Please educate me on egr position

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richieski
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Please educate me on egr position

Post by richieski »

Here is my issues
am getting p0490
Engine speed2152rpm Engine coolant temperature081°C EGR valve relative position053% Air flow per cylinder0629mg/stroke EGR valve position009%

p1459
Engine speed2281rpm Engine coolant temperature081°C EGR valve relative position092% Air flow per cylinder0300mg/stroke EGR valve position009%

so @2281 rpm is my valve actually at 92% or 9% and which one should it be? the valve had been replaced with a complete new unit. Not sure which make though.
I presume at those rpm it should be low.
Also similar revs on both codes but the air flow is almost doubled

I just don't understand
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Re: Please educate me on egr position

Post by RichardW »

It's not relative position it's reference position. This is what the ECU is requesting; the other number is the position the ECU is seeing from the EGR. The two should track closely; if they don't then you will get the fault codes and Depollution Fault. Given that you have fitted a replacement valve and it is stuck at 9%, it suggests to me that the message is not getting to the ECU. If you took the valve off and then connected it and got Lexia to cycle it you should be able to see the valve moving (might not be all that easy...!). I saw your PM, I'll try and find the wiring diags.
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richieski
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Re: Please educate me on egr position

Post by richieski »

thanks, so i have the day tomorrow to work on it. Do you think i should take it off and test it via diagbox first?
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Re: Please educate me on egr position

Post by RichardW »

Couldn't find it on the Berlingo, but here is the one from a same age C4 Picasso:
egr.jpg
1297 is the valve, 1320 the ECU. 32V GR on the ECU means the 32 pin grey plug, 48V MR a 48 pin brown plug. The pin locations should be numbered, and the wires will be numbered. Somewhere :rofl2:

On the EGR pin 2 and 3 are the power supply - you can't measure these directly as it uses a pulsed signal AFAIK. Pin 5 should be ground, and pin 1 5V. Pin 4 should vary between 0 and 5V depending on the position of the valve.

I think I would run an actuator test in the valve in situ with diagbox to see if you can hear it moving. If you can, then, check the signal on D4 of the grey plug to see if it is changing. If it's not moving then do a continuity check on the two power wires from the ECU to the valve.
Richard W
richieski
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Re: Please educate me on egr position

Post by richieski »

Thanks a million, I do really appreciate your help. I'm getting a solid noise from egr actuator test. Nothing from exhaust heat recovery electrovalve
richieski
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Re: Please educate me on egr position

Post by richieski »

Also my ecu is giving 44% turbocharger position reference value all the time, even with engine off at idle etc.
The position indicator of turbo is 0 at engine off, 100 on idle and starts to drop when rpm is increased which I believe is correct. Basically car is hesitating which I think could be down to this false reference not the egr fault codes. Would I be right? No anti pollution etc.
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Re: Please educate me on egr position

Post by RichardW »

There's no feed back of turbo position on the 1.6 16V engine AFAIK - it just puts out the position, and modulates this to give the required manifold pressure. Small EGR faults don't put the EML on - it took me ages to work out that the reason ours kept putting the handbrake / ESP light on was because of the EGR valve....! And EGR problems give hesitation usually around 2k rpm. If the valve sounds like it is moving then you need to look for the signal output at the ECU, and if absent, investigate where it's gone!
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Re: Please educate me on egr position

Post by MikeT »

Hmmm, reviewing my Turbo Opening Control, it does show fluctuations, from 54% at engine off, rising to 60% at engine start/idle and varying under driving conditions.

richieski, can you monitor Turbo Pressure Setting vs Turbo Pressure Measured (millibars)? One should closely follow the other.
richieski
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Re: Please educate me on egr position

Post by richieski »

Right, valve moves with diagbox. Reference Voltage checked (0-5v) while forcing egr by pc at the valve and checked the continuity of this cable from ECU to valve.
Everything looks good at the egr...
I'm not sure this is a curve ball, as my issue is hesitation 1k rpm - 2k rpm, only while coasting and not under acceleration.
I just took it for a test drive and it ran like a dream, until i checked it when i returned to find i left the electrical connector off the MAF!! aaahhh. Connected it up and fault is back.
Mike, i will just charged laptop and try to look at turbo pressure.
Thanks for sticking with me guys.
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Re: Please educate me on egr position

Post by Hell Razor5543 »

Then that strongly suggests the MAF is at fault.
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richieski
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Re: Please educate me on egr position

Post by richieski »

Turbo pressure is about 60 millibar more than reference value in the problem rpm range 1300 - 2100. Once above 2100rpm ref turbo pressure and reference turbo pressure are almost identical 1041 measuring about 2200rpm
MikeT
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Re: Please educate me on egr position

Post by MikeT »

richieski wrote: 15 Jul 2017, 18:19 Turbo pressure is about 60 millibar more than reference value in the problem rpm range 1300 - 2100. Once above 2100rpm ref turbo pressure and reference turbo pressure are almost identical 1041 measuring about 2200rpm


That doesn't appear overly concerning to me, though I'm no expert. As James says, the MAF could be an issue though. All I know when I accidentally left the MAF disconnected, the engine light came on and it would struggle to rev up to 3K max. I didn't bother trying to drive it at that point.
richieski
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Re: Please educate me on egr position

Post by richieski »

I tried a second hand MAF and it made no difference. Obviously i would love to try a new one or a known working one. I need to hire a berlingo for a day and do a part swap...
I have been driving 2 days now with MAF unplugged, it brings up EML and anti pollution but drives like a dream....
Obviously the car can run smooth, just something giving an incorrect input. Anywhere i can buy a MAF and return if it's not the solution?
Any advice anyone?
I can't find a mechanic who can be bothered, they just want to fix the error code by putting another EGR in.
What gets overridden when the MAF is unplugged?
MikeT
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Re: Please educate me on egr position

Post by MikeT »

I don't know but the MAF measures the amount of air entering the engine and calculates the right amount of fuel to inject for the (other) given conditions, but expect your economy and emissions to suffer, at least.

Does your engine have DPF? I'd imagine it won't regenerate without a MAF input (though I could be wrong).
Last edited by MikeT on 19 Jul 2017, 02:07, edited 1 time in total.
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