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        General >> Problems >> Can a rev gauge be out by 500rpm?
        
(Message started by: amigafan2003 on Sep 18^th, 2007, 1:35pm)

Title: Can a rev gauge be out by 500rpm?
Post by amigafan2003 on Sep 18^th, 2007, 1:35pm

Let me explain my problem (Scorpio Cosworth):-

The engine idles at an indicated 1300rpm but it doesn't sound like it is. There is only a normal amount of creep from the auto box.

Gears seem to change at the correct indicated road speed but a bit high up in the range (i.e. 1st to 2nd on light throttle is about 3000rpm).

Cruising at 40 mph shows 2900rpm, 60 mph shows 3500 and 75mph shows 3900rpm.

Planting the throttle, kickdown activates and the revs shoot off past 7000rpm before the gearbox changes.

Torque Converter locks in correctly. No OD lights flashing.

So, if I didn't have a rev counter, I would say everything is running okay, which leads me to suspect the rev counter isn't showing the correct value.

Any ideas anyone?

Title: Re: Can a rev gauge be out by 500rpm?
Post by jonnycab on Sep 18^th, 2007, 2:35pm

Is it possible that the needle is seated wrongly on the spindle ? :-/

Title: Re: Can a rev gauge be out by 500rpm?
Post by amigafan2003 on Sep 18^th, 2007, 2:51pm

That's a thought. I'll have to borrow my friends timing light that also shows the rpm and compare the two.

Title: Re: Can a rev gauge be out by 500rpm?
Post by Highlander on Sep 18^th, 2007, 3:12pm

I wonder if you have a 4 cylinder instrument panel. someone possibly has replaced it in the past.

If you hold the milage reset button down for a few seconds and go into the diagnostics what value does it give for TYPE?
For the 24v it's usually 9 or 11 but can be 8 or 10 for Km models

Type - Type of Instrument Cluster:

0 4 cylinder petrol, low series, km

1 4 cylinder petrol, low series, mph

2 4 cylinder petrol, high series, km

3 4 cylinder petrol, high series, mph

4 4 cylinder diesel, low series, km

5 4 cylinder diesel, low series, mph

6 4 cylinder diesel, high series, km

7 4 cylinder diesel, high series, mph

8 6 cylinder 24V petrol, low series, km

9 6 cylinder 24V petrol, low series, mph

10 6 cylinder 24V petrol, high series, km

11 6 cylinder 24V petrol, high series, mph

12 6 cylinder diesel, low series, km (not installed on Scorpio)

13 6 cylinder diesel, low series, mph (not installed on Scorpio)

14 6 cylinder diesel, high series, km (not installed on Scorpio)

15 6 cylinder diesel, high series, mph (not installed on Scorpio)

16 6 cylinder 12V petrol, low series, km

17 6 cylinder 12V petrol, low series, mph

18 6 cylinder 12V petrol, high series, km

19 6 cylinder 12V petrol, high series, mph

Title: Re: Can a rev gauge be out by 500rpm?
Post by Dave on Sep 18^th, 2007, 3:14pm

My 24v starts cold and idles at about 1000rpm briefly before dropping back to just over 800rpm.

50mph in top gear = 1750rpm
70mph in top gear = 2500rpm

On a light throttle on a cold engine going up a slight hill out of the road in the morning it changes from 1st to 2nd at about 1700-1800rpm IIRC. At 3000rpm it would be fairly shifting :D

Title: Re: Can a rev gauge be out by 500rpm?
Post by amigafan2003 on Sep 18^th, 2007, 3:23pm

Highlander, you clever b****r - I've just nipped outside to check and it is indeed a type 03 cluster - that would explain the 33% difference in revs then! A little happier now that my instincts about it simply being displayed incorrectly were correct.

I checked the PULSE value in the diagnostics and it's 41 at idle, pretty much spot on.

I wonder if the pulse decoding can be changed then? Am I also correct in thinking the mileage is held in the ECU, not the clocks, so I don't have to worry about having an incorrect total mileage?

Title: Re: Can a rev gauge be out by 500rpm?
Post by Highlander on Sep 18^th, 2007, 8:03pm

not sure about the milage, i think it would be easier fitting the right instrument cluster though :)

Title: Re: Can a rev gauge be out by 500rpm?
Post by amigafan2003 on Oct 27^th, 2007, 9:13pm

Okay, I have now fitted TWO sets of clocks, both taken out of 24v Ultimas and when fitted to my car, they BOTH show as Type 03 and the rev counter is still incorrect. No idea whats going on or how to resolve it.

BTW, the mileage is kept in the clocks themselves, so I have a set of clocks that show 91k and 101k instead of my real cars 126k - I though these cars were difficult to clock? Looks like you can just swap a set of clocks from a lower mileage car to "clock" them. Hmm.

Title: Re: Can a rev gauge be out by 500rpm?
Post by Highlander on Oct 27^th, 2007, 10:10pm

unlikely as it seems i'd try another set just in case you DID get two wrong sets of clocks, after all you had them in yours ;)

Title: Re: Can a rev gauge be out by 500rpm?
Post by amigafan2003 on Oct 27^th, 2007, 10:26pm

Well, I've already spent £70 on two sets of clocks so Im not willing to try again :-( - I need to get rid of these clocks now.

Title: Re: Can a rev gauge be out by 500rpm?
Post by jonnycab on Oct 28^th, 2007, 12:14am

Quote....."BTW, the mileage is kept in the clocks themselves, so I have a set of clocks that show 91k and 101k instead of my real cars 126k - I though these cars were difficult to clock? Looks like you can just swap a set of clocks from a lower mileage car to "clock" them. Hmm."

That's interesting to know when I decide to sell my Scorp with already 170K on the clock ;)....... ;D

Title: Re: Can a rev gauge be out by 500rpm?
Post by cossie_al on Oct 28^th, 2007, 12:28am

Now Now jonny, You know as well as we do thats just not fair. ;D
Best of luck mate ::)

Title: Re: Can a rev gauge be out by 500rpm?
Post by Highlander on Oct 28^th, 2007, 12:38am

Johnny, I have a set of 2.3 clocks with 50,000 on them... ope n the bidding ;)

Title: Re: Can a rev gauge be out by 500rpm?
Post by jonnycab on Oct 28^th, 2007, 12:41am

Honestly, would I do something like that ::).....besides, It'd probably only be worth 50 quid more ;)

Stuart....50K you say....hmm.......how much ?.... ;D