Jump to content
Manxey

That First Start of The Day

Recommended Posts

Hi Folks,

Ive been struggling with this for a little while now, and ive been fiddling with all sorts of little settings, and to cut a long story short, ive decided i dont really know what im doing and its time to ask for help!! :blush:

The trouble is; that one the first start of the day the motor (3.9 v8 running MS1 Spark and Extra) fires and runs for a couple of seconds then stalls, then if you crank it again she fires up and runs perfect. It'll start perfectly all day then, but come the next morning it'll be crank-run-stall-crank-run.

Has anyone had any similar problems? Or got any solutions?

Ive attached my cranking, and ASE settings if its any help :)

ASE

Crankingsettings

Morecrankingsettings

Share this post


Link to post
Share on other sites

Mine does this as well. Although i've found that it isn't as bed when it's cold, what about you ?

Not a clue what my starting settings are :lol:

Share this post


Link to post
Share on other sites

Ditto, mine does this too!

Just been reading part of the megamanual, the first start enrichment does NOT fire unless the TPS value goes above the FLOODCLEAR figure 3 times before you crank -in other words, 3 full strokes of the pedal with ignition on, then start.

Just jumping in and starting will result in a 'normal' start. I quote:

'This is to assist starting a motor that requires additional fuel to start only on the first start after sitting a long time. If the engine fails to start on teh first attempt, the First Start Enrichment can be reactivated after the engine has been sat for 2 seconds without cranking'

So that figure wont affect it unless you pump the pedal 3 times before starting.... maybe that's what we all need to do -read the manual :):hysterical:

Share this post


Link to post
Share on other sites

Wow... Good find....

Manuals.. Who'd have thought they might have some useful information !

Please feed back to us if this does work as it's a definite nugget for us all if true.

I've not suffered from the symptons above, but do have to crank for what feels like a prolonged time if the engine is left standing for a few weeks.

Neil

Share this post


Link to post
Share on other sites

Actually found it in Megatune, open up the 'more cranking stuff' and press F1 :)

Share this post


Link to post
Share on other sites

Hmmmm seems like a few of us have this problem. I tried upping the first start enrichment figure this morning with no effect, so this would tie in with what Bowie69 has said....

Does anyone have any other suggestions about how to cure this?

Share this post


Link to post
Share on other sites

Mine does this also, so would be very interested in finding out why and how to cure it.

Share this post


Link to post
Share on other sites

Mine starts first time every time but nearly dies a second or two after if very cold....

What images you want uploaded from what settings? Got to be worth comparing...

Three as above for starters...

post-1475-0-70894900-1329243807_thumb.jpg

post-1475-0-39562200-1329243809_thumb.jpg

post-1475-0-65198700-1329243810_thumb.jpg

We going to go for PWM settings etc as well ?

Neil

Share this post


Link to post
Share on other sites

I managed the one time to cure it, something in the pwm settings iirc. But then for some reason as soon as i went into water i had absolutely no power - so the old map got put back on :lol:

G

Share this post


Link to post
Share on other sites

Zim, Can you remember what you did at all?

Ive attached a copy for you all to have a look at, yiou, just in case its something blatently obvious :blush:

PWM

PWM2

Share this post


Link to post
Share on other sites

Manxey,

First thing that jumps out in PWM is the frequency. Most set it at 100 but yours is 200... That means all your settings below should be non-standard because of it...

Have you actually tested if the 25 in the "closed (dc)" field for the valve is actually closing the valve ??

My frequency is 100, but closed is actually 45 on my valve.

I basically ran engine up to temperature so it would tick over. Removed PWM and blanked the two holes in plenum so PWM was operational, but not controlling tickover in reality.

I set my tickover up to approx. 900 manually (I usually have it at 800 manually and rely on PWM to lift it to 850- 900 ish) so the engine would stay running. I then raised the revs while looking into the PWM valve.

When the revs go up, the valve should close. At the 25 setting recommended widely for the Bosch valve, mine was still wide open.

Thankfully I have a nice long serial cable so with laptop on the wing, I amended the closed field until I found a value that did actually close the valve as I raised the revs.

Or course, this may not solve your problem, but it will help others to help you if your frequency is set to 100 (You can always amend once you understand what is causing your issues) and making sure your PWM valve is closed will change your fuel table, so you will need to tune again as there will be a different amount of air going into the engine with the valve truly closed.

Once I knew the closed value, I amended my tickover back down and re-connected the PWM valve.

I'll post up my PWM settings when I get home tonight.

