Tuning my 3500!

[PCGUY112887]

OK, figured I best start a thread on this.

Mods/car in sig, I'm using a Powrtuner for my tuning. I am running a 97 Venture PCM with a 97 venture DHP 1.5 file.

I have been reading a lot, learned about Eddie's tool on the Powrtuner forums so I am using that now as well. Bear in mind that I am still sorta new to this!

Was told that I should do a VE tune first, so I did the whole copy good spark thing, disable PE, and drove around and logged info. Plugged it into Eddie's tool (using all default options) and put it back into my BIN.

Now driving without my MAF plugged in is HARD. It is hard enough for the car to idle with my cam with the MAF plugged in, when I have it unplugged the car dies around every turn if I don't roll through the turn and gun it. It came to the point where I did 2 30ish min scans for VE, plugged in the data, and I am not going to be able to do anymore anytime soon. Almost got hit on the road a few times from stalling out.

VE is closer now, it could be better but I don't think I should worry about it anymore? I am within +- 5 last time I checked.

REGARDLESS I am onto MAF now. Did a cruise and did some changes, all seems well. Did another cruise and hit 4k RPM's and held it, wideband went max lean for a while till the computer could compensate. OK. Looks like I just need to do this more for a closer tune.

Problem is after reading a bunch, it sounds like tuning like this does not work for WOT, or anything over 7000hz MAF. I hit just over 7000hz MAF at 4k RPM's. Normal? I am afraid to push the engine any harder if the computer can't compensate fueling at WOT, I do not want to run 18:1+ at high RPM's.

Should I need to modify when PE gets enabled at all?

What would be the best way to add a good bit of fuel up top now, THEN go and drive and see how much I am off? I am positive I will be lean if holding 4k RPM's is ultra lean.

Do I need to mess with AE at all? I read what it is and I see people talk about it, but I just don't get what it is changed for and what parts are changed.

[pwmin]

have you looked on the powrtuner forum and found the tuning guide? theres some typical changes in there to the PE and AE tables, as well as others.

[PCGUY112887]

Yes, however the tuning guide is horribly old and inaccurate. Almost everything I read is for boosted apps on the forum

[z34phoenix]

ok a few things... first if you can get a copy of your scan and a bin i can help you out much more... but for the time being, lets say your LTFT lock in at +15 when in PE (WOT) what i would do is go into your MAF table and from the Hz's your getting your LTFTs to lock multiply from that range to the top of the table (well bottom the max values) would multiply by 10% to 12% for starters

personally i like to get most of my tuning done thru the MAF table... other tuning i use the PE rpmVStime table.... i use this to balance O2 variations over the RPM range.

i dont do much with AE. i have alot of it tuned out. so that i know the MAf tables are correct and the PE tables all do their thing. i have seen VE isnt as important on NA cars as boosted cars. not saying its not worth doing, but i wouldnt spend a lot of time on it. esp when your new to tuning. put the effort into MAF tuning and getting everything else dialed in.

[3400-95-Modified]

Stupid question... but you re-enabeled PE while doing a MAF tune right?

[PCGUY112887]

Yes, also got my first bit of KR today, about 2* for a moment. It seems that since I started tuning, my car uses MORE gas now! Like a quarter of a tank for an hour of driving... I guess because of how much extra fuel it's dumping to keep it happy?

Here is my most recent scan, coming home from school. The a/f on there is from the stock narrowband sensor, the wideband is actually all over the place especailly at higher RPM's. I need to hook my wideband up for my next run.

My BIN file is also attached.

http://www.theopia.com/scan.csv

(will want to open in Excel or something)

[SappySE107]

i have seen VE isnt as important on NA cars as boosted cars. not saying its not worth doing, but i wouldnt spend a lot of time on it. esp when your new to tuning. put the effort into MAF tuning and getting everything else dialed in.

Either im out of it, or this is the worst advice I have seen in a while. VE is crucial for a 3500 running on a 3400 code. The efficiency between just the top end swap and what he is basing it on leads me to believe the VE needs to be increased everywhere, more so at higher load (whatever obd2 VE looks like). The cam is going to be easier to tune for than some other cams though so thats a plus. Still,the powerband is broader, the airflow is better, the flow quality is better (look at the carbon stripe leading to the seat and then look at 3500 heads), and the runner length is shorter.

