On the last `major' drive in my Fury (an epic european tour) I took my laptop along , for fine tuning of the mapping on those long boring motorway bits .
I managed to get it as near as perfect as I thought possible (38mpg out of a 2.5 V6 on throttle bodies !) , but I found that once the laptop was disconnected , it would run richer ?
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Re-connect it , and it was straight back to where I set it . This got a bit tedious after a week or so.........then my laptop broke
On the final leg back up from Dover , the cruising AFR had dropped from around 15 , to a rotten 11.5 to 12 - with fuel consumption to match
Is this common , and something that can be easily sorted ?

Hi Claire!
Can I suggest that you post this problem on the relevant Megasquirt forum? (if you haven't already)
I've not had the same problem on my setup but I do get a small shift in AFR as read on the dashboard gauge when I connect the Lambda to the ECU.
It's only about 0.2 of a ratio though and I think it might be due to the lambda then being earthed twice.
MS is very susceptible to earthing issues. Do you have all the earths routed to the block?
Are you sure that the AFR is actually changing?
What Lambda sensor are you using? Did the problem exist before your last "major drive"?
If not then re-instate a previous MSQ and see if it still happens.
Are you running Megatune or Tunerstudio?
Tunerstudio has a feature to directly compare two MSQ's and helps highlight things that you have changed.
Are you connecting using a proper serial connection or using a serial-USB adaptor? These adaptors can also be problematic.

Geoff

I have tried various megasquirt forums in the past , but I found questions either never get replied to , or take months to get an answer - so I thought I'd ask here !
I have everything megasquirt related onto good chassis earths , and a good engine earth .
I am pretty sure the AFR is changing - I have an LC1 and gauge , and the reading on the gauge is very close the the reading in megatune - and dropping from high 30's to low 20's MPG is a bit of a giveaway !
I may try tunerstudio on my new laptop - it wouldnt run on the old , now dead , laptop .
The change seems to happen when the car is turned off for a while (fuel stops etc) - would this be relevant ?

I'm A bit rusty on MS now. But.

From memory, don't you have to send/ save the fuel tables to the flash memory to permanently save it.

Hi Claire

This does sound familiar to what David (Flak) and Coozer were chatting about at Newark (could have been Stoney) dont think that either of them got to the bottom of it, maybe worth a u2u if you don't get a reply?

Is it almost like the setting arent being saved on the ms and using default ones but when the lappy is connected it uses the right one?

Cheers

Rich

It sounds like you are using more than one earth point and they are on the chassis. The manual stresses that all the MS earths should be connected to the engine block. They should not be combined before reaching the block. I had ECU reset issues when I was earthing on the chassis.
If the sensor has a separate earth for the heater then this can be earthed separately IIRC but other than that all sensor earths and ECU earths should go to the block to the same point.
Are you saying that the AFR stays OK when you disconnect the laptop, but then changes once the ignition is switched off and back on?
Which ECU are you using? What code? MS1? Extra code? MS S'n'S?
Is it only the cruise AFR that is affected?
I'm no expert on MS Claire, but the more info you can give, the better.

Read the following page from the Manual Claire.
Talks about Auto tuning. Look halfway down the page....RAM UPDATE

Is this relevant?

MANUAL LINKY

I'm using Ms1/extra and edis , and I always sane/burn before disconnecting or switching off - I even tried doing the save bit 2 or 3 times but to no avail...........
The problem does get progressively worse - each time I re-start , it is running a little bit richer
I'm not too sure about earthing to the block - that would mean a whole bunch of earth studs somewhere on the block.........? I allready found I cant combine the earths , as this has caused all sorts of hassles (AFR guage switching off when the lights come on !)
I know my wiring is a bit of a nightmare , but how can running a half dozen more wires to the block help - after all , earthed is earthed , right ? ?

quote:

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Originally posted by clairetoo
I know my wiring is a bit of a nightmare , but how can running a half dozen more wires to the block help - after all , earthed is earthed , right ? ?

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Well done Scudderfish!
I've just been scanning the manuals for these diagrams. You beat me to it!!

So..........if I'm understanding this , I need to extend the earths (not sure which ones yet ? ?) , bundle them together , then connect them all (with separate ring connectors ?) to a single earth stud on the engine ?
The ECU has three earths coming from the plug - do these need to be individual wires all the way to the earth stud ?

Yes,yes,yes and yes.
This may not be the cause of your AFR problem though.
Does the ECU reset wnen you connect or disconnect the laptop?
Does the engine momentarily stutter?

