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Idle Hard.... Still....



  Clio 1.8 16V
Hi Guys,

When i take my car over 4k(ish) The idle jumps to 1.5k (normally it is just under 1k) and the car is not as responsive as normal.

It does this normally when the car is wamer but has been known to do it from cold.

I have been told its the speedo earth cable gone high resistence.. I have added another earth wire and the problem is still there... Anymore ideas?

The only way to stop this happening is drive under 4k (but then whats the point of having a valver??) or to restart the car (i can do this whilst on the move, bumping it, basically)

Any help would be greatful... Cheers.
 
  1.6 Rotrex High Comp
On my mk1 1.4 RT, I installed the bottom half of a laguna 1.8 spi throttle body and am now encountering the same problem as you...

I had a spare speedo cable, known to be fine - installed that, and double checked all the connections - It made no difference (mine is of course a 'mechanical drive' speedo - I don't know about yours.

On my throttle body, I have a non-adjustable 'throttle-stop' which the throttle quadrant hits when idling - so I have enough slack in my accelerator cable.

I also have another adjustable screw which when the car is 'idling' (anywhere between 750rpm and 1300rpm!) that hits my idle speed control motor (again, I don't know if your car'll have this)... I played with this, disconnected the battery, re-connected and everything seemed fine for 3 days...

Now my motor, like yours, idles perfectly when cold (both the engine and the ambient air), but the idle after giving it some 'welly' and the engine is warmed up hits anything between 1050rpm and 1300rpm.

If have 4 possibilities to check - if you search my other posts, I have posted in more detail:

1. throttle-pot - I think possibly some of the tracks have worn a bit and the computer isn't talking to the idle speed motor properly.

2. lambda-sensor - perhaps it's too cold and the computer thinks it should put the 'choke' on...

3. idle speed motor - perhaps it's clogged up with years of dirt and won't return back far enough.

4. perhaps one of my throttle-body gaskets/seals has gone - but all the bolts are tight as, and I can't hear any whitling.

Note about 'number 3' - even when i'm idling high, the throttle is completely against the aforementioned 'stop' and after whipping the airbox off, the throttle is closed.

I hope this information helps you a bit - if you find out the cause, please PM me or post here.

Regards,
86sixsix
 
  Mk1 Hybrid
i have the same problem on my 1.4 mk1 clio i have just put a new engine in and it varys from 750 rpm to 2,000! :S its really wierd it can be idling at 2,000 while im at some lights, and then all of a sudden it will drop down to 750! its well wired can you let me know also if you find a soloution to this!

Cheers Dan
 
  1.6 Rotrex High Comp
Hi Dan, aren't RT's fun? Have you put another 'energy' engine in, or have you transplanted another type?

On a serious note - at what engine temperatures does your erratic idling occur? Mine tends to be fine when the engine's cold, but gradually increases the hotter it gets.

I have so far replaced my throttle-pot with a new, calibrated one and it wasn't that.

I put yet another throttle cable in, and added more ground points. No difference.

I have also torqued up the 4 bolts through the throttle body again, so no excess air should get in that way - again, no different.

I have swapped the lambda sensor from the one in my Renault 19 (still with a 1.4 energy engine) and no difference there either.

I have another idle speed motor somewhere in my garage and I'm going to put that on tomorrow and see what happens.


Also, some technical people I work with have suggested I spray some 'Cold Start' around the throttle-body and inlet manifold (making sure none can get in the air-box). Logically, if I do this, and the engine speed increases (I'm told that 'cold start' is more combustible than unleaded and air) then there is a leak somewhere and the motor is sucking in unfiltered air.

It's years since I've seen or heard of 'Cold Start' or a substitute for it, but I'll find something I'm sure.

Dan and MrP_16v, let me know if you find anything extra about the problem.

86sixsix
 
  Looking for a ph-quick...
Sounds like if its not the speedo earth (Provided you've eatherd it properly) it sounds to me like the lamda sensor. It could be over fuelling, Could be the idle speed control valve (Take it out and clean it then spray with a little wd40 making sure that the central spindal is moving freely).

Not sure what would cause over fueling, is your exhaust blowing?

Amir
 
  1.6 Rotrex High Comp
OK... Problem solved... For the time being...

Whether this'll work for anyone else - I don't know...

Further to all my previous messing about...

This morning, I've taken my throttle-body off (again)... To find that now, the gasket between the inlet-manifold and the lower half of the T/B had cracked between the two bolt-holes nearest the bulkhead.

Not having any brand new gaskets, I reused one from another throttle-body (from a Renault 19) but used the front and back of a cigarette packet as temporary seals. One between the manifold and gasket... The other between the gasket and T/B.

For good measure, I also took off my throttle-pot and gently wiped it's tracks with a paper-towel. A lot of what looks like carbon came off onto the towel and the tracks seem more 'prominent'...

Put the whole thing back together.

Disconnected the battery for 1/2 an hour (I should've done this before messing with the multi-plugs... I know)

Connected the battery...

Stuck a screwdriver between my idle screw and the idle control motor.

Switched on the ignition (but didn't start the engine)...

Switched off...

Took the screwdriver out...

Started her up... No problems... Idled at 1200, warmed up, idled at 900rpm... Took her for a 'spirited' drive... And she idles perfectly...

The only thing I do get is a very slight whistle under really full throttle acceleration... Whether it's still got a tiny vaccuum leak I don't know... But hey, it works...

I will of course head 'round to my *cough* very helpful Arnold Clark and get 2 new replacement gaskets and 4 seals as soon as I can...

For now, I'm motoring...


Keep me posted if any of this helps you...
 
  Mk1 Hybrid
Hey there, i got fed up with putting 60 quid a week in fuel, so i called out a auto electrician! He pluged all my car in and hey presto he found the problem! IT was a blanking pipe off the back of the throttle body! it was drawing in too much air, and the car thought it was going to stall so it was pumping more fuel into the throttle body! just check that u have two pipes of the back of the throttle body and a blank! Itll save u the bill from an auto electirican! ;)
 
  1.6 Rotrex High Comp
Hi,

I think I've got a different throttle-body assembly than you... Mine doesn't have any pipes or connections apart from:

Fuel in, fuel out, throttle-pot plug, idle motor plug, injector plug.

The inlet manifold on the other hand, has about a million vaccuum hoses and coolant lines running out the back of it. They all seem in place and there aren't any plugs/holes without an associated pipe...

Mine is the one with 3-holes through the throttle body... Same on my other Renault Energy 1.4 engines...


Our problems are all the same, though... Far too much air...

I'm currently running a 1.4 inlet manifold ground out to match the bottom half of a laguna body, with the top half from my clio, and the laguna injector in.

After doing the gaskets, it's never run better in the 5 years i've had it...


After some more servicing, I'll be getting a chip re-map... I shall see if there's a way to limit the fuel at a given throttle-position... The only problem with this I can see is that if there is too much air, the engine will run lean...

Ah, well...
 


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