is more advance set at idle really going to make a huge difference in FE or top end HP?