Renault Master power loss
I have a Renault Master LM35 DCi (100), 2.4.
I keep having problems with loss of power (limp mode).
All the symptoms pointed to EGR valve. This did indeed need doing, as it was gunged up, so the garage replaced it and also the glow plugs. Now, when warm, the van runs better than ever, but when I first start it, there is no power at all - it runs but won't go up hills. Sometimes struggles to start, I have to keep engine idling for ages, or run up and down the main (level) road until power kicks in. Three garages have admitted they don't know what to do next.
Diagnostics shows a fault with the air flow meter but there isn't one in this model. The costs have wiped me out.....the mechanics admit they don't know what to suggest, as everything will be costly.
Any ideas???? I'm at my wits end!
If the EGR was gunged up then the rest of the inlet system will be as well. It is no use just replacing the EGR valve, that is poor workmanship. It may not have been faulty at all.
To do this job properly, the throttle flap (or airflap) will have to be removed and cleaned out properly. The pipes that go to/from the EGR valve will also have to be removed and cleaned out fully. Your engine may/may not have air flaps in the inlet manifold that allow extra fuel and air when under load. They need to be cleaned and tested.
The turbo may also be gunged up as once this process starts, both inlet and exhaust will soon get clogged. If the turbo is sticking then the exhaust cannot escape so you lose power. The garage can clean this with a special fluid such as this:
The diagnostics are poor. If no airflow meter then the air is calculated by measuring the manifold pressure and throttle opening. Also, it suggests that the diagnostic tool is not good enough to correctly identify the exact engine ECU on your van. Without this there will always be spurious readings and codes.
So, have the mechanics actually compared the live readings from all the sensors and components with the specified readings as supplied by the manufacturer? It sounds as though they haven't.
My advice is to go to a garage that specialises in diesel engines that comes recommended or locate your nearest Bosch Service Centre as they will definitely have the proper diagnostic equipment. http://www.boschcarservice.co.uk/
Last edited by Hometune; 27-08-14 at 17:14.
Thank you..that makes a lot of sense. I am naively *assuming* the garage did a thorough job. The garage I usually use for repairs also had a look (after the first garage fitted the EGR), and cleaned out all the intercooler pipes which were also gunked up. They didn't even charge me for this.
..just to add to this, I have noticed that, when stationary, the engine will rev to about 4,000 but when the clutch is depressed (even though no gear is selected), the revs will not go above 2,000.
If the intercooler pipes are gunked up then the turbo will be too. Sounds like the variable vanes on the turbo itself may sticking until there is enough heat or pressure to move them. That cleaner in the link above can shift a lot without any dismantling of the engine.
I didn't want to post earlier, because I didn't want to tempt fate, but the problem has gradually lessened over the past week or so. If I leave the engine to tick over and warm up for about 5 minutes, it annoys the neighbours but there is instant power. If I set off straight away, there is no power, but I now only have to go about 1/2 mile before the power kicks in. I gave the van a really good run today, and took it into the Peak District, and it went like a dream, and flew up all the hills.