1400K Supersport Idle & Tyres

[Brucey]

1st, many thanks for your responses to my previous questions. Now need help with the following:

 

1. Tickover fluctuates from 1000rpm (Iassume this is correct idle speed) to 1200rpm (even when hot). Advised to clean pot on throttle body (ref: JZX 2963). Took it off, wiped it and put it on again! (No servicable parts there then). Should I just change it? is it a Rover part?

Looked at the stepper motor opposite the pot on the throttle body and checked plunger operated freely, but not sure if I should pull unit apart. I tried resetting the ECU, but no difference.

 

ALSO, engine stalls after going down hills (usually when changing down gear after longish overrun) when engine temp at 90 deg (normal temp). Any ideas?

 

ALSO strong petrol smell after filling up tank. Is this normal?

 

2. Rear tyres (Michelin XGTV) tyres 205/45/16 will need replacing soon (1mm ish to bar). Front tyres were new when I bought the car (Goodyear Eagle 205/45/16). I know there not the most popular diameter, but I like them. Handling was very skitish, but improved dramatically when I reduced pressures from 45psi (I guess the previous owner pumped them up for winter) to 20psi all round. I also repacked the front wheel bearings and adjusted them until all the free play was just removed when wiggled with the wheels on. (Nuts about 1 flat over hand tight)

Should I buy the same tyres for the back that have recently been fitted to the front? Do all 7's understeer on high speed corners?

 

That will do for now, any advice would be much appreciated,

 

Many thanks in anticipation,

 

Bruce (Hythe, Kent)

 

Brucey

[Tony Whitley]

1. It is a Rover part but get one from a breakers - £10 vs £50+ IIRC. Not sure that will cure your problem though - when mine was broken the idle was all over the place and the car drove like a pig. Depending on your exact model/year it might be the IACV sticking but I'm not an expert on those.

 

2. I think Michelins are OK (and fun) in the dry but scared the *eek* out of me in the wet - I don't expect to lose grip at 70 in a straight line 205 is very wide for the front - mine wandered a lot with 195s and is much better with 185s. And I think you can go further with the pressures, I used 18 psi with Michelin Pilots I think.

 

Fatalism means never having to wonder if it's safe to overtake

[Sheds Moderator]

1. Tickover fluctuates from 1000rpm (Iassume this is correct idle speed) to 1200rpm (even when hot).

Mine does too. You get used to it.

Should I just change it?

If you want.

is it a Rover part? Yes.

 

ALSO, engine stalls after going down hills (usually when changing down gear after longish overrun) when engine temp at 90 deg (normal temp). Any ideas?

IACV usually

 

ALSO strong petrol smell after filling up tank. Is this normal?

No but they are prone to overflowing. Have you checked for leaks betw filler hose and tank?

 

2. Rear tyres (Michelin XGTV) tyres 205/45/16 will need replacing

Most people say "bin the Michelins and fit soft tyres in 13"." Look in the archives for pages on tyres. "Scudo Stunners" are dirt cheap and well received as road tyres as they are soft. Track day boys swear by Yokohama 021/032/048 R but you need to replace these faster than the cheese in the fridge.

[Brucey]

Many thanks Tony,

 

My 7 is a 1993 with 34,000 miles and reasonably well cared for.

 

I'll try 18psi all round to see what happens. I guess I could put the front tyres on the back and put narrower tyres on the front and hope I don't get a front puncture!

 

What exactly is an IACV?

 

Brucey

[Dartmoor7]

Caterham handbook says 16 psi for 205/45x16.

I ran mine at this pressure when I used 16" wheels and the centres of the tyres still wear first, handling/grip-wise I wouldn't go higher.

 

Jerry Parker

L7 SVN

1.4 Supersport

[Tony Whitley]

Idle Air Control Valve. Stepping into "I don't really know what I'm talking about" - it allows a little air past the throttle body (when idling I suppose) and they are known to stick - that is more likely than the TPS (throttle pot) what you need to strip down and clean.

 

Fatalism means never having to wonder if it's safe to overtake

[The_ASH]

1400K idle probs are well documented on here if you dig deep enough, try looking back 2 or 3 years as there was plenty of chat about it back then. There seemed to be quite a few cars fitted with the first style ecu with the same problem. Have you seen idle as high as 1600/1800rpm if so could be one of the items below, even so it is more of an annoyance than anything car remains as drivable as ever, just embarasing to pull up at a junction and the rev's will not drop back. It is even possible to set the idle speed with engine warm and then disconnect the IACV, however if engine is allowed to cool idle will not be achieved until engine has reached correct temp again but IACV operation can be mimic'd by light throttle application until warm.

 

Things to check from memory were :-

1. Throttle body. Plastic ones are known to ovalise if the filter circlip is overtightened try loosening, however if it has been tight for some time or the plastic has decided to age/relax then upgrade to a metal one slightly more hp as the butterfly is not three feet thick (I kid you not !) also try for the 'Trophy' body as it's 52mm as opposed to your present 48 unless already previously upgraded.

 

2. IACV usually dirty & grubby, clean it up and the hole it sits/extends into do not power it up with the valve removed from the hole or even loose ! or it'll self destruct it is possible to put them back together quite easily but better not to have to in the first place.

 

3. Sensors, I was told the crank sensor can go a bit screwy but can't remember what the test for it was, equally the temp sensor on the intake plenum is worth checking/replacing if old. Water temp sensors again worth checking but messy to change. Also wiring to sensors can give wierdo readings so look for contact integrity or in laymans terms no nasty green stuff on the connector blades or on hidden contact in plugs.

 

4. ECU, has pressure sensor built into it, if faulty new ecu or refurb unit or upgrade to Emerald and gain a few hp and a mass of torque.

 

A visit to someone with proper MEMS intrerrogation software could tell you straight away what is up or as with me that everything was working fine no alarms at all, and still the car idled oddly.....

 

 

Ashley Webster.

Looking for the Summer..... and another job.....

[Brucey]

Thanks guys!

 

I'll pull the little stepper motor thingy off and give that a clean (with the battery cut off activated).

If that doesn't work, I'll find someone with the right diagnostic kit to check it.

 

As it's a supersport, I already have an alloy throttle body (K&N filter faces forward), although bigger trophy one sounds interesting.

 

Will any of this help prevent stalling on over run as this problem is really starting to bug me? I am starting to dip the clutch early when pulling up to junktions just in case the engine stalls.

 

Brucey

[Allen Payne]

Also check the condition of the vacuum hose that goes from the manifold to the ECU - make sure it's not leaking and also not full of oil like mine was.

[Colin Mill]

Hi

A collegue of mine had his Rover 400 doing anything up to 2500 at idle. We simply re-mated the connectors around the throttle pot and stepper motor and its been fine since so you could just be lucky and have a poor connection.