Danno

"so what your saying is that with 55 pound injectors your arc2 will allow you to get to the proper 2% duty cycle, but any injectors that are bigger like 65 or 72 pounders your in need to change the chip because the map runs out of tunable lookup reference points, because with 65 or 72 injectors the chips map will not allow you to look up a idle fuel duty cycle below 2%? Right?"

yes...

"Your saying beside the other benefits of the high or lean end cures of your chip, specifically you chip is mapped for bigger injector that gives a lower injector duty cycle than can be reached with a normal chip, so furthermore i would need your chips new lower injector duty cycle maps and utilize my arc2 to find this lower 1.4 or so duty but since your chip is on target for the size of the injector i can put the arc 2 at 12:00 for the low setting, meaning zero adjustment, right?"

Yes, that's my goal with the test chip I'm sending Ian...

"Also does this mean then if you goto a 65 pounder than goto a 83 pounder, yes once again you need a custom mapped chip for idle, correct. "

No, our chips have switching capability to work with stock 34.6-lb/hr and 55/65/75-lb/hr afermarket injectors using the same look-up points on the chip (no skewing needed, ARC2 ***** stay in same place regardless of injector sizing).

The 65-lb/hr injectors are good for 390rwhp @ 80% duty-cycle. However, anyone using 75 or 83-lb/hr injectors definitely need a fuel-pump upgrade as well.

Lastly Ian is running 52 55 pound injectors, if he isnt below the 2% duty cycle needed yet to get a proper mix, why do you both feel changing his chip makes a difference, you state that the concern lies with the big 65 or 72 pounders not the 52 sized ones, right?"

I suspect Ian has a similar problem that you have, a high-idle. This moves the look-up point further away from the 2% clipped edge. The high-idle may be pointing towards a 4% or 5% duty-cycle range.

"The only thing i can think of is you both feel that his map should be fine for 2% duty at idle but since you didnt make the chip your just trying to eliminate any possible sources for his high idle, and a custom chip would end the questions to if his map is off at idle right?"

Well, I'm going to correct the idle map for larger injectors and higher fuel-pressure as well. This will give more overhead (flow-volume capacity) on the upper-end. Lowering fuel-pressure ends up defeating the purpose of going to larger injectors.

" Or are you saying that no autothority stage 2 chip will allow you to idle properly and get the 2% duty cycle with any arc2 control if you go bigger than stock sized injectors, ie you need a custom mapped chip for idle if you get bigger injectors... "

Yup, no Autothority chip has less than a 2% duty-cycle value. No matter how low you adjust the voltage, it will always give at least a 2% duty-cycle.

"This all sounds like get if you injectors, then you must get a new mapped chip, even if you got the arc2. For idle quality of course im talking "

Not necessarily. With 55-lb/hr injectors, you can get away with it by turning down the LOW-**** almost to the minimum. Pushing the standard 3% duty-cycle at idle down to 2% gives a 33% reduction which closely matches the 37% larger injectors.

tecart

very good then, ill stay awake and look for ians post on his new chip and idle outcomes, do you have a target date either of you for the testing finish so i know when to look here? thanks for the insight

Perry 951

So Danno, I had Chris White burn me some chips to match my K27/8, #55's, MAF, etc. Do you think the look up tables will remain the same if he programmed the -37% duty cycle?

Danno

Yes, the adjustment tables should remain the same. You can scale the initial duty-cycle between Steps 1 & 2 above. I guess it comes down to how he scaled the -37%. There are several ways to do this.

Also was it a straight drop-in upgrade? Just swap injectors and plug in chip, or did you have to make adjustments?

IanM

Hey guys,
Actually my idle is rock steady at around 850-900rpm. To be totally honest, one of the reasons I'm trying Danno's chips is just as an experiment. My car runs so great, I'm looking for new things to tweak! I'm not an expert on how the DME uses fuel maps and tweaks them based on the ARC2 settings, so I can't comment. With my Low **** at 10:00, the car starts fine and idles fine, but I can smell that it's on the rich side initially. Once it warms up, the ARM1 display dithers back and forth, and it runs great. My a/f ratios have been checked using a wideband O2 sensor, and the idle a/f ratio (warm) is around 14.7:1, cruising conditions are the same, and under boost it goes to 12.5:1 as it should. I haven't checked the a/f ratios with the wideband when the engine is initially started from cold, but the smell tells me I'm rich.

When the car is warm, I can turn the ARC2 Low **** down a couple clicks, to around 9:00 and it usually continues to dither okay. Any lower on that **** and the ARM1 shows a lean condition. It just seems to dither best with the Low set to 10:00, so that's where I've left it. I'm sure I could tweak things a bit, but I haven't been bothered.

The main reason for going to the Guru chips (coming soon Danno?) is that I like the idea of having chips specifically burned to match my 52# injectors at 3bar fuel pressure, rather than having my ARC2 ***** all over the place trying to compensate for APE Ver2.7 chips designed for a stock 1989 w/ the K26/8 turbo. I've also been teased with the idea that I'll unlock some more power by having my unskewed ignition advance curves where they're supposed to be.

