Leganza surge at idle

[caprice]

Hello I have a 2000 leganza SE 2.2L auto transmission, and the engine surges. Its constant and i would say its 2 or 3 times a second. It kind of reminds me of running on three cyllenders... but it is not completly skipping

It only does this in closed loop.
It only does this at an idle at 800 RPM or so
No engine codes
I just bought a scanguage, and it says it is using .7 Gallons/hour cold and .5 or .6 warm. By comparison, that is what my dad's 2003 Chevy Tahoe uses, with a 5.3 liter V8. My 1998 Ford zx2 escort uses 0.2GPH, one third that of the daewoo.
Also, scan guage tells me the timing advace is all over the place, anywhere between -4 to 25!! I belive that may be a major clue to whats wrong...

I unplugged the first O2 sensor, and it seems to idle normal. Of course it stays in open loop, and set a code. Timing advance is stable.

I can't drive the car because it is niether insured nor registered. Today I started to replace the timing belt. I wish I had taken it for a test drive ealier to get a road MPG.

What may be causing this problem? I think it may be a O2 sensor. but they are not returnable, so I wanted to see what you guys thought.

Thanks,
David

[caprice]

So the timing belt and company swap out procedes, and after I remove the timing cover I turn the engine till the bollom mark matches up and Look at the top cam marks, and the intake cam is dead on but the exaust cam is one tooth off! One toothe retarded. Would that cause unstable idling? I think so, I think it would be open too long then. when the Intake cycle starts the exaust valves are still open, and it acts like the egr valve is broke.

I am exited

This is the first time working on a daewoo, and I've notices it is a lot easier than most FWD cars to work on.

So my question is, would the exaust cam one tooth off cause unstable idling?????

Thanks

[MMamdouh]

if the timing is off then expect problems... fix timing then recheck engine.

MMamdouh

[caprice]

The hardest part was slipping the belt on right. I did it 10 times before all the marks matched.

It idles twice as good now, but it is not steady like it should. The RPM speed goes up and down about 4 or 5 times a second. It only does this at an idle. Idle speed is 900-800 rpm. If you listen to the exaust, it sounds like is is backfiring, and skipping.

I took it for a test drive on the freeway, and it drives good at all other speeds. It set code P1404 at 166F degrees, 4.9 MAP, 1137 RPM, 36 MPH, TPS 0%. It may be usless info, but I provided it anyway.

Is that the IAT sensor or the EGR? http://www.troublecodes.net/OBD2/Pcodes.shtml What do you guys think of my discription of the problem? Thanks for any help!!

[Spider]

Hey Caprice,

Have you disconnected the battery ground and done the computer 're-learn' procedure ?

look here;
http://www.daewootech.com/forum/viewtopic.php?t=3063

[caprice]

Yes, I just did that. It seems to run better, but is hard to tell. The exaust normally soulds like puff puff puff puff but randomly, (average every five seconds,) I hear a puff puff puff Cough, and It retards the timing when it does that too. It has 118,000 miles. Should I worry about how smooth it runs? Also when I had the intake off when I changed the TB, I noticed the trottle body was dirty. think dirt could be cloging the IAC too? I am going to check plug colors and check compression tomorrow.

[MMamdouh]

a full TB, IAC and intake cleanup always helps idling.

MMamdouh

[Spider]

a full TB, IAC and intake cleanup always helps idling.

MMamdouh

..and let me add?
a new air filter, fuel filter and try running a can of Berrymans B-12 or Sea Foam thru the tank. That will help clean the injectors.
Also? how about your spark-plug wires ? After that many miles they could be leaking.
Try this for an easy test. Remove the valve cover plastic cover and on a dark night, watch the plug wires while the engine is running
at idle and higher RPM's if you see a blue lightning show ? replace the wires.