How to lower IPW at idle??

[Ben Charles]

UPDATE:

SHE RUNS now (again) but IPW seems high still, been told it needs to be around 1.7IPW to get a clean idle (seems to do ok even now though) opinions?

I added slowly (5 at a time) to the idle cells to get it to start and idle. And it seems to still be lean, I thinK once I match commanded through startup to actual I will be good to start tuning.

1st log is the car running, and me just watching data. It shows 2% TPS, but I performed the reset and all is good (second log shows good IAC counts in the mid 50's too)

2nd log was a hot restart and notice the lean condition until I intervene with the VCM controls. Again this was operating temps and based off the VE tune If I would have corrected the fueling to match commanded, it may not have been lean?

Nitrous or anyone else opinions? I plan to adjust the VE table some more, and insert your hot start values Nitrous, but now it seems I just need to lower the IPW. Tips on that? Short pulse adder, etc? but then again thought I had the correct data?

[robbyredneck]

good to hear. i would worry more about your wideband than the ipw though. get it to idle then kind of trend your ve table on the rich side, then use your wide band error. you will at least get real comfy with tuning your ve if you use different data. is your car 383 c.i. because if it is you can't really define a idle pulse width. that thing should scream when your done.

[Ben Charles]

Thanks Rob, yea I was watching both the entire time. Do larger CI engines require more IPW at idle?

I went over the scanner info and adjusted the VE table as neccessary (making it richer where it read lean)

[robbyredneck]

more cubes more fuel

[DrLoch]

I got pretty much the same setup as you with a few exceptions. I'm running my rail pressure @ 43 until I get things sorted out and my Stoich AFR is set @ 14.57651. FWIW I have a IPW of 2.3 to 2.5 at temp closed loop MAF.

[Ben Charles]

I will play with it some tomarrow, but it may get as good as its going to get.

I have noticed when I tap the throttle its very sluggish. At one time it was very responsive. All goes back to this injector data I believe.

[Nitroused383]

Now that you have all the correct injector data you will need to tune your entire VE table with your AFR % error via your wideband. You really shouldn't worry about IPW at all, delete the thing so you don't think about it at all lol. Min IPW is only an issue when you cannot get the thing to idle lean enough or decel is too rich. Shoot for 14.5-15.3 idle AFR and do not worry what your IPW is, it doesn' matter at all. A 383 running a cam with relatively low overlap will require more than 1.7 ipw, but that doesn't matter anyways because no one tunes cars based on IPW. My 346 with a cam that has 7 degrees more overlap @ .050 uses an IPW of 1.8-2.0 to idle around 15:1 AFR. Bigger cubes require more fuel at idle and cams with more overlap decrease the low engine speed efficiency thus requiring less fuel at idle.

I see your IAC counts are down in the 20's? Make sure you set your IAC counts while the engine is fully warmed up to temp and your fans are turned off. 20 maybe be a bit low and you might want to close your throttle body just a touch to get in the 40-80 range. This will give your IAC a little more control at idle.

Looks like your over / under speed spark tables are bouncing around pretty good at idle. Try these settings from the picture below to see if it helps smooth your idle out. Having the underspeed table add more timing in the -100 to -300 can be a nice quick little feature that helps prevent stalling by adding a little engine torque via additional timing.

[Ben Charles]

Nitrous I still need to close the TB screw some to increase IAC counts some, but I attempted to do some WB error tuning and after getting the AFR correct in the idle range I did a little 1 minute drive and those same cells I had 14.6-15.1 in are now 16.00?

So I decided to go ahead and do the part throttle only tuning in closed loop, then later check everything with a wideband and do WOT tuning.

Before closed loop I did the Russk idle config to dial in the park/neutral RAF table, then added 10% to that to dial in the gear RAF for now.

Here is my closed loop small idle log, look at bank 1?
Plan to use my RTT to quickly tune in the VE table using STFT error.

P.S. I use to have good starts, now I have to crank it over 2-3 times before it will actually start, don't know what to do about that?