Neil

Share this post


Link to post
Share on other sites

Well I tried that, 3 pedal strokes before starting, and no difference whatsoever, stalled after starting.

I could keep it running I am sure by giving it some loud pedal, but that's not really the point is it :)

Second start it fired and then idled at 950 quite happily....

Will try playing with the settings later today to see what I can do, but of course this sort of thing can only be done once a day....

Share this post


Link to post
Share on other sites

Manxey,

First thing that jumps out in PWM is the frequency. Most set it at 100 but yours is 200... That means all your settings below should be non-standard because of it...

Have you actually tested if the 25 in the "closed (dc)" field for the valve is actually closing the valve ??

My frequency is 100, but closed is actually 45 on my valve.

I basically ran engine up to temperature so it would tick over. Removed PWM and blanked the two holes in plenum so PWM was operational, but not controlling tickover in reality.

I set my tickover up to approx. 900 manually (I usually have it at 800 manually and rely on PWM to lift it to 850- 900 ish) so the engine would stay running. I then raised the revs while looking into the PWM valve.

When the revs go up, the valve should close. At the 25 setting recommended widely for the Bosch valve, mine was still wide open.

Thankfully I have a nice long serial cable so with laptop on the wing, I amended the closed field until I found a value that did actually close the valve as I raised the revs.

Or course, this may not solve your problem, but it will help others to help you if your frequency is set to 100 (You can always amend once you understand what is causing your issues) and making sure your PWM valve is closed will change your fuel table, so you will need to tune again as there will be a different amount of air going into the engine with the valve truly closed.

Once I knew the closed value, I amended my tickover back down and re-connected the PWM valve.

I'll post up my PWM settings when I get home tonight.

Neil

Thanks Neil,

I will amend the frequency to 100 and check to see if the valve is actually shutting.

ta

Jon

Share this post


Link to post
Share on other sites

Well I tried that, 3 pedal strokes before starting, and no difference whatsoever, stalled after starting.

I could keep it running I am sure by giving it some loud pedal, but that's not really the point is it :)

Second start it fired and then idled at 950 quite happily....

Will try playing with the settings later today to see what I can do, but of course this sort of thing can only be done once a day....

I think you will find that the 3 strokes of the loud pedal was programmed out a long, long, time ago. If you do a search on the MS forum I think there was a whole thread about it. I think it was gone even before MS extra and MS -msns

It is the ASE (after Start Enrichment) that settles the engine once it has fired and started. Once the ecu has detected that the engine has fired & started, ASE then kicks in for a predetermined time (default 11secs) to stabilise the engine before the ECU takes it to the warm ‘Warm up’ tables.

If its starting on the button and stalling after a couple of seconds then you probably need to richen up ASE by quite a lot in its early stages.

If its not starting on the button then give it a longer priming pulse and slightly longer cranking pulses.

It’s important to get each stage correct in the right order for it to pan out OK ………. If not you will find yourself putting in settings to correct other settings and that is not good for ending up with a smooth running setup.

Share this post


Link to post
Share on other sites

Will watch this with great interest as...

Mine does it to!

I thought it was just me being a numpty.

Share this post


Link to post
Share on other sites

Ah cheers BBC, will take a look, shame they never updated the documentation in MT then :(

Share this post


Link to post
Share on other sites

As you rightly say ............. you will only get one crack at this in a day, or maybe two if you do one in the early morning and have another go in the evening.

TBH ..... ASE & the warmup tables are by far the hardest part of the tuning process.

Share this post


Link to post
Share on other sites

One thing I've found as a common cause of this comes down to the way the warm up enrichment is set up relative to the cranking pulse width. There is usually a temptation to overfuel on the cranking setup and then use less warmup enrichment. The biggest problem being that the cranking pulse tends to be "tweaked" during the installations first ever start to find a point at which it fires and it tends to get left at that while the rest of the settings are tailored around it. The result is that you end up with a good effective cranking pulse due to the WUE but once the engine starts the WUE is too small to sustain a completely cold engine.

To find a better cranking pulse I look at the pulse width being used at hot idle and use the same pulse width for cranking. I then increase the WUE to compensate for the, normally, reduce cranking pulse.

ASE isn't normally necessary for a V8, particularly if you have the IAC set up. ASE when you have a good crank pulse width and WUE setup will just make the mixture too rich when the engine is in it's most "vulnerable" state, causing more problems than it resolves. It's often just "disguising" a problem with the rest of the setup.

