hdi engine problem

[mcglynn]

bought a 306 there and sorted out a few niggles with it, but there's a slight problem with the engine.

its not so noticeable from the front of the car but the noise is quite apparent from the rear of the car.

it sounds like a 'puff-puff-puff' noise from the exhaust through the rev range, almost like a misfire. The note changes as you rev it but there's a constant 'putter putter' noise that speeds up as the revs increase. It happens both under load and off load revving, and i'm not sure what the problem is.

the car does let off some black smoke during off load revving which i have been told is unusual for a standard hdi, which tells me there's definitely an issue on the fueling side. When i removed the fuel filter the fuel in the bowl was quite mucky with dirty deposits in it, so i'm thinking that it could be a problem on the injection side of things.

The car DOES need a service so i will be doing this, but in the meantime hopefully get this issue sorted.

things i have tried so far are;

remove back box in case of collapsed baffles
drained fuel bowl (really dirty in there)
put some injector cleaner into the fuel (been told this is a bad idea)
checked air filter for water
removed MAF and this makes the engine note change on idle but doesn't alter the main issue.

[Poodle]

Smoke off load isn't that unusual once you get into normal boost range, as the car won't make anywhere near full boost at a stand still, could well be the maf at fault there.

If it's missing you've only got a few options in terms of what the issue can be: fuel, air or compression.
-Air supply issues tend to be all or none, so it's unlikely to be that, only thing it could really be is something stuck in a port.
-If it's fuel, an injector will either be firing too much or too little fuel, you could do a leak-off test to give you some idea, but the only way to really know is to get the full set tested by a specialist.
-Most likely imo is a compression issue, whether it's a bent rod (perhaps the car has been hydrolocked in the past), or a broken cam train part or a leaking injector seat is a bit harder to tell. You might be able to see some deposits around the base of one of the injectors if it's a leaky seat, but otherwise it's going to be a long/specialist job again to find the issue and fix it.

Tbh if it doesn't affect the running of the engine i'd be inclined to leave it, otherwise you could spend a lot of time and money chasing the issue.

[mcglynn]

Seem like very valid ideas, it seems underpowered, and whether thats due to coming from 160bhp and 260 ftlb I dont know.

The reason I want to sort it is I dont see any point investing money in the likea of remaps, exhaust mods, cooling mods etc if its not a pretty good base engine to start with, I have a feeling its a misfire but it starts and runs fine with no lumps or knocks, but there is a noise from the exhaust side of it.

[Poodle]

Hahah, it'll feel VERY underpowered compared to that, i'm on about 140/240 and the other less-than-healthy hdi i had felt horribly slow. You'll probably find a good service does the world of good. How many miles has it done? Got much recent history with it?

[mcglynn]

Hahah, it'll feel VERY underpowered compared to that, i'm on about 140/240 and the other less-than-healthy hdi i had felt horribly slow. You'll probably find a good service does the world of good. How many miles has it done? Got much recent history with it?

yeah, ive been driving around in a 59hp (from factory, probably less now) 1.4 polo so the 306 should be 'powerful' in comparison lol!

I really want to know the deal with this engine as its really make or break whether i keep the car, im not clued up on the high pressure common rail diesel engines, and they seem costly to repair which i dont like, so ideally id like to sort it cheaply and get a good runner!

its strange i think its going to have to be an injector out job, are they hard to remove do you know? like i say i have done injectors on my mg, but theyre direct injection so theyre a lot easier to work with (in my opinion, no fancy wires or fancy looking injectors) lol

[Poodle]

These are direct injection mate, depends how mechanically able you are really. You dont sound clueless by any means, so should be alright. I'd suggest having a quick read around on how to work on cr diesels if you're going to take the injectors out, they work at about 200 times the pressure of your average petrol di and are correspondingly more sensitive. The link in my sig shows how to remove injectors and offers advice on best practice.

[mcglynn]

Aye direct injection but I meant the difference being commin rail and standard pressure injection. These seem much more sensitive to work around, which worries me!

How do I conduct a leak off test, need any equipment or is it just a case of pulling off the leak off pipes lol!

[Poodle]

Check out the link in my sig mate.

[mcglynn]

Had a read through buddy, cant see how to conduct a leak off test? I will try capture the sound via video and could email you it or upload it to photobucket.

[Poodle]

Right you are mate, sorry about that, think i've written some more of that guide and not uploaded it yet, fail! Cullys done a guide somewhere, but I cant find it for the life of me, so here we go...

Ok, well you'll need a good length of injector leak-off pipe, 4 small screws (a size that'll fit tightly in the pipe) and four small pots/bottles/jars/containers that you can balance/secure easily on the running engine and a small measuring jug with a fine scale.

