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Black Smoke, hissing, EGR valve........HELP!!!!


 
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KellyL79
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Joined: 15 Jul 2011
Posts: 8
Location: Elgin,Morayshire

PostPosted: Tue Aug 02, 2011 14:10    Post subject: Black Smoke, hissing, EGR valve........HELP!!!! Reply with quote

Hi everybody,
Need a bit of help with the truck as it's beginning to become a bit of a nightmare at the moment. So here's the story............
Got a 2000 3.0L 4JXI Auto Citation, and a few weeks ago we started to notice that it was running a bit rough, shaking and sounding like it was going to die at idle, reduced power and seemed to be misfiring. Also got black smoke on acceleration. After asking for advice from the forum we changed the oil filter, oil to 5w 30 fully synthetic, changed fuel filter and air filter. For about a week the symptoms seemed to improve-or so we thought! It just wasn't right. Still had the black smoke on acceleration (no wonder nobody wanted to drive right behind us!!) and it wasn't happy just gently accelerating, especially up hills and started juddering between 1500 and 2000 revs unless you floored it to get it to drop down into third gear. Rang our (not so) local Isuzu garage who suggested it sounded like air in the fuel system i.e a hole in one of the fuel lines coming out of the tank. So we checked the tank etc etc and it wasn't that. Time for more head scratching. The next thing we tried after looking on here was to clean the MAP sensor pipe which actually was virtually blocked with carbon and ming and so was the rubber hose that connects it to the sensor. After cleaning that and taking the truck for a drive it ran a million times better and had power, less judder, ran smoother, but still had the black smoke on acceleration (no smoke when it's just sat idling). Any ideas on the black smoke? Is it to do with over fuelling? Next thing was we took off the EGR valve to see if that was minging too, but wasn't as bad as i'd thought.
Anyway, to cut a long story short while fiddling with the EGR valve, noticed a hissing air sound (with the engine running) coming from that general area. What is it? Any ideas? Presume it's not normal. Also, yet another EGR question- I assume that the valve is fully closed when the piston is extended and the vacuum pipe is there to suck it open? Or am i getting that completely wrong? The reason i ask is because when we took the hose off and the car was idling you could feel the vacuum sucking against your finger but when you revved the car a bit the vacuum died. I would have thought it would have worked the other way round? How can you check if the valve/vacuum is working properly? How should it open and close? Where does the vacuum come from? We are planning to blank it off anyway but just wondered because something tells me it's not right!. Also where can we get either a blanking plate for said EGR valve / a template for one to be made? Sorry for all the questions!
Ok, i think that's everything so i would be reeeeeeeeeally grateful for any help from anybody, and i apologise if any of the questions seem a bit stupid but i am a girl!! Laughing
Thanks,
Kelly
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eithan h
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PostPosted: Tue Aug 02, 2011 19:35    Post subject: Reply with quote

black smoke is either too much fuel or not enough air and the egr will give you black smoke as it replaces the air with exhaust gasses.
the way it works you are correct about, it gets a vacuum to open the egr on idle but when you get to a certain revs or if you floor the accelerator it switches the vacuum off which shuts the egr valve as you don't want burnt exhaust gasses going in to a cylinder when you need full power.
as you have checked the map sensor and pipe and i presume the air filter try unbolting the exhaust from the joint just by the oil filter on the drivers side pull the exhaust apart and wedge it so it can't vibrate shut then go for a drive. if this cures the problem your catalyst is blocked or blocking up and will need replacing or something else doing to it  Laughing  Wink  Wink
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KellyL79
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Joined: 15 Jul 2011
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Location: Elgin,Morayshire

PostPosted: Sun Aug 14, 2011 23:19    Post subject: Reply with quote

Hello again,
Finally got round to checking the exhaust today after 2 weeks of particularly rubbish wet and wild Scottish weather, and the results were fairly inconclusive to be honest!
The black smoke didn't seem as bad with the exhaust disconnected pre cat and didn't seem to leave such a toxic cloud of s**t behind the truck when driving it down the road. Thing is, if we change the cat and the black s**t is still there then that's more money down the drain! What it does exactly is starts fine from cold and hot, no black smoke - just a puff of grey smoke which i would have thought was normal for a diesel, and if it just sits at idle there's no smoke, but as soon as you put your foot on the accelerator and rev the engine or even just gently put your foot down to pull out of the drive then the black smoke appears. Obviously the more you rev the worse it gets whether under load or not. The smoke smells really sooty and carbon like if that makes any sense - like an old bus!! The smell's there all the time but obviously worse the more you rev it. If you put you finger inside the end of the exhaust it is absolutely caked in carbon / soot, and reminded me exactly of the chimney in our front room which needs a damn good sweep!!! And i'm still convinced it's not running as well as it should and seems a bit sluggish / slightly misfiring sometimes and doesn't tick over as smoothly as it probably should but nothing drastic. Anyway, as i said before we've changed all the filters, cleaned the MAP sensor pipe, checked all air hoses etc for splits and leaks but nothing obvious. Bunged up the EGR vacuum pipe and that made no difference either. The injectors were changed in 2009 so hoping it's not them, and Isuzu claim we'd have the check engine light come on if an injector was down. This may be unrelated but we took off the intercooler to have a look at that and there was a bit of oil in it (a bit dripped out when it was tipped up) and there seemed to be quite a bit of oil in the hose that comes off it on the EGR side to whatever that valve is which was also fairly caked in oil (sorry for the rubbish description!), and also took the big air pipe off that goes to the air filter from the turbo, which also had a bit of oil in it, but that was literally a tiny bit, and a bit of oil on the impellor thingy on the turbo-is this normal?? I feel like we're looking for a needle in a haystack here, and may have to admit defeat soon and take it to the garage. Everything i've read about black smoke points to incomplete or poor fuel combustion due to lack of or too much air? Where do we go from here??!! This is the thanks i get for giving it a good home. Cleaned, serviced, treated to some lovely new tyres, and the ungrateful thing pulls this stunt on me!! The truck is coming very close to getting pushed off the nearest cliff! Evil or Very Mad
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richard wilkinson
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PostPosted: Mon Aug 15, 2011 7:43    Post subject: Reply with quote

