Air flow meter fault, symptoms

Air flow meter.

I have written about this before in another post but have decided to write about it in its own right. I'm talking about a faulty air flow meter. The best way to find this fault is with a test drive and to listen very carefully to the driver's description. It is no good sticking the vehicle on a computer because as lots of you have discovered it does not show up in the fault codes. Have any of you wondered why? Finding this fault is down to good old mechanical detective work.

The symptoms:

In the initial stages it is quite subtle. The van starts and runs as usual and drives off as it should you then notice that you are having to use a bit more throttle than you used to get out of the turnings; this may go on for some time. Next, in the ebb and flow of traffic the van is not picking up as it should, almost sluggish in the way it gathers speed pointing to a possible turbo problem or a worn clutch in some cases. Finally driving away from a stand still is almost impossible! You have to push down the accelerator pedal a lot just to get up any speed to change up to second gear. On lifting your foot off the accelerator pedal to change gear the vehicle speeds up while you are changing up. On pressing down on the pedal again the van struggles to gain speed. It feels like it is holding back, this is because the air flow meter is not telling the 'brain' the airflow has increased.

I'm sorry to say changing the crank sensor will not do the trick but what is a good idea is cleaning the ERG valve because it will be close to being blocked if the vehicle is being used for a lot of stops start. The combination of these two things will make it purr like a kitten.

Stop! Stop! Stop!

It has been some time since I have posted here. That is because there have been no major running issues, which belies all the things that friends, and neighbours have been telling me is wrong with this Van. That reputation is down to the way the motor trade has dealt and still deals with faults. By using a process of changing parts to eliminate them as faulty instead of following a procedure to determine what the actual fault is. Then charging the customer for the privilege.

 

The van had not been used for some weeks, so it was quite a surprise that when running it up the road to get some supplies that two red lights started to flash on the dash. The STOP and what looks like an outline of an engine. After the initial annoyance I considered whether I should do what it was saying and STOP. However I carried on. With my mechanics head on I started to reason out what could be happening. To a certain extent it looked like the light was flashing every time I hit a bump, but then it looked like it was flashing for the hell of it! I reasoned – could something be loose? or could damp have gotten in causing a short?  I decided as soon as I returned home, I would look in the owner's manual.

 

With the manual in my hands, I look for the icon page. OK the outline is of an engine. Which means: Engine. stop. See page 25. or Engine electronics, exhaust emissions. See page 26. What does it say?

•         Page 25: will light up in conjunction with STOP engine if coolant temperature is too high. The temperature gauge was slightly higher than usual but not off the scale. “It can't be over heating, can it?”

•         Page 26: Control indicator lights up when ignition is switched on. Goes out shortly after engine starts. There are then two headings here, one about flashing when engine is running, which is the one I took note of for obvious reasons because it states: For fault that can lead to destruction of catalytic converter. Look to another Page 94. I did look at the other page for reference. Talk about strike the fear of God into you that you now may have a bill coming the size of the national debt. I have got to say I took this statement with a pinch of salt until I knew for sure that all indications lead down this route. If it does oh man!

 

There was nothing I could do as I had a long trip planned for the next day. Just have to see what happens. I know a break down far from home means an expensive tow. I'll cross that bridge when I come to it. The long trip gave me time to think about what could be happening. I've got to say that it was running really well so it cannot be the converter. (As both lights flash for the hundredth time) I looked at the dash from time to time when the lights were flashing but noted nothing else wrong. Then it went out and stayed out for the rest of the trip.

 

The trip home started well no flashing lights at all. Then we hit a major down pour could hardly see out of the windscreen at double wiper speed. Then I noted that the same two lights were flashing again. By the time I arrived home there had been some further developments the head lights were sort of flashing getting brighter and softer I also noticed that the temperature gauge was oscillating in time with the lights. When I turned the engine off, I notice the cooling fan was running.  This is looking like a cooling temperature sensor problem.

 

With the bonnet up it's time to track down this fault. I still have it in the back of my mind that it is a dodgy connection. But until I find this allusive sensor, “where the hell have, they hidden it?!” Sometime later I track it down to the right-hand side of the engine behind a number of pipes with the sensor facing the bulkhead. Now I have to thread my hand through the pipes like a snake (what a joke) to feel if the connector is loose. There is a bit of movement but not enough. After some fiddling, the connection is removed and reconnected. Oh Well here goes. The engine has now been running for a couple of minutes, no flashing lights.  Better take it for a spin to check and make sure. While I'm out I'll get a cooling sensor.  

 

Since doing the connection I have not had the time to replace the sensor due to workload and the fact you have to drain the whole cooling system down. I hope to come up with a solution that negates this, If I do, I will let you know. But I'm happy to say that the red lights have not flashed again. Bad connection!? Time will tell.  

 

When it comes to red lights flashing on the dash, I am not condoning that you should ignore them and carry on regardless. The situation in which it occurs needs to be taken into account and then the appropriate action taken.

The smell of burning!

Overheated rear brake disc.

I was in a hurry the other day to get the dog to the vet. It was not until I was part way up the bypass that I realised that the handbrake had stuck on. Even though the hand brake leaver in the cab was completely off, the smell of brake linings was overpowering. It's just as well the vets was not too far, even so the back wheels were so hot you could not touch them. Just before we made the return journey I slipped under the van and pulled back the little arms that operate the handbrake on the back of the callipers. Man, they we tight! This does not bode well for those new wheel bearings that were fitted earlier in the year. A sticking hand brake is one of the reasons why the bearing failed in the first place!

