Loss of power when in gear

[K T M Rider]

Sorry to cast doubts on your DIY skills, but you say you changed the oil seal on the tensioner. Just wondered if there are any visible oil leaks from there, or elsewhere on the engine?

If your precats did break up somewhere around Chichester (I really hope not) then that could not only explain the big loss of power, but also the big increase in oil consumption, which can be caused by the hard ceramic precat debris being ingested by the engine and damaging the internals. However, if your engine had taken in enough precat debris to result in a dramatic increase in oil use, I would have thought it would now be sounding alot more mechanically noisy.

[paulkeen]

Sorry to cast doubts on your DIY skills, but you say you changed the oil seal on the tensioner. Just wondered if there are any visible oil leaks from there, or elsewhere on the engine?

If your precats did break up somewhere around Chichester (I really hope not) then that could not only explain the big loss of power, but also the big increase in oil consumption, which can be caused by the hard ceramic precat debris being ingested by the engine and damaging the internals. However, if your engine had taken in enough precat debris to result in a dramatic increase in oil use, I would have thought it would now be sounding alot more mechanically noisy.

Your quite right to doubt them, However this was one of my better moments. it had been leaking but no more leaking since the change.

The car doesn't too bad at all ticking over, I guess its a bit noisey when reving it up etc... but nothing out of the ordinary for any other car I have owned when its feeling sorry for itself. I got the impression of the Precats have gone it will be awful sounding.

[Wabbitkilla]

I got the impression of the Precats have gone it will be awful sounding.

That really depends if the material has got into the engine.
If it's collapsed and is blocking the main cat then the engine will be breathless and under powered. Not good to run the car like this as you can imagine a heavily blocked exhaust and back pressure can cause quite a bit of damage to the engine.

[paulkeen]

Right, I have been a bit limited to what I could get up to but:

Air filter - pretty clean - quick turn over without it in place also made no difference.

MAF - looked clean, gave it a clean for good measure - No difference - ran car with it unplugged = really lumpy - so assuming this means its ok.

attempted to check the "crank or cam position sensor" but its on my sloping lawn at the moment and I cant find any images of what I am really looking for, so i just checked every connection in sight to be sure it was not loose. Nothing seamed to be suspect... but this is not ruled out.

Precats - the heat shield bolts are rusted to pieces, seeking a bit of advice on this one. IF i drill them out what else do they secure? I know I can get the O2 sensors out without removing it, but IF that reveals the precats are on the way... then it will have to come off. Plus while I am in the swing of it I might have the precats out (if I get to the bottom of what the original problem is).
Dont have a large enough spanner for the o2 sensor to hand, but I am off to see my Dad later "happy birthday, by the way I am just stealing all your tools!"

Also getting my garage cleared of the crap I had in it for other people so I can put the car on safer ground and get it on axe stands etc...

Would posting a video on youtube be helpful???

[Wabbitkilla]

The heatshield bolts are really crap aren't they   s:wink: :wink: s:wink:  
Usually a soaking of plusgas helps them get moving and then they shear off anyway   s:lol: :lol: s:lol:  
TBH the heatshields are there to keep the precats warm, so once they're out you don't need the heatshields.
Word of warning though, in recent weeks / months Ste has removed precat manifolds that didn't look too bad from the sensor holes, but when looking up from the main cat union they were breaking up badly.

One thing I've learned recently is to take your time, don't rush, get the car up and stable, and don't panic.
O2 sensor sockets are available on ebay and Halfrauds, and I recommend you get something like a single LED pinpoint torch to shine in there.

[paulkeen]

Nowt left of the heads on the heatshield bolt to even start doing anything but drilling them out. Here is a link to the video, but sound quality is so poor on my camera you can't really hear it right. I will get my video camera back ASAP and make a better effort.

 m http://youtu.be/6nsJWPvNkkM m

[mrzwei]

The sound doesn't seem to alter with engine revs so the only parts turning around like that in neutral are in the gearbox?
I'm not confident about that but I'm sure others will be along.

