Recently Fitted Mi Started Smoking...

[SweetBadger 94]

Ey up, need a bit of advice on what to do next to diagnose a smokey MI.

 

Fitted the current engine in my 205 a few months ago, and it's been running very well - pulls well and gave over 45mpg on a trip from Manchester - London

 

Gave it a little check over tonight as it's been missing on very light throttle at 1500-2000 rpm, and noticed a small amount of smoke coming from the exhaust. Didn't think much of it until I saw the exhaust looking from under the front of the car - it's quite a lot of smoke when viewed from this angle!

 

Smoke looked blue and it smokes the same as idle, if not more so, when revving - points to the rings so I did a compression test:

 

cyl 1: 220 psi

cyl 2: 222 psi

cyl 3: 221 psi

cyl 4: 220 psi

 

Bloody great results - as good as my old rebuilt MI using the same comp tester, so why is it smoking!? Can the oil control rings go before the compression ones?

 

If it's valve stem seals I though it should only really be smoking on idle?

 

 

In addition to this the plugs were very badly carbon fowled - worse I've seen. I do a lot of sitting in traffic but my last MI did the same journeys and the plugs were still tan coloured, unlike these which were totally black... So it's overfuelling on my commute sitting in traffic but gave great economy on a motorway trip.

 

Not sure what to do next:

 

- Could the obvious overfueling be causing the smoke? Obviously need to sort this out, thinking new plugs and HT leads first (have already replaced the ecu temp sensor a couple of years ago)

- Could it be stem seals? I know this engine's only done about 70k but it's sat for a while before being run in my car, could the seals have aged and gone brittle?

- Is it likely to be oil control rings even though the compression is excellent?

Edited May 7, 2010 by SweetBadger

[24seven 104]

Based on the compression pressures I'd say it's your stem seals, but the only real conclusive way to find out is to remove the head. If it's burning oil you'll soon notice the level on the dipstick dropping if you check it regularly (which you should on an Mi to minimise the risk of starvation). Either way it sounds like the head will have to come off regardless.

[luggy 13]

Had a similar issue on my MI, smoking and missing between 1.5-2K. This was on a newly rebuilt engine so I new the stem seals were OK. Turned out it to be a leaky injector.

 

Only way I could clear the problem was to:-

Remove the plugs

Remove fuel relay

Turn it over for 10 seconds (Engine would run like a bag of spanners for a few secs)

Plugs back in problem sorted.

Short term fix tho!

[SweetBadger 94]

Well, replaced the spark plugs and that's cured the miss fire, will have to see if the new ones get sooted up, look fine so far.

 

 

Injectors should be fine, had them refurbed recently.

 

Oil level isn't going down, still on the max mark on the dipstick after approx 500 miles and oil looks clean.

 

 

Noticed that it doesn't smoke when stone cold, only when warm. You can't really see the smoke when looking directly at the exhaust, only when looking from under the front of the car so it's not burning excessive amounts of oil... It's definately blue smoke though.

 

 

Having had another look today it does smoke more on idle and clears a little when revving but not totally, so looking more like valve stem seals especially considering the compresion test results.

 

Looks like it's head off time .

 

 

Just don't want to replace the stem seals only to find out it's the oil control rings... Anyone have any experience of valve stem seals starting to go on an MI? Can they cause smoking when the engine's revving or is it generally only on idle?

[luggy 13]

Just don't want to replace the stem seals only to find out it's the oil control rings... Anyone have any experience of valve stem seals starting to go on an MI? Can they cause smoking when the engine's revving or is it generally only on idle?

 

Im doing the H/G on my Citroen this weekend as its been leaking water for the last 20k and I have the same concern about rings as its done 110k so with the head off Ive budgeted for big end bearings, rod bolts and piston rings so she should be good for another 100k.

[SweetBadger 94]

Im doing the H/G on my Citroen this weekend as its been leaking water for the last 20k and I have the same concern about rings as its done 110k so with the head off Ive budgeted for big end bearings, rod bolts and piston rings so she should be good for another 100k.

 

Aye, is tempting to do rings & bearings too, plus I have a 30k set of MI liners in another engine that I could use.

 

Thing is I know the bearings have already been done on this engine and compression is very good (plus it's only done about 70k) so I think it'd be worth a punt on just the stem seals.

 

Head Skim (if necessary) + HG + Coolant + Stem seals = about 60quid whereas add rings, honing of liners, beaings and you're talking more like 250 quid

 

Flipping thing!

[SweetBadger 94]

I am an idiot! I fitted a chip off ebay for a higher rev-limit as I kept slamming into the standard limiter (power doesn't tail off till 7000rpm ish with the inlet camshaft). I know you can't really improve on the standard mapping and don't buy in to the +10hp bullsh1t but figured the chip would be useful for the higher rev-limit...

 

So I was investigating the overfueling issue this afternoon, wired in k-light and fitted the standard chip, no error light or codes. Also far less smoke!

 

Went for a blast, engine running far smoother, and when I got back no more smoke - phew, problem solved.

 

Guess the 'upgraded' chip was dumping too much fuel at low revs contaminating the oil and making it smoke...

 

Here's a warning to anyone considering buying one of these chips: http://cgi.ebay.co.uk/Performance-Chip-Tun...=item414ef351fe

 

Don't do it, had I run with it for much longer I reckon it could have caused permanent engine damage...

[Pugnut 9 1 Cars]

i'de also change the oil asap .