Not a happy car

jasst

Member
Messages
792
While leading the piston heads tour into the Sherborne classic and supercar show today we have developed a problem, the car ran fine to the meeting place of Haynes museum, but when we left it would not rev above about 4000, and really misfired and emitted lots of smoke and sparks from the exhaust, below 4000 the car sounded fine and behaved normally, upon arriving at the show, we stopped and while waiting to go through the crowds someone noticed a pool of oil coming from the area of the air filter. Had to start up to get out of the way, and sounded normal but did not rev it much, but oil pressure was down to 2.5 bar (is normally around 5bar), not prepared to risk driving it home so have had it recovered back home, but had to start it to get it off the road, bit of smoke but oil pressure was back up to 5 bar. Any body any ideas what could possibly be wrong? hopefully something simple like a blocked breather, but I somehow doubt it.
 

Zep

Moderator
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2,424
It certainly sounds like you have a lot of oil in the inlet which is making the smoke. As to why it is there, if it won’t rev and you
had sparks from the exhaust, sounds like a disintegrating cat. If the exhaust is partially blocked the pressure in the cylinders could mean it blows by the rings and forces oil out of the breather.

Hot oil pressure at idle on mine is 2.5 bar, 5 bar when cold. So that at least is fairly normal.
 

jasst

Member
Messages
792
That's a very interesting theory Zep, and is certainly something I will investigate first, I only have primary cats, and they are not original as were re-cored by previous owner , often wondered if the amount of 'pops and bangs' I get is in fact damaging the cats?
 

masertel

Centenary Club
Messages
72
Had the same problem on an Alfa and a twin cylinder Kawasaki lawnmower of all things. Both would not rev out cleanly and sounded constipated- the internals of the exhaust is both instances had collapsed and was blocking the exhaust. Sounds like Zep is bang on- hope that's all it is. Good luck!!!
 

jasst

Member
Messages
792
Well, Ive got the induction system removed, and oil everywhere, but found a breather pipe from the oil tank connected in just before the throttle body, so if the cats have collapsed and causing obstruction, hence back pressure, then that could be the route the oil has taken, and oil all over the MAF would have resulted in the misfire? Next step cat removal, God how I wish I had a proper workshop with a lift.
 

jasst

Member
Messages
792
I'd think I'd died and gone to heaven if I had somewhere like that, sod the house, what's the garage like!
 

jasst

Member
Messages
792
Well the cats are out, and unfortunately they look ok, from the front anyway, will get my inspection camera out and have a look from the other end in a bit, but am feeling really rather depressed now:too_sad: So what is next? compression test I suppose, somehow cant see me driving it again certainly this year, if ever.
 

hashluck

Member
Messages
462
This certainly sounds very similar to what I experienced on a Saab 9-5 Aero once. The cats had not broken up but were 'blocked' or destroyed in some way due to unburnt fuel getting to them. They looked fine but were not. Good luck whatever it is!
 

GeoffCapes

Centenary Club
Messages
9,092
Do you have white residue on the exhaust tail pipe? If you have, then it's the cats.
Sounds similar to mine when the cats went. But I don't think I had sparks.
It ran ok wish when cold, but when warm the car wouldn't go over about 4k revs.

As long as the engine hasn't ingested any of the ceramic material from the cats you should be fine with just replacing them.
 

jasst

Member
Messages
792
Ok, I'm back and feeling slightly happier, due to the wonders of modern technology ( a £5 inspection camera from e bay) this is what I have found, pic 1,3,4 are of the inside of the RH cat, pic 2 is of the left hand cat, so it does indeed look like my RH cat has disintegrated, although not visible from the front, phew!. This does bring into question the honesty of a certain exhaust place used by the previous owner, as according to the service history, backed up by receipt from said place, he paid to have 4 cats rebuilt with new cores, the secondary cats (which I have removed are def not oem, but the primary cats have not been touched, so they pulled a fast one on him there. So, off down to my local exhaust place, who happen to hold the UK franchise for Magna flow, and Power Flow, and see if they can re core them.
 

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Contigo

Centenary Club
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17,459
Well done mate that's £5 very well spent. I use mine too for checking wishbones etc...
 

masertel

Centenary Club
Messages
72
Good luck getting the exhaust sorted- hope that's the end of your woes. I have swapped out the standard exhaust for the Larini replacement that deletes the secondary cats and frees up more power and increases the volume. It's an expensive system but well made an boy does it sound good!! Still less than half the price of OEM and 10 years on no issues even after 30+ track days driving flat out. Probably best to delete the secondary cats and replace the fronts will 200 cell units if you plan to re-fabricate the OEM exhaust. Provided the senors fore and aft of the fronts cats remain the car wont throw an engine light.
 

jasst

Member
Messages
792
My secondary cats have already been deleted, so re-coring the primary cats is not an option due to their shape, I will be taking a hammer and chisel to what's left of the internals, will then have my custom x pipe modified to incorporate 200cel sport cats, or do I go the whole hog and go Larini, as I already have their back boxes!
 

masertel

Centenary Club
Messages
72
Moving the cats back will necessitate moving the O2 sensors back in order not to mess with the ECU and throw the engine light so not that straightforward. Also you will still have the issue of the squashed exhaust under the steering rack. If the funds are there best to save yourself much hassle and fit the Larini and enjoy the extra bhp and volume.
 

jasst

Member
Messages
792
Just been browsing all the exhaust threads I can find on the forum, think if you get system built you leave front 02 sensors in same position and cable on rears is long enough to reach to rear of sports cats. Larini would be nice, but the vat is the killer, and as not vat registered cant claim it back. Will gut primary's and bolt it all back together as is for now and see what happens regarding cel lights.
 

Zep

Moderator
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2,424
Just been browsing all the exhaust threads I can find on the forum, think if you get system built you leave front 02 sensors in same position and cable on rears is long enough to reach to rear of sports cats. Larini would be nice, but the vat is the killer, and as not vat registered cant claim it back. Will gut primary's and bolt it all back together as is for now and see what happens regarding cel lights.
I guess from this that you have the euro style squish pipes? You are going to need a cat of some description to pass an MOT and avoid CELs. Cheapest option is to have sport cats fitted to your existing squish pipes in the position of the secondaries. Next is to have a custom squish pipe made with the redundant primary cat boxes removed and the cats in the position of the secondaries. If you put the cats in the x pipe you run the risk of having warm up issues as the distance from the engine will mean they take longer to heat up and start working. Or you can go Larini of course. This assumes of course that this is actually your problem!