BMWs and Burnouts - my journey into HPTuners

[nsogiba]

I'll start by saying that you folks have a great resource here, I have spent many hours lurking and reading these forums trying to absorb just a piece of the knowledge that's floating around on here. I know this is just a hobby for most of us, and that work/family/life comes first, so I'm grateful for any help I can get around here (hopefully I can return the favor some day).

My current toy is a 2001 BMW 540i with a forged 370 (originally an iron 6.0 out of a 2002ish truck). Built T56, 3.91 M5 rear, yadda yadda. I have been through various iterations of tune and motor from a junkyard Express 6.0 (stock interally) all the way up to the most recent build. From the time I originally swapped the car, I left the tuning to local professionals, and although they did a mostly good job (under WOT at least), the driveability/idle/starts always left me looking for that OEM feel. So, I am jumping into DIY tuning head first and seeing if I can get this thing to start and putter around like a luxury car, while still ripping around like the sports sedan that it is.

While browsing through the general tune I did find a few interesting things - such as the fact that 3 separate tuners (mail order, local buddy, and local pro tuning shop) have had their hands on this PCM while it has been in my possession, and torque management was still turned on. The transmission type was still set to 4L80E (probably didn't matter much), the rear gear and tire size was incorrect (left on old settings),

In case anyone is interested here is the build thread for the car:
http://ls1tech.com/forums/conversion...-bmw-540i.html

and for the fresh motor:
http://ls1tech.com/forums/generation...ld-my-bmw.html

Here is the modification list so that we are all on the same page.
2002 LQ4 Iron 6.0 pulled from "steak" truck - craigslist yeehaw special.
Stock crank, .010 undersize mains
Sealed Power Speed-Pro flat top pistons (4.030" Bore)
Forged I beam rods, ARP rod bolts
New Clevite P rod bearings, cam bearings, main bearings, etc
GTO oil pan, pickup tube, windage tray
Sticking with the same cam, TSP 228R (228/228, .588/.588 @ 112*)

Top end:
stock 241 heads,
No porting, stock otherwise
GM 6.0 MLS headgaskets
ARP headbolts
TSP pushrods, dual springs, titanium retainers

Intake:
Stock LS6 intake manifold
LS6 throttle body
3.5" aluminum intake pipe with stock LQ4 MAF, large cone filter
Stock LS6 fuel rail, with 42# Ford Greentop injectors

Exhaust:
CTSV cast iron manifolds with the cats removed, into OEM BMW exhaust with 2 secondary cats.*
3" QTP Cutout/exhaust dump before all mufflers/ resonators

Drivetrain: Stage 2 T56, 3.91 M5 LSD rear.

The PCM is out of a 2003 Express Van 3500 (6.0, 2WD).

The issue I am encountering currently is a hard start condition when the engine is warm/hot (say, above 150F or so). I have read about this issue on other cammed LS Gen 3 cars and it seems that it is related to an imbalance of fuel and air while the engine cranks. From what I have read it looks like the cure is either added airflow during cranking, or reduced fuel by changing Cranking VE, Startup Airflow Initial, and Cranking FA Mult Stage 1. I spent a good 3 hours this evening learning the effect that changing each of them had on the quality of the startup. I think I improved on what it started as, but it is still far from good. The car starts AWESOME when cold - just a revolution or two and she's already thumping along. My goal is to recreate that great start condition at all ECT values.

Here is my tune file, and a log of a Hot Start. Keep in mind that this is with Cranking VE, Startup Airflow Initial, and Cranking FA Mult Stage 1 all modified from factory settings. It's better than it was when I started but still needs lots of work to be as good as the cold start is.

If there is any information I left out please let me know, and I can update the thread.

Thanks again!

[nsogiba]

also, just for fun and to keep this fun, here are some shameless glory shots!

First week after getting it running, yeehaw












Drove it home after my wedding




right after the junkyard 6.0 let go due to broken valve spring, wife took it well

[Markmx6]

I have no advice to offer you, but it looks like a cool project.

[nsogiba]

no advice on hard starting when hot?

[nsogiba]

geez, tough crowd. I will try over on LS1Tech.

[5FDP]

Yeah, help can be hard to come by sometimes. Alot of people havent done major motor builds or cam swaps and the folks that do or know how to help are normally busy or just can't always get online to offer help.

I wish I knew more about your issue to help but I to havent dealt with a build such as yours.

Sweet car/project though.

[jaydubb71]

I have a G8 GT that I recently had a cam put in. Gen3 vs Gen4. Cable throttle (???) vs DBW. I just kept adding startup airflow in the higher ECT ranges to where it fires up just right when warm/hot. Hope this helps.

[nsogiba]

Thanks. I did add startup airflow and it does start much easier now, but flares up quite a bit after starting. I will have to back it off to find the sweet spot.

[gagliano7]

I would do the Russ K idle config for your RAF table(Idle>Base running airflow). It seems to be very high to me which will cause startup problems. I would also check to see what your IAC count is at hot idle should be around 50-80.

[rao]

http://ls1tech.com/forums/pcm-diagno...cay-delay.html

I had to change the the startup frictional airflow on mine due to the supercharger, but that might not be a bad place to start.