[paulkeen]

The sound doesn't seem to alter with engine revs so the only parts turning around like that in neutral are in the gearbox?
I'm not confident about that but I'm sure others will be along.

I think its the quality of the sound, might be best to ignor that video... probably more missleading than helpful.

[K T M Rider]

If your precats did break up somewhere around Chichester (I really hope not) then that could not only explain the big loss of power, but also the big increase in oil consumption, which can be caused by the hard ceramic precat debris being ingested by the engine and damaging the internals. However, if your engine had taken in enough precat debris to result in a dramatic increase in oil use, I would have thought it would now be sounding alot more mechanically noisy.

The car doesn't too bad at all ticking over, I guess its a bit noisey when reving it up etc... but nothing out of the ordinary for any other car I have owned when its feeling sorry for itself. I got the impression of the Precats have gone it will be awful sounding.

That really depends if the material has got into the engine.
If it's collapsed and is blocking the main cat then the engine will be breathless and under powered. Not good to run the car like this as you can imagine a heavily blocked exhaust and back pressure can cause quite a bit of damage to the engine.

Thinking about this some more, I reckon that if precat debris just blocked your main cat but none entered the engine, you might still see a big increase in oil consumption. My thinking being that the engine would be having to work much much harder to overcome the partial blockage in the exhaust which could in itself cause it to drink more oil. The exhaust gases have got to get out of the the combustion chamber somehow and if the route out through the exhaust is partially blocked then my guess is you could see an increase in 'blow by' past the piston rings, leading to a increase in crankcase pressure that would then start to force the oil out past seals and out of the crankcase vent.

Will be interesting to see exactly what you find inside the exhaust manifold. If a blocked 'Cat' is the issue then hopefully with that sorted your oil consumption will drop back to where it was before.

[Wabbitkilla]

I repeat ... Don't Panic, just get in there and look to see what the problem is.
When you find it, then you will know how to fix it.

[paulkeen]

Thinking about this some more, I reckon that if precat debris just blocked your main cat but none entered the engine, you might still see a big increase in oil consumption. My thinking being that the engine would be having to work much much harder to overcome the partial blockage in the exhaust which could in itself cause it to drink more oil. The exhaust gases have got to get out of the the combustion chamber somehow and if the route out through the exhaust is partially blocked then my guess is you could see an increase in 'blow by' past the piston rings, leading to a increase in crankcase pressure that would then start to force the oil out past seals and out of the crankcase vent.

Will be interesting to see exactly what you find inside the exhaust manifold. If a blocked 'Cat' is the issue then hopefully with that sorted your oil consumption will drop back to where it was before.

IF IF IF, this is the problem... I am looking at a new cat? assuming I "fix" the precats with a hammer. Seen them advertised online for about £200 incl VAT, sound about right? not rushing out to buy anything just yet, just trying to assess what the potential damage is.

I now have the tools so should be able to have at it tomorrow and see whats behind those sensors, but very much of the opinion I am going to get the precats out anyway.

[2 of the left]

Should the origin of the problem be the precats -then I must apologise for sending you in the wrong direction regarding gasket - As precats were removed before I bought my 2 I've had no engine malfunction in that area!- I was going on Mk2 case history  s:oops: :oops: s:oops:

[paulkeen]

Should the origin of the problem be the precats -then I must apologise for sending you in the wrong direction regarding gasket - As precats were removed before I bought my 2 I've had no engine malfunction in that area!- I was going on Mk2 case history  s:oops: :oops: s:oops:

Its still far from solved just yet, knowing my luck it will be the gasket as well! There are 3 ways for a Rover head gasket to blow and I had all three back to back despite looking after it really well. Hopefully tomorrow will shed a little more light on things

[2 of the left]

Well - I do hope you finalise it - There's nothing worse than standing looking at your 2 and not being able to drive it!!  s:evil: :evil: s:evil:

[mrzwei]

Without linking to a specific post, if all the plugs are black and wet after a run and you think it is fuel not oil then it is overfuelling (black would suggest overfuelling but wet would suggest oiling up and oiled up plugs will cause missfire under load).

