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Discussion Starter #1
My 2002 1.4 HDi went into limp mode and the code it came up with was the EGR valve. Now in the history of me and this car I bought it at auction without knowing it was in limp. I went through every system on the car that could cause this fault and eventually found it was the glow plugs that were the culprits. They were all open circuit but I was advised that I could fool the circuit by replacing the feeds to them with a resistor in the circuit. At the time the only code was from glow plugs. Although the census of opinion was that this failure would not cause limp mode it turned out that it depends on the fuel system fitted to the car. Mine had the system that did! Anyhow this time,as I mentioned earlier,the code was listed. I have removed the valve and checked it on the bench with my vacuum pump and it works and the pipes also passed the vacuum test. So the next thing is the solenoid. I replaced that during my first limp mode as I did not know how to test it. I assume it is a simple open shut jobbie but when I check continuity across the two pins there is no circuit. Now I assume the control of the solenoid is through the ECU and that the feed is probably 5V Any body got the engine circuit diagrams and know how to check the operation of the valve. Or got any other ideas
 

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Discussion Starter #2
I have refitted the one I removed as per above. Checking the solenoid valve on the bench there is a flow through the vacuum connections travelling from the egr to the vacuum pick up from the pump. The egr valve with engine stopped is spring loaded shut so on engine start up the egr valve will open and as the revs are increased it will be commanded closed by the ecu by shutting the channel in the solenoid. That is I see it anyway. Any thoughts/
 

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From my experiences on 2.0 HDI the solenoids have a resistance of somewhere around 20 Ohms.

They are controlled via a ECU pulsed signal to vary their duty cycle and indirectly the vacuum exerted on the EGR valve to vary the amount of EGR based on the map.

Where the valves have no electrical feedback signal the ECU calculates the EGR amount based on expected airflow vs MAF detected airflow (the difference is EGR amount).

On the solenoid with no power/zero duty the outlet should vent to through the valve to atmosphere (third port) as the duty cycle increases it switches between the vacuum and third port (most also have a one way valve incorporated to ensure they fail to atmosphere to stop overboost in event of failure
 

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Discussion Starter #4
There are two pipe connections and what looks like a filter on mine. As I mentioned there was no reading on the removed one across the pins. I will check the "old" one today to see if it has a reading. Thanks for your reply.
 

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Yes third port is the filter bottom one, top should be Vac in and middle Vac to EGR
 

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Discussion Starter #6
The layout on mine is different. The filter sits next to the electric plug on the left as mounted with the two vac hose connectors at the right hand end on the bottom of the body. The inner is egr and the outer the vac feed from the vac pump tee. Rechecked the electric solenoids with my Avo meter and both read 18 Ohms. The first time I used a pen style battery and bulb but it is a bit hit and miss. The trouble is the pins on these electronic stuff are tiny and it is difficult to get the Avo plugs to fit. I suppose I will have to get some female pins to extend them beyond the connector outer case to make it easier!
 

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Where is the EGR valve on the 1.4`s Donald, and is it easy to get at?
I`ve heard they can get really crudded up with exhaust fumes - was yours?
 

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Discussion Starter #8
Who is Donald? Anyway it is at the rear of the head, gearbox end. The valve has a connecting pipe that runs to the front of the head where it enters the manifold atop of the engine. The first time I did the check a couple of years ago the valve was clean, as it was this time. A bit sooty but no carbon build up. The manifold end was semi gunged up right by the pipe inlet on the first inspection but nice and clear this time. I am still awaiting a new gasket for the valve so that I can get it back together.
 

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LOL. I`ve been reading your user name as Mad bad Donald for the last 4 years.
I`ve just realised what it actually is!!
Sorry, but you`ll always be Donald to me now..
 

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Discussion Starter #11
Got it all put back together and running but still in limp mode and the anti-pollution message comes up. The EGR system was all ok so I decided to check the resistor I fitted in the glow plug circuit which caused the original limp mode. And lo and behold it was duff! Luckily I bought a couple more and fitted another 1 Ohm one and bingo it is out of limp. The anti-pollution message did ping on but at least the engine is back to running properly. Will see how long that lasts. Whilst under the car I noticed that the Lh inner drive shaft boot is torn. Both shafts were replaced with new ones last year so I am not happy with that. The same garage that did it will do the MOT soon so they can sort that out
 

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Discussion Starter #12
One for the electricians. The old resistor showed that the wire coil had indeed broken. Now it was a ! Ohm resistor and was put in the circuit to fool the ecu into thinking the glow plug circuit was intact. Using ohms law it seems that 12 Amps would be going through that resistor albeit for a very short time, if at all, dependent on the outside temp. Would it be better to say fit a 4 Ohm resistor as that would then be only 3 amps? I am not by any means an electrician by the way!
 

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Discussion Starter #14
The photo is of the resistor I had been using. The end pieces looked like they had been subjected to a lot of heat and I think that is what caused the windings to give up. hence my thoughts of putting a bigger value one to reduce the current.
 

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I would look for a 5 or 6 ohm 25watt resistor to simulate glow plugs.

If you use ohm's law volts = amps × resistance

An average glow plug is about 6 ohms so 12 = amps × 6

So it will draw 2 Amps Power = volts x amps so it will generate 24w of energy (heat) so a finned 25 watt resistor is the minimum needed to stop it cooking again long term

Hope this makes sense

Sent from my SM-T830 using Tapatalk
 

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Discussion Starter #16
I had bought new glow plugs when I first found that they did not work. But as it is a pain to change them and that is if you get them out without them snapping! I measured the resistance of the plugs and each read 2 Ohms! The chap who advised me to rig the resistor in place of the plugs (mechanico-he is no longer a member I believe) suggested that it just needed "a" resistance and recommended the 1ohm resistor. I thought my Ohms law idea was correct and so as I have a 4 ohm type of the one I showed (it has fins and is mounted on the rad mounting structure right by the headlight/airbox) There is no sign on the resistor as regards the wattage so I will look into getting the size you recommend to be safe. Thanks for you reply.
 

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Discussion Starter #18
I mentioned the left hand inner drive shaft boot has split. Anybody know the sizes as there are a number shown as applicable on the ebay. Three dimensions, the shaft the gearbox fitting and the length.
 

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Discussion Starter #19
Having had a update using Google on the correct way to work out the resistance of resistors in parallel a set of 4 glow plugs each of 2 ohm resistance would have a combined resistance of 1.25 Ohms making the current draw 9.6 Amps. That makes a wattage of 115.2 watts which is why my resistor probably failed! If I use the 25w 6 Ohm resistor then the wattage will be 24watts so should be OK.
 
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