Management Light

[taximark]

I'm looking at getting a d4d Avensis t-spirit some time early next year on a 05 ish plate but the thing that is worrying me is this management light issue that i continuously seem to hear about. I've posted on another thread regarding my sisters Y plate Avensis that she has now took three times to the garage in about 4 years to replace an oxygen sensor relating to a heating circuit or something to that effect.

Are the new Avensis still getting these problems or have most of them been resolved, her car is a vvti 2.0 petrol which i would say has a slight more chance of having more O sensors on it but at nearly 300 quid a go its something i don't want to have to keep paying.

This issue might make me choose another car if the new version still has this problem.

[cmia]

I asume you are looking to get a Diesel..

Well, The engine mangment light isnt that prone.

To be honest in wakefield we have a majoroty of Avensis 03+ on HC and only some have suffered problems with the engine mangment light.

Typically it is to do with the Fuel pump (not maintianing the fuel pressure) or the turbo not spooling up, VAC pipes disconnected.

[taximark]

Cheers for that mate.

[Stephen Andrews]

Hi can you help me i have a Avensis verso 04 last year we went on holiday & i got the aircon re gassed but after 2 weeks when i got this done the management light came on!! so i disconnected the Battery lead put it back & light was out!! however a week later it came back on!! stayed on for a 2 3 weeks then off & there was no power loss or fuel trouble & a year to the day it has came back on!! now i was using my aircon cause its hot in july But im thinking is it something to do with the air con!!!?

[korat102]

Who knows. Try retrieving the fault codes instead of just resetting the thing. Then we'll have a clue.

Get someone who has a reader to pull them out of the vehicle for you. Or do it yourself with an OBDII reader. They're not too expensive and can give you some really useful help when it comes to diagnosing faults. You're just stumbling around in the dark without one.

[Stephen Andrews]

Thanks there! so if i had this OBDII reader. where about,s do i connected it to?? on my Avensis D4D year 04

[korat102]

It's a white (it's usually white though I have seen black ones) socket which, in every Toyota I've ever seen, is in the most awkward back-breaking place they could put it. Most often under the dashboard on the drivers side pointing down at the floor. It might have a plastic cover protecting it, or it may not. If you can see what looks like a cover down there but no socket, take a look behind that cover.

[Stephen Andrews]

Thanks.... & can you tell me what the

EGR valve on the Toyota Avensis Verso does??

[Raistlin]

The interrogation process

Modern EGR systems are a sophisticated affair as its purpose in a diesel engine is to introduce quantities of exhaust gas into the air intake. This does two things: firstly it reduces the total quantity of oxygen in the combustion chamber and secondly, by bringing in exhaust gas which contains CO2 and H20 (the products of combustion), we spread out the oxygen molecules in the combustion chamber.

The exhaust gas quite literally gets in the way when the fuel and oxygen are trying to find each other during the combustion process. This slows down combustion and reduces the peak temperature. Why is this necessary? Well it’s at temperatures above 1800°C that the nitrogen combines with the oxygen and forms oxides of nitrogen, which is something that’s heavily restricted in emissions regulations.

EGR Control

EGR is not used all the time and it has to be metered when it is. It’s not used on start-up, initial warm-up or at high loads. To encourage EGR, the Avensis has a throttle plate fitted in the inlet. This makes sure that the pressure in the inlet manifold is lower than in the exhaust.

EGR Feedback

The ECM has to know what the EGR valve is doing and this is done in a number of ways. The latest diesels use wide band oxygen sensors but in this case it is monitored by the airflow meter. By opening the EGR valve, less air comes in from the air intake. The air flow meter reports and an EGR value is calculated.

Diagnosis

To prove our theory we used the Blue Print G-Scan to sample some codes and data. We retrieved code ‘P0102 Air flow meter open (low)’ before the code was then recorded and subsequently cleared.

Flight recording

Now for the data!The G-Scan displays ALL parameters as text or as graphs, although individual parameters can be selected. To get a better picture for analysis we ‘flight recorded’ the event so it could be looked at in detail afterwards. A great feature of the GScan is how easy this is, as all you do is simply press record. We recorded all the engine data and a short drive allowed the problem to occur again. Although the data can be analysed straight away on the G-Scan, on this occasion I transferred the data to my laptop via the SD card.

Working out what happened

The problem pointed to EGR and airflow. Was the EGR sticking? If it was, the air mass meter would show reduced air flow even when the EGR valve is supposed to be closed. So, we need to know how to work out how much air is coming into the engine.

Air mass calculations are a little complicated, but they can easily and accurately be estimated…

For the calculation we need four figures: engine capacity in litres (divided by two because a four stroke engine takes in half its capacity in air, every revolution), engine RPM, intake manifold pressure and air density. The vehicle in question has a 1998cc engine and we can take the RPM, and intake manifold pressure reading from the G-Scan; now all we need is a figure for air density.

Air weighs about 1.3 grams per litre at 0°C and 1 gram per litre at 80°C at atmospheric pressure. Assuming the temperature of the air in the cylinder is around 80°C; air density in this case can accurately be estimated as 1g/l.

Multiplying half the capacity in litres with the three other values, then dividing it by 60 to change RPM into seconds, will give us an air mass figure in grams per second:

Air Mass = (engine capacity (litres))/2 x (RPM x Intake Manifold Pressure x Air Density)/60

So for the first reading (Fig 1) the engine is at a light load (16% ‘Accelerator Pedal Opening’):

Air Mass = 1.998/2 x (1055 x 1.1 x 1)/60 = 19.32 gm/s

[t-spiritpete]

Thanks.... & can you tell me what the

EGR valve on the Toyota Avensis Verso does??

Recirculates some of the exhaust gas and this helps to reduce emissions along with what Raistlin says ;) .