Also check your log files for things like baro correction and MAT correction. Baro correction might explain why you get a change in AFR every time you restart the car, as it is set using the MAP sensor every time the ECU is powered up.

Does sound similar to what happened to mine. But mine wouldnt talk to the laptop at all, but would only run with it plugged in... In the end I sent it off to Phil at ExtraEFI and he repaired it for me. There were some damaged tracks on the board, but neither of us could work out what could have caused it.

Post on the msextra forum, Phil and others are on there and usually offer a solution pretty quickly. You will only get help if its a genuine MS unit though and not a copy (M-tech)

Having read the links posted, the automatic correction seems to be what its doing, slowly correcting to what it thinks is 'right'.

I've read in the past that you need to set up the offset voltages for the wideband, they normally report between (made up example) 0 and 1v, megasquirt looks for values between 0 and 5v. If the tunning software is set to 0 to 1v then you'll set up the car correctly and it will autocorrect whilst driving to silly values.

Have you got the auto correction running? and have you got the voltages for the wideband set correctly in the megasqurt software (not tunner studio).

I'll go hunt for the bit about wideband voltages whilst i'm watching football focus.

quote:

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Originally posted by MikeR
Having read the links posted, the automatic correction seems to be what its doing, slowly correcting to what it thinks is 'right'.

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I'm thinking it is a correction issue - the longer I run it (typically 250 to 300 miles between stops) the richer it got .
I even tried writing the target AFR with super lean figures (15 to 16 everywhere) and it made no difference - it still got progressively richer
But........when I hook up the laptop , and read whats in the ECU (without loading a map) it is just where I set it , and it runs perfectly - it makes no sense to me at all

quote:

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Originally posted by clairetoo
But........when I hook up the laptop , and read whats in the ECU (without loading a map) it is just where I set it , and it runs perfectly - it makes no sense to me at all

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This might have already occurred to you but could the fuel delivery be compromised over a length of time?
Is the tank vent functioning? A blocked vent could slowly reduce the AFR. It would be OK again after a fill-up.
Could anything else be affecting the fuel pressure?
Just a thought.....



EDITED... sorry, I forgot ,your car is getting richer, not weaker.
Doh!!

[Edited on 20/11/10 by SPYDER]

Couple of ideas:

Have you connected up directly to the serial port on the LC-1. That will not be sensitive to earth voltages like the analogue outputs (that are going to MS and to the gauge) are. My LC-1 came with a little plug and serial cable for this.


Are all cylinders doing the same thing, i.e. similar looking plugs.
and no significant oil consumption (sorry just sanity checking). Sorry these are both egg-sucking questions.


I don't quite understand how you are using the Target AFR tables with MS1. I thought with MS1 that they would be used for EGO correction, and also off-line if you run the "autotune" option in MLV. I didn't think that EGO adjustment changes were permanent, and that these values would reset when you restart. If MS1 has autotune then I would be surprised. I thought the way of getting the VE table right was to throw MLV a log of the


A log showing what the PW are when AFR is good, and when AFR is bad would tell you if it is MS issuing the incorrect commands, or if it is "something else".


Of the "something else", most things would result in leaner running as temperature increases:
Hot injectors, have longer opening times.
High battery, will result in quicker injector opening times, this might matter if you are running lots of squirts and battery correction isn't perfect.
Where is your MAT sensor? ITB's only warm up after a fairly long run, and their temperature can affect the true temperature of inducted air (bit tricky to deal with) although the effect is nothing like the 20% fueling that you see.


I have spent a lot of time trying to understand MS and getting it working, but I am no expert (who is?). Changing from MS1 to MS2 (i.e. purchasing the daughter card) was one of the best upgrades that I have done, it is much nicer to work with, although I don't see why it would fix this problem.

Good luck, posting msl and msq might help.

Matt

Hi Claire,
I've briefly read this thread, so forgive me if I have missed something.

Do you have any logs of it running normally then some with it rich? Where is your air temp sensor, and does it read roughly correctly?

How do you know that without the laptop connected its rich then with it connected its lean? I take it you have a gauge, if so how is that connected or are you reading the AFR direct from the laptop off the lambda controller?

What sensor do you have and is the signal ground completely seperate to the heater ground?? This is a MUST DO as youll get a drift on the AFR reading with current, etc!! To be honest, before doing anything, ensure your grounds are correct, as this can affect every input to the ECU which could cause the issue you have and more, See here:
http://www.extraefi.co.uk/wiring_basics.html

Phil

Now that is quality.

No need to post on the Megasquirt forum, now they come and find you whichever forum you post on.

Awesome.

Matt