2001 Vectra SRI 150 2.2: Power Loss

150_sri

Hello everyone,

Wondering if you will be able to help. Issue is as follows:

Revs stop at about 4500 - 5000rpm and wont go any further also power is 50% down. called RAC out to look at car and the onboard computer produced error code P0300: 'Random multiple cylinder misfire'
I have had the compression tested on engine and all is perfect, replaced spark plugs, bought new coil pack and replaced, however issue is still there with no improvement.
Car makes a metalic, rattle on accelerator depression (when you rev and let of the accelerator) also happens when you turn the car off.
CAT is fine and manifold has no cracks or leaks.
What we did notice thoughis the following. I removed the heat shield covering manifold and then held a srewdriver onto top of manifold. then i put my head onto other end of screwdriver, whilst i did this a mate reved car and then released accelerator. when he released accelerator and the car settled back down to idle, i could feel a clonking/rattle coming through the screw driver from the manifold! Therefore this appears to be a more fundamental issue near to the engine.
As i say car is running fine and there is no misfire however has lost about 50% of power and is sluggish only pulling to 4500 - 5000rpm. Compression is perfect and new coil pack has been put on along with spark plugs.
Is it possible that a valve has dropped orr something like that?
I really need the car as i use it for work however have not driven it for 5 weeks to prevent causing any damage so any help/advise will be much appreciated.

Have you got any idea what could be wrong with the car..?

Cheers Mike.

JohnnyN

I would have a look at dropping the downpipe from the manifold and having a look at the precat. Sounds like its broken down and blocking the main cat. Defiantely worth a look there first.

Removal is the best option. There is no need for it to be there other than when it first left the factory. I would go as far to say that its one of the first modifications to help the exhaust system flow better.

Welcome to the site by the way. How did you find us?

:thumbup:

150_sri

Cheers, that sounds like a viable explanation, i will get onto that and let you know how i get on.

Thanks for the welcome. Ive had a Z22SE for 5 years now and not really encountered any problems until now, its been an excellent car. So as i need the problem resolving without paying stupid prices at main dealer i though i would do a search on google for z22se clubs and this one popped up in the seach results.

I am already a member of vauxhall owners network however have not had much response to this issue on there so though i would search elsewhere.

Cheers Mike.

rod1-sri

the pre-cats a common fault if i remember correctly... thats y i got shot of mine 🙂

150_sri

Will this affect emissions on the car if i simply remove it and do not replace it?

JohnnyN

No emmission problem.

150_sri

I just called my mate who will be doing the work on car and he has asked if you would be able to describe where the pre-CAT is in the exhaust system?

JohnnyN

Detach the downpipe from the manifold and the precat is sat in the opening at the top of the downpipe.

See here for How to guide. (Bottom of page)

viewtopic.php?f=14&t=10729

:thumbup:

150_sri

Great thanks for the reply, just downloaded the .pdf. Excellent document, thats made the job easier. cheers.

Hareng

While down pipe is off check main cat as well.
Removing precat will feel like an immediate 5hp on a good one, been off at least 3 years and passed two MOT with 200 cell cat only.
See what happens with this first.

Going back well over 3 years i had similar metallic symptoms 63k though not as bad didnt knowingly have misfires, cured with new timing chain and Tech2. My reckoning was timing was out due to chain stretching throwing timing out over the twin cams, could well have slipped a cog along with loose ish tensioner. Of course yours could well have jumped a tooth or two. Any rattle tensioners can break as well?

RoniN

I was wondering, if I will remove precat. Will that can couse lambda false reading, ending as error on dashboard?? I will be changing crank seal on thursday, so I may remove precat as well.

vocky

the ecu works perfectly fine with the 'precat' removed :thumbup:

the 'main cat' cannot be removed without causing ecu error codes

RoniN

Exelent! I will do that at thursday 🙂

150_sri

Hi Guys,

All sorted now, car is fine.

Removed downpipe from manifold and pre-cat was rattling around at the bottom of downpipe, not at the top of downpipe where it should be seated. It was all in one piece which was weird, anyway removed it and put exhaust back on. started the vecky and there was no noise at all except for the 2.2 :-) Took it up the road and it went like a rocket, so thanks for all the advise, much appreciated.

Another Z22SE back on the road 😃

JohnnyN

Brilliant news!! Well done!

thumbup

150_sri

Hi Guys,

Need to re-open this thread.

Timing chain was changed at main dealer some time ago and is fine. As suggested above, the pre-cat had dislodged and was at the base of downpipe rattling around, so i had this removed, and re-attached to manifold- so there is no pre-cat now.

Car sounds perfect now and all power is back. However, i havent driven the car for a while as ive been driving my company car. I re-taxed the car earlier this week and took it out for a drive, first time since removing pre-cat, all appeared to be ok and went like a rocket. However after a 20 mile drive, i came to a standstill at some traffic lights, ofcourse the car was simply on idle at the lights and it started to sound a bit lumpy whilst ticking over ( Revs were fluctuating from 500 - 800rpm) However when i took of from the lights, the car was pulling fine, so just appeared that on idle there was an issue.

Then when i got home and parked the car, again on idle revs were fluctuating, so i turned car off and left for 5 minutes. When i went out after 5 minutes and turned car back on, it wasticking over nice and smooth as normal, so took it out for a drive again and after 10 mins driving when car was hot, on idle, again revs were fluctuating. So there i an issue here when car warms up revs fluctuate. Also fumes from exhaust smell quite rich.

Taking into consideration the pre-cat has been removed, do you think revs are fluctuating because management system has realised there is no pre-cat?

If not can you make any suggestions?

Cheers,

MikeS

hmm the only sensor that works off engine temps is the coolant temp sensor

however i would be more inclined to clean the throttle body & EGR valve first if you haven't blanked it

150_sri

Re: 2001 Vectra SRI 150 2.2, error: PO420

Hi All,

Further to all previous posts, engine management light has now come on in the car.

Might be a good idea for you to look at history of this post so you can see what the history is.

Basically i had the pre-cat removed as the power was restricted and it had dropped to the bottom of the downpipe. After this, the car seemed fine and performance came back. But then the car would occaisionally act odd when stationary, the revs would fluctuate and feel lumpy. This seemed to clear and car was fine until this weekend when the revs started to fluctuate again. Then whilst on a 150 mile drive home, the engie management light came on and has been on for about a day, therefore i just called out the RAC.

The RAC connected their computer and produced the Error code: P0420. Which refers to the catalyst system and in-efficiecy in the exhaust emmisions.

RAC said the revs fluctuating issue was due to the car not knowing the correct amount air and fuel to inject because the pre-CAT had been removed.

Can you please offer me your opinions?

Cheers

vocky

rac are talking bullshite

there are several hundred z22se cars with no precat and you are the only one to get a fault due to removing it - I don't think so

you said the precat had fallen down the downpipe, that sounds like it had probably damaged the main cat :thumbdown:

silver_SRi

Do you still have the EGR in place? as said above...