Injector DC Questions

[Calan]

I've read a lot about injector duty cycles, etc. but I'm a bit confused.

MMCd shows injector pulse values which usually read between 1.5ms and 7.0ms under normal driving up to maybe 3500 rpm. They go into the low 20ms area when I attempt a WOT pull.

What should I see here? How can I use these values to determine if I'm having serious issues with my MAFT/GM MAS and 650cc injectors?

My car runs like fried ass at the moment, and I'm guessing my injector/air/fuel settings are hosed. I've got a WB o2 coming soon which will hopefully help.

Here is a typical log:

TIMA FTRH FTO2 O2-R TPS MAFS RPM KNCK INJP
08° 102.2% 099.8% 0.00V 10.6% 0037.7Hz 1281 00 00.00ms
08° 102.2% 099.8% 0.00V 19.2% 0062.9Hz 1281 00 02.82ms
22° 102.2% 099.8% 0.00V 20.4% 0113.2Hz 1313 00 03.33ms
22° 102.2% 099.8% 0.02V 20.8% 0113.2Hz 1344 00 03.33ms
23° 102.2% 099.8% 0.02V 20.8% 0100.6Hz 1313 00 03.33ms
25° 102.2% 099.8% 0.02V 10.6% 0106.9Hz 1344 00 02.56ms
16° 102.2% 099.8% 0.04V 10.6% 0062.9Hz 1906 00 01.54ms
27° 102.2% 099.8% 0.02V 10.6% 0044.0Hz 1875 00 01.28ms
33° 102.2% 106.1% 0.00V 19.6% 0075.5Hz 1781 00 02.30ms
34° 102.2% 117.8% 0.00V 22.4% 0132.1Hz 2063 00 02.82ms
34° 102.2% 133.4% 0.02V 28.6% 0176.1Hz 2031 00 04.10ms
31° 102.2% 150.5% 0.21V 29.4% 0213.9Hz 2188 00 04.35ms
31° 102.2% 135.7% 0.82V 30.2% 0226.4Hz 2281 00 04.35ms
31° 102.2% 117.0% 0.64V 30.6% 0245.3Hz 2406 00 04.35ms
31° 102.2% 124.0% 0.62V 30.6% 0257.9Hz 2563 00 04.35ms
32° 102.2% 138.8% 0.72V 30.2% 0283.1Hz 2688 00 04.61ms
33° 102.2% 116.2% 0.80V 29.0% 0283.1Hz 2813 00 04.35ms
34° 102.2% 106.1% 0.21V 28.6% 0276.8Hz 2969 00 04.10ms
35° 102.2% 134.2% 0.76V 28.2% 0270.5Hz 3063 00 03.84ms
36° 102.2% 135.7% 0.29V 27.8% 0276.8Hz 3156 00 03.84ms
36° 102.2% 124.8% 0.14V 26.7% 0276.8Hz 3281 00 03.58ms
38° 102.2% 115.4% 0.72V 26.3% 0257.9Hz 3375 00 03.58ms
39° 102.2% 130.3% 0.80V 26.3% 0257.9Hz 3469 00 03.33ms
40° 102.2% 120.1% 0.12V 25.9% 0257.9Hz 3531 00 03.33ms
40° 102.2% 113.9% 0.76V 25.9% 0264.2Hz 3563 00 03.07ms
40° 102.2% 099.8% 0.14V 25.5% 0251.6Hz 3625 00 03.07ms
40° 102.2% 122.5% 0.72V 25.5% 0257.9Hz 3688 00 03.07ms
40° 102.2% 095.9% 0.72V 25.5% 0251.6Hz 3750 00 02.82ms
40° 102.2% 106.1% 0.88V 10.6% 0088.1Hz 3750 00 01.28ms
40° 102.2% 099.8% 0.92V 10.6% 0050.3Hz 3469 00 01.28ms
40° 102.2% 099.8% 0.90V 22.7% 0081.8Hz 3219 00 02.56ms
38° 102.2% 109.2% 0.02V 36.5% 0295.6Hz 2906 00 04.86ms
32° 102.2% 136.5% 0.64V 37.6% 0301.9Hz 2563 00 05.38ms
30° 102.2% 115.4% 0.78V 35.3% 0327.1Hz 2656 00 05.12ms
30° 102.2% 093.6% 0.64V 29.8% 0301.9Hz 2719 00 04.61ms
32° 102.2% 113.9% 0.23V 27.8% 0276.8Hz 2750 00 04.35ms
