Quick question.

Does the suspension need to be in tight tolerance mode when calibrating the suspension?

I have the IID tool and and will be replacing both front strut assemblies.

I’ve already tried out the suspension height calibration using the iid tool, but it occurred to me that it might be better to be in tight tolerance mode during the calibration. 2007 3.6 TDV8

I'm going to stand corrected I'm sure ... but ...

I can't see how replacing a strut affects the geometry such that the suspension needs re-calibrated.

The sensor is attached to the subframe, and its arm is attached to the front lower arm. Its measures movement of that lower arm and nothing else. The arm is attached to the hub, which you are not replacing and will slot back together in the same place when you put the new strut in.

When the system powers back up, it'll simply add / remove whatever air it needs till that sensor reads the correct amount. It doesn't really know whether its a replaced strut or not, the strut will just extend to the whatever height its told to.

So as long as the sensor, arm and hub remain unchanged, then the height settings should not need calibrated ???

( Different story if you are replacing the sensor as each sensor will send back different signals for a given height which the ECU needs calibrated to ) V8 or else ...

I mistakenly left mine in tight tolerance mode after I had finished, big mistake compressor was running almost constantly as car tried to keep itself within the tight tolerances. Geoff

Cheezels, I put the car in tight tolerance mode when I calibrated my suspension, which I think the GAP manual advises to do. Just remember to change it back afterwards to normal.
As Fisha says, you might not need to recalibrate at all, but I found it took 5 minutes to do, so you might as well I suppose.

Have never used tight tolerance mode... .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

nor have I - but I will be getting Kwik Fit to do my wheel alignment on their Hunter Hawkeye laser system in the New Year, and have found out that it's pretty easy to do with my IID tool

IID / Services / Suspension ECU / Tight Tolerance Mode

Height calibration isn't required if replacing the suspension struts, geometry alignment is though. Personally I have always used tight tolerance mode when carrying out any geometry adjustments, if it was my own vehicle, I'd check height calibration before & after geometry adjustment. If it was a customer vehicle, I'd drop it into tight tolerance for the geometry but only do the height calibration if requested / paid for. The reason for checking the height calibration is that during repair operations, the suspension (and height sensors) are manipulated in directions and positions that wouldn't happen on (or off) road, it makes sense to me to check the calibration given the number of moving parts, linkages etc. that all have manufacturing tolerance in them. Once the vehicle has settled under it's own weight, the likelihood of variances from the previous calibration are (to me) high enough to justify the time taken to check and reset.

Tight tolerance mode is not required nor is it advised in the GAP IID calibration procedures. Worthwhile during wheel alignment as is doing a height calibration before having a wheel alignment done. Also make sure all the adjusters are not seized and that there is no play in any of the bushes or bearings. 2012 TDV8 Vogue (L322)