Egr Problems. More Of The Devil's Work?

[falcon7]

MY Avensis 2-0 D4D is misfiring when the engine gers hot and I believe it is an EGR problem, although the plunger in the solenoid and the moving parts in the EGR valve are free to move.

But bearing in mind that a solenoid is usually fully on or off, how do you get a variation in the gas flow?

I can't see it operating quickly between on and off with a variation in mark/space ratio to give the variation as that would still be slow compared to the rapid exhaust pulses with even a slow revving engine.

Two code reads at different days and different places indicate an EGR problem.

The EGR solenoid in question has two windings, one of about 8 Ohms across the outer pair of terminals which would indicate that that is the main winding. The other winding measures about 150 Ohms with a third connection roughly at 70 or 80 Ohms. Both windings are separate and not connected to each other.

From these measurements, I believe that the solenoid is OK but is it? How does it all work to get a reasonable variation in valve opening?

Can someone explain the workings of this mysterious device please?

Thanks,

Ron

[Cyker]

The EGR's sole purpose is to reduce NOx emissions by suffocating the engine a bit to lower combustion temps so I don't see how it would cause a misfire?

AFAIK it just has open and closed positions as opposed to a half-open position (Well, unless it gets jammed )

It generally opens if the engine isn't doing much work and feeds exhaust gases into the cylinder to !Removed! combustion. If it gets stuck open it kills the performance of the car below the turbo threshold and if it's stuck closed the car will feel a bit more perky at low/mid-accelerator settings but eventually a check-engine light will come on.

What do you mean by misfire anyway? Is it a sort of jerkyness, like the engine's hunting up and down?

[falcon7]

Thanks for the quick reply.

The misfire that I have is very regular ie one cylinder is not firing, so I suspected that one injector was faulty.

However having the code read, only revealed an EGR problem, After the codes were reset a later code read again pointed to the EGR valve. I did fabricate and fit a blanking plate, which did inprove the performance but when the engine got hot on a long journey, I had to call out the RAC and the guy didn't like the idea of a blanking plate so he took it out.

He freed up the valve and off I went with a now cool engine and it was OK for a while but again when the engine was hot the misfiring started again.

A few days later I limped home with a few stops on the way to let the engine cool down.

[Collie72]

Thanks for the quick reply.

The misfire that I have is very regular ie one cylinder is not firing, so I suspected that one injector was faulty.

However having the code read, only revealed an EGR problem, After the codes were reset a later code read again pointed to the EGR valve. I did fabricate and fit a blanking plate, which did inprove the performance but when the engine got hot on a long journey, I had to call out the RAC and the guy didn't like the idea of a blanking plate so he took it out.

He freed up the valve and off I went with a now cool engine and it was OK for a while but again when the engine was hot the misfiring started again.

A few days later I limped home with a few stops on the way to let the engine cool down.

What mileage is on your car? Have you tried cleaning out the EGR yourself? There's a good post somewhere on this forum about cleaning out the EGR with photos

[falcon7]

Hi Collie72,

The mileage is 118k or thereabouts, I cleaned the EGR a few months ago and checked it again before the troublesome journey. What I didn't do though was to check that the solenoid moved easily.

The RAC man freed it up but it wasn't much better. He threw up his hands in horror when he found the blanking plate and took it out.

Further investigation when I got home revealed that the engine cooling fans weren't working. There was no supply to the relay coil or contacts that operates them but the fuses were OK.

The fans work OK when wired directly to the Battery, Not sure whether that is the source of the problem though but I'm still investigating.