1.5 DCi possible turbo on its way out?

D

doz_SR20

I've got a 1.5 DCi that now has 90k on the clock. It was re-mapped at around 44k and I do about 25k a year in it so it gets used to say the least. I always change the oil every 6k miles and clean the EGR as if its a service item. Recently its been getting really laggy and kicks out more black smoke then it ever used to. It doesnt come on full boost untill about 2400 rpm where if memory serves me it used to be almost instant. Its getting to the point that whenever I pull out of a junction it leaves a fat line of black soot on the road. I've checked it for fault codes and there are no issues saved. I've checked the air filter etc isn't blocked, cleaned the MAF, EGR and inlet, I have also checked that the wastegate isn't ceased open and theyre all fine. I can't think its anything else other than the turbo getting more and more inneficient.

Just wondering if anyone else has any experience/ideas with these. I've ordered a new turbo but am keen to try anything else before fitting it.
 
I have now changed the turbo - the old unit despite being to my supprise healthy in terms of bearings etc had cracks around the wastegate and was therefore bleeding off exhaust when it should't have been.

However the car is still as it was if a little better, and is still getting continually worse. I did a leak off test on the injectors yesterday and one was worse than the rest, so I was going to change this injector. However I did a diagnostics check tonight that revealed that my Inlet Air temp was reading -40! So I set about this evening trying to find the Air inlet temp sensor as they are only 11 quid from GSF. Problem is I can't find it for the life of me, I can find the inlet/turbo pressure sensor, un-plugged this and it confirmed what it was as the manifold pressure reading dropped to 0. I'm beggining to wonder if my car's got an inlet temp sensor at all as I really can't find it anywhere for the life of me. I've had the front grilles off, battery out etc with no joy.

Any help appreciated!
 
Mine's the asthmatic non-intercooled DCi but the senor(s) you seek are stuffed into the plastic tube that feeds air into the engine. IIRC mine has one jst downstream of the airbox reading the temp being fed intot he turbo, the other is in the plastic elbow between the turbo outlet and the EGR elbow and IIRC the wiring goes to the same loom as the pressure sensor you have found, presumably on top of the engine.
In fact the temp sensor should be very close to the pressure tube tapping that serves that sensor.
 
intake air temp sensor should be in the rubber pipe that goes from the airbox to the turbo, also have you changed the fuel filter? this gives these symptoms
 
Doz, I drive a dCi 86, any chance you could do a picture tutorial of removing the EGR system :)? Just a thought as well, if the ECU thinks the inlet air is at -40C, it'll be injecting alot more diesel to compensate - I think you're on the right track!
 
Got to the bottom of this! It was a faulty EGR, although it was clean and looked ok I tried a new one and the car is spot on!

You can use this to check your EGR, I found it very useful as my old egr the resistance values where all out:

http://www.partinfo.co.uk/files/Pierburg-SI0085-EGR Valve Sticking.pdf

Problem is, I was un-plugging sensors in the engine bay with the engine running and it wasn't activating any MIL lights! Turns out the electrical architecture on these engines is fairly primitive and a-lot of it is open loop so the ECU can't tell when some things up the guff anyway! The -40 reading was due to the car not having the capacity to relay IAT back to the OBD reader, so the OBD reader was seeing a certain voltage and default reading -40!

If the diagnostics system was better I would have saved time and money but hey ho its a learning curve!

Next time I clean the EGR I'll take some pictures and do a write up, its really easy to get to and I'm sure anyone with a few tools could do it!

Cars back on form now tho and I bought some wheels to celebrate :p
 
Also for some bizzare reason mine doesnt have an IAT sensor in the pipe between the air box and turbo, its in the intercooler pipe just before the EGR.

Its one of these:

http://www.ebay.co.uk/itm/181046164671?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

I've got it on ebay as there was nothing wrong with the old one.

I spoke to Nissan about this part and it appears mines a weird model as most either have a MAF attached to the air box or an IAT as people have said in the rubber pipe between air box and turbo. Bizarre...
 
doz_SR20 said:
Got to the bottom of this! It was a faulty EGR, although it was clean and looked ok I tried a new one and the car is spot on!

You can use this to check your EGR, I found it very useful as my old egr the resistance values where all out:

http://www.partinfo.co.uk/files/Pierburg-SI0085-EGR Valve Sticking.pdf

Problem is, I was un-plugging sensors in the engine bay with the engine running and it wasn't activating any MIL lights! Turns out the electrical architecture on these engines is fairly primitive and a-lot of it is open loop so the ECU can't tell when some things up the guff anyway! The -40 reading was due to the car not having the capacity to relay IAT back to the OBD reader, so the OBD reader was seeing a certain voltage and default reading -40!

If the diagnostics system was better I would have saved time and money but hey ho its a learning curve!

Next time I clean the EGR I'll take some pictures and do a write up, its really easy to get to and I'm sure anyone with a few tools could do it!

Cars back on form now tho and I bought some wheels to celebrate :p
Click to expand...

I'm getting the same symtoms any chance you could give me some idea on how to get to mine to clean and check it? thanks
 
Will grab a couple of pics for you in the morning bud, bit dark now. But it's easy to get to, just whip the engine cover off and a bit of inlet pipe and its right there.

I've since blanked my egr, done a another 45k since this dilemma and no dramas to report!

Sent from my HTC One_M8 using Tapatalk
 
Would that be the sensor that measures the pressure of the boosted air between the intercooler and the engine intake?

Update: Just done a Google and I think it is. Look here at picture E:, probably the easiest part on the car to find and remove :D.
 
Last edited:
Guy said:
Would that be the sensor that measures the pressure of the boosted air between the intercooler and the engine intake?

Update: Just done a Google and I think it is. Look here at picture E:, probably the easiest part on the car to find and remove :D.
Click to expand...

Ive only owned the car about 2 months and been under the bonnet about 5 times so not familiar with yet :) looking at the photo it must be under the cover ?
 
Guy said:
Yeah, just pop the engine cover off and it's right in front of you.
Click to expand...

Hi Guy i have found the air flow sensor i think i can unplug it without taking the cover off but having had a quick look at the cover how the hell does it come off? My last car a peugeot 206 had a cover with 2 bolts right in front of me holding it on but cant see anything on the micra..
When i had similar symptoms on the 206 a peugeot garage mechanic told me unplug the air sensor ( map sensor ) and take it for a drive and if the car performs better it's more than likely the fault which in this case turned out correct i replaced the air meter and it was all sorted.
I'm thinking of doing the same test on the micra today to see if the flat spot and idle seem better...
 
The cover just yanks off. It's held on by 3 rubber sockets that click onto 3 metal ball things.
 

Similar threads

M
SE 1.5 dci help please
Replies
2
Views
2K
majikatt
M
raptoranderson
Nissan Micra K12 1.5 dci turbo
Replies
27
Views
7K
raptoranderson
raptoranderson
J
1.5 DCi Cold Start challenge
Replies
9
Views
4K
Master tech
M
P
1.5 dCi turbo?
Replies
33
Views
3K
doz_SR20
D
S
Changing DCI 65BHP Turbo
Replies
4
Views
1K
Bombardier
B
Back
Top