Sluggish (diesel) Terrano

"Robin Nicholson" wrote in message news: snipped-for-privacy@4ax.com...

I'm not that familiar with terranos, but the problem could be caused by various things. Mechanically, there could be quite a few possibilites. When you rev it up, is it black smoke? Black smoke would indicate that there is not enough air getting into the cylinder. Possible causes are blocked air cleaner (always start with the simple things), leaking turbo hose causing boost pressure to be lost (normally you'd hear the whoosh off the air escaping), even possibly a burst inlet manifold gasket, sticking EGR valve (only easy way to check is by replacement, or to blank it off), valves needing adjusted, seized/faulty turbo wastegate. If it is black smoke, the engine is getting fuel, so I would rule out any major problems with the injection system.

If you're getting white/grey smoke when you rev it up, that would indicate a fuelling/timing problem. It's unlikely to be an engine timing problem, as I'm sure the Terrano engines were all chain/gear driven. So it would indicate a problem with the pump timing, which would take a specialist to diagnose and repair.

I'm pretty sure the Terranos didn't use much electronics in the engine management, but even if it has, the black smoke is unlikley to be caused by an electrical fault. (Any fault would normally cut fuelling, which would give the symptoms described, but normally wouldn't produce much smoke)

Try some silicon/teflon 'dry' lubes on the rubber seal. These should help, but whatever you do, do not use anything oil based as it'll make the problem far worse.

Guess that Frank doesn't know that diesels don't have spark plugs.

Certainly a new take on the problem to me.

All Terrano II's- that is from ~S reg onwards use fly by wire throttle and EDC using a bosch VP pump.

It has a myriad of overly complicated small vacuum pipes, and controls, EGR, turbo regulation, vacuum operated throttle valve, etc etc etc These all need going through with a fine tooth comb- splits and leaks are the norm at this sort of age from engine heat / vibration . This should be your first port of call.

Anyhow some more history and information is really required- does it smoke heavily under acceleration, is the smoke dense black, is starting and idling performance as normal, and is MPG any different, have you had any non routine servicing done after which performance was down ?? Has it faded over a time or been a sudden drop...etc ??

There are many other reasons why you could be experiencing reduced performance so we need to narrow it down alittle.

The 2.7TDi is usually a fairly willing if alittle agricultural worker and generally reliable, and with proper maintanance, I would not expect it to be deteriorating at 90k.

Tim..

Thanks for clearing that up. I haven't had to work on a Terrano for a couple years now, and the only things i can really remember about them was how awkward the oil filters were to change, and that the front wheel bearings used to need regular adjustment.

Tim: it has been a gradual decline over the last year-18 months. I think the key place where I noticed it is on a nearby straight hill halfway (7 miles away) to work which I normally used to go over in

5th allowing for a slight slowing from an inital 65mph, but never felt the need to go to 4th. When going in 4th had little effect ( better decsribed as No effect) and I was down to 3rd to maintain speed to between 35/40..then I decided to do something! It has been regularly serviced according to schedule. I have certainly added injector cleaner on a regular basis and especially over the last year. It has not failed an MOT It does not smoke under acceleration (that I can see through the mirror-and I have been watching), it starts first time and is a bit rough before settling-only if I rev it up on the hardstanding will I get a cloud-and certainly not black-more blue I think! It idles pretty well. I get the impression that mpg is down,but not dramatically so. Only one odd thing has happened- some 4 months ago, along the A303 and a slight incline, she suddenly lost acceleration in 4th-as if someone was holding her back. With foot on throttleand in 3rd she suddenly picked up, faltered back,shuddered and then picked up again. I had the fuel filter changed at that point-though it was between services. After that she has been normal,with the above description of gradual lack of performance. She has not got worse and worse, judged by the same route I take very day to work, but having become sluggish, sluggish she remains! Having said that, she purrs along the M3 without issue-till I come to slightly steeper than normal inclines-and most motorways in the south have nothing dramatic in my opinion I really appreciate both replies-thanks Robin

Robin, thats good info, thanks.

I feel fairly sure that you either have a vacuum leak from one of the hoses or a faulty map sensor, or you have a mechaincal issue with either the turbo wastegate or throttle valve.

A split line to the MAP sensor for instance will drastically reduce performance, because the ECU isnt seeing turbo boost and adding more fuel.

After checking all the vacuum lines, I think I would personnally connect up a boost gauge go for a drive and compare it to spec, which would help narrow it down before going further.

Tim..

Hi

Check the MAF (Mass Airflow Sensor). If you have a dirty hotwire then the signal it passes to your vehicle's ECU will be wrong, which could account for the smoke and loss of power. Had the same problem with my Audi 80 Avant TDi.

Pretty sure you should be able to purchase 'exchange unit' from Nissan dealership.

Spart

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Thanks Spart - it was just that. Now she purrs along - a staggering difference- and no longer do I have to change down to 4th (no effect) and then to 3rd (not much better). Have just gone from Aldershot to Yeovil on the A303 and apart from roundabouts etc did not have to get out of 5th. Cheers Robin

Glad to hear your Terrano is back on the road. The MAF sensor is a small but essential piece of kit. Think sensor is susceptible to contamination - certainly if you don't replace the air filter regularly enough. Think this should be done every 15-20K. Depends on driving conditions also.

Spart

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