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Guru

Join Date: Jul 2005
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Exhaust Gas Recirculation

04/29/2016 10:55 AM

I have a 2004 Mondeo, 2 litre petrol (UK model). Several years ago the the engine management light came on. I got a garage to put it on the code reader, said EGR valve and cleared the lamp - £15. About 1 year later it happened again, this time £25. After another year it came on again, I considered buying a code reader, but found on the internet how to clear it - disconnect battery, switch on headlamps for a few minutes, switch off, reconnect battery and bingo, light off. I've done that 3 or 4 times since, but it seems to be getting more frequent.

When it first happened I got an EGR valve from a breakers, been putting off fitting it as it means draining the coolant. Just resolved to tackle it, so as a preliminary removed the actuator thingy from the valve and replaced with the breaker's one. The internal plunger moves smoothly, feels just the same as the breaker's, so I'd be rather surprised if going to the trouble of changing the complete valve would make any difference. It's possible changing the actuator has cured it, but I won't start to be confident it has till it's gone a few months without recurrence.

I assume the actuator modulates the position of the plunger to control the flow of exhaust gas recirculated, depending on engine rpm, manifold vacuum etc, but I'm a bit puzzled by the Haynes manual. This says - to test the valve remove the vacuum hose and apply vacuum using a hand pump. There is no vacuum connection on mine (4 cyl). According to Haynes, there is on the V6 (petrol) and diesel models, and it refers to an electrical connector on the diesel. It doesn't say where the vacuum comes from, whether straight from the inlet manifold (V6) or the brake vacuum pump (diesel), or whether it is modulated to give variable plunger position. My guess is it's the former, and modulated electrically at the valve, Haynes having forgotten to mention the electrical connection on the V6.

Also I'm curious as to what the engine management system looks for when deciding the EGR is faulty.

Can anybody comment?

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Guru

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#1

Re: Exhaust gas recirculation

04/29/2016 11:48 AM

You should clean the original and keep for swap out.....they just get dirty and start sticking....

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Popular Science - Weaponology - New Member United Kingdom - Member - New Member

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#2
In reply to #1

Re: Exhaust gas recirculation

04/29/2016 12:29 PM

GA. I helped my Daugh't clean out the one on her Suzuki Carry van what is called "Binky"... his raison d'etre is to carry stuff... he's a happy little van.
We've had to do it twice over the years, no big deal once you've done it the first time. I don't s'pose many garages even know how to clean 'em these days.

Del

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Guru

Join Date: Oct 2008
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#3

Re: Exhaust Gas Recirculation

04/29/2016 12:48 PM

About the only sensor these new vehicles don't have is the driver's, rectal temperature probe.

Go on-line and buy a cheap OBD plug-in module.Amazon.com: Vgate Bluetooth Scan Tool OBD2 OBDII Scanner and download a free app to rread it with your smart phone.Mine cost $12.00USD and the app is free.

New vehicles sense everything the car's doing.

0-60 time, acceleration, ave speed/fuel mileage, barometric pressure,engine load,fuel trim bank sensor for eacxh cylinder, gps bearing,volts, thrittle position are just a few of the things you don't really need to know, but can. And codes, too.

It plugs into the OBD port and communicates by bluetooth to your phone.

Get one, you won't regret it.

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Guru

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#13
In reply to #3

Re: Exhaust Gas Recirculation

04/30/2016 12:22 PM

Good idea, I'll get one. I've a fair idea what it will say in this instance, but fun to play with and for future problems

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Guru

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#15
In reply to #13

Re: Exhaust Gas Recirculation

04/30/2016 12:54 PM

Yes, it's cheap and fun.

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#20
In reply to #3

Re: Exhaust Gas Recirculation

05/16/2016 6:40 AM

My car hasn't got a thrittle.

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Guru

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#4

Re: Exhaust Gas Recirculation

04/29/2016 2:47 PM

The simplest fix I have found is to cut the pipe off that feeds exhaust gases from the exhaust mainifold plug the exhaust end of it and then reroute the EGR to suck clean air from the engine side of the air filter.