 

Showing handbrake arm on Calliper

With the back of the van up in the air and both the wheels off, it is time to get to grips with sorting this problem out. On further investigation it turns out that the shaft that sticks out of the back of the calliper with the handbrake actuation arm on, has rusted tight. Even though there is a little rubber cup that sits between the calliper and the arm to protect the shaft from the weather. I believe this is its downfall because once the water gets behind the seal it remains there helping the rust to build up causing it to seize. 

 

Once the handbrake cable has been loosened you can remove the end of the cable from the arm more easily, with a bit of fiddling. To free the arm off you will need to tap it backwards and forwards with a medium weight hammer. Do not over do the amount of force you use when hitting the arm with the hammer. The idea is not to do it in one hit but to keep moving it up and down until the sprung loaded arm moves back to the off position on its own. When it feels like it has freed off enough to move it easily by hand, you need to check it's at the off position. If not, it is time to take a closer look at the spring. If the metal of the spring is pitted and heavily rusted it is possible that it has lost some of its tension. For the three or so pounds each it costs to replace these springs it is not worth messing about. Removing the spring from the arm is a bit annoying but straight forward with a pair of pliers.

Handbrake arm spring old and new

 

There is one last thing to do as a suggestion before you box it up and that is to get some white grease and push it in behind the little rubber seal that protects the handbrake arm shaft this will help to keep things moving and the weather out.

 

I have used this method on my van and so far, the hand brake has not stuck on again.

 

Related post   rear wheel bearing replacement.

 

 

 

A glow in the dark before you start.

Glow plug not working. 
Note the reading on the meter.

The glow plugs are a preheat device allowing the engine to start more easily from cold. There is an icon on the dash to show that this is in progress when the light go's out the van is ready to start. This sign does not tell you that the glow plugs are in working order. Most people only notice there is a problem when they have trouble getting the engine to start and stay running first time which is something I have been experiencing with the van.

 

It is a quick and easy test to do with a voltmeter if you have one. The air filter housing needs to be removed first.  Set the voltmeter to resistance (ohms) on the meters dial. Touch the two probes to gather, this will give you a reading which will also show that the meter is working. Remove the wire connection from the top of the plug place one probe on the top of the plug where the wire was attached. It does not matter whether it is the black or red probe. Then touch the other probe to the hex nut that is part of the plug. Be careful not to touch the same area the other probe is already attached to as it will give a false result. If the meter gives a reading the heater element is OK. No reading means that it is a dud and needs to be replaced.

Working glow plug.
note the reading on the meter.

 

Be careful when removing the glow plugs from the engine. Remove any debris from around the base of the plug before removal otherwise it will fall into the cylinder. If you have trouble loosening the plug, try not to be to heavy handed you can round the nut off or snap the top off (they are made from aluminium) leaving the rest of the plug stuck in the head - which will be a whole lot of trouble. If the glow plug feels that it is over tight, spray some easing oil on the plugs thread and try again. If it still will not move, put it all back together and run the engine till it is hot and try again.

Tool for the job

 

To remove the glow plugs you will require: a 10 mm deep socket, Wobble head extension bar - at least 150 mm long, a ratchet and or tee bar. The glow plug at the front of the engine (left hand side) may need the top engine mount removed to allow proper access to the plug this depending on engine fitted. The torque settings for the glow plug are Fifteen to Twenty Newton meters.

Vivaro couldn't pull the skin off a rice pudding.

The van has developed a running fault that started a month or so ago and has become progressively worse. It has taken us some time to chase down the cause of this problem.

The symptoms:

 This fault shows it's self when you drive away from a stand still. You have to push down the accelerator pedal a lot further than is normal to get it to speed up enough to change up to second gear. On lifting your foot off the accelerator pedal to change gear the vehicle speeds up while you are changing up. On pressing down on the pedal again the van struggles to gain speed. It feels like it is holding back.

 

Thought process and action.

 

This suggests that it is a fuel problem. But it has nothing to do with fuel, injectors, high pressure pump, fuel filter or related sensors. Another suggestion was the turbo, but we could hear it spooling up. We checked the turbo pipes, ducting was tight and not blocked. We found a couple of lose hose clips but not enough to cause power loss. Also checked to make sure the waste gate solenoid worked as it should.

At one point we thought the ECU needed a re-boot, again it did not seem likely. Thinking about it, it was a flow problem the only other thing that came to mind was the air flow meter. Before we paid out on a new meter we surfed some motoring forums for pointers, but no one had this fault it would seem. We came across a thread that suggested the changing of the airflow meter would sort it out, but this gentleman also had the crank sensor replace. After a short discussion we decided to go with the air flow meter. Bingo! got it in one and what a relief, it would have been an expensive mistake otherwise.



Air flow meter

 

Extra work.

 

While we had the air filter housing off, which is a pig remove, we thought it prudent to check the glow plugs as it only takes a couple of minutes with a voltmeter. We found that two of the plugs didn't work. The ERG valve drew my attention because the inlet manifold was covered in oil suggesting the gasket had failed or the bolts were loose. You have to be patient when removing it as it has a build-up of oil residue. On removal, it was found clogged with a thick coagulated oil that took a bit of cleaning up.

 

It runs and pulls like a train now. The rice pudding skin doesn't stand a chance!