Also get a wideband or 2, you'll eventually need them

[nsogiba]

okay, collected the data for idle desired airflow using the RussK config - it's significantly lower than the actual RAF figures so we will see how that affects the idle startup. It's not "bad" now but something is obviously causing those funky startup issues - with a lower startup airflow number it takes multiple revolutions to actually start, but with higher startup airflow it flares way up and takes a while to return to actual idle (900). I also need to make sure that the data I gathered for idle desired is not affected by the STIT/LTIT and other fuel figures.

I'll be using this guide going forward

http://www.hptuners.com/forum/showth...highlight=idle

[SultanHassanMasTuning]

i will do the following

return your FA crank fuel to stock seems like in the hotter temps there is almost no fuel

your injectors arent stock not sure but i am guessing someone trying to scale 42's

other needed injector data hasnt been changed. also assume your car is returnless

I will also apply SD as the car will feel much better

[nsogiba]

Yes, they are 42# injectors, and yes returnless (C5 Vette FPR underneath feeding stock LS6 rails)

What other injector data needs to be changed?

Why would I get rid of MAF? I don't have any radical modifications.

[nsogiba]

i spent a bit of time last night working on the tune. I used that Idle tuning guide and it has been very helpful in putting this together.


I made some changes a few days ago to my throttle pedal and DBC throttle body to allow for a more fluid movement - there was a sticky spot in the pedal and I wasn't happy with how it was affecting driveability. Fixing the sticky spot was easy, but of course it affected how the car ran since the TB blade had to be opened a hair.

First off, I took the data gathered from my RussK idle config last Saturday (idle desired airflow) and pasted it into my base running airflow values. STIT was much improved at -6 lb/hr as opposed to the much more negative figure it was before (I don't have my old log in front of me to compare right now). I assume there is still some room for improvement there as STIT should be as close to 0 as possible. I also noticed that my adaptive idle airflow for Min PN/ACOff was different than the value for Min INGear/ACOff, so I changed that as well to match. Results were pretty positive as I was able to throw revs at it at idle and it would return and "recover" almost like stock. Still had a bit of warm start difficulty but that's to be expected since I hadn't changed startup airflow yet.

Unfortunately when slowing down and putting it in neutral at around 2K in certain conditions, the revs still fall fairly quickly without recovering and the engine dies - looking at the charts I see timing being pulled as this is happening, so I am going to play with Idle spark advance in that rev range to see if it helps. I don't know what it would be called, but I'm wondering if there is a parameter that can be modified that controls timing during decel/no load in various RPMs vs KPA or MAF g/sec. It obviously is a "hole" in a table somewhere since I can rip to redline and throw it in neutral and it'll fall and recover with no issue. same thing with cruising around 1500 rpm. it's just on that occasional decel that it does it, i just need to find out which parameter is causing it.

i wonder what would happen if I disabled my MAF and drove around in SD trying to get it to die - that would probably indicate if the issue is with airflow in a certain area, or with timing.

[E$O3200]

There is actually a table that does just that. It is the DFCO (Deceleration Fuel Cutoff). Here is a small how to from PT.net. http://www.performancetrucks.net/for...-422959/page3/

[nsogiba]

There is actually a table that does just that. It is the DFCO (Deceleration Fuel Cutoff). Here is a small how to from PT.net. http://www.performancetrucks.net/for...-422959/page3/

I purposely disabled DFCO in order to avoid random changes to timing during decel, so that I could figure out what was causing it to die. Car is down for a new clutch right now, I'll be getting back into tuning it this week.

[nsogiba]

ok, still fighting some issues with the car stalling when coming to a stop. I have been able to pinpoint how it happens and I'm hoping someone can tell me which parameter is related to that condition.

If I'm cruising along with TPS at about 5%, and need to slow down for a red light, sometimes I will depress the clutch and put the car in neutral. Revs drop, come down to about 900-1000ish, and generally stay solid until the vehicle comes to a stop. No problem.

However, same scenario, cruising along with minor throttle input, and I take my foot off the gas to coast (0% TPS for at least 5 seconds or more, roughly); after the car has been decel'ing in gear for a few seconds, if I then push in the clutch and put it in neutral, the revs will controllably drop to 0 and the car stalls completely. I can recreate this time after time. Is this a function of running idle airflow? Why does it only do this after I've been coasting for a few seconds? Perhaps the throttle follower has already decayed away and there is no airflow left?

I am posting up my log and tune - I also noticed that the timing is doing some crazy things while the car is in the process of stalling. Could be something else to look at. Pretty frustrating stuff since the car drives around town pretty nicely otherwise.

[nsogiba]

Here is my tune and a log of the stall events
Norb7 stall saver on throttle cracker on 2x multiplied.hpt
watching cracker, crazy high timing causing dying possibly.hpl

The stall event starts at frame 2400

I push in the clutch at frame 2403

Timing goes beserk immediately after (full advance).



Another stall condition starts to occur around frame 2779 when I push in the clutch again after a long decel (5 seconds) in gear (coasting down). However this time I blip the throttle to save it. Timing again goes beserk leading up to it.

I am wondering if it is being caused by a lack of airflow or incorrect timing.

Any help is greatly appreciated!