EGR valve fault

Neil_Sedaka

Wifes 1.0L corsa has been running like a ball of Sh**e for weeks now, engine management light constantly on, serviced it last week but still the same.

Fault code says it's the egr valve but they are stupidly expensive (€200 + vat + fitting)
I heard someone once say that you can remove a dodgy egr valve and clean it - anyone any advice here please?

AMurphy

$200, ayaaaaa for a $60 item.

Easy to check and clean if not broken, ie a broken diaphram.

first off find the EGR valve and make sure any and all hosing attached to it are intact and connected. also check any steel tubing into it for leaks and.or cracks.

YOu might need a Hand Vac Pump + gauge to check it.
Is it ideling OK?. or ideling & stalling a lot?.

2 main problems, the Vacuum lines & valves between the intake and the valve give trouble, but the EGR valve itself is OK.
Coak builds up inthe pipes and ports but the the EGR and air valves are ok. Simply remove the valve and piping and clean them out, replace. However, if you plan on using sealant, make sure it is O2 Sensor safe.

If you obtain a hand vac pump I can tell you how to test the system.
Meanwhile find out how many intermediate air (vacuum) valves there are and let us know.

Meanwhile disconnect the vac line to the EGR valve and plug both tube and nipple, see if it responds any better.

tombull82

Opel Garage's are replacing these reguraly,
they seem to be a prob on almost every astra around 2000(I know you said Corsa but this is from my learnings) but they reckon it IS the Exhaust Gas Recirculation valve itself, and they are charging €280 which is ****, as it should be half covered even by warrenty as they must see they have a flaw if they are all going!!!!

:mad:

AMurphy

Do you know exactly what the problem is.
Gunk and overheating is one thing, which could be blamed on anything from wrong fuel to the alignment of the stars, failed Vac. diaphrams is another, which has only one source, poor design/construction.

Neil_Sedaka

Hmmmm, don't really know the exact cause other that the computer says it's the egr valve. Was suggested to me to get a gasket set for it and remove and clean. All the pipes seem fine around it btw.

AMurphy

Given I have no insight into your particular engine I do not know the details of construction. However, irrespective of the construction the end result is about the same.

You can test the system fairly easily or change a whole bunch of stuff willy nilly, your choice. I'd test it first, given it is easy to test and it is expensive to replace.

The EGR valve is vacuum controlled, (have not seen an ECU + stepper motor controlled one yet, but it's possible), via vacuum from the inlet manifold or vac source.
Between the vac source and the vac diaphram on the EGR valve there is a modulator valve of some kind, to enable it to switched on/off when needed/not needed
The modulator valve can be thermo operated off the water jacket, or solenoid operated via the ECU and ECU temp sensor + Throttle sensor. Or a bit of both.
The solenoid valve can be seperate or integrated into the EGR valve.

See the diagrams in the links below.
Before you go ripping things apart it is worth doing a little diagnostics, as it is easier to remove/replace rubber hosing than valves & piping.

for which you need at least a vac gauge and if possible a hand/vac pump or Vacuum source capable of generating >10" Hg. (plastic one in a kit of connectors, etc, would cost about $40)

First off, check there is NO vacuum present in the tube from the modulator to the EGR valve at idle, with a cold and hot engine.
Check that there IS a vacuum when the engine is hot and racing.

If the vacuum is on the line from the modulator to the EGR valve all the time or not at all, the EGR is not the immediate problem, though it too may be defective, so check it anyway.
For example on the Toyota EGR (same as my 89 Camry). The VSV valve or the Modulator may be faulty, so your have to figure out which one with the gauge and a DVM.
Or it could the ports off the throttle body may be blocked with gunk and causing the Modulator to misbehave.

With the hand Vac pump, Check the EGR valve can be opened at idle, when it opens at about 5~10" Hg, the engine should stall. If not, it never opened OR the ports/pipes are blocked. Disassemble, clean and verify it opens/closes. With it off the engine you can usually see if it opens or closes.
Make sure all drilled ports in the manifold are free flowing. I have had to drill out a few with masonary drills to clear out.

Check the EGR valve diaphram is not leaking. Pull 15" Hg and let it sit for 10 min. Should hold at 15". If it drops, make sure the pump is not leaking, Clamp the hose shut.



EGR!

Toyota EGR

About.com

btw, for anyone with a (~ post 1990) Toyota, turn to page 6 of the pdf file. Note the DLC1 connector. there are (usually) 2 pins in that connector that when shorted will enable you to read the check-engine codes and another that ties directly to the O2 sensor(s) so you can easily check the sensor with a std DVM, with no fuss.
The connector is located near the Left Side wing, and if not, you have an OBDII connector, on the fuse box most likely.

lomb

or find an opel forum. i believe this is a common problem with them.