Rover Gauge Data gives very high road speed vs actual

[blaze_away]

Continuing on my thread of poor fuel consumption I've now improved the situation from 10 mpg to 20 mpg but still not convinced that I have fixed the problem fully, the mpg should still be a tad better than that. The 20 mpg I have achieved was steady motorway driving at 50-70 mph over a 200 mile journey.

The Rovergauge data that is clearly not correct is 'Road Speed' it is reading very high eg I am doing 50mph it is reading 80mph

So question is does Road Speed have a direct correlation with the fueling ?

If the answer is yes then how do I 'fix' the high values being used by the ECU ?

[Steve_D]

The road speed data seen by RoverGauge is generated by the speed calibration box behind the dash and as you say is wrong but all it is doing is telling the ECU if you are moving or stopped. The ECU only uses this to set the idle speed high as you slow down to a junction or traffic lights. When you stop it will drop down to normal idle.

Steve

[blitzracing]

Check the fuel trims in RoverGauge- specifically the long term, make sure is less than 100%. Also check the vacuume advance is working on the dizzy.

[spend]

Steve_D said:

The road speed data seen by RoverGauge is generated by the speed calibration box behind the dash and as you say is wrong but all it is doing is telling the ECU if you are moving or stopped. The ECU only uses this to set the idle speed high as you slow down to a junction or traffic lights. When you stop it will drop down to normal idle.

Steve

Suspect the OP's Chim will have LT77, so road speed sensor off box (as per LR) and speedo separate sensor & wiring off diff then no box in dash.

In this case it is likely the speedo (ecu) drive gear in the box is the wrong variety (there are several different colours). TVR originally used one on pre-cats (griffs) suitable for the speedo so maybe wrong calibration from factory (chims phased in when Griffs changed from stewart warner to ECB gauges) as it only went to ECU or possibly post factory install of wrong toothed version. Either way I don't think it really matters & is probably still far more accurate than later cars with the black box signal splitter

[blaze_away]

Thanks Blitz, Spend

Really appreciate your posts, have just had the rockers off for a bit of a tidy up and found a split hose on a vac line to the Stepper, probably not too significant, but fixed anyway.

Now I've got an intermittent 'ignition light on' situation, suspect I've created a dodgy connection to the alternator, so onto that tomorrow now, alternator was new only a few months ago so that should be OK.

I'll hook up the RoverGauge and do a run with it.

[SILICONEKID346HP]

Fit a wide band lambda and you can see what its doing ,then rip it out and fit Emerald .

[blitzracing]

SILICONEKID346HP said:

Fit a wide band lambda and you can see what its doing ,then rip it out and fit Emerald .

Whats happened to the all singing and dancing Megasquirt then?

[SILICONEKID346HP]

blitzracing said:

Whats happened to the all singing and dancing Megasquirt then?

It was the dodgy wiring, had the lot ripped out , Jools then did his magic ..

I have the Bosche Fiveo Gen111 injectors set at 2.6 bar .. 30mpg at 60 to 70mph .. and three switchable maps which i can change on the move .