LS1 232/234 Cam Install (Wont Start Without Throttle)

[BENN0]

Hey guys,
I installed a cam over the weekend (232/234, 110 LSA) and im having dramas getting it to start and hold idle. Its a 5.7 LS1 conversion (Manual)

The tune base (ive tried a bunch of tweaks relating to spark,air and fuel also) is speed density (MAF fail at 0Hz), LTFT disabled, forced open loop. I did some driving with it before the cam swap and it was great.

Steps taken for the cam tune:
Timing bumped up (High octane, low octane, in drive, in park) to low 20s
RAF increased across the board (by 3g/sec)
Start up air flow initial increased (by 2-3 g/sec)
Base idle at 850rpm

It wont start without giving it some throttle and then will not idle without throttle. When trying to start the IAC is at 310 steps, so unless im missing something, I cant add more air. When warm the IAC counts are at 40.
The only way I have had it idle:
1) Keep it alive on the throttle
2) While giving it throttle, set the IAC to 0 using special controls
3) Turn off IAC control override and let it do its thing
It then revs up over the idle setting and then comes back down and idles like a dream (The IAC counts then come dwn below where they were when it was tryinig to die all the time)

Im not sure what im missing..... What stumps me is why the IAC can control the idle if I manually "reset" it using the special functions and why I can get it to start without a bunch of throttle.
The log file shows it no starting, then starting with throttle, and then idleing ok after I do the IAC set to 0 then off again (You can see in the log where the IAC commanded and position goes to 0 then back up, right before the revs climb and then settles on a decent idle speed). The tune file is the tune used from that log.

Ive followed the LS1 cam install base tune instructions ive found plus tried a bunch of different things to try and increase air flow at start up. The log will show the fueling is a little off, but I havent really had it running enough to nail it down.
I appreciate the help up front!

9.39 Throttle start then idle IAC.hpl Channels CAM.Channels.xml L277904 V9.39 VE & RAF & Start Up Air.hpt Wideband AFR.MathParameter.xml

[5FDP]

Change the MAF dtc's to MIL on first error, see if that helps with the start up.

Your base running airflow is way way higher than stock, even with a camshaft that big it shouldn't be that much. Most engine don't want to start up and be at stoich straight away either, cold engines will be much happier at 12.0-13.0afr while it warms up.

[BENN0]

Thanks for the reply.
Will update the MIL dtc.
In relation to the base running airflow, I got these numbers by adding a 3g/sec to the initial tune. The initial tune RAF was set based on what it "wanted" based on the STIT and LTIT.
As it didn't want to start without throttle, it assumed it wanted more air.
I will command a little richer AFR (12.5) using the ECT modifier.

I will update all based based on your advice and see how it goes.

[blindsquirrel]

'More throttle' doesn't just give it more air, it also raises the TPS which gives it more fuel... in short, not a good diagnostic tool since you can't tell which one made it start.

[BENN0]

Copy that.
MIL on first MAF error
Less base running air flow
Richen up AFR when first starting

Will give it a go tonight and report back

[BENN0]

Had a play with a few things tonight (Approx 25 iterations....)
I went around in circles a few times. Less RAF and start up air didnt seem to help But im still not sure if it was not enough air or not enough fuel.....Reducing air didnt help on its own. Reducing fuel didnt help on its own.

I have attached a tune and log of where I ended up. Hot start (90deg C). No throttle required. This was the only tune in which it would start withouht throttle.
The RAF is high! But without bumping it up based on the histogram, it didnt like it. The IAC is still at 310 steps most of the time. When driving it lower it would stall.

Next step would be to open the throttle blade some more to get the counts down when hot? It is already more open that it was when stock (0.69v vs 0.55v when stock). Could it be as simple as it not getting enough air even when the IAC is maxed?I initially didnt jump at this becuase it has already been opened a fair way.

9.67 Warm Start no throttle.hplL277904 V9.67 VE.hpt

[BENN0]

Opening up the throttle blade did help a little, but i wouldnt call it a solution.
It JUST started without the throttle and took approx 15 secs to catch its idle and was very rough when it did so.

