N75 valve on 2.2 DW12 2.2 HDi engine

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exec406
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N75 valve on 2.2 DW12 2.2 HDi engine

Post by exec406 » Sat Sep 29, 2018 10:28 am

Hi

I'm trying to find the Peugeot part number for the N75 valve (vacuum solenoid) for the DW12TED4 2.2 engine (turbocharger controlled by ECU not conventional wastegate)

If anyone knows this, if you could please advise.

Thanks
2003, '03' 406 Executive 2.2hdi 136.

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GingerMagic
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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by GingerMagic » Sat Sep 29, 2018 12:09 pm

Hi.
The 3 solenoids on the bulkhead are all the same part number - 1628 HC - but the ECU uses them in different ways.

My T4 has an N75 valve, but it's boost controlled, not vacuum :cheesy:
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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by exec406 » Sat Sep 29, 2018 12:49 pm

Thanks.
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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by rwb » Sat Sep 29, 2018 6:05 pm

I thought there were two types: ones that are either open or closed, and ones that can open partially?

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by GingerMagic » Sat Sep 29, 2018 6:13 pm

I think the ECU uses rapid open and closing to determine how 'open or closed' the valve is..?
I'm probably wrong :roll:
1999 T4 family wagon
2005 Vauxhall Meriva
1998 406 V6 Coupe - Midlife crisis..!
PP2000 user, can help with faults / diagnostics in the Bournemouth area.

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by Doggy » Sun Sep 30, 2018 9:48 am

There's certainly a difference in how they're controlled.
Air doser and swirl flap are all or nothing, while egr, turbo and the other one I can't remember :oops: are modulated.
I thought I read somewhere that they were different valves too, but I could be wrong. [/senior moment]
2003 HDi 2.2 6-speed Exec Estate

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by exec406 » Fri Oct 05, 2018 6:54 pm

GingerMagic wrote:
Sat Sep 29, 2018 12:09 pm
Hi.
The 3 solenoids on the bulkhead are all the same part number - 1628 HC - but the ECU uses them in different ways.

My T4 has an N75 valve, but it's boost controlled, not vacuum :cheesy:
Hi

The part I'm after is under the airbox, some sort of a valve looks a bit similar to the 1628 HC. Possibly turbo related part, but I can't find the description or part number. I've seen 'electrovalve' mentioned but not sure if that's it.

If you have any info? It's for a DW12 engine.

Thanks
2003, '03' 406 Executive 2.2hdi 136.

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by GingerMagic » Fri Oct 05, 2018 7:39 pm

Ah, I think this on is a similar number, 1628 CH, but I'll check online later.
I'm not sure what this electrovalve controls, if it's the one with the blue plug, air dosers possibly, as both my 2.2hdi estates has a simplified vacuum system - only the turbo solenoid was used, the swirl flap ( which is prone to a leaky diaphragm ) was bypassed, the rest were made redundant....

Just checked on Service Box - http://public.servicebox.peugeot.com - and the numbers are;


Swirl flap electrovalve - 1628CH
Airbox electrovalve - 1628LQ
Bulkhead electrovalves - 1628HC
1999 T4 family wagon
2005 Vauxhall Meriva
1998 406 V6 Coupe - Midlife crisis..!
PP2000 user, can help with faults / diagnostics in the Bournemouth area.

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by exec406 » Sat Oct 06, 2018 7:36 am

Thanks, can't seem to locate a replacement 1628CH part at the moment...

Do you know where the part 1628LQ is located on the engine?

A pic of 1628CH located near the bottom of the page on a French Peugeot forum:

https://www.forum-peugeot.com/Forum/thr ... 30/page-13
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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by GingerMagic » Sat Oct 06, 2018 10:27 am

Hi.
The LQ is attached to the bottom of the airbox - the CH is bolted the engine just to the left of the airbox (unless you have a Coupé then it's under the airbox on a separate bracket)

The CH is the solenoid that opens and closes the swirl flap, however the 2 bigger spouts are prone to breaking off and leaking vacuum. As an interim fix, you can unplug the rubber feed to this solenoid and block the rubber pipe with a large screw.
This makes your car a full time 16v which sounds good but there is a minimal loss of performance below 2000 rpm. You will also need to fix the tiny ball and socket, on the top right of the engine, in the upright position as it'll flop around now.

This should stop any vacuum issues the solenoid may have, and keep the vacuum high enough for the turbo demand.
1999 T4 family wagon
2005 Vauxhall Meriva
1998 406 V6 Coupe - Midlife crisis..!
PP2000 user, can help with faults / diagnostics in the Bournemouth area.

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by Doggy » Sat Oct 06, 2018 10:32 am

Can't be certain, but I too think it's to operate the air dosers. Cant check on mine as it was removed years ago.

On a 2.2 the air doser is used to bypass the intercooler, route the charge air through the air/water heat exchanger behind the radiator to assist warm up. It never operates after the coolant temp reaches 70C.
The other possibility is the control for the swirl flaps. The actuator spring returns to the open position allowing air to reach all 8 inlet valves. When the engine's running, the ecu will close the swirl flaps at speeds below 2100 RPM.

You will never notice any difference if you don't use either of these features and you significantly reduce the number of potential vacuum leaks your car can suffer. It costs nothing to remove/plug the vacuum supply to either or both electrovalves, will not cause any other issues and can be reinstated if you ever want to.
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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by exec406 » Sat Oct 06, 2018 11:06 am

Thanks, the issue with the valve was identified when I was getting the coolant temperature sensor changed. Basically on occasion, I lose acceleration / power (limp mode) at about 55mph plus. It will then come back to normal when at lower speeds.

Issue also happens occasionally when turbo wants to come in at lower speeds e.g. going uphill.

Edit to add: After checking today, the part I've actually to replace is the 1628LQ Airbox electrovalve not the 1628CH.
2003, '03' 406 Executive 2.2hdi 136.

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by exec406 » Sat Oct 20, 2018 6:34 pm

Hi

I got the 1628LQ Airbox electrovalve fitted and now I'm getting a new issue that I didn't get with the old one (the previous one had one of the two small plastic pipes broken, and was causing (I think) limp mode at over 50mph constant.

With the new part fitted, I'm getting some sort of 'turbo lag' When accelerating, the power would suddenly go as if I took my foot off the accelerator and pressed the brake a bit, it would then come back on and I can get up to speed.

Strangely, this doesn't happen all the time. Going up an incline when at 50mph, you can sometimes feel the car decelerate even when I've got my foot on the accelerator.

Could this issue be a defective new 1628LQ Airbox electrovalve, or could it be something to do with the vacuum?

I'm not getting the limp mode happening at higher speeds anymore.

Thanks
2003, '03' 406 Executive 2.2hdi 136.

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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by GingerMagic » Sat Oct 20, 2018 7:09 pm

Are the vacuum pipes fitted the right way round on the solenoid to the left of the airbox?
When the engine is running, the little ball and socket should be laying backwards, nearly horizontal - and when you rev the engine then it should lift up to the vertical position. If it does the opposite then the pipes are incorrect.

I think the solenoid you have replaced just opens and closes the air dosers, maybe there is an issue there?

If you are local to Bournemouth I'm happy to have a look at it for you.
1999 T4 family wagon
2005 Vauxhall Meriva
1998 406 V6 Coupe - Midlife crisis..!
PP2000 user, can help with faults / diagnostics in the Bournemouth area.

exec406
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Re: N75 valve on 2.2 DW12 2.2 HDi engine

Post by exec406 » Sun Oct 21, 2018 11:17 am

Hi

Thanks for the info, appreciated.
2003, '03' 406 Executive 2.2hdi 136.

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