Computer Trip - Help Please

[dlm2310]

Hi Guys,

Just got my car back from a 30k service and have noticed the avg mpg trip is all over the place.

I know the real time trip moves about a bit but the average should stay pretty constant.
I've just been out and on a 5 mile journey the avg was started around 80mpg and got to 108 !! then on way back was 30 mpg !!

Even if I am doing say a constant 50 mph the trip will dance around from say 37 to 40 to 39 to 44 for example.

Weird how it never did this before the service.

Any ideas please ?

 

[klawit]

Just got my car back from a 30k service and have noticed the avg mpg trip is all over the place..... Any ideas please ?

Hello dlm2310,

first of all, the service will reset the service interval itself and (as far as I remember) the other cumulative figures as well.
Did you check if your computer is set on [1] or [2] (which is measuring overall consumption)?

Maybe you were only watching this cumulative storage [2] lately, which does't move significantly up and down, as it measures in relation to total distance (*) ... and are now surprised by seeing the figures jumping on display [1] on short trips?

greets ... Klaus


(*) I know that "total distance" is unprecise ... as the cumulative display [2] resets to zero automatically after 99.99 hours or 9999 km (miles as well?) driving.

 

[Tell]

Well there will be a techo-mechanical answer related to censors or it will the computer corrupted / playing up the trip.... you wouldn't know I was a consultat would you. If it was the censors it would effect your spot readings, so I watch them. If they look OK then it's the trip computer.

 

[dlm2310]

Hello dlm2310,

first of all, the service will reset the service interval itself and (as far as I remember) the other cumulative figures as well.
Did you check if your computer is set on [1] or [2] (which is measuring overall consumption)?

Maybe you were only watching this cumulative storage [2] lately, which does't move significantly up and down, as it measures in relation to total distance (*) ... and are now surprised by seeing the figures jumping on display [1] on short trips?

greets ... Klaus


(*) I know that "total distance" is unprecise ... as the cumulative display [2] resets to zero automatically after 99.99 hours or 9999 km (miles as well?) driving.

Hi Klawit,

Thanks for your response. I was aware of the 1 and 2 settings and was definetely watching the 1 setting.

The fact it even goes past an avg of 100 mpg seems weird and suggests a computer fault.

If I take it back to SEAT will their computer detect an onboard computer fault and if so is it an easy fix ?

Thanks

 

[klawit]

The fact it even goes past an avg of 100 mpg seems weird and suggests a computer fault.
If I take it back to SEAT will their computer detect an onboard computer fault and if so is it an easy fix ?

Strange behaviour ... and it's way beyond my little knowledge of all the technical interrelations, sorry.
I'd rather follow Tell's explanation ... and if there is an error stored in th ECUs, your garage should know how to deal with it.

Nevertheless I would appreciate to hear about any conclusions and results, maybe even the error code.

Good luck ... Klaus

 

[Tell]

I'd follow Klawit's advice .... if the instant reading looks within acceptable range but the more averaged reading isn't then it will be problems with the trip computer I'd guess since they both use the same source information but one averages over a greater period / miles [that's an assumption over the same information, but that must be true]. I'd have to read the manual of what that is. Sure you are not swapping these around in your head ?. Just a thought.

 

[dlm2310]

I'd follow Klawit's advice .... if the instant reading looks within acceptable range but the more averaged reading isn't then it will be problems with the trip computer I'd guess since they both use the same source information but one averages over a greater period / miles [that's an assumption over the same information, but that must be true]. I'd have to read the manual of what that is. Sure you are not swapping these around in your head ?. Just a thought.

No, I can physically see the reading moving about, I don't think it should.

If I've done say 10 miles at an avg of 50 mpg and I keep a constant speed I wouldn't expect to see the trip go down to 35mpg, not even 45 mpg without booting it.

It all seems to have changed since I got it back from the service yesterday

 

[Tell]

I think there are two averaging methods, one is over the last period and the other is over a longer period 1 and 2 that Klawit mentions plus the more instaneous one. Sure you didn't always look at 2 and the garage has got it on 1. I never bother with 2 myself ie. I don't do the procedure to find 2 since I can't be bothered.

 

[dlm2310]

I think there are two averaging methods, one is over the last period and the other is over a longer period 1 and 2 that Klawit mentions plus the more instaneous one. Sure you didn't always look at 2 and the garage has got it on 1. I never bother with 2 myself ie. I don't do the procedure to find 2 since I can't be bothered.

Guys,

Thanks for your comments

Just to clarify. I am aware of the 3 settings, 1,2 and instantaneous and am aware that the 2 setting would hardly move.

However, next time you are out have a look at your reading and see if you can understand me.

If I have the setting on 1 and I go on a trip for an hour the 1 setting is the avg mpg for that trip. After even 10 mins of steady driving the trip should have settled down, it should not move about every couple of seconds by upto 5 mpgs, that is the instantaneous one that does that.

So to recap I am looking at the same setting I have always looked at and am not confusing myself.

I will call the garage tomorrow and let you know what they say.

Cheers

 

[Tell]

That being the case then the trip computer is faulty, I'd get it seen too.

 

[dlm2310]

Well would you believe it. ?

A few days after this post and the trip has calmed down back to normal, must have been just one of those quirks.

I've had the problem once before last year in sub zero temps and thought it was the cold playing the computer up but the weather has been mild recently.

Anyway all is well, thanks Klawit & Tell for your input.

 

[Tell]

Good, good, well my motorised dish has decided that everything is in a different position in the sky since yesterday which is kind of fun, worrying that it had ceased up, shouldn't I put someone on the roof with WD40 to oil it each year. I have to be careful that I don't get carried away and push it too far by moving it to new positions which are the old positions. Could be the wet whether getting in it.

Perhaps your system did a reboot if the power was off for long enough... perhaps.