Please look at my log and let me know about the inj

JDR7919 · 10-18-2005, 06:52 PM

Ok I just did a 3rd gear log the car pulls really hard and then feels like i hit a wall and buck and jumps.

My fuel trims are low 85 mid 96 high 100
I dont understand inj p/w at all i tried looking for some info on what kind of #s it should be but could not find any.

Here is the log.
rpms knock timing o2 inj
2000 0 29 .53 1.03
2500 4 15 .65 10.26
3468 2 14 .65 20.00
4718 0 19 .63 23.59
5187 34 9 .61 24.87
5375 40 12 .53 12.82

Ok Im runing about 18 psi. Fuel pressure is about 42psi. Base timing is 5*
Inj has a nice steady increase from 6.92 to 23.59 then it jumps around. Is this what fuel cut looks like?
I know you cant tell much by o2s but I look really lean; how could that be if my fuel trims are ok.

What am I doing wrong here please give me some input!!!!!
I would like to go to the track but I would be crazy right now.
Thanks
jon

JDR7919 · 10-18-2005, 08:50 PM

How could my fuel trims be ok and my o2s say i am so lean?
Does anyone know where I can read about inj pw I have been looking on here and on dsmtalk and have not found anything.
How do I know if i am overruning my inj and if so would that cause fuel cut. Can fuel cut make the knock sensor read as knock?

Please help

pneumo · 10-19-2005, 12:37 AM

The ECU doesn't use the fuel trims during WOT. Fuel trims are only used to adjust fuel at part throttle driving. That's how you can be running lean at WOT and still have good trims.

If you're hitting fuel cut, you'd see the inj. pulsewidth go to zero for a second, O2 volts also go really low at the same time.

If you're getting a bad misfire the inj pulsewidth stays up, but the O2 volts drop off for a split second.

If you're getting MAF overrun the airflow reading and inj pw will be erratic. They're supposed to be smooth.
Here's the formula to calculate injector duty cycle; (inj.pw X rpm)/1200.
at 3468 rpm the injectors are open 57% of the time.
at 4718rpm duty cycle is 92.7%.
at 5187rpm you're at 107.5% That's bad!
That could be why you're getting all that knock. Get more fuel, or turn down the boost!

JDR7919 · 10-19-2005, 06:36 AM

Ok so I went for another drive; turned up the wot and down on the boost.

In third it started again @ 4906 rpms.

Rpms Knock Timing o2 Inj
2468 0 32 .49 3.33
2531 0 26 .63 6.15
2656 0 23 .61 7.18
2843 0 14 .69 14.62
3250 1 15 .71 19.74
4187 0 18 .69 22.82
4906 0 33 .51 3.85

My o2s and inj drop at the same time and my timing goes up.

So does it sound like I need to get bigger inj?
I have heard that the maft is not very good for anything bigger then 650s is that true?
I was wondering if I could set my maft for a lower inj size would that give me some more room to tune with?
What about changing my base fuel pressure?

Thanks for the help!

spyderturbo007 · 10-19-2005, 06:49 AM

Quote:

Originally Posted by JDR7919

So does it sound like I need to get bigger inj?

Yes, go get some 650's

Quote:

Originally Posted by JDR7919

I have heard that the maft is not very good for anything bigger then 650s is that true?

Most guys that run the MAFT also run a SAFC for the fine tuning. It just add some flexibility.

Quote:

Originally Posted by JDR7919

What about changing my base fuel pressure?

Leave the FP alone. I never recommend changing FP to compensate for a tuning problem. Increasing the FP makes the injectors larger, but the fuel pump smaller and vice versa.

On a side note: pneumo gets a rep point for a "balls on" thorough post. Keep up the good work!

JDR7919 · 10-19-2005, 11:26 AM

Ok so for now the best thing I should do is turn the boost way down.

So does it look like this is fuel cut?

Thanks

spyderturbo007 · 10-19-2005, 11:43 AM

No it just looks like you are running out of fuel.

I don't think you have enough fuel to cover your airflow. Cut back the boost and make another pull.

But now that I think of it, have you done a leak test lately? If you do lower the boost and make another pull.....log airflow so I can see where the ECU is putting you on it's timing maps.

Also, let me know what your SAFC settings are from 4k up when you post up the next log.

pneumo · 10-19-2005, 10:09 PM

Could you also log throttle position? I have a feeling you let up off the throttle right at 4906rpm on that last log. That would explain why the timing went up and knock stayed down.

Thanks for the rep point, spyderturbo007!

JDR7919 · 10-20-2005, 06:48 AM

Thanks for the info guys,
I dont have afc to change my fuel above 4000rpms, I only have the maft for now.

I did a leak test a few weeks ago but I will make sure I do that again.

I will make another log later today with throttle pos when I get home.

I did have a question. I pulled alot of fuel out of the wot and my inj only went up to about 17 or 18 ms if i remember correctly. I still had about 30 counts of knock; how could I pull out fuel and have 10 counts less knock.

Thanks again for the help!

JDR7919 · 10-20-2005, 03:58 PM

Ok here is the last log i have I was on 12 psi.
I had turned my wot nob down to 0

rpms knock timing o2 inj
1562 0 29 .67 4.36
3125 0 35 .61 6.92
5250 0 29 .59 5.64
2468 0 26 .67 9.74
4312 0 21 .65 14.62
5343 1 27 .65 14.10
7312 0 21 .63 8.46
4500 7 16 .65 15.13
5375 5 23 .65 15.38
7281 3 18 .65 9.74
5000 11 18 .67 16.92
6218 30 12 .67 18.97
6406 33 19 .57 9.74
5093 32 10 .71 17.44

pneumo · 10-20-2005, 09:50 PM

I'll give it a try, but it's hard to tell what's going on because the resolution of your logs aren't so good.

From looking at the rpms it looks like you logged a full run through first, second, third, and maybe part of fourth gear. Is that right? That could explain the knock; you're heatsoaking at the end of the run.

It's hard to tell what the timing is doing because it's hard to tell where the rpms are coming down between shifts and where they're going up from accellerating.
You can get better resolution by only logging what you need. If you're logging everything all at once the sample rate drops, which is how your logs look. Either that or you need better logger software. HTH

JDR7919 · 10-21-2005, 06:34 AM

Hello,
Is there away to just down load the log because Im just looking at and writing it down for you.
I do have a FMIC so I dont think heat soak is a problem.

JDR7919 · 10-21-2005, 10:56 AM

Ok I did a leak test and found that I have a leak on the throttlebody. I checked the bolts to make sure thet were tight and one on them is stripped. Does anyone have any ideas how I can get this bolt off?