faulty injecter wont trigger a check engine light maybe time for a new dealer
ethan be around later im sure he has a whole list of ideas for you to try dont give up yet  Wink
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eithan h
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PostPosted: Mon Aug 15, 2011 20:08    Post subject: Reply with quote

when you take the egr valve off, where the rod comes out of the housing is the hole round or oval? if it's round thats good if it's oval thats not good and will need replacing if in doubt post a pic up and let us have a look.
when the cat was disconnected did you have turbo boost still?
that valve between the intercooler and manifold is it just oily or does it have a build up of crud on it as well? i had one that was so built up it held the flap shut when the egr operated and obviously stopped the air getting to the engine.
i take the air filter is clean?
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KellyL79
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Location: Elgin,Morayshire

PostPosted: Mon Aug 15, 2011 23:20    Post subject: Reply with quote

Hi, Thanks for the reply
we have oil coming out of the pcv hose going into the air duct and traveling through to the turbo. from there up through the intercooler , down into the throttle valve and into the intake manifold.
having cleaned out the pipes and egr valve earlier which were clogged with old oil we think this may have been caused by the above symptom.
air filter is still clean after changing it the other week-about the only thing that is still clean!!
cat removed from main down pipe / black smoke still coming out, turbo is cutting in we think - paying more attention to looking for smoke!
also the cat may be blocked due to the excess rubish being pumped out of the car,the deposits in the tail pipe are in excess of around 4mm plus thick.
the rod on the turbo waste gate is in the position of pushing towards the front of the car would this be in the closed or open position as i believe it should be open all the time?
Didn't look whether the hole was round or oval when we took off the EGR but will have another look tomorrow.
Does this mean that the pcv is the cause of all of the trouble? Is it easy to change? Also, is it likely that the turbo will be ok after sucking oil through it or am i getting my hopes up here??!! Isuzu say any contamination in turbo means it's new turbo time, but then they probably would!! Any suggestions?? Confused
Many thanks
Kelly
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KellyL79
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Location: Elgin,Morayshire

PostPosted: Tue Aug 16, 2011 15:09    Post subject: Reply with quote

Just a quick update...
Spoke to I.M this morning after getting all excited that we may have found the cause, only to be told that our particular engine doesn't have a PCV valve on it. So where exactly does said air pipe go into? And why is there oil in it? Am i to be thinking worst case scenario here-i.e as I.M said piston damage or something of that nature? Thing is, i would have thought our symptoms would have been more catastrophic if that was the case? Car starts ok, not losing any oil, no blue smoke - only black smoke on acceleration, not massive power loss. Trying to avoid the long trip to the dealers mainly because it's 50 miles away but also because they seem to have about as much of a clue as we do about what's wrong, which doesnt fill me full of confidence really, and they'll probably charge a fortune for doing not a lot!!!!  Sad  Sad  Sad
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Gribble
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PostPosted: Tue Aug 16, 2011 16:04    Post subject: Reply with quote

If you rev the engine hard when its warm does it still pump out black smoke or only when you drive it ?
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KellyL79
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Location: Elgin,Morayshire

PostPosted: Tue Aug 16, 2011 16:20    Post subject: Reply with quote

Yes it does still pump out black smoke, maybe not as much when warm though. It does it whether just revving it or driving it.
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Gribble
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PostPosted: Tue Aug 16, 2011 18:49    Post subject: Reply with quote

Try taking the pipe from the intercooler to the inlet manifold off and rev it again - this makes it a non turbo engine so helps in the diag work  Wink
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eithan h
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PostPosted: Tue Aug 16, 2011 19:25    Post subject: Reply with quote

if you have scored bores or piston blow by due to a dodgy piston then usually if you pull the dipstick tube out with the engine running it belches smoke out of the tube. little puffs are ok though but anything with any pressure in it is bad!
it does sound more like an injector problem at the minute, does it have a harsh knock to the engine when you pull away?
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