With the engine turned off, pull one end off each of the injector leak off pipes and block the open end with with a screw. Number your four containers amd set them up, one in front of each of the injectors. Cut four lengths of leak-off pipe that will comfortably reach from the injectors to your containers, feed one end of each into the container and the other onto the open end of the T-piece on your injector. Make sure all your pipes are either blocked or feeding a container and the containers are secure, then start the engine and run for half an hour on idle.

After half an hour, stop the engine and measure the amount of fluid in each bottle. If one is a significant amount different to the others, you've found the culprit. I'm afraid I can't remember the exact numbers for correct leak-off flow, possibly ~8ml for every 15 minutes...? Either way, with your problem it shouldn't matter as there should be one thats different to the tune of 3ml or so

[mcglynn]

Riteo, seems lengthy lol! Thanks for the in depth write up bud, and the fact your the only one to yet offer any advice!

Much appreciated! I shall conduct that soon and let you know the outcome, kills two birds with one stone I guess, new leak off tubes too!

[mcglynn]

had a drive in this car finally after getting it MOT'd, seems its just noisy injectors and maybe a duff maf.

I have it in the dishwasher as i type so i will report back how it goes. Few guys on the mg forum have done so and report good results, so i shall see. Had nothing to lose anyway as it was pigging and have been running the car without this last few days.

[Jimbo]

Have what in the dishwasher? First ive heard
Any theory behind it

[mcglynn]

Have what in the dishwasher? First ive heard
Any theory behind it

Have the MAF (Airflow Sensor) in the dishwasher. A lot of people will probably shun me for this, but apparently there has been good results with doing so.

Mine was dirty with oil all over it, so it wouldn't be doing it's job correctly, therefore leading to an underpowered engine. (it tells your ECU air temp, air volume/flow rate etc. which then calculates how much fuel to inject)

It can be cleaned with alcohol or contact cleaner, methylated spirits, even heard of carb cleaner being used, these yielded no results on my mg zr diesel so i got it MAF'less remapped. Not so sure this is possible on the 306's though. so i'll give the dishwasher trick a shout and see if it performs any different.

[Jimbo]

Crazy.
Good luck but dont expect much ...,,

[mcglynn]

Have no expectations what so ever bud, ill see how it goes haha!

[Jimbo]

Have no expectations what so ever bud, ill see how it goes haha!

Yeah be interesting to see what happens

[mcglynn]

Have no expectations what so ever bud, ill see how it goes haha!

Yeah be interesting to see what happens

Have it in the oven now at 100° to dry off a bit more, wouldnt want a short from water in around the sensor basically

---

Done n dusted, will plug it in 2moro and see if it changes the car.

[Toms306]

100c in the oven? Surely that's too hot, its only supposed to work with ambient air temps up to like 40c!

[Poodle]

As above, be interested to see if it works, hope it does!

[mcglynn]

Haha well ive nothing to lose as it wasnt great, all I can do is gain nothing I guess

[Poodle]

Absolutely mate, fair play for trying it out!

[mcglynn]

Have what in the dishwasher? First ive heard
Any theory behind it

Way I see it is its not 'working' when at 100°. All of thosematerials could withstand boiling water with no harm done so 100° in the oven for 10 mins shudnt kill it.

Just assumptions obviously

100c in the oven? Surely that's too hot, its only supposed to work with ambient air temps up to like 40c!

[bigtone0777]

I'd be interested to see if this helps, would save a few quid on a new maf if it does!

[mcglynn]

Doesnt seem any different with the maf plugged in and the maf unplugged, which makes me think its totally snagged and the car performs as though its unplugged any time.

What are ebay mafs like for these? I know for the mg rover diesels it was a big no to buy a non genuine one as they died sometimes within weeks.

[Toms306]

Oh well, as you say you haven't lost anything!

Steer clear of ebay for any engine sensors IMO. Better to get a working 2nd hand genuine one if you're on a budget.

[mcglynn]

Yeah I thought that dude was just checking it out on here to see if its the same accross the board.

Id rather buy new, but realistically mine mightnt be knackered, id need to see the airflow figures and compare them with known good figures.

Ill report back on that issue when I get an obd2 reader

[mcglynn]

Well had the friend out in the car last night and he thinks it pulls marginally harder with the maf plugged in.

The only to tell would be to time it but I think the difference is so small the innacuracies in manually timing it would make the difference minimal.

Going to straight pipe it and service it and see if its any different, map might have to wait until next month depending on pay and student finance being slow lol

[Midnightclub]

If you know someone with PP2K then it should show the exact values from the MAF.. easy way to tell if it's working or not

[mcglynn]

I dont even but I think generic readers and the likes of torque app for android will give me the values.

I just need to know 'good values' then I suppose to see if its correct/a good maf.