So, despite my contradiction, if it's overfuelling then the ecu is signalling to the injectors to put in too much fuel. This may be because the maf is sending it the wrong signal but if you have cleaned it then that won't be a problem. It could be a blocked filter so to test that, just take it out and drive the car.
The ecu also needs to know when the pistons are at top dead centre and how fast the engine is turning so that it can instruct the injectors to put the right quantity of fuel in at the right time. Crank and cam sensors send the required info to the ecu. Faults with these sensors are usually flagged up with a code but poor running under load is an obvious symptom.

If oil is the symptom then you are looking firstly at how much you are using. It would have to be a fair bit to significantly effect the performance, secondly, the gasket issue (do a compression test), thirdly the precat issue.

My personal course of action?
As has been advised really, check the pre-cats (my opinion is that these won't be the issue because the car seems to rev ok).
Clean the maf again and run the car without the air filter.
Check for any codes.
Fiddle with the sensor wiring.
Pull the plugs after a run, are they wet? If so it's oil, do a compression test.
If it's poor compression then you have choices to make.

[Wabbitkilla]

Hi Paul, maybe there's a member in your vicinity who can come along and you can try their maf in your car?
There's also the possibility that when they experience what's going on with your car in person they'll figure it out with you.

[paulkeen]

So far I haven't seen anyone crop up closer than Portsmouth, which isn't very close.

After a bit of wrestling and loss of skin on my hands the heat shield is off and I could take the O2 sensors out (which was refreshingly easy). Left hand side which appears to service 2 & 3 looks okish although some pictures I have seen on here show the honeycomb as a flat surface, mine seams to undulate a bit... which makes me wonder if its falling apart bellow the surface.

The right hand side however, services 1 & 4, well... I couldn't see anything there at all, so gently edged a screwdriver in the hole... its empty! Looking around I am 99% sure there should be something to see, or certainly feel here.

Last owner was a woman who didn't even take the hard top off as she had a baby and couldn't manage it herself (soft top even had that new smell when I finally showed it he light of day!) So I very much doubt she got it de-catted... and even then... why do only one side???

So looks like we have a winner in the arena!

IF my above assumptions are correct:
Firstly – without taking the engine apart I guess there is no way to know if there has been any bits flying around casing damage. However its not very noisy so I might have had a little luck here.
Secondly – I clearly need to de-cat what is left. Then I need? A new main cat... anything else?

[K T M Rider]

Secondly – I clearly need to de-cat what is left. Then I need? A new main cat... anything else?

personally I'd want to be doing a couple of oil flushes & oil & filter changes.  

I'd want to dump whatever is in there straightaway (along with the filter) then maybe put in a fairly cheap oil along with an oil flush, get the engine nice and warm (till the fan comes on) and then dump that out too (along with the filter again) before putting in a better quality oil.

Then once your back on the road watch your oil level like a hawk. If the oil consumption is bad and you don't fancy doing a full rebuild then something like 'Engine Restore' (you'll find it on Ebay) might be worth a punt for £20. ( awaits onslaught of disparaging comments about engine additives   s:lol: :lol: s:lol:  )

i might be able to help you on the new cat, I've got one in my garage that has only done 20 miles (er, you are now the third member on here i've mentioned that to in as many weeks   s:oops: :oops: s:oops:  ) and before anyone asks that is not the reason I got in on this thread. My first car was an oil burner and I like to pass on the benefit of my experience if I can   s:) s:)

[MattPerformance]

I clearly need to de-cat what is left. Then I need? A new main cat... anything else?