33° 102.2% 124.8% 0.12V 27.5% 0270.5Hz 2813 00 04.35ms
34° 102.2% 116.2% 0.51V 27.5% 0264.2Hz 2875 00 04.10ms
34° 102.2% 130.3% 0.82V 27.5% 0276.8Hz 2906 00 04.10ms
35° 102.2% 105.3% 0.70V 27.5% 0270.5Hz 2938 00 03.84ms
35° 102.2% 127.1% 0.12V 27.5% 0270.5Hz 3000 00 04.10ms
35° 102.2% 111.5% 0.80V 27.5% 0270.5Hz 3031 00 03.84ms
35° 102.2% 120.1% 0.59V 27.5% 0270.5Hz 3094 04 03.84ms
33° 102.2% 118.6% 0.74V 27.5% 0276.8Hz 3125 04 03.84ms
34° 102.2% 121.7% 0.78V 27.8% 0270.5Hz 3156 03 03.84ms
35° 102.2% 135.7% 0.45V 27.8% 0276.8Hz 3219 00 03.84ms
36° 102.2% 124.8% 0.66V 27.8% 0276.8Hz 3250 00 04.10ms
37° 102.2% 126.4% 0.74V 27.8% 0276.8Hz 3281 00 03.84ms
37° 102.2% 132.6% 0.78V 27.8% 0283.1Hz 3313 00 03.84ms
37° 102.2% 104.5% 0.21V 27.5% 0276.8Hz 3344 00 03.58ms
38° 102.2% 139.6% 0.51V 26.7% 0264.2Hz 3375 00 03.58ms
39° 102.2% 119.3% 0.16V 25.5% 0245.3Hz 3406 00 03.33ms
39° 102.2% 124.0% 0.74V 25.1% 0245.3Hz 3438 00 03.07ms
39° 102.2% 123.2% 0.80V 24.7% 0245.3Hz 3469 00 03.07ms
39° 102.2% 110.0% 0.16V 24.7% 0232.7Hz 3469 00 03.07ms
39° 102.2% 120.9% 0.82V 24.7% 0232.7Hz 3500 00 03.07ms
39° 102.2% 096.7% 0.21V 24.7% 0226.4Hz 3500 00 02.82ms
39° 102.2% 119.3% 0.74V 24.7% 0226.4Hz 3531 00 02.82ms
39° 102.2% 110.0% 0.78V 24.7% 0232.7Hz 3531 00 02.82ms
39° 102.2% 099.8% 0.08V 24.7% 0232.7Hz 3563 00 02.82ms
39° 102.2% 095.2% 0.43V 24.7% 0226.4Hz 3563 00 02.82ms
39° 102.2% 117.8% 0.18V 25.1% 0232.7Hz 3563 00 03.07ms
39° 102.2% 102.2% 0.51V 25.1% 0245.3Hz 3594 00 03.07ms
39° 102.2% 096.7% 0.76V 25.5% 0251.6Hz 3594 00 02.82ms
39° 102.2% 092.8% 0.55V 54.9% 0383.7Hz 3625 00 05.63ms
32° 102.2% 099.8% 0.20V 87.5% 0528.4Hz 3719 00 07.17ms
24° 102.2% 099.8% 0.78V 87.5% 0912.1Hz 3875 28 15.36ms
09° 102.2% 099.8% 0.94V 87.8% 1081.9Hz 3969 28 16.38ms
07° 102.2% 099.8% 0.94V 87.8% 1176.2Hz 4125 27 17.15ms
07° 102.2% 099.8% 0.94V 87.5% 1220.3Hz 4125 27 18.43ms
08° 102.2% 099.8% 0.94V 87.5% 1377.5Hz 4188 26 19.20ms
08° 102.2% 099.8% 0.94V 86.7% 1409.0Hz 4250 26 20.48ms
08° 102.2% 099.8% 0.92V 85.9% 1534.8Hz 4313 25 22.53ms
08° 102.2% 099.8% 0.04V 85.5% 1157.4Hz 4375 25 13.06ms
14° 102.2% 099.8% 0.94V 69.0% 1289.5Hz 4313 24 10.50ms
18° 102.2% 106.9% 0.02V 10.6% 0125.8Hz 3969 07 01.28ms
40° 102.2% 099.1% 0.94V 10.6% 0069.2Hz 3781 00 01.28ms
40° 102.2% 099.8% 0.86V 10.6% 0056.6Hz 3469 00 01.28ms
40° 102.2% 099.8% 0.90V 10.6% 0037.7Hz 3188 00 01.28ms
39° 102.2% 099.8% 0.90V 10.6% 0044.0Hz 2906 00 00.00ms
26° 102.2% 099.8% 0.02V 10.6% 0037.7Hz 2500 00 00.00ms
25° 102.2% 099.8% 0.00V 16.5% 0056.6Hz 2156 00 01.79ms
37° 102.2% 111.5% 0.02V 25.9% 0163.5Hz 2500 00 03.33ms


