^ agree with that. Also, IDC can be expressed by some ECUs with its denominator as the available time for injection, which may not be all the time, so people do sometimes talk of "125%" IDC and find their fuelling changes even over "100%" IDC (these figures are probably really 100 and 80% as you would measure by a scope, just that the available injector time has only been set to be 80% of the engine cycle). However, as long as the injector doesn't overheat or stick, the available time is all the time IMHO.

 

So if someone said they had a 105% IDC then it means that it will take more than 5% less IDC before the injectors will have a chance to get a break between pulses?

For me as long as I have methanol added to the mix from another source, the stock injectors remain (I'm less than 100% anyways).

Is it just me or do others notice that people start having issues with their cars after upgrading injectors (and headstuds for that matter). For the average enthusiast it seems to be a system too delicate to mess with mechanically, and too in depth tune.

 

"So if someone said they had a 105% IDC then it means that it will take more than 5% less IDC before the injectors will have a chance to get a break between pulses?"

Yes, usually means the ECU wants 105% IDC, but the injector can only run 100% (unless they are measuring it in another way as above - some MoTeC setups do this if limits are set on the allowed injection angles IIRC).

 

Ha! You people and your low altitude. I'm peaking at 70% with a full turboback at 24 psi. Of course, I have 20% less air to work with than at sea level.

d

 

The only injector issues I have seem to be related to the curve of my aftermarket MAF.. However when I balance the trims using scale and voltage latency, the higher load cells run lean unless I raise the MAF output slightly.. This is why I was investigating the new settings I started coming across, however I have no useful data on that yet since I am working through several issues simultaneously and its having an impact on my ability to gather useful information that you guys can use.

 

Let me add that my car has a stable voltage of 13.7v that doesnt drop more than 3/10ths of a volt at idle, and never has gone over 13.9v ever.. So my latency values are acting more as a scaling modifier.. I need some sort of dead time value that will be affected by RPM, at idle dead time isn't as critical as at higher RPM, so when I get perfect trims at idle, it runs lean at higher RPM, and if I get it where I want at high RPM, the idle is too rich for the trims to compensate..

This is partially the MAF curve I'm working with, but the values themselves are within range and reasonable values for the level of boost I'm currently running.. so its obviously related to dead time (or some compensation)

In reality this isn't an important issue for me.. However I spent some time trying to match the injector scaling so my AFR's are similar to what the arbitrary AFR values in the map show, for me it would make quick adjustments easier. Plus I'd rather have to take fuel away than add fuel to the maps..

 

According to the formula posted here, My evoscan IPW values are about 91~98% of Max IDC. And I have 680cc injectors running only 20~21 psi.

 

I am currently running 25 psi @3600 rpm (peak) in 3rd gear tapering to 20.5 psi @ 6800...My AFRs are ~11.5 - 11.6 from 3500 to 6800 but my IDCs are > 90% from 5000 RPM up and are 98% + from 5800 RPM up...

I am seeing a tad of knock (3 counts or less) from 5800+ so I am wondering if the injectors are maxed out and causing knock issues or if I am just running too much boost (@5800 I am @ ~23.5 psi). Although I am getting knock, my Octane Flag is still staying at 100 and timing does not appear to be being pulled.

For a referrence @ 6800 I am at 14* AFR is 11.6 and calculated load is 213.

So the question is, should I:
(a) reduce boost
(b) get injectors -- rec. please
(c) get a meth / alk kit
(d) other - please be specific

Thanks a bunch!

 

What are you running for timing?

If your timing is way to advanced, and just because your not knocking doesnt mean it isn't, your probably dumping excess fuel to compensate the earlier burn and perhaps control knock.

There really shouldn't be any reason to max out IDC with methanol, not even with stock injectors.

What is your timing at peak, 6000 rpm, and 7000 rpm?

 

Sorry I don't follow your response...Are you saying that I am running too much timing and that I am dumping fuel to control knock ???

@3600 RPM timing is 4/5, AFR = 11.4, 2 counts knock, IDC 68%
@6000 RPM timing is 9, AFR = 11.4, 3 counts knock, IDC 99%
@7000 RPM timing is 14, AFR = 11.7, 2 counts knock, IDC 102%

 

Not with timing that conservative

Maybe FPR leaking under boost.

My IPW is 18 - 19 ms peak and 70% at redline

Wait, you have a IX. Seen that before with IX's - they run more power than 8's and use more fuel, put a 675 cc nozzle and spray 80% and maybe that will work

 

The best way to find out if your injectors are maxing out is to install a wideband measurement system. Its also possible that the timing could be a bit high for your combination of boost and afr. I'm running 24.5 psi with a similar afr, and my timing is around 10-11 deg BTDC at 7000 RPM max load.

 

Mrfred -- I have a Zeitronix wideband and use it to record my boost, AFRs, etc.

Anyone else ---- ??? Thanks

 

http://www.stealth316.com/2-calc-idc.htm

 

^^ Interesting link...it appears the formula on that site differs just slightly from what I was using (RPM * IPW) / 1200, b/c at 7300 I calculated an IDC of 102% vs. the site 98+%...Either way I would say that my IDCs are too high....So back to the original question....

So the question is, should I:
(a) reduce boost
(b) get injectors -- rec. please
(c) get a meth / alk kit
(d) other - please be specific

Thanks a bunch!