Poor Idle When Warm

**byron** · 21st December 2006, 04:59 PM

Originally Posted by byron

Well I'll throw in the fact that when I removed and cleaned the Stepper Motor IAC with spray Carby/Throotle Body Cleaner and then took off to clean the PCV hoses with the same spray, I saw that the small hole/aperture/bleed was TOTALLY blocked with gunk [I accidently broke the plastic Tee - it had gone brittle and really fragilewith age and heat etc] I cleaned up the hoses and replaced the Flame Trap wire filter on front of RHS rocker cover and put a new filter on rear of LHS rocker cover. I got a replacement chromed brass Tee (with correct sized orifice) and my idle problems are now solved!

Further to the above:
...........remember that the PCV system puts in a proportional amount of AIR and unburnt or partially burnt post-combustion process GASES for "re-cycling". Land Rovers [that I'm familiar with, at least] use FIXED ORIFICES rather than the more common PCV VALVES to control the amount of gases going back in. So if you've got partially or fully blocked orifices [very easy to do] or dirty or blocked FILTERS or FLAME TRAPS you're going to have problems at idle and low speeds.

LR Service Schedules for all the different models from Series to Discovery to Range Rovers list times/mileage intervals [usually at each oil change intervals]
for CLEANING of the ORIFICES and CLEANING or REPLACEMENT of FLAME TRAPS and REPLACEMENT of FILTERS depending on the type and style fitted to different models [ Series/RR/Disco etc] and engine fitted whether petrol 4/6/V8 [2.25, 2.6, 3.5, 3.9, 4.0, 4.2, 4.6] etc or diesel 4/6 [2.25, 3.9, 200 Tdi, 300 Tdi, Td5, TdV6] etc and model YEAR and TYPE of the PCV system fitted on the particular vehicle.

I don't know why, but the PCV system is one of the most neglected/overlooked systems in any make or model of car, not just Land Rover!

P.S.:**** A clean and properly functioning PCV System also keeps your oil and lubrication system CLEAN and functioning well, thus making your engine last a lot longer!****

**4bee** · 21st December 2006, 06:54 PM

So, if there is dirt on VSS then this can give erroneous signals to the ECM, also it may have been moved/dislodged from correct clearances [by a flying rock or whatever].

Byron, what does this VSS look like from under the vehicle? A couple of wires going to it?

**PhilipA** · 21st December 2006, 07:18 PM

I have not experienced it but I think your speedo would also be erratic with a bad VSS, as it runs from the pulse.
On a 93 Range Rover it is on the LH chassis rail next to the gearbox, and a speedo cable runs from the transfer to it. To me it looks like a cylinder on the end of the speedo cable LOL!
Regards Philip A

**byron** · 21st December 2006, 09:04 PM

Originally Posted by 4bee

Byron, what does this VSS look like from under the vehicle? A couple of wires going to it?

Yeah, a couple of wires going to it, it,s about 50-60 mm long x 25-30 wide, between the brake drum and the Transfer Case [screwed onto T-Case] on driver's side I think.

**byron** · 21st December 2006, 09:18 PM

Originally Posted by PhilipA

I have not experienced it but I think your speedo would also be erratic with a bad VSS, as it runs from the pulse.
On a 93 Range Rover it is on the LH chassis rail next to the gearbox, and a speedo cable runs from the transfer to it. To me it looks like a cylinder on the end of the speedo cable LOL!
Regards Philip A

I think that's the Sender for the electronic speedo and from memory is different to the VSS which I'm talking about which is used on cars that have a cable driven speedometer head[on dash]. The one I'm talking about only tells if output shaft is moving or not, and signals that to the ECM. It's definetly there on my 3.9 although my Disco was originally 3.5 Mar 93 build. I know the one you're talking about [had it on earlier RR Classics] but this is a different sensor!

**4bee** · 22nd December 2006, 07:49 AM

Yeah, a couple of wires going to it, it,s about 50-60 mm long x 25-30 wide, between the brake drum and the Transfer Case [screwed onto T-Case] on driver's side I think.

Thanks.

So, what does one do with this gizmo?

Unscrew it & clean the end.

Clean externally?

**byron** · 22nd December 2006, 08:06 AM

Originally Posted by 4bee

Thanks.

So, what does one do with this gizmo?

Unscrew it & clean the end.

Clean externally?

Ther's not much you can do to it.....you just check security and cleanliness of the sensor, its plug and wiring.

No clearance adjustment needed as it's fitted correctly when peg and hole engage correctly.

Sorry, not much more info I can give - I just double checked in factory workshop manual it basically says exactly what I just wrote.

**4bee** · 22nd December 2006, 07:18 PM

Ok, found that one. What a bugger of a spot to get at, eh?

Will have to wait for a while to remove, but visually seems ok .

What is the other one on the outside of the T-case at 90o to the VSS? 2 wires also. Inside is a plain brass blank.

**PhilipA** · 22nd December 2006, 07:32 PM

My guess is temperature sensor on transfer.
Regards Philip A

**byron** · 22nd December 2006, 07:37 PM

Originally Posted by 4bee

Ok, found that one. What a bugger of a spot to get at, eh?

Will have to wait for a while to remove, but visually seems ok .

What is the other one on the outside of the T-case at 90o to the VSS? 2 wires also. Inside is a plain brass blank.

Probably the OVERHEAT SENSOR for the T-case.....only thing it can be on the T-case.

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