Daewoo Lanos lack of power?

Very common on these is either a faulty EGR valve controller, OR a blocked exhaust (restriced thro wadding coming adrift or cat broken up)

Tim..

Thanks for that. Is it possible to clean EGR valves with carb/injection cleaner? Although I was also wondering if it could be a blockage in the exhaust. The car runs normal on the flat during light acceleration but when you need that bit extra power it just ain't there, or come to an incline and it feels as though the engine is losing compression. I've replaced the plugs and did a compression test and that's Ok with number

1 cylinder @ 12.5 Bar (180 psi) all the others were 12.9 Bar (188psi) Can exhausts be checked for blockages in situ without having to remove sections?

With EGR valves, its worth having a go at cleaning them, if it doesnt work, you've not lost anything and will still need a new one, however i have had good success with cleaning them in my ultrasonic bath for about 30mins in a mixture of parafin, and diesel.

If you have a friendly Lucas (LSUK) service center, (most common location of an US bath), or a dentist (will probably object to filling theirs with diesel tho) they'll possibly have a go a cleaning it.

Carb cleaner etc is unlikely to work, but by all means have a go!

Compression shows the engine is mechanically healthy.

Depending on the angle of dangle and ease of removal, a quick test drive with the o2 sensor removed from the exhaust will tell you if it is indeed blocked,(beware of melting anything with the blast of hot exhaust gases) or else uncouple the downpipe as far forwards as you can. This does have the added benefit of often being able to examine the innards of the cat (or lack of)

Finally, the last thing which can cause flat performance is a knackered airflow meter. A quick test is to unplug it. You'll probably (should do) get the MIL lit up on the dash, but if performance is not better or worse, then it is a strong contender as being faulty.

Eliminate the first 2 causes first though.

Tim.

Thanks Tim. I had a look at the valve and it does appear to be knackered. If I suck the vaccum pipe leading to the EGR valve there is very little resistance felt and not enough to move the plunger, so I think the diaphramn inside the valve must be split! I took the valve off and cleaned it the best I could but it also does not appear to be closing completely. If I open the valve by hand and blow through the bottom opening I can easily blow through to the other chamber, but even with the valve in the closed position I can still slightly blow through to the other side!

What I've done as a temporary measure is put the valve back as it is and plug the vacuum pipe and disconected the wiring plug at the vacuum sensor which leads to the EGR valve. The "Check Engine" light remains permanently lit but I would say there is now a 30% increase in performance. Probably be even better if the valve was shut tight as it will now be acting as a vacuum leak. I will see if I can get a spare valve from a breakers but at least the car is now running much better. Can it do any harm to the engine running it like this and with the check engine light lit?

I didnt say before, but really as u have determined the problem- is to mechanically block off the EGR passage with a cut piece of tin as a gasket between the valve and valve seat, so that no EGR can take place.

Reconnect the vaccuum and electrical connections and your MIL should remain un-lit.

Tim..

Cheers Tim, great idea. I will do just that if I don't manage to get another valve. Would it be ok to use something like a soup tin to make the gasket (assuming it is completely flat) and use the old one as a template to cut around and align the bolt holes?

Yes yes and yes. Or a coke can flattened out.

EGR does nothing but hurt response, mpg and efficiency.

Tim..

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Well, apart from cut NOx emmisions.

Well the EGR gasket is in place and although it seems to have slightly improved performance the engine still appears to be holding back during the mid to high range of acceleration. In fact, if I floor the throttle it feels like the car actually slows down before gradually building up speed. My local garage took a look and discovered that there is very little vacuum suction from the inlet vacuum pipe that leads to the EGR. He says it shows all the signs of a blockage in the exhaust system and the back box is usually the culprit of these cars. Will try it with the back box disconnected tomorrow and see what that does.

All good, keep us posted.

Tim..

Well, I tried it without the back box connected and although there seemed a slight increase in performance, the engine was still holding back during the high throttle range! It's booked in next week to have the cat checked out. I did notice when driving without the back box that although it was pretty loud there was very little popping during over-run. The popping seemed to be muffled so I don't know if that could be further evidence of a blocked cat?

Before I have the cat inspected, would it be further evidence of a blocked cat if the car is more responsive and runs better when the air filter is removed?

The reason I ask is because I tried the car without the air filter installed and it ran much better and was much more responsive at top end acceleration. Not perfect but a hell of a lot better! I fitted a new air filter and although it did perform better than the old filter, the car was actually more responsive when there was no filter in place! With the new filter fitted there is still that loud roaring induction sound through the air intake when throttle is applied and I am wondering if this is symptoms of a partially blocked cat?

More symptomatic of a clogged air filter.

It is a brand new air filter. I tried it without a filter fitted and there was much better performance so I fitted a new one. It is running better with the new filter but ran better when no filter was fitted at all. I've left it with the new filter in place but it's still lacking power, and use more throttle only increases the roaring induction noise through the air intake without delivering the power to match.

Well you could stick a pressure guage in the O2 sensor hole & see what it says. Or try getting it run up on your local rolling road.