One thing I noticed was that when I increased the timing tables, I only did so for the cells below 0.28g/sec airmass. I'm idling at 0.36g/sec airmass (78kpa MAP. Seems pretty low). Effectively the timing has been left stock where I am now idleing.
I will increase the timing in this area to low 20s and see if it helps.

[BENN0]

Timing didn’t help a whole lot.
When warm the iac was almost maxed out. Idle trims maxed out when below 90deg C. It feels like it needs more airflow.
I opened up the hole in the throttle body slightly and things started to improve. I will try again tomorrow when its cool and go from there.

[Alvin]

Sounds like you are on the right track with opening up the hole in the blade or cracking the blade more open (less favorable IMHO)

But I wanted to give you some warning. IF the fueling isn't pretty darn close already it will need more air than it would if it is tuned well. SO if this is pig rich and you get the IAC adjusted, when you get the fueling right you'll have too much air. Just keep that in mind.

[BENN0]

Thanks for that.
I went up to 0.75v on the TPS sensor (and then reset so it read 0%) and it still needed more air.
IAC counts were up at 290-300 when fully warm.
Opening up the hole 0.5mm dropped the counts an the start up was much smoother. I will take baby steps on this so it gets the air it needs and I can close the throttle blade back to around 0.60V

[Alvin]

You might have a flat out bad IAC. If you command it around with the scanner does it move? Does the idle change? I'm seeing a lot of bad ones lately

[BENN0]

Yes, I can command the IAC to move and it does move (Can hear it when not running and it will effect the idle when running)

[Hondaeater]

Hey guys,
I installed a cam over the weekend (232/234, 110 LSA) and im having dramas getting it to start and hold idle. Its a 5.7 LS1 conversion (Manual)

The tune base (ive tried a bunch of tweaks relating to spark,air and fuel also) is speed density (MAF fail at 0Hz), LTFT disabled, forced open loop. I did some driving with it before the cam swap and it was great.

Steps taken for the cam tune:
Timing bumped up (High octane, low octane, in drive, in park) to low 20s
RAF increased across the board (by 3g/sec)
Start up air flow initial increased (by 2-3 g/sec)
Base idle at 850rpm

It wont start without giving it some throttle and then will not idle without throttle. When trying to start the IAC is at 310 steps, so unless im missing something, I cant add more air. When warm the IAC counts are at 40.
The only way I have had it idle:
1) Keep it alive on the throttle
2) While giving it throttle, set the IAC to 0 using special controls
3) Turn off IAC control override and let it do its thing
It then revs up over the idle setting and then comes back down and idles like a dream (The IAC counts then come dwn below where they were when it was tryinig to die all the time)

Im not sure what im missing..... What stumps me is why the IAC can control the idle if I manually "reset" it using the special functions and why I can get it to start without a bunch of throttle.
The log file shows it no starting, then starting with throttle, and then idleing ok after I do the IAC set to 0 then off again (You can see in the log where the IAC commanded and position goes to 0 then back up, right before the revs climb and then settles on a decent idle speed). The tune file is the tune used from that log.

Ive followed the LS1 cam install base tune instructions ive found plus tried a bunch of different things to try and increase air flow at start up. The log will show the fueling is a little off, but I havent really had it running enough to nail it down.
I appreciate the help up front!

9.39 Throttle start then idle IAC.hpl Channels CAM.Channels.xml L277904 V9.39 VE & RAF & Start Up Air.hpt Wideband AFR.MathParameter.xml

Howdy BENNO. Do you have the unmolested stock file? The repository file I compared to must be wrong and would like to see the original if you have it. I have an 04 UTE file too but YOUR stock file would be better to compare with.
Would you try logging these channels and lets take a look at the baseline as it warms up into "CL". I know it may take some work to put back into both fuel models and CL but that will give the best picture.
If you start out by reducing the Startup airflow initial and put the delay back to stock it would help. 20* timing from 0-1200 RPM and from row axis 0.08-0.40 g/s for idle spark In gear. Personally I would tighten up the underspeed adaptive idle from -25 and -37.5% to 5* and -50 set to 7* the rest leave at 9*.
Remove the catalyst heating too in spark advance. If it can't idle w/o pedaling it then use throttle to bring it up to op temp. Let's see what the IAC are at operating temp before drilling any more. Did you reposition the set screw after drilling out the blade?
IAC channels list.Channels.xml

[kingtal0n]

'More throttle' doesn't just give it more air, it also raises the TPS which gives it more fuel... in short, not a good diagnostic tool since you can't tell which one made it start.

Not to nit pick. I love your posts and you are far more knowledgeable about HPtuners related stuff than me thats for sure.

But are you aware of 'clear flood' and associated algorithms? As TPS% Is increased during cranking or while engine is off, more air is added, while fuel is generally reduced or remains constant. There is no/never any setting which will increase fuel flow for increased TPS% while cranking - unless you specifically set up a table to do so. For example in Holley's latest and greatest ECU there are such tables where you may specify to increase or decrease fuel as TPS% Is changing. Nevertheless I am sure the OEM ecu programming will not increase fueling for increasing TPS% when cranking as it goes against the logic of clear flood, which is of course that ultimate TPS% Point over which the ECU completely shuts off fuel and only air is cranking through an engine. All ECU use clear flood, it is standard.

[BENN0]

Original tune attached.
The engine/gearboox is out of a HSV Ute, but is now in a Torana.
It never liked to idle cold (before the cam) without increasing the base running air flow. Only mods were long tube 4 into 1 extractors, intake pipe, filter and replacement MAF.

I reduced the VE table in the 400rpm cells and it helped a little with firing up, but it immediately stalled (peaked at 1000rpm then stalled). Started ok with some throttle and held its own idle after 20 seconds or so of throttle. So its getting closer.

I will update the timing tables and log a cold start with the IAC channel log and report back.

Original Tune.hpt

[Hondaeater]

Don't forget to lower the Startup airflow initial and put the delay back to stock. Zero the Spark catalyst heating table too, that will help a bunch for cold start. No cats right?

[BENN0]

Don't forget to lower the Startup airflow initial and put the delay back to stock. Zero the Spark catalyst heating table too, that will help a bunch for cold start. No cats right?

I lowered the start up air and delay (back to stock). It didnt help. I am running cats.

I went MAF only last night and took it for a drive to to try and dial that in a little and not worry about the cold start idle. It was fairly close and didn't need much of a touch up.
The initial cold start required throttle to fire up and keep it running. But after about 15-20 seconds or so, it would idle on its own.

With the MAF pretty close and the fuel table not too bad, I will give it a cold start using all of your suggestions and logging as per the below and report back.

Interestingly when running MAF only, the IAC counts when hot were approx 20 higher than running in SD mode. The idle also felt smoother.

[BENN0]

Update:
I have been running MAf only to tune up the MAF side of things. Have been playing with timing at the same time.
Its in a spot where it runs great but still its terrible to start. It wont start (cold or hot) without some throttle. Then it needs to be feathered for 15-20 seconds or it will stall. Then it comes good. While needing throttle to stay running, it runs rich (richer by an AFR of around 2)

It getting close to being defeated!
Attached is a my "best" cold start and idle. IAC counts at 310 when it can idle on its own, then they drop to 0 when hot.
During this log I used the bi-direction controls to set spark in a few instances, drop the idle speed when it was warm and to also set the IAC to a controlled number of counts (to try and get some sort of IAC vs air flow correlation)

Idle desired is up around 40 g/sec when cold the down to 2 g/sec when hot. I beleive this is a function of the IAC steps vs Effective area table? So if the table is out, then the calculate desired air will be incorrect.

Dropping the RAF table numbers didnt help. Idle trims were higher.

I dont get it.....It seems like it wants more air when cold, but less when hot. So many changes since the cam went in and nothing has changed the way it starts.


11.14 Tune.hptSB Channels.Channels.xml11.14 Cold Start.hpl

[Fast4.7]

I had a 6.0L with about the same cam profile that wanted to fire and die. I halved the idle flare spark retard. Helped a ton as the engine becomes alot more sensitive to retarded spark timing with a cam.

[Fast4.7]

Another thing that helped me tame a couple of setups. The startup airflow is immediately decayed out after the delay, straight down with no taper off. The friction airflow is decayed out by a modifier and also has a delay. I added my startup airflow to the friction table, added about 20 crank revolutions to the delay and halved the decay value so that it tapered off more slowly.