[robbyredneck]

don't do any ve tuning in closed loop. that's why you bought the wideband. only polish the ve table in cl.

[Ben Charles]

Rob looks like a might have a Vacuum leak on the driverside considering my positive fuel trims on that side. Letting the car cool and then going back to the shop to check

[robbyredneck]

that might make things a little more consistent. keep posting i want know when this thing rips.

[Ben Charles]

O I will, getting advice from you guys helps a lot.

Sprayed soaping water on the driverside headers, fuel injectors, manifold, and vacuum fittings. NOTHING

Fuel trims steadily go positive on the driverside and stay consistant on the passenger side. Thing is my WB has been plugged in on my passenger side, just left the O2 in on the driverside.

Using basically brand new ACdelco 02's

Any Advice?

[Nitroused383]

Does it look like the o2 sensors are switching properly in closed loop? You will need to log o2 voltage for both banks. Try swapping your o2 sensors from side to side to see if its the sensor or the bank itself.

If you had your idle cells dialed in and they were off after a cruise I would say it's IAT sensor related. Where is your IAT sensor located, I imagine it was heat soaked after a cruise. Heat soaked IAT will lean things out quite a bit. Try copying these tables if you have issues with hot starts.

[Ben Charles]

Nitrous just switched 02's from side to side, be back in a little with results (shop is about 30 yards from my house)

Be back in a little

[Ben Charles]

OK here is a log, turned CL on after about 15 seconds of running with the VCM controls. Not an 02 sensor problem but a bank problem instead (still showing positive values)

My config listed below too (showing 02 MV's)

I have a FAST IAT sensor about 4inches in front of the TB. Supercharger tubing it all aluminum with a jethot coating

If you had your idle cells dialed in and they were off after a cruise I would say it's IAT sensor related.

I noticed IAT's went from around low 90's to around 117 tops, went for about a minute cruise and when I got back to my shop histogram values were in the 15.8-16.0 range (were they were perfect before) I thought though, maybe it is recording DECELERATION lean values???? Maybe I can filter that data out?

[Nitroused383]

I didn't have time to look at your log. Are these new injectors? Any chance one of them is plugged or needs cleaning? Maybe even one of the injectors is unplugged or a bad wire? Go for a cruise and stay around 2000 rpm or more and see if they fuel trims stabalize. Sometimes with a cam and long tubes the o2 sensors do not switch properly at idle.

[Ben Charles]

Injectors are brand new, less than 100 miles on them, everything is plugged in, I will check to make sure they are on the correct cylinder just to double check. Wiring harness is a new one from EFI connections.

I will increase the RPM some to see if the fuel trims even out in a little when I go look for a vacuum leak again.

[Ben Charles]

Went to work on the car and today and try to find the problem with bank 1.
Injectors are in the correct cylinder, intake bolts are tight, used my light and mirror and I don't see any carbon buildup at the headers.

I did however notice that #1 spark plug on bank 1 was loose so I tightened it, all others tight.

Here is a small log, any one have any ideas on where or what this could be, has to be on bank 1 (even with small rev problem still exists)

[Nitroused383]

I would do a leak down / compression test on the engine. You can also try the cylinder balance test on the vcm controls > special tab. You have to set your RPM and IAC on the same page before you can try the test. If there is a major problem it should point you to which cylinder it is.

[Ben Charles]

What does the cylinder balance test do?
I have a few more ideas, then I will try some of the above for sure.

The test is a simple one, you maintain a constant idle sped by controlling the IAC motor steps, we sample that RPM as use it as the refernce RPM.

Then each injector is disabled for 2 seconds and the RPM sampled during that period and the result is presented as a % of the reference RPM. The theory is that if you disable an injector, and the RPM doesn;t drop much then that cylinder is weaker, and another cylinder that results in a larger drop is stronger.

It's not highly accurate but is a basic indicator of an issue somewhere if you see large variances.

http://www.thetuningdoctor.com/HPTun...ancetest2.html