[lags04]

Q1.

I have an 04 Lag II dCi, when changing gear the revs aren't instantly dropping, and in fact give a slight kick before they do.

Also, when coming to a stop, the revs are dropping low, and has stalled on occasion, but as soon as stationary they rise to normal again.

It has been suggested the latter is the turbo pressure sensor on the plastic intake pipe going from the intercooler to the inlet manifold?

I tried one from another car but the orange light on the dash came on, the glow plug (curly line)one and what looks like an engine block (usually ECU symbol), as soon as the original was put back this went off, they where a different shape (plug at 45deg on the other one, original is totally flat) but I don't think that matters?

Q2.

Also, I noticed that the reverse lights weren't working, so removed the plug from the switch and fed power through it to see if the lights would work, in order to check for continuity, which they did, so this would suggest a faulty switch.

Thing is, after I did this, the car wouldn't start without the clutch pedal being depressed, suggesting the car is in gear, which it wasn't, after a while this recified itself but has now returned.

I have noticed that the switch that the clutch pedal is meant to depress when fully up isn't actually touching the pedal, it's about 1mm away, though pressing this in by hand doesn't make the car start without the pedal being depressed.

Could this be down to the faulty reverse switch?

The car recently had a new turbo and EGR (not second hand).

Q3.

When you start the engine the fan fires up straight away, and stays on until you turn the engine off and the shut off valve activates, as soon as the shut off valve activates the fan goes off, so it's not been wired directly to the ignition as some do if there is a faulty TS.

Temp is just below half way which is normal, but I'm sure my last Lag II dCi didn't do this?

Any help greatly appreciated.

 

[lags04]

Ref Q1:

Just noticed an error and I can't edit, it's not a picture of an engine block, it's a square with a zigzag line, but when that sensor (TPS/MAP) is disconnected there is no power.

Disconnected the MAF and that made no difference, as I had cleaned it with engine cleaner spray, and I read that this can damage them?

It didn't actually start with the problem with the revs until after I cleaned the intake system with Nitrox rocket boost spray, but can't think how that could have caused a problem, coincidence?

 

[lags04]

Anyone?

 

[madnoel10]

The so-called wonder spray may have damaged the sensor elements in the MAF sensor. It;s not recommended on engines fitted with a MAF.

Also applying voltage via the wiring loom to the reverse lights may not have been a good idea.
The lighting and starting systems are comtrolled via UCH's and they don't like voltage up the wrong way if you get my drift. Most work at around 2.5 volts.

It may be worth checking if the clutch switch is actually working correctly - you'll need to remove it in order to test.

 

[lags04]

Like I said, disconnecting the MAF made no difference, so I dobt that is at fault?

The Nitrox wasn't applied through the MAF but after it, and I've used it in the same way on my old Lag dCi without issue.

Regards starting, you have to depress the clutch in order to start the engine, meaning it thinks it's in gear, so a switch somewhere is working, but the pedal isn't touching the switch when it's fully released, how many switches are there on the clutch pedal? Pressing the pedal switch at the top doesn't do anything regards starting.

Any ideas on the revs and the fan?

 

[Rentech]

the reverse light switch is 3 pin one for reverse and the other for neutral selction, there should also be 2 clutch switches one for starting and one for injection ecu, if the air con is on the cooling fan will run, also the cooling fan will run if the temp sensor or connector or wiring to it has a fault. When the turbo was replaced was the manifold and air pipes cleaned out as it could still be running on it's own oil in the air intake system. Could soon damage the new turbo if there is still oil in the system.

 

[lags04]

Yes, the reverse switch is three pin, and I figured it may have a part in the neutral signal too, so I'm going to replace it, don't have a socket big enough for it yet though.

Turbo and EGR was fitted just before I bought the car (receipt to prove) and had done no miles since fitting, that was why I ran the Nitrox cleaner through the intake system just incase they hadn't cleaned the pipes, I also removed the EGR to make sure all was still clear and it is.

No signs of heavy oil ingress in the pipes.

It was the garage the done the work that said the TPS/MAP sensor was at fault causing the revs to drop too low when comming to a stop.

Aircon isn't working.

Regards the clutch switch, as I said, the one at the top for when the pedal returns isn't touching the pedal, it's about 1mm shy.

Any idea on why the revs aren't dropping as they should?

Could that be down to the switch not touching as it should?

 

[Lagdti]

You've already answered part of your question,the clutch switch isn't touching the pedal and this will be causing the problem with the engine revs rising when changing gear.The switch plunger has a ratchet in it,press the pedal down and pull the plunger out,then release the pedal and the plunger will click back into place.

 

[lags04]

So do you mean that the switch itself has got partly stuck in the housing?

I'm able to press the switch in and out by hand, I'd say the plunger is out about 10mm, should it be more?

So I need to pull the plunger out further, am i reading you correctly?

 

[Rentech]

if the switch is not making contact when up that would mean it thinks the clutch is pressed so the revs should drop, there may be two switches. Lagdti refers to the inner part of the switch switch which can be pulled out and reset. The revs dying on idle could be the EGR adaptive's not being reset upon replacement, but revs staying up could be switch or oil in manifold. A lot depends on how the turbo failed and if any valve damage occurred by the engine over-revving

 

[Lagdti]

So I need to pull the plunger out further, am i reading you correctly?

Yep,push the pedal down,pull the plunger out,then allow the pedal to return.

What usually happens is that the clutch master cylinder is replaced (a common failure) and when the old cylinder is removed the pedal springs upwards and pushes the pluger fully back into it's body,the new cylinder is fitted but the switch isn't reset.I've seen this exact scenario happen a few times,once reset you should notice that the revs will drop correctly whilst changing gear and also you may even gain a little engine performance.

 

[lags04]

Right, revs not dropping sorted, I suspected it was that switch, thank you for confirming it and telling me how to fix it, though the fact it's got stuck probably means it will need replacing soon, as it wasn't doing it when I bough the car.

Luckily there was no horror story regards the turbo failure, as it didn't fail as such (no catastrophe), it was replaced after the garage diagnosed the EGR at fault, then informed the owner the turbo was leaking oil as well, so both were replaced at the same time.

Funny thing is, (could be concidence) after sorting the clutch switch the revs aren't dropping off either (when coasting).

So now for the reverse switch to fix the starter button issue (though not a big deal), and I suspect a fault temp sensor for the fan, but better running all the time than not running at all.

My car has the clutch pedal "recall" spring on it, so I'm guessing that at some point the hydraulic return has failed and I know this was the fix that Renault introduced for it.

Funny you should say about the way it drives changing, it has, it's got a little smoother and the turbo isn't kicking in so suddenly.

Cheers guys.

 

[lags04]

Anyone know the socket size for the reverse switch?

 

[lags04]

Just I need to buy one and don;t know what size it is, just know it's bigger than any of the ones I have