Thanks

 

[steve]

MMCd shows injector pulse values which usually read between 1.5ms and 7.0ms under normal driving up to maybe 3500 rpm. They go into the low 20ms area when I attempt a WOT pull. My car runs like fried ass at the moment, and I'm guessing my injector/air/fuel settings are hosed. I've got a WB o2 coming soon which will hopefully help.

Here is a typical log:

TIMA FTRH FTO2 O2-R TPS MAFS RPM KNCK INJP


39° 102.2% 102.2% 0.51V 25.1% 0245.3Hz 3594 00 03.07ms
39° 102.2% 096.7% 0.76V 25.5% 0251.6Hz 3594 00 02.82ms
39° 102.2% 092.8% 0.55V 54.9% 0383.7Hz 3625 00 05.63ms
32° 102.2% 099.8% 0.20V 87.5% 0528.4Hz 3719 00 07.17ms
24° 102.2% 099.8% 0.78V 87.5% 0912.1Hz 3875 28 15.36ms
09° 102.2% 099.8% 0.94V 87.8% 1081.9Hz 3969 28 16.38ms
07° 102.2% 099.8% 0.94V 87.8% 1176.2Hz 4125 27 17.15ms
07° 102.2% 099.8% 0.94V 87.5% 1220.3Hz 4125 27 18.43ms
08° 102.2% 099.8% 0.94V 87.5% 1377.5Hz 4188 26 19.20ms
08° 102.2% 099.8% 0.94V 86.7% 1409.0Hz 4250 26 20.48ms
08° 102.2% 099.8% 0.92V 85.9% 1534.8Hz 4313 25 22.53ms
08° 102.2% 099.8% 0.04V 85.5% 1157.4Hz 4375 25 13.06ms
14° 102.2% 099.8% 0.94V 69.0% 1289.5Hz 4313 24 10.50ms
18° 102.2% 106.9% 0.02V 10.6% 0125.8Hz 3969 07 01.28ms
40° 102.2% 099.1% 0.94V 10.6% 0069.2Hz 3781 00 01.28ms

Your car might be running "like fried ass" right now because it's knocking almost as soon as you open the throttle, the timing is drops into the gutter and your dumping fuel in.

IDC is calculated from the RPM and Injector Pulse Width. You need to know how much time is available from the RPM and how much was used to get a percentage (IDC).

Current versions of MMCd will show you the IDC is you log both RPM and IPW.


Steve

 

[Calan]

Yeah.... I'm having a hard time determining if the timing is dropping because of knock, or if the knock is happening because my timing/air/fuel is hosed because of my setup.

I'm pretty sure I'm running into the issue of the timing maps being off because of the piggyback, but I don't know how to correct it without big $$$ for link and an eprom.

There has to be some way of sorting this out with what I have. I just haven't been able to figure it out.

Current versions of MMCd will show you the IDC is you log both RPM and IPW.

Not sure I understand... I see the DC data, but it doesn't look anything like the DC values I've read about. Mine reads more like "4.6%" or something, which seems so far off that I just disregarded it as non-functioning.

Ahhh... I miss the good old days of turning the distributor and adjusting a needle valve on the Holley 650 double pumper

Thanks Steve

 

[steve]

There is no question it's dropping due to knock but your setup could be causing the knock.
Make sure the CAS is correctly set to provide the ECU with it's timing signals at 5* BTDC per spec. (750 idle, temps > 186F, disconnect the datalogger, ground the timing check connector, adjust the CAS) Make sure you have a good knock sensor. If it's original it's overdue for replacement. When they are starting to go bad the sealant turns gooey and leaks out. Once it's all gone the sensor is junk and hyperactive.