I haven't had to tweak much for AE, but a wideband would probably be a lot nicer to have for it than narrowband.

[PCGUY112887]

My VE is already "fairly" tight, I just can't make it tighter since I can't get the car to run well enough to do anymore. Whenever I unplug the MAF, I can bairly hit the brakes or the engine dies.

[z34phoenix]

oh... sorry... i was going off the tuning i do to my car... if the bin wasnt for your specific motor and you add in the cam... i can now see where VE would be very important to get right.

but like he said he alread got it to +- 5 so its pretty close. could be closer but i still think it should be fine. But reading that the car doesnt want to idle right without the MAF... then i would think either more VE is needed prob or maybe air/fuel adjustments to your open loop base AF by coolent temp ... i know your motor is much diff then my LQ1 the values in that table change a good deal with temp. my AF at operating temp is 14.2 and your bin is looking for 14.6! i would find out if it is rich or lean at idle and then set a good AF from about 158* to the 194* section... my gues is that it is leaner then it should be. still keep the AF rich up top where it is there to protect from overheating though.

again the question was to raise top end fuel... i perfer to do that with the MAF tables to keep things simplified.

bottom line i think you should make those above table adj's and then do another few VE tunes then dive back at the MAF table. personally i havent had the best of luck doing the VE tunes on my Z. but i got them to aleast where the car would run fine even without the MAF... idle, cruse, ect were all fine. just was fighting me from getting the values all locked in as tight as i would like.

[PCGUY112887]

I think it not being able to keep alive without the MAF is just due to the low vac my cam creates. It's when I'm in a turn with the brakes on that it dies, otherwise it's fine to drive and it CAN idle but when I hit the brakes there is just not enough vac and things go to poo.

Just driving around I am typically about 14:1-15:1 on my wideband. When I first start the engine now it idles in a "safe" range, but for a moment before it goes into closed loop it goes super lean.

As soon as I get around 4k RPM's I start to need more fuel, however as I said earlier I don't think the computer can compensate at WOT, and I don't want to be running around at high RPM's anyways with a lean running motor.

Since I have started tuning, my car seems to use SO much more gas!

[SappySE107]

Low vacuum? What is your idle vac? Perhaps your spark timing should be retarded. In fact, I wouldn't even start with the DHP 1.5 if I were you. I think GM used too much timing from the factory.

MAF is important just like VE, so by all means tune the MAF tables.

[PCGUY112887]

MAP reads 40 at idle, I don't know what it would "usually" read that is just my guess.

[SappySE107]

That cam shouldn't be low vac, and its not. Stock idle is .35 to .45. If it was in the 60s or higher, then it would be low vacuum.

[PCGUY112887]

OK then, I went out and got another scan. I think between it being 90* outside and me using a stock airbox, I am getting some KR when the engine starts to get fairly warm. There are a few frames in my latest scan showing up to 1* of it.

I read many ways to increase A/F at WOT, easiest looking to be MAF. I figured since I am modified, the engine does truly flow much more air than the stock MAF table says so it should be a reasonable adjustment.

I added 15% from 7000hz and up, regardless of any changes that were already made from previous scans (which weren't many, few cells end up 18-20% over stock).

Went for a run, wideband didn't go straight to lean! Held around 14-15, hard to watch since I'm at WOT watching the road. I have my wideband hooked up to log with the Powrtuner, however due to a bug in the latest version of the software it doesn't log after a few minutes of driving

Narrowband shows around 12:1 at WOT, I guess this is because of PE commanding a different A:F? Does GM do that for safety or are you supposed to run rich at WOT?

Regardless here is my latest BIN file and log from today. Ignore the ADC Input 1, it's the wideband and after 2mins into driving it's values freeze up.

http://www.theopia.com/tune.zip

Any advice? LTFT's are still +10 in a few areas, would like to ensure I have all fuel taken care of first before I move onto spark. Also want to ensure I am not dumping too much gas, since right now I am getting shitty MPG.

[scott0999]

when you have PE disabled, you dont really need to get into high RPM's anways. up to 4k should be fine, then just scale the table accordingly for the rest. then turn PE back on and have at it