AAaaarrrgggghh I wish I was a mechanic

[The PIT]

Great I've got two garages (One being the warrenty holder) arguing whether my car is buggered or not. Each one calls the other an idiot and they don't know what other are talking about.
According to one the inlet manifold is leaking and this is before the Lambda sensor which then makes the correction. The other says this is complete bullshit and the sensor won't be able to correct this.
I've now taking the car to Renault dealer whos going to check things out and the dealer whos got the warrenty I going to pay for any work.

[Jorden]

What kind of car are we talking about, btw?
Tried the forum on your brands car-site already

[Brian R.]

Bet it's a Renault.

[Gurm]

It's a Renault. Heh.

But seriously, if your Intake manifold is knockered, there's NOTHING any sensor can do to "compensate" or "fix" it. You need... wait for it... a NEW INTAKE MANIFOLD.

And... err... is this an extended warranty? If it's a new car warranty it doesn't matter where you take it - just take it to the nearest Renault dealer.

- Gurm

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Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

[Kruzin]

I'm so glad they stopped importing those things to the states over a decade ago. Almost all of em have died now, so you don't even see too many of em on the roads these days here. I spent many years working parts in a Renault dealership. The French make many things well (food, booze, women, art, etc.). Cars is NOT on this list

[Brian R.]

Gurm - Think intake manifold gasket...

[SCompRacer]

How about those fast idle problems too.

Remember when Motor Trend named it Car of the Year?

[The PIT]

It's a Renault Clio. Intersting about your comments and we've never had a prob til now. It's my first renu but the rest of the family used them without probs.
It is the inlet manifold gasket thats suspect by the way.
Warrenties since it's a used car most things aren't covered. Normally it's the bolt on the back thats covered. I've done well to without having to be threatning to get he exhaust replaced and speedo cable. Also when claiming on the warrenty your dealer is the first port of a call over here anyway.
But when you got Two sets of mechanics saying each other are plonkers theres not a lot you can do bar going to a third party and then sue the bastereds the warrenty is with.

[Gurm]

Ahh... ok, well the intake manifold gasket will need replacing then. There's no "sensor" that "fixes it".

But, it's a good bit cheaper than a new manifold, although potentially labour intensive (dunno how hard it is to get a manifold off and back on again in a Renault).

- Gurm

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Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

[Raptor^]

I think the lamba sensor may be able to compensate for (not fix, compensate for) a blowing inlet manifold gasket to an extent, provided its a very small leak.

Fundamentally, the leak just messes up the fuel/air mixture and I think that the sensor can instruct the electronic fuel injection to adjust the mixture according to the contents of the exhaust gasses (I'm not that great with modern engines, A-series from my Mini is more what I'm used to )

You will probably lose a bit of performance and economy too. The situation is only gonna get worse

[This message has been edited by Raptor^ (edited 03 November 2000).]

[Gurm]

Yes, sorry. A bit of a retraction of my earlier stance.

It can be compensated for, but only in very small amounts. Normal leakage, or improper fit, or a very small crack. Basically the lambda sensor is designed to not leave you stranded when you get a shitty fuel/air ratio due to a gasket going bad.

But once the crack gets big enough, nothing can fix it except a new gasket. The gasket itself is cheap (just rubber) but in some cars it takes a bit of doing to get installed.

- Gurm

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Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

[The PIT]

Well one nice thing about the warrenty I've got roadside recovery. So if the car is ****ed I just ring up recovery. According to the garage thats says that theres nothing wrong the Lambda sensor can't compensate. Driving it I feel theres something wrong the fuel comp is shit round town and if you want the darn thing to move at 60mph you've got the foot to the floor and keep it there which for a small car with supposed 80bp is shit.
I'll just wait for the 3rd garage and I'll have a look myself tomorrow weather permitting if I see something I'll mark the darn thing up with chalk and say suck that you dummies.

[Rags]

The Pit,

Lambda sensor, I take it that is what europe calls an "Oxygen Sensor". Oxygen sensors do only one thing: they measure the difference in oxygen between the atmosphere and the oxygen in the exhaust stream by puting the sensor in the exhaust stream. The sensor changes the voltage it produces depending on how much oxygen is in the exhaust stream. The computer in your car reads this voltage and determines, along with many other factors, what the injector pulsewidth(s) should be. The computer is programmed with certain parameters in mind, to determine what is running rich under which condition, and what is running lean under certain conditions. Having a vacuum leak that is detectable throws the whole strategy out of whack. It can even cause more severe problems if the vacuum leak is isolated to one cylinder, rather than distributed amongst all (four?) of them. The sensor cannot know which cylinder is running lean, therefore cannot compensate directly for that cylinder. If the leak is divided amongst the cylinders evenly, then you are puting an unnecessary load on your engine. While driving down the road, the computer sees the vacuum is low for what is expected with your current throttle position, and would richen and advance the timing at the same time to give more power, this causes more heat in your cylinders and heads, and also causes a decrease in your gas mileage. If the leak is severe enough, it can cause damage to your exhaust valves, and damage your catalytic converter (if yours has one). There are many other possiblities for damage. In short, if there is a leak, get it fixed, and have it fixed properly. A leaking intake should be removed, cleaned and checked with a straight edge for warping, and the cylinder head's intake facing should also be checked at this time. The intake should also be thoroughly inspected for cracking, or loose vacuum fittings. But don't let this go, get it fixed.

Rags

[Ali]

Well answered Rags. I was going to say pretty much the same thing, specially since its under warrenty.

Also remember if there is an air leak, then that air isnt going through your air-filter.

Even little bits of dust into the bore is not good news. (trust me, the K&N fell off my Cooper S once, and F***ed a stage 3 engine that had only done 1000 Miles).

Ali

[The PIT]

Thanks for the info. Well another garage looked at it A Renu dealer checked it all out and found nothing wrong. I checked it myself before they did and couldn't see anything.
Strangly the car seems to be running better even though they said they hadn't done anything so go and figure.