S2 lost power funny exhaust noise, Help

[jamieda]

Hey Guys,

After a bit of advice, just got back from a track day so been driving the car all day,

1.5 hour drive there

6 x 15min sessions so plenty of breaks in-between

3hour drive back (M4 closed due to accident GGGRRR)

about 5 miles form home the car lost power revs felt high but no power to the wheels (or i may have imagined that) when at lights the exhaust note was weird to say the least....

any thoughts

You tube video of noise https://youtu.be/SUjVhRJyinI

Cheers

 

[colin944]

Sounds like its not running on all 4. have you checked simple things like plugs and leads?

 

[jamieda]

Thanks

Just got home, will check em tomorrow, not liking the sound of that, I've used a load of coolant today as well.

 

[robwright]

Head gasket? Any steaming from the exhaust? First thing I would be doing is a compression test. Maybe get a local garage to do a sniff test on the coolant. It checks for the presence of hydrocarbons i.e. combustion gasses.

 

[jamieda]

nothing coming from the exhaust, the car uses more coolant than normal on everyday use, i took it to Northway for a compression test a couple of months ago because of the coolant use and it all checked out fine, its just had a full service and gearbox rebuild.

I guess i need to get it checked again.

How do i check the plugs and leads myself? what am i actually doing?

Cheers
J

 

[robwright]

If it was missing you would know. The engine would feel lumpy. There are some great troubleshooting guides on www.clarks-garage.com Plugs can easily be removed and checked for condition. A spark tester can be bought from most motor factor shops. Simply remove the leads and put the spark tester in line with the plug and lead. Check leads for condition. Look for chafing. Even the smallest imperfection can track to earth. Maybe even worth replacing them for completeness.

 

[944Scott]

Did it feel a bit lumpy, you said it felt down on power? I would not be surprised if one of the plug leads has not come unseated.

 

[jamieda]

It doesn't feel lumpy, when i press the throttle the revs don't match the power going to the wheels if that makes sense, the power per rev is down...

The distributor was pretty worn as was the rotor so i changed both and all plugs, when i started the car it ran as normal for about 5 seconds then went weird again, its like the exhaust isn't attached or there is a hole in it or something......... but when i blip the throttle it doesn't sound right, like a loss of power.

one of the spark plugs was very white on the end not sure what that indicates...

new youtube - http://youtu.be/YJ7t1PnUy_U

 

[Waylander]

That's only running on 3 cylinders, you can hear the complete loss of compression on one cylinder and I don't like that knocking noise.

Think the head needs to come off that engine

 

[jamieda]

that sounds expensive!!!

so what could be the cause?

 

[jamieda]

ORIGINAL: Waylander

That's only running on 3 cylinders, you can hear the complete loss of compression on one cylinder and I don't like that knocking noise.

Think the head needs to come off that engine

I'm happy to take the thing to bits but not sure what id be looking for?

 

[jamieda]

looks like a fresh oil stain on sump, something has gone.....

 

[Waylander]

If you take it to bits I think it will be blindingly obvious

 

[gothatway]

ORIGINAL: jamieda
so what could be the cause?

The engine wasn't happy either with your preparation for the track day, or your treatment of it on the track. What were the oil pressure and coolant temperature like while tearing round the track ? When had the oil last been changed ? When was the timing last checked (an unlikely culprit) ? Did you check the oil and coolant levels between sessions ? If so, presumably you didn't notice any contamination of either oil or water.

I reckon if you're lucky you've just blown a head gasket, but it could be a dropped valve. Or worse. [&o]

As said, the first step is to whip the head off. If you really don't know what you're doing you might be best advised to find a local specialist.

 

[jamieda]

Thanks for the replies

after a bit more poking around cylinder 2 isn't firing

The car has been prepared well, full service, timing belts, chain and tensioner changed in feb at Northways, gearbox rebuild march, again at Northways, i had the car fully checked and put everything right no expense spared over Feb and March this year in prep for track work. Compression tests the lot.

All fluids checked last weekend and night before track day, checked again after lunch all fine. checked again today, all fine.

Oil pressure was fine all day and fine when cylinder 2 stopped firing about 10mins from home which was about 3 hours since the last track run, the oil pressure is still showing as fine.

I was acompainied on the track day by Mike wilds and his son as part of driver training so everything was done to the letter.

would blowing the head gasket stop cylinder 2 from firing?

 

[944Scott]

Definitely sounds like its running on three cylinders but if you had dropped a valve I'd say it would sound a lot worse than that. A very white plug would mean that cylinder is running lean, out of interest what cylinder had the white plug? (end of the fuel rail maybe) do you have a fuel/ injector issue at that cylinder?

I'd do some further investigation before whipping the head off and the oil leak might not be related.

 

[robwright]

Absolutely it would. You need 3 things for combustion air/fuel, compression and spark. If the gasket is blown then you may well have lost compression and therefore no bang!

 

[Monkeythree]

What have you done to establish that it is no.2 which is not firing?

It can only be spark, fuel or compression so it seems that if you know no.2 is not working then you must have identified that one of these three things is missing in that cylinder. That being the case, you have diagnosed the problem and now only need to pinpoint the cause and then fix it.

Let us know how you concluded that it was no.2 and then we'll go from there.

 

[robwright]

Back to my first reply. The first thing I would be doing is a compression test.

 

[jamieda]

drop of oil on each exhaust manifold close to engine, only 3 burned off, cylinder 2 exhaust manifold the old spot stayed damp.

ORIGINAL: Monkeythree

What have you done to establish that it is no.2 which is not firing?

It can only be spark, fuel or compression so it seems that if you know no.2 is not working then you must have identified that one of these three things is missing in that cylinder. That being the case, you have diagnosed the problem and now only need to pinpoint the cause and then fix it.

Let us know how you concluded that it was no.2 and then we'll go from there.