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[minerwilly]

Hi everybody, I'm a new Omega owner and really need some help!

I bought a 1998 2.5 V6 Auto just over a week ago. On the short test drive that I took, everything seemed absolutely fine, but then as soon as I had to do any real distance (driving the thirty five miles home from work) everything went to pot.

For a start, it turns out both cats had collapsed and were causing the exhaust to overheat and sending burning material out from the rear end. This I'm not too worried about. I've temporarily removed the cats completely and installed straight pipes. Obviously I'll replace them before the MOT.

What is more worrying is the fact that when driving, after the first couple of miles (or less if up hill and the engine is under load), the car seems to go into some kind of limp mode and loses all its power. There's a lot under the bonnet, and as a newcomer to these cars I'm not in a great position to start making potentially expensive assumptions about what the problem is.

I've checked the ECU for error codes and there are none at all, which was a bit of a surprise to say the least.

I really need to get this car up and running as soon as possible because I have a seventy mile a day round trip to work and back! Also, I've spent as much as I can afford on the car in the first place, so I'm at a point where I have no choice but to see it through. Apart from this loss of power, the rest of the car is great, but the way it is at the moment it's undrivable!

Any help or advice would be very gratefully received.

Cheers.

Marc

[TheBoy]

Does the EML ever come on (either when driving or initially when turning on ignition)?

Crikey, just looked up your location, as my Scottish geography is bad

[minerwilly]

Yep, I'm as far north as you can get without leaving the mainland

The EML did come on a couple of times when the cats were in but hasn't come on since I took them out. Having said that I haven't driven it far since then.

Thanks for replying.

[TheBoy]

Hmmm, the last decatted Omega I drove ran down on power as well, but no sudden, massive power losses, just generally down a bit on power.

Is it just down on power, or is it actually misfiring? Misfires with no codes = check HT side of things

[minerwilly]

No misfire, it just feels limited.

It was doing this before I took the cats out as well though. My instinct tells me that it's the ECU acting on wrong information, but I have no experience of these cars at all so I will bow to the opinions of you guys.

Marc

[cem_devecioglu]

"Also, I've spent as much as I can afford on the car in the first place, so I'm at a point where I have no choice but to see it through"
 
Willy, before spending any extra, let it be checked by a mobile mechanic and he may be able to tell you other hidden expenses..
 
those cars are cheap for a reason.. and if yours are badly abused by previous owners , it will be good for your wallet to learn whats coming next before its too late.. sorry , but I feel necessity to warn you  
 
ps: do you know the history of car/prevous owner.. any service papers, cambelt, head gasket etc etc.. ?

[TheBoy]

Check multirams are working - think its described in our Maintenence Guides section, although that normally affects low down power...

[minerwilly]

It's actually a well looked after car. 80k on the clock, everything works, nice clean engine, mechanics all fine. The ash tray hasn't even had a cigarette in it.

It's had two previous owners and sailed through its last MOT. It should hopefully be a good car when I get this power issue sorted.

What are the multirams if you don't mind me asking?

Cheers.

[cem_devecioglu]

It's actually a well looked after car. 80k on the clock, everything works, nice clean engine, mechanics all fine. The ash tray hasn't even had a cigarette in it.

It's had two previous owners and sailed through its last MOT. It should hopefully be a good car when I get this power issue sorted.

What are the multirams if you don't mind me asking?

Cheers.

glad to hear those.. 

[TheBoy]

Multirams are a pair of valves in the intake to change the intake length, to flatten the torque curve (Omega is a heavy car, so the standard peaky torque curve is not so drivable).

[minerwilly]

Cheers, that makes sense. I'll have a look at the pages on them and get them checked.

It would be great if I can just find the problem and get it fixed before I get sacked

Marc

[Andy H]

I wonder if the original fault that caused the cats to self destruct is still present.

If I have understood correctly the thing that damages cats is unburnt fuel so looking for a misfire or overfueling.

[minerwilly]

It could well be over fuelling. Cats only have a limited life anyway though, and as a 98 car, I wasn't that surprised they were dead.

If it was over fuelling what do you think the cause and cure would be?

[TheBoy]

If you have access to equipment to read live data, what are MAF readings at idle, 2000rpm, and idle and partial load trims for both banks.

[Kevin Wood]

For the cats to fail in a spectacular way there needs to be excessive unburnt fuel in the exhaust, so I'd suspect either a misfire or overfuelling.

Worth checking that the little rubber pipes in the SAI system which feed air to each exhaust manifold are still present, IMHO. They are unlikely to have survived the cats blocking and, if they've perished, they will be letting air into the exhausts before the lambda sensors and upsetting the closed loop mixture control, which might well explain why it's sluggish.