snettell

Took the car to the drag strip last weekend. The car is very slow to get to my desired PE setting. It is taking between 3 and 4 sec consistently and I'm in second gear by then. 60ft times aren't all that great and not as consistent as I would like. Originally had the PE ramp at 2. Changed it to 3 without much change and then changed it to 4. No change. I have attached a scan and a my tune file for someone smarter than me to look at and maybe point me in the right direction to get this to respond quicker.

1974 Camaro, ls1, trickflow heads, nick williams, fast ported intake, 42# injectors

Russ K

iTrader: (1)

What are your cam specs? Also it looks like your IFR table is too low, as your Maf table is a lot lower than stock.

I also fought with tuning my Maf, once the WOT AFR was right, the part throttle AFR was way too rich. I removed my Maf & run a SD tune. Any Gen 3 pcm car with more than a very mild camshaft, I always disable the Maf & tune in SD.

Your car enters PE instantly as is, and that isn't the problem.

Russ Kemp

snettell

Thanks for the reply. The cam is a comp cams 591/598 lift 230/234dur 112 lobe sep. I have done a lot of logs to get the afr right on. Even on the attached log of my run the histogram of maf error is within +/- 3 by the end of the pass. Its just the first few seconds that i cant seem to get ironed out. Would really like to stay with the MAf for now.

Russ K

iTrader: (1)

Yet I've never had that AFR delay with a Gen 4 pcm in a cam'd car. Why do you want to keep the Maf? You can still leave it in place, just fail it in the tune and watch you AFR respond instantly.

I tune cars as part of my auto repair business, and seen you issue many times. Tuning them in SD is the only way. Maybe if you had a stock airbox it may of helped, but no modded/cam'd car has the stock airbox.

Russ Kemp

HeavyMetl

iTrader: (2)

Wow...this thread is exactly what I needed to see. I just took my new LS1 combo to the track and had the same problems. Lean at launch and staying lean all the way down the track.

snettell

Thanks again Russ K. I'm really not that good with tuning. I know the very basics at best. I payed for this tune and it has been great in all areas to this point. I was also led to believe that in my case an maf tune would work to my satisfaction and it has until now. Am I to understand that if my tune is right, all I have to do is fail the maf and it will be good to go? Or is there more to it than that? At one point earlier this spring I unplugged the MAF and couldn't get the car to start. I plugged it back in and started it then unplugged the MAF and it seemed to run fine. I have had 4 people tune this car over the last 2 years and 3 have failed miserably. I'm a bit hesitant to start all over. again.

ddnspider

iTrader: (26)

A cam that size hardly requires the MAF being turned off. The cam doesnt even have that much overlap.

snettell

Anyone have any thoughts regarding the lean at launch question. Is there any changes I should make or try with my current tune.

ddnspider

iTrader: (26)

If you look at your log you ARE commanding PE immediately at WOT, a little leaner than I would like, but it is commanding at WOT. I would guess run is on to something that your MAF table/VE table isn't tuned correctly.

Old Geezer

iTrader: (3)

What's the fp doing at the hit?

snettell

Not Sure. I Have A Fuel Pressure Gauge Installed On The Fuel Rail But I Can't See It With The Hood Closed. That Is Something I Should Check Out. thanks

snettell

As Far As The Maf And Ve Tables Being Off. The histogram For Ve And Maf Error For This Pass And The Previous 3 Are Right On At +/- 3. I Would Like to To Keep Trying To Get This To Work Before I Go To Sd tune

danieloneil01

OP, on the histogram under #7 (VE - AFR Error) copy the info for 95-100 and paste it in your VE table as Paste Special -> Multiple by percentage then smooth the tables around it. Anything lower than -10 may run a bit richer but you can correct it much easier than running it lean and pulling the engine.

If you do this decrease the enrichment rate to 1 or 2. 3 seems a bit high for a NA motor.


Remember when you go WOT everything is moving very fast and your WB may not be reporting near fast enough. Spark plug reading is the most accurate way to tell you how the engine is running on a given WOT tune.

snettell

Thanks danieloneil01. I will look at that. Appreciate the info

MontecarloDrag

iTrader: (3)

Delete all the unnecessary PIDs from your main table, the datalog you posted has very little resolution. Delete anything you don't need to log to keep the data rate high. 23 bytes or less is ideal.

The PE is being commanded quickly but you have 10% or more AFR error in the affected areas.
Make PE 15% richer from 1600 to 2800 then ramp it back to 12.92 from 2800 to 4800. Something like this

It should work better while you tune the MAF and VE. The goal is to match commanded AFR vs wideband.
You need to work on your histograms and don't trust them blindly. There are spots where the AFR error is 10% but the histogram shows 0. Use filters and increase cell hits to get reliable data.

danieloneil01

Try this filter in your VE - AFR Error for when you log a WOT run

[SENS.90] > 80%

Paste it then reload data.

snettell

Again thanks for the info. Gives me more to work on and some areas of my tune to get figured out

snettell

Its been awhile since I have had a chance to make changes to my tune and do some testing but was able to get out yesterday. I adjusted my pe to richen things up and adjusted my ve table some. I also removed some of the excess from my scanner to get more accurate information. I am still way lean in the first 4 seconds of my launch with wide fluctuations. Its slightly better in some areas but no where near what I need to be at. I have made some 10% changes to the ve with only minor results in the commanded vs actual afr. Im starting to think it is mechanical instead of the tune. does someone smarter than me have any additional help so I can get this figured out.

MontecarloDrag

iTrader: (3)

It's not that bad but you need some changes.
Set your whole PE table to 1.176 (12.5 AFR)
Your tune is using a MAF, if you make changes to VE table the changes are going to be very small.
You need to change the MAF calibration using a MAF-AFR ERROR histogram
Copy-paste special, multiply by % until you have 2% error or less
Then set your tune to speed density and tune the VE table to 2% or less error

Delete STFT and LTFT from your scanner config, you need to have 23 or less bytes for faster datalog

snettell

Thanks Montecarlo. I understand the MAF calibration part using the MAF-AFR ERROR. I am off from 7625mhz to 9875mhz. Correct and smooth that area. Don't know all there is to set my tune to speed density. I know I fail the MAF. Is there more to it than that? Then after that go back and work on the VE table again. Correct? Appreciate the help