With the engine hot and with no ASE or IAC, if the cranking pulse is correct you should be able to "start it through the window" and it will crank, fire up and go straight to idle without any throttle input. WUE can then be used to make it do the same when it's cold once you have the IAC set up.

Share this post


Link to post
Share on other sites

Dave, I've been reading the Megamanual again, and what you say actually makes a lot of sense, thanks for sharing, I am going to try this over the next few days :)

Share this post


Link to post
Share on other sites

Well I've had a play, albeit only one day... but results are significant, so I thought worth posting.

Firstly I sat and thought for a long while, V8's tend to warm up pretty quickly, so rather than wast the first 17seconds with a decaying fixed map, and based upon what Dave above says about being able to run properly immediately on WUE, reduced this to 5 seconds. I am thinking of putting this down to 1 second at a later date and see what happens :)

To combat the long-ish starts in the morning, I changed the 'Cranking / Prime table' settings a bit, firstly I changed the pump prime to 'Always', changed the 'Fire priming pulse' from 'power up' to 'Twice', and adjusted the Cranking/Priming PW table' figures to give a bit more fuel whilst trying to start. It's really the first tim eI have looked in such detail and things have 'clicked' about Crank/ASE and WUE. Realising the Cranking/Priming PW table' is fixed and the Fuel VE table is ignored completely in cranking mode makes complete sense, but it also means that the figures have to be best guessed over time, and too little fuel = long crank, too much and a cloud of black smoke after starting.

Anyways, a quick SS of the resulting Cranking / Prime table:

post-4193-0-18126000-1329411508_thumb.jpg

The cranking figures I had were about 60% of what is in there now, I used Neil's figures from above, as it made sense that mine needed to be richer due to longer cranking times.

So first one down, moving on to the 'More cranking settings', not much to see here, I set the flood clear figure a bit higher, and left first start enrichment on and at 30%, I may try turning this off in future, but for the moment it is on and OK.

post-4193-0-47703700-1329411509_thumb.jpg

Next was 'After Start Enrichment', the only thing I did here was reduce the 'ASE TOTAL TIME' to 5 seconds, as the engine should be able to run purely on the WUE table, but 5 seconds, decaying, seems a fair figure. All the other settings were left as is, I think the ASE table is pretty standard, but as said, only active for 5 seconds ;)

post-4193-0-09844600-1329411506_thumb.jpg

Next was the WUE, logic dictated that 17 seconds of ASE was probably masking the fact my WUE was too weak, so as a starter for 10 I picked up Nige's WUE figures from his most recent TunerStudio graph : http://forums.lr4x4....10

Another reason for believing that WUE was too little, was after ASE had stopped, pressing the throttle pedal resulted in a massive bog-down and then the engine would rev up -weak mixture symptoms in my book (and hopefully everyone elses!)

So... here's what I ended up with, including the figures on the RH side:

post-4193-0-51125300-1329411511_thumb.jpg

It looks complicated, but basically you are only interested in a few points on the graph, grab a point and drag it up or down and listen to the engine, you will eventually find a happy medium where it sounds best, mine ended up pretty similar to Nige's in the end in all honesty, but it is definitely much better for it, it actually drives nicely when cold(!)

Oh and that starting? It turned over 3 times, fired, idled at 1100 for a sec, then dropped down to 950 as the PWM valve closed a little. When ASE finished, it remained running with no engine note change, probably due to the nice way MS decays the ASE over time rather than switching it off immedaitely after a few seconds. During warm up and WUE tweaking, when pressing the throttle there was no hesitation at all.

Overall I'm a pretty happy bunny, hope these figures help other people too, I'll probably tweak them again, but I think I must be 90% of the way there now.

BTW, mines a 4.0 P38 engine, Kent H200 cam, 9.35:1 pistons, skimmed and ported heads, inlet and exhaust, 3 angle valve seats, and trimmed valve guides.

Lastly... first time I have actually had a chance to use TunerStudio in anger, if you are still on MegaTune, go get TunerStudio, you won't regret it.

Share this post


Link to post
Share on other sites

Bowie,

Where did you download TunerStudio from please?

Share this post


Link to post
Share on other sites

Tunerstudio is Phil Tobins development of MLV, and a big improvement, especially realtime tuning and UX improvements.

Download and buy here: tunerstudio.com/index.php/tuner-studio

:)

Share this post


Link to post
Share on other sites

Can concur.

Moved from MLV 6 months ago...Not looked back, especially like live tuning...

Neil

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy