E38 idle tuning

[ringram]

Hi mate, your attachment link doesnt work.
Ill drop cranking down a little more to see what happens there in the interim. Thanks for the extra tips.

[swingtan]

Try this then, not sure what happened....

Good-StdCal_swing_0000.tun

[swingtan]

Just throwing this out there as I have had it happen on 2 different e38 car's. 06 & 09 model

Basically idle is perfect, but if you turn the car off and then go to start it again the car will not idle/fire correctly.

If you attempt to touch the throttle the car struggles to rev or it just dies out as if it's not firing.

I have spoken and sent the tune to Joel to look at and unfortunatly none of the changes made a difference, it's as if the car is looking for the maf on a restart.

If you leave the car off for a few minutes the car will fire straight up.

I reckon that is dynamics. On a hot restart, the ECT is up, but the IVT is way down from where it should be for normal running. As usual, post a log and matching tune.

Simon

[Tre-Cool]

I would like to agree with you, but it played up badly today when we got it on the dyno. it wouldnt start for 30 minutes. with multiple changes to the tune.

i ended up reverting to a tune prior to the maf & etc limits as per normal before it would work again.

What i did find interesting though was when it was playing up i started logging it with the engine off, if i put the pedal to the floor there was a good 2 second delay before the scanner registered the tps change. then the same again when i lifted. even on small pedal movements there was a significant delay.

P.S the first car was a stock cam statesman with the maf removed. as soon as we plugged the maf back in it would work. 30 minutes later with the exact same tune it would run fine without the maf.

[swingtan]

PCM reset and ensure you wait 15 seconds after a flash? Both of these should clear any "in memory" issues with the tune. I've seen weird stuff happen if you try and short cut the 15 second wait, Idle spark control that gives up after a couple of seconds is a classic. Were you doing laptop logging? I'm guessing yes with the dyno and I've seen very slow response when laptop logging at times. Normally a reboot fixes it up though. Did you check the actual throttle blade to see if it was responding slow as well?

Personally, I feel that the stock tune commands too much fuel on hot start. I've leaned mine out to 14.5:1 and have no starting issues. I still think it's fuel related and the slow throttle was a Scantool / USB issue. I'd need to see a good log of the start up though to get an idea of what is going on.

Simon.

[ringram]

Ok 7mm hole drilled. Far too big. Now cant close throttle enough and I get a P0068, so weld is required :(
I think I tuned the DTC out with the ETC processing tables.
But from the initial results it seems it might help. Just a FYI start small unless you want a 1000+ rpm min idle.
Also idle hangs pretty badly. Probably can tune that out with the correction tables, but I need a smaller hole anyway... Ho hum..
Definitely some tables missing!

Update: If I had a cam big enough to warrant a 1000rpm idle then Id be set. Cold start worked well. Tuned out the DTC no problem by c0805 and c0806 tweaks.
Ive had to ramp up integral corrections by a shed load and drop all my other tables back to stock. Still too much air and idle still hangs but not as bad.
Anyway, I think Ill weld her up and bung a 5mm hole in there.

Hopefully one day Ross can find a few more idle control tables and avoid such a crude method

[doubledip]

Start with 3mm or if cam big enough 4mm but that's all

[ringram]

Im with you on that now

[The Alchemist]

Ok, tuning going well with this supercharged Ute BUT.....have been trying to get dead cold start spot on..
Hot idle setting 51/52 set at 1.1 (18.8% TP) in "open loop" with 18deg average timing at 800rpm. I set minimum idle air to about 9.3g/s where the TP starts trimming > perfect!
Cold start another story!
Obviously you need more throttle cold so I started with the 0.08 extra as suggested by Hymey the next morning > starts and stalled immediately. tried 1.3 (20.4% TP) starts, just idles timing at 28deg (this seems to be a hard limit for timing at idle hot or cold? correct?) won't accept throttle or in gear load until its been idling for 30 sec or so.
Now...
Whats weird is that increasing 51/52 to 1.4, 1.5, 1.6, 1.8 with reflashing and an idle reset before starting the TP stays as 20.4% regardless and idle is OK at about 750rpm with timing at 28degs yet desired is 1000rpm dead cold . Why is this happening, surely as you increase 51/52 the idle TP% should increase. Once you get over 1.9 the TP is still 20.4% but you start to get a light idle surge or hunt for the first 60sec or so that decays away.
With idle learn do you need multiple cold starts over a few days for the tp% to actually learn upwards past 20.4%???
Any suggestions guys? Been mucking around with this over the past 5 days.
Mike

[ringram]

Same issues as me by the sounds. No matter what the table settings they are no good. Perhaps they do learn over time. But I ended up with a hole.. too big, to compensate.
I think there are tables missing. I need more air in the 440 with 18* overlap, but the only way I could get it was to drill. As mentioned above, start small and work up. You will find the etc will still trim and compensate, but no longer gets the same caps as you are adding air via the hole to the inbuilt limits. I suspect there are some settings missing. There could be a hard idle cap at 20.4% which we dont have access to for example.