Vauxhall Astra G 1998 2.0 DTL

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Vauxhall Astra G 1998 2.0 DTL

Postby Technician » Sun Mar 19, 2017 5:10 pm

Customer complaint of power loss when driven and engine management warning lamp intermittently illuminating.

Code read provides P0400 critical system malfunction (2), and P1125 critical system malfunction (1).

Following the checking procedure for P0400 I didn't get past the point in the checking procedure of checking the vacuum hoses and connections before I found problems. The main vacuum hose from the pump to the EGR solenoid valves appeared to be melted with a hole in it, to date I have no idea how that pipe has melted in the position it is along the lower side of the battery tray. I also found the rubber elbow connector that holds the vacuum pipe into the EGR solenoid(s) also looked as though it had been cut/damaged with a sharp tool, possibly someone previously trying to remove it?

As a matter of course I checked the engine oil level at the correct manufacturer recommendations, and the vacuum pump operation which was creating a vacuum of 27 in hg, directly measured at the pump rubber connector using a separate tube. I then replaced the original vacuum pipe to the pump and tested all vacuum pipes fitted to each of the three solenoid valves, no other leaks were found.

Having replaced the defective vacuum pipe and rubber elbow with Vauxhall genuine parts and cleared codes I road tested the car and while doing so recorded live data using the VERUS, this is so if a problem occurred out on the road I could re-play it back at the workshop. No fault codes re-appeared and no data showed any further problems. The car has covered some 70 miles and the customer rang me this morning advising the warning lamp has illuminated!

Now the only element of doubt I had while testing the system out was whether the vacuum pump actually would create a constant vacuum without drop outs, the reason for this was because during testing I thought I saw the gauge drop as low as 15 in hg at one time but when I moved the gauge the reading was back at 27 in hg.

I've been searching the internet with little success and will have to ask snap on next week if no luck, but I would like to test the vacuum system dynamically over a good road test to see if the pump is intermittently failing, hence some type of pressure transducer that I could plug into my VERUS and record data.

Anyone got any ideas?

Thanks
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby Dcunning35 » Sun Mar 19, 2017 6:28 pm

Could the drops in vacuum not be caused by another solenoid bleeding off after actuation. Try splitting off with one way valves to ensure you have constant adequate vac at your egr.
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby Technician » Sun Mar 19, 2017 7:28 pm

Thanks Danny, something to look into. Observing the data graphs on the VERUS I am looking particularly at the Swirl Control Valves when comparing the data streams, while driving along at reasonably constant speed all data graphs are reasonably horizontal along the axis but the Swirl Control (%) is varying most of the time between 0.00 and 65.0 (%). I wondering if that is pointing towards a vacuum loss as the only other time I have seen the Swirl valves operate like this is when I depress the accelerator pedal hard down accelerating and then the swirl valves (%) increase to 65% and then immediately drop back to 0% while cruising.
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby STC » Sun Mar 19, 2017 7:33 pm

The car has covered some 70 miles and the customer rang me this morning advising the warning lamp has illuminated!

I think it would be a good idea to plug it in and see DTC's you get. That light could have come on for hundreds of different reasons.

hence some type of pressure transducer that I could plug into my VERUS and record data.
Anyone got any ideas?


Snap on sell 3 different transducers specifically for the Verus, Modis, Verdict ... .... .....
0-100 psi, 0-500 psi, 50-5000 psi. all 3 will require the EEMS301A05 split lead adapter to work with your Verus.
Here is a link.
https://www1.snapon.com/diagnostics/UK/Diagnostics.htm

Don't forget that the Pico WPS500 will work with any scope including your Verus, is faster, more accurate, less noisy
There are several forum discussions on this at Snap On & Autonerdz. Here is a link to the first one I found

http://productforum.autorepairdata.com/ ... php?t=6476
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby Technician » Sun Mar 19, 2017 7:36 pm

Thanks STC, will look into those.
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby Dcunning35 » Sun Mar 19, 2017 7:58 pm

Im not saying for certain but the swirl flaps are usually actuated to help the egr mix so what you are seeing could well be normal. I take it the egr position isnt monitored.
Might be worth looking what happens on the maf when you get your vac drops whilst comparing the duty on the solenoid.
The last time I saw something like this it was an old 2.5tdci ranger it logged egr or swirl errors and turned out to be a restricted air filter element .
Think simple .
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby Technician » Sun Mar 19, 2017 8:01 pm

Thanks Danny, never gave the air filter a second thought.
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby Dcunning35 » Sun Mar 19, 2017 8:07 pm

Or maf sooted basically is it seeing the maf drop when the egr is commanded if it isnt thats why the dtc is logged.
From knowing that you can form a test plan , the maf output will be good to scope and another channel on the duty of the solenoid with a transducer even if its an old map sensor capable of reading vacuum you should see the bad man .
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby Technician » Sun Mar 19, 2017 11:51 pm

I was quite confident that when I had fixed the car it was fixed although we are human and things are always a possibility to go wrong, however when I delivered the car back to the customer and he run me back to the garage he was a very abusive driver. Today when he rang me I politely let him know that his driving style was not really good for the car, after all its not a race car, just a production model some 19 years old, that said he asked if I would look at it again Wednesday next week and I said I would, however this evening he has text me and advised that a vacuum pipe had become detached and since refitting it the car runs OK again now, so hopefully he'll learn to drive properly and the car will be OK.

Thanks for all the advice.

STC, thanks for the links I have invested in 5 pressure sensors, well 4 and one vacuum sensor so some learning to do with them when they arrive. :)
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Re: Vauxhall Astra G 1998 2.0 DTL

Postby STC » Mon Mar 20, 2017 3:24 am

I have invested in 5 pressure sensors, well 4 and one vacuum sensor


I was under the impression that the 0-100 & 0 to 500 are PSIA not PSIG
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