On Fords that little trick is good for an extra 1 - 2 MPG or better for those who drive civilised.

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Guru

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#5
In reply to #4

Re: Exhaust Gas Recirculation

04/29/2016 5:19 PM

You may be able to do that in the backwoods of ND, and maybe they can in the UK.

But Where I live you can't get a vehicle license plate (or renewal) if the check engine light is on.

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Guru

Join Date: Jun 2009
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#6
In reply to #5

Re: Exhaust Gas Recirculation

04/29/2016 6:20 PM

Just more reasons to I love where I live and how we run things!

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Guru

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#7
In reply to #6

Re: Exhaust Gas Recirculation

04/29/2016 6:27 PM

The sad thing is that 90% of the cars on the road in Arizona are new enough that they don't pollute anyway. They just plug into the OBD port, charge you $20.00 and send you on your way 5 minutes later.

Politicians were bribed to start the program in late 1980's.

The lead author of the bill to institute testing went to work fr the testing company a year after the program was started. We still have it.

The only good news is we can renew our plates for two years, if we want to.

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#10
In reply to #6

Re: Exhaust Gas Recirculation

04/30/2016 4:13 AM

Out in the sticks, they probably don't have emission tests at all, but what about in the big city or two?

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Guru

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#12
In reply to #10

Re: Exhaust Gas Recirculation

04/30/2016 11:53 AM

Nope. Could care less there too!

It's just one of the perks of having a state government run by farmers and those who came from farming communities and not life long politicians who only cater those who stuff the pockets while whining the most about the least of our problems.

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#21
In reply to #5

Re: Exhaust Gas Recirculation

05/18/2016 10:56 AM

Hi Lyn,

That's a big No NO in the UK. After 3 years old a car has to pass an MOT (Ministry of Transport) test every year which includes an emissions check.

Best regards,

John

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Guru

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#8
In reply to #4

Re: Exhaust Gas Recirculation

04/29/2016 11:21 PM

I had a 98 Chevy Metro with a 1 liter engine. The EGR system failed, as the high piston temp caused oil to burn, mainly in the groove of the oil control piston ring, fouling it. This prevented this piston ring from scrapping down the oil, which then burned, and plugged off the EGR port (upstream of the EGR valve) in the cylinder head. This disabled the EGR system, and because part of what it did in reducing the 'bad emissions', was to reduced the flame temperature during combustion. What ended up happening, is the exhaust valves over heated and burned pie shaped sections from them, resulting in total loss of compression.

The catalytic converter did a marvelous job of preventing any blue smoke out. Before total failure, it was burning 1 qt of oil per 300miles.

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#11
In reply to #4

Re: Exhaust Gas Recirculation

04/30/2016 7:13 AM

Interesting, but I don't think it's possible on mine. Pics below. It bolts directly on to the cylinder head, no pipes to intercept. The 2 big holes (15mm dia) are (I assume) for the exhaust gas, the small one to top left connects to the pipe and takes cooling system water. I'm not sure what the idea of that is, it doesn't go near the electric actuator, so I don't think it is for coolant temperature input, and there are other temperature sensors in the system. Maybe it's to cool the exhaust gas a little before feeding to the intake.

Thanks anyway

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#9

Re: Exhaust Gas Recirculation

04/30/2016 1:17 AM

I'm not familiar with this particular vehicle, but most OBD-II vehicles have a temperature sensor on the intake manifold side of the EGR valve, near the valve, which tells the computer that the valve has, indeed, opened and closed when it is supposed to. If this sensor, which isn't terribly expensive, fails to operate correctly (i.e., indicate a rise in temperature when the valve opens), a DTC will be set in the computer's memory. Frequently, the sensor has not failed but is suffering from built-up carbon which is preventing the exhaust gas from reaching the sensor.