We'll see how it goes once my chips arrive, I install them, and tune the ARC2 again with the wideband.

BTW, Danno, Marren Motorsport told me that my injectors are rated at 52 lb/hr (2.5 ohm), but the Motec catalogue rates them at 50 lb/hr (Bosch M0280 403). I asked you to set those chips up for 52 lb/hr at 3 bar, hopefully that's right.

Perry 951

I have not run it yet, so not sure on the ARC 2 adjustments. Bloomberg had a set of chips mapped for that turbo by Chris, but for the small injectors and diffrent MAF. He hit 330 and had a great AF ratio. I wanted the same, with the larger squiters because I know he maxed out the stock ones.

Anyway, I told him exactly what I had, what I was going to run, and he said he mapped the chips to match it.

His chipd do make the power, I just wonder if it will be as reliable as stock.

Porscheman101

Ok. Whenever my car stops moving and my car is idle the reading goes back and forth between rich and lean. But grey smoke comes out of my exhaust. i try to correct it by turning it down but that does nothing but kill my engine. My idle is from 1000 RPM - 1100 RPMS
It only does it at idle. I have stage 2 performance chips with my stage 3 MAF. How can I corect this? Any ideas. Right now i have 2 forums going. So please check both of them.
Thanks
Porscheman101

Huntley Racing

Are you sure it's fuel and not oil?? If you adjust the LOW **** up and down and don't see any effect on the smoke but the car goes rich and lean then it sounds like other than fuel smoke.

Porscheman101

Well how long would it take for the smoke to stop coming out of my exhaust. Also my exhaust only started smoking since I installed the stage 3 MAF.
Like i said on the phone, I do have an oil leak, but I believe this fuel smoke. It is greyish white. Also when i come to slow down, and shift, the reading goes rich and then when i let off of the clutch it goes back to normal.
But when i do come to a stop, and the temperature outside is cool, it starts to pump out smoke.

Porscheman101

Also, How would the engine just suddenly decide to burn oil. It just doesnt make that much sense to me.
Now tunning it, I never reall understood. So i tried and this is what i have gotten so far. Under some acceleration the reading dithers back and forth from lean to stoich. And under heavy load it is rich. But when it comes to idle, thats where the problems start. When the smoke starts coming out i try to adjust the arc2 and just end up almost killing my engine. But I see no improvements when trying to adjust it. So I turn off my engine, let it sit for a few minutes, start it back up and take off.
I cant take much more of this.
Justin <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

David Salama

Porscheman,

I had and occassionally have the exact same problem. My car was spewing white grey fuel smoke at idle after installation of my 55 # Siemens injectors. Look at my signature for my other mods. The white smoke was more common on cool days and with prolonged idle. If I spooled the turbo or drove aggressively, it would go away. I was able to get rid of the problem by playing with my fuel pressure, arc 2, and idle screw. There is only a narrow range of fuel pressure between 35psi and 38psi that the smoke would go away. Any higher or lower, and the smoke would return. In addition, it helped to turn the low setting of the arc2 down (mine's at 10 oclock)and open the screw on top of the throttle body a bit. This will help with the overly rich idle. Once the white smoke starts, I believe it is a viscious cycle since unburnt fuel fools the O2 sensor to thinking the exhaust gas is lean, not rich !! It then gives signal to the DME to increase fuel which worsens the problem. I think a really hot engine burns the fuel more completely, so the smoke is worse when its cold, or perhaps when the O2 sensor is cooler (speculation). Hope this helps.

Porscheman101

Just a second ago i warmed up my car, and drove it around the block, and not using the turbo. When I came home and pulled into the garage, guese what. The smoke was right on cue. So I lowered the lean as much as possible and there was no reading the air/fuel gauges. But the smoke was even more thicker. So i tried the opposite. I turned the lean up untill i was rich on the gauges and the smoke got thinner. So I played with the mid and the high as well, the smoke was still there but wasnt as noticeable.

After my engine cools down i am going to try it again. I have no idea what is going on so any insight from Huntley of Danno would be helpfull.

Porscheman101

Porscheman101

Allright. I cooled down my engine and then took it for a spin again. Came back and right on cue the smoke started billowing. I need help.

Justin <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

Huntley Racing

If the car is dithering at idle it is not too rich and hence the smoke is not fuel. You may have oil smoke, water (blown headgasket) or condesation in the exhaust. The ARC2 seems to be functioning correctly, the car is running well so the mixtures seem fairly close. Are you loosing coolant?

Porscheman101

Ok. I do not have a coolant leak that I know of. All I know is that I have a oil leak that seems bad. I just dont understand how the oil could get into the exhaust. Does this mean that I do have a blown headgasket, and if I do how much would that cost to replace.
Also I checked the coolant and there is no oil that I can tell and my oil is clean and is rather full.
But isnt oil a black smoke. This is whitish grey smoke.
Thanks for your help
Justin <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />