Race chips and matching to injectors?

[Fred 86 GN]

I was thinking...

Race chips go to full static on the injector pulse width at WOT, right? If that is the case, then wouldn't a race chip made for stock injectors work for 009's? At WOT, the ECM would be telling the injectors to go full boogie, and it doesn't know what injector size it is controlling.

Would a stock race chip make the 009's even more rich at idle?

Thanks,

 

[JayC]

There's this little thing you're forgetting called an injector constant. Also, not all injectors have the same type of flow curves and last but not least, not all race chips go static at WOT. Would you want a 12 second car with MSD 50s in it going static at WOT?

 

[Sleeper]

Food for thought

Wrong. The pulse width is based upon many sensor inputs and other factors, such as injector size. If the ECM is commanding 100% duty cycle you are out of injector. 85 to 90 % is a safe DC range to operate in, the injectors are actually opening and closing and properly metering fuel. When you run over 100% or static, there is no room for error, and you are walking a fine line of going lean and burning up your motor.

Chips are cut for specific injector sizes and the injector constant selection (as well as many other tweaks) in the programming tell the ECM how much fuel to provide in all ranges. Just because you are at WOT does not mean the ECM says dump all the fuel you got into it. MAF #'s, blm, int, inj const, rpm, afr, PE trims, all play a part in deciding how much fuel is going to be added.

Race chips also are programmed for more timing and boost and require a higher octane rating of fuel to be used with them.

Disclaimer: Some people have programmed 100% duty cycle chips. Useless idea

HTH

Paul

 

[JayC]

I'd be careful how I threw that "useless idea" term out. I know several of who I consider to be very good calibrators who set their race chips up for 100% duty.

Also, while on the subject sort of, there used to be this chip sold by the infamous "Turbo Tune" in New Jersey (Not to be confused with the Turbo Tune US Ltd in NC) called "The Smart Chip" that was a one size fits all chip. Basically they removed all the block learn restrictions and let the chip try to control the fuel. Hate to see what would have happened when the O2 went bad.

 

[Sleeper]

Point taken Jay There are always exceptions to the rule.

Smart chip

Paul

 

[TurboJim]

Re: Food for thought

Originally posted by Sleeper
Wrong. The pulse width is based upon many sensor inputs and other factors, such as injector size. If the ECM is commanding 100% duty cycle you are out of injector. 85 to 90 % is a safe DC range to operate in, the injectors are actually opening and closing and properly metering fuel. When you run over 100% or static, there is no room for error, and you are walking a fine line of going lean and burning up your motor.

Not really Paul. I have personally seen DS display 100% DC when it COULDNT have been 100%. For example, I use a 44.1 constant in 009's. 2Eh When I did my first 009 inj, I used a 42# constant. That car USED to go to like 80% DC at 12.0, now with the 2E constant goes to 99%. At both times, the car was going the same MPH in the traps and O2's were 78x thru the whole pass. I think the DC in DS is more of an expected DC, or calced DC, kind of like the AF ratio displayed. It may SAY 9:1 or 5:1, but the car is actually 11 or 12:1. I thinhk unless you're gonna log it on a scope, you shouldnt put too much weight on DS's calcs with that respect. I will put more weight on say 009's going 11.4 at 95% in a 3700# car. SO knowing THAT I'll run them static yes.

But anyway, back to topic, a stock chip for 009's might work if you drop the BLM low limit to like 20 But if yer gonna do that, just make the chip right for 009's

 

[Sleeper]

Jim
I’m not even going to pretend that I know half of what you have forgotten I throw this out for the sake of argument… Isn’t the PW displayed by DS based upon the actual commanded values being sent to the injectors, and the calculated DC based upon the measured inputs, RPM & PW? Wouldn’t that make it pretty accurate? Didn’t Carl make a code patch the displayed PW that checked against DS’s?

Sticking booth feet in my mouth, and I know I’m jumping in way over my head (but I gotta learn) wouldn’t any fudging of the inj const be compensated for by the adjustments that would have to be made in the PE TPS, RPM, etc., trims, and bring the PW back to where you started from with the original inj const? Doesn’t the ECM just take MAF # s, inj const, rpm, AFR, PE trims, etc., and multiplies them together to arrive at a PW ?

Just wondering, when you said that the MPH was the same on the traps, were the RPM’s also the same? Did a cell 15 lock and fuel pressure adjustment come into play in your tests?


Paul

 

[TurboJim]

Originally posted by Sleeper
Jim
I’m not even going to pretend that I know half of what you have forgotten I throw this out for the sake of argument… Isn’t the PW displayed by DS based upon the actual commanded values being sent to the injectors, and the calculated DC based upon the measured inputs, RPM & PW? Wouldn’t that make it pretty accurate? Didn’t Carl make a code patch the displayed PW that checked against DS’s?

Paul

BAHAHAH!! And I dont know .00001% of what Jay knows.