Try finding the sensor and removing it so that the sensor and the area between the sensor and the exhaust gas port can be visually checked; a quick probing with some orange sticks or bamboo skewers will clean out the passages, and a brass wire brush will take care of the sensor. Don't worry about the carbon which falls into the passageway; it will be drawn into the engine upon start-up, but it is much too soft to harm anything. If a good cleaning doesn't fix the problem, a new sensor almost certainly will.

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#14
In reply to #9

Re: Exhaust Gas Recirculation

04/30/2016 12:24 PM

Thanks for that, sounded promising, but I can't find a temperature sensor in the gas stream, either in the Haynes manual or having a good search on the engine. There's the coolant temperature sensor, which could be dicky, as to change the subject, the car takes a long time to warm up, specially in cold weather. At least according to the gauge it does, heating and defrosting seem pretty normal. It eventually reaches temperature (on the gauge), so I don't think it's the thermostat, and anyway on this car you have to change the stat complete with housing for about £80, roughly what the car's worth!

There are also inlet manifold and exhaust temperature sensors but I doubt that any of them controls the EGR valve, so maybe there's a sensor I haven't found. But if it's a faulty sensor, I'd have thought the diagnostic would say that, rather than EGR valve fault. I'll just have to see if the light comes back on and take it from there. It's not urgent, the car drives OK.

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#16

Re: Exhaust Gas Recirculation

05/06/2016 11:11 AM

Most likely, your engine control module (ECM) is taking readings from your oxygen sensors. The ECM can compare all inputs for air/fuel, then readings for combustion products, and compare those with what it believes to be correct. Your exhaust gas recirculation will effect readings the ECM gets from the O2 sensors, and your ECM will make adjustments to the valve to limit/allow more EGR.

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#17
In reply to #16

Re: Exhaust Gas Recirculation

05/06/2016 11:29 AM

OK thanks. In that case I assume the valve isn't achieving what the ECM wants, either because the actuator isn't working properly or the valve is blocked (as the fault code says EGR valve). The lamp hasn't come on again yet, but it's early days. As I said before, the valve plunger moves freely, but of course that doesn't prove the ports aren't blocked.

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#18
In reply to #17

Re: Exhaust Gas Recirculation

05/09/2016 12:30 PM

A bit of context for my comment:

My wife has a 1998 Volvo, the 5 cylinder with turbo and charge air cooler. That model also has a smog pump that feeds high pressure fresh air just ahead of the catalytic converter, to aid in burning a rich fuel mixture. That smog pump went out, full of water since the factory did not seal it from rain/water under the vehicle. The smog pump costs $500, and no refurbished units are available. I wasn't about to pay 500 stinking dollars for an air pump!!

Of course, the check engine light came on, and stayed on, when the smog pump failed. And, since the engine is now running in "open loop mode", the gas mileage suffered greatly (from 32 mpg down to 22 mpg). To fool the ECM, I tried putting a resistor in place of the pump, thinking the ECM was reading current flow to the smog pump motor. Didn't work. Check engine light stayed on. Looking further, there was no electronic sensor in the circuit-not electrically at the pump motor, nor downstream at the check valve going to the catalytic convertor. So....just how did the ECM know the smog pump had failed?

The answer was in the readings from the upstream and downstream Oxygen sensors, that were inputs to the ECM. The ECM was comparing inputs to known values and thereby detected the smog pump failure. (I dug through old parts in my garage, found an old air mattress pump, found a 400 watt 12 vdc-120 vac invertor, wired and plumbed them in, and problem solved. Had to water proof everything and protect the 120 vac wiring.)

From your description, I would say that's how your ECM knows of the EGR problem, namely, by comparing values from the Oxygen Sensors.

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#19
In reply to #18

Re: Exhaust Gas Recirculation

05/09/2016 1:19 PM

You're probably right about how the ECM identifies the EGR fault. Now spring is here I must get round to changing out the rest of the valve and cleaning the ports.

Congrats on curing the Volvo problem, amazing the air mattress pump did the same job near enough to clear the engine light.

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