Make sure your fuel pressure is correct and stable. From the log you could be having a lean condition initially. See the O2 voltage drop just before you start knocking.

It's always a good idea to check for intake pressure leaks (boost leak test) and double check your MAFT settings.

Steve

 

[Calan]

1. Base timing is dead on at 5* BTDC

2. Knock sensor is brand new and properly tightened.

3. Fuel pressure is 38 and stable on new Aeromotive AFPR.

4. Boost leak test looks good, holding 25psi with slow bleed... mostly through air compressor connection. (Replaced TB shaft seals this weekend).

5. Compression check is 170-175 across.

6. Temp is usually 206* steady (209-210 at idle)

7. Tried both 6's and 7's for plugs, no difference.

I forget what else

I'm dialed down to 11 psi boost, 93 octane gas.

Next is an FMIC, but this is annoying as hell. I should be able to dial out the knock at 11psi and 93 gas, right?

EDIT:

I was also fighting some PK, but quieting the lifters seems to have helped that. This is real knock that I'm dealing with now.

As for the MAFT, I've been all over the place with it, but it is basically set "in the neighborhood" for 650cc's, minus a few ticks. I've tried several different settings though.

 

[spyderturbo007]

I would also check out your TPS since it's only reading a max of 87.5% at WOT.

 

[steve]

I would also check out your TPS since it's only reading a max of 87.5% at WOT.

But since it's reading 10.6% at what I guess is closed, it's set right. I'd check the throttle cable and make sure the throttle is opening all the way. On all the cars, as long the throttle closed setting it correct the WOT reading is what it is.

Steve

 

[90 TSI FWD]

Do you have the latest version of MMCD? If not, I'd download that so you can view your INJD[injector duty cycle] whenever you select INJP, but know that if you log INJD on your palm, it shows up different once uploaded on the computer. It fooled me saying 85% when it was actually 121!

 

[Calan]

I have mmcd 1.8 I believe... the latest I could find. Any info on how to read/interpolate IDC is greatly appreciated, as I can't seem to figure it out. I see numbers like 3.5% or something, which doesn't seem to make any sense.

Steve... That is what I was thinking on my TPS. And I'm guessing that I was a bit light-footed at WOT since I let up immediately because of the knock.

The throttle cable is adjusted for instant engagement. I also checked the ICS when I replaced my TB seals, and it shows 29-30 ohms across all coils.

UPDATE:

I filled up with half 93 and half 101 today, and STILL have some knock above 5-6psi, although it seems to be just a bit less. I'm installing my WB tonight, so maybe it can shed some light on this.

My next mod is gonna be either a FMIC or water/meth injection, to try to get this knock under control. Any recommendations or other ideas?

This knock problem seems somewhat random, but not to the point of being PK, if that makes any sense. It appears to be real knock, but it doesn't happen consistently. Usually it's around 5psi or higher boost, and pops up at 3k-4k RPM range while shifting through the first 3 gears. When it happens, I can slightly hear some actual detonation, and I haven't heard any mechanical problems in the motor (rods knocking, etc.)

FWIW, I pulled the plugs last night and they look fine; no pits or carbon... not fouled... nice off-white insulators... etc.

 

[steve]

Any info on how to read/interpolate IDC is greatly appreciated, as I can't seem to figure it out. I see numbers like 3.5% or something, which doesn't seem to make any sense.

What seems to be the hangup on understanding the IDC. It's simply the percentage of available time to deliver fuel used by the Injector Pulse Width. You should be aiming to not go over 85% or so. Once you hit 100% your injectors are maxed out and never close. At idle you have short IPW's and lots of time between cycles so the IDC is low. As the RPMs climb even if the IPW remains the same the percentage would rise because there is less time available.

Somewhere around here I have the math for calculating the IDC from IPW and RPM.
It just converts RPM to time period and computes the percentage that IPW uses.

Steve

 

[BISHILVR]

You are also hiding air from the ecu when you use the afc or maft to dial in the 660's. That can give crazy looking ipw and probably idc readings since idc is calculated from ipw.

 

[steve]

You are also hiding air from the ecu when you use the afc or maft to dial in the 660's. That can give crazy looking ipw and probably idc readings since idc is calculated from ipw.

Would you care to explain what you mean by crazy? The IPW numbers don't look that much different than what you see when you change the injector global inside the ECU.

Steve

 

[oldman]

Somewhere around here I have the math for calculating the IDC from IPW and RPM. It just converts RPM to time period and computes the percentage that IPW uses.