Anyway, I could be wrong, but dont think I am as I have witnessed DS displaying what couldnt be true. Hell, *MY* car on PUMP GAS with 50# cant be using 80% DC! That means its burning fuel for 480hp or an 11.50 pass on pump gas? Not a chance buko

I think it comes down to the TQ/HP readings. I dont know how accurate they are.

 

[Fred 86 GN]

OK, bad idea. Thanks for the Replies!

 

[JDEstill]

Jim, I believe that Direct Scan does, in fact, give the actual commanded injector pulsewdith. It is not a calculated number like the hp/tq values, or the a/f ratio value. As for the a/f ratio value, it would be about right (ballpark anyway) if the MAF could read over 255 gm/sec. That's the big problem with that calculated number, at WOT the A part of the A/F gets stuck at 255. Hmmm... what kind of a/f ratios come up on DS when using a Translator with Extender chip? Just curious, if anyone wants to share.

Anyway, I know this comes up once in a while, and I emailed Kent a while back about it. Here's his response:

=====================
Date: Mon, 9 Jul 2001 08:08:14 -0500

Howdy John,

If I remember correctly, the injector pw is taken directly from the ECM's
working RAM. I believe that the ECM takes this value and applies it
directly to the injectors. I have to use an equation to convert the basic
hex number into the inj. pw number. From the information that I have, the
correct equation was used.

An interesting tid bit is that the chip controls the injector pw to a great
extent. In other words, the chips programming and data tables can actually
try to command a very large pw (i.e.: greater than 100%). DS displays a
dotted line in the graphic displays to indicate to the user what the
theoretical max pw is. As you can probably guess, the theoretical max is
simply based on the current engine RPM. Afterall, the intake valve can only
be open for so long at a specific RPM. That time is the max that the
injectors should be on since any more would cause the fuel to "puddle" up on
the valve and possibly even evaporate due to the heat.

I don't see any reason to not trust the number. There was some confusion
very early (i.e.: v1.0 s/w) as to how accurate the number was. However,
after conferring with multiple sources, the current displayed value should
be accurate.

Thanks,

--------------------------------------
Kent Chu

==========================

You could also review one of our threads from way on back, http://www.turbobuick.com/forums/showthread.php?threadid=5187&referrerid=908
Todd K mentioned in there that his homebuilt device that measured actual inj pw flanged up pretty well with what a scan tool would spit out.

Now, if DS is saying your car is using 80% DC, then I would believe it. I would guess that in that particular situation you would be pretty rich if you don't have the airflow to match it, or that your engine is particularly inefficient if you don't get a reasonable amount of hp out of it. Just saying that you could be throwing a lot of fuel at it and not making big hp for a number of reasons, I don't think this is a valid reason to think that DS (or any other scan tool) is wrong.

John Estill

 

[bruce]

Originally posted by JayC
There's this little thing you're forgetting called an injector constant. Also, not all injectors have the same type of flow curves and last but not least, not all race chips go static at WOT. Would you want a 12 second car with MSD 50s in it going static at WOT?

If it was flowing 480 gms/sec (give or take) you'd need for then to to get you 11.5:1 AFR. So under those conditions, it's a kludge to cover the fact it's out of injector.

 

[bruce]

Re: Food for thought

Originally posted by Sleeper

Disclaimer: Some people have programmed 100% duty cycle chips. Useless idea

Steady state?.
Or is this a transistional thing?.
AE from LV8, and TPS can take a while to decay out.

Any one running an injector static, steady state is just trying to cover for the lack of injector size, unless they are already running 80#/ hr injectors, and are just out to make a point about how far you can go. There are no advantages to it, and there are possible problems with an injector hanging 1/2 open, and leaning out a cylinder.

Course there's always someone trying to do something just because someone said it couldn't be done.

 

[bruce]

Originally posted by JDEstill
Jim, I believe that Direct Scan does, in fact, give the actual commanded injector pulsewdith. It is not a calculated number like the hp/tq values, or the a/f ratio value. As for the a/f ratio value, it would be about right (ballpark anyway) if the MAF could read over 255 gm/sec. That's the big problem with that calculated number, at WOT the A part of the A/F gets stuck at 255. Hmmm... what kind of a/f ratios come up on DS when using a Translator with Extender chip? Just curious, if anyone wants to share.

All the chips start going nuts at about 220.
By 255, the MAF, and LV8 numbers are jibbersish.

With the extender thou, that 255 is really 510 grams per second.

While the Commanded AFR reads the same, the PW are flickering.

 

[JDEstill]

I don't think you got my point Bruce. Or at least you didn't answer my question.

It's not uncommon to see a commanded a/f ratio of, I dunno, lets say 9:1, show up in DS. This is because of the stock MAF limit.

When you are running the Translator/Extender combo, does the commanded a/f ratio stay around 11.5-12.5:1 all the time at WOT? Is this number not so imaginary as before? How does it compare to your wide band numbers? Does it track it well, is it in the ballpark, is there no relation?

John