A new engine!  The oil contamination of one of the pre-cats must have been severe to cause it to break up.  In my experience it's unlikely to have got into the engine (a compression test would prove that for sure) but the cat is clearly blocked and the oil consumption indicates that the engine requires more than just a flush.  If you've seen how the piston rings go you'll understand why a flush is unlikely to offer anything other than a superficial clean-up which would not help an engine in this condition.  My advice would be to get the engine done and sort the remaining pre-cat and main cat at the same time.  Any other course of action will be a waste of time/ money.

[K T M Rider]

Reading between the lines it sounds like your engine could be burning alot of oil. As you mainly use the car for local shortish trips then perhaps you don't have an exact feel for how quickly it uses it? Based on your first post it would seem your car burned at least 2/3 a litre on a circa 250 mile round trip.

I would agree it is now, but on previous longer hauls it hasn't used it like that. So I would say the higher useage is linked to the problem (whatever it is). I am hoping this afternoons fiddling session will help me narrow it down a bit. No rain so looks like I might get a fair bit done.

Agree that level of oil consumption looks pretty bad on the last trip (running with a blocked cat) but OP reckons oil consumption was ok before   s:? :? s:?

(EDIT) Ok so you have a professional opinion that a new engine is required and I for one do not wish to contradict it, however it is not the first thing I would personally try. If the reason for engine replacement is excessive oil consumption then I personally would want to know what the rate of oil consumption is before deciding on the rebulld / replacement option.

Agreed it looks like it was bad while running with a blocked cat for 200 miles. Given that it was apparently OK for oil consumption before the Cat got blocked I would personally, out of sheer curiosity as much as anything else (oh and a desire to save upto around £1500 If in any way possible I suppose   s:lol: :lol: s:lol:  ) want to run it on fresh oil and an unblocked exhaust for a few hundred miles just to see what happens   s:) s:)  (particularly in regard to oil consumption).

Bunging a new cat on at the moment is quite possibly a complete waste of money, as if your engine is chucking loads of oil out you risk wrecking your new cat in short order, but you can't run the car on your current clogged Cat either, so I would be considering other options (e.g. just completely degutting your main Cat and welding it back up - I think you would not then be the first MR2 roadster owner to run with no effective main cat in place).

if after doing so the oil consumption is still dreadful then I know that some early 1ZZ owners (not just in MR2s) have managed to revive an oil burner just by fitting new pistons & rings and giving the bores a very light hone / deglaze.

[paulkeen]

OK,

Got it all apart. Right hand side precat was clean as a whistle... very odd, would have expected a few hangers on in there. left hand side was all in V good condition.

Took the main Cat off and shock it about, some bits fell out. not 100% if they are pre cat honey comb bits or main cat bits... Either way, cleared that right out.

Possibly unadvisable, but quickly bolted it back together again. Fired it up, same problem. So hoping that means main cat is just blocked with stuff that wont shake out. Took main cat off and flicked it over, between the fact it only had the manifold on and its now in the garage I only succeeded in making my ears nearly bleed, but the one slight gunning on the engine I braved did seam a bit better. Impossible to really tell as not a completely fair comparison and it was literally a 5 second test.

Next step is to get a new Cat and see how that goes. Even if its not the complete solution, I don't suppose the existing CAT is very happy about having those bits floating about in it for however long. So I will need a new one at some point.

[MattPerformance]

The precat is mounted with a material that is like a heat resistant cotton wool which will obviously clog the cat and doesn't lend itself to being shaken back out.  Alsot he force at which the substrate fires into the cat means that it will embed itself so most of that won't come out either.  It's pretty normal that the whole lot will have disappeared from the manifold.

[paulkeen]

Thanks Matt,

[Anonymous]

I would grab this cat if I were you.   l viewtopic.php?f=37&t=38352 l

[paulkeen]

Just a quick note to say all bits should arrive tomorrow, so should have something to report but Thursday. Fingers crossed!