Available time = 1/rpm *2 (2 crank rotations)

08° 102.2% 099.8% 0.94V 86.7% 1409.0Hz 4250 26 20.48ms

4250 rpm/60 = 70.83 rps

1/70.83 * 2=.0282 sec = 28.2 ms

IDC = IPW/available time = 20.48 ms/28.2 ms = .726 = 72.6%

 

[Calan]

What seems to be the hangup on understanding the IDC.

It's not really a hang up on IDC, more of confusion over the accuracy of my logger. MMCd has two parameters: IPW and IDC. IPW usually shows something like 3.5ms to 25ms, which seems reasonable. But IDC shows maybe 6.5%, up to around 35% I think is the max I've seen, which doesn't make sense to me.

The car is running "ok" except for the knock which then pulls timing, etc etc. Fuel and O2 trims are within +- 2% of 100. I'll have better numbers after I get the WB installed.

So, I'm thinking these "IDC" numbers that MMCd is reporting are either off (shouldn't I be seeing 80-100 or more?), or there is more to that parameter that I don't understand.

I'll look at some logs and do the math on RPM and IPW and see how it relates to the IDC parameter in a while.

 

[oldman]

So, I'm thinking these "IDC" numbers that MMCd is reporting are either off (shouldn't I be seeing 80-100 or more?), or there is more to that parameter that I don't understand.

With 11psi on EVO3/650s at 4.5k rpm, I certainly hope not.

 

[BISHILVR]

Would you care to explain what you mean by crazy? The IPW numbers don't look that much different than what you see when you change the injector global inside the ECU.

Steve

Are we gonna mince words here? I think that he knows what I meant. There will be a difference than what he will see on a stock car (if he compares them) because he has modified the airflow that the ecu will use to determine injector on time.

 

[BISHILVR]

It's not really a hang up on IDC, more of confusion over the accuracy of my logger. MMCd has two parameters: IPW and IDC. IPW usually shows something like 3.5ms to 25ms, which seems reasonable. But IDC shows maybe 6.5%, up to around 35% I think is the max I've seen, which doesn't make sense to me.

The car is running "ok" except for the knock which then pulls timing, etc etc. Fuel and O2 trims are within +- 2% of 100. I'll have better numbers after I get the WB installed.

So, I'm thinking these "IDC" numbers that MMCd is reporting are either off (shouldn't I be seeing 80-100 or more?), or there is more to that parameter that I don't understand.

I'll look at some logs and do the math on RPM and IPW and see how it relates to the IDC parameter in a while.

You will see less because you have larger than the stock injectors that the ecu was programed for and you are compensating for them by spraying them less often to get the same amount of fuel out of them. The percentage of fuel that you took away with your afc or maft added to the percentage you are seeing on your logger will be what the car would be seeing if it was completely stock.

 

[steve]

Are we gonna mince words here?:.

No we aren't. Why don't you run along son.
It's not like you have anything to add to the discussion.

Steve

 

[BISHILVR]

No we aren't. Why don't you run along son.
It's not like you have anything to add to the discussion.

Steve

Oh Steve-o you sly little devil you. And your not even my valentine. To the original poster, if you want to you can pm me, I have an easier way to explain injector pulse width and duty cycle if your not sure.

 

[steve]

And your not even my valentine.

Go try and make nice to oldman I'm not interested.

I'm sure if calan has any questions that we are more than able to help him out.

Steve

 

[BISHILVR]

Go try and make nice to oldman I'm not interested.

I'm sure if calan has any questions that we are more than able to help him out.

Steve

Oldman is way too boring, your a little more fiesty! Cmon you big teddybear.

It was just an offer to calan he does'nt have to accept it.

 

[Calan]

Why do I suddenly feel like the middle car in a train? WTF

Thanks for the help guys... I'm gonna look at some numbers and what you have posted here and absorb it for a while... I'm sure I'll get back to this thread with some more questions....

 

[BISHILVR]

No problem, good luck bro'.

 

[Calan]

Available time = 1/rpm *2 (2 crank rotations)

Shouldn't that be:

Available time = 1/rps *2

?

 

[oldman]

Shouldn't that be:

Available time = 1/rps *2

?

What's the difference? Time is time whether it's in minutes or seconds, you can convert it from min to sec before or after the calculations, you will still get the same answer.

Are we gonna mince words here?