Dodgy AFM

[brianuk]

Hi all,

I'm a new member with a 2000 lwb 2.7tdi terrano.

I had a large amount of service and repair work done by a local garage which included the supply of a new AFM. When i got the car back it was much faster and the check engine light was no longer on. But after doing about 100miles the same thing happened again, car went very slowly everywhere and the check engine light was constantly on.

Took it back and the garage kindly changed the AFM for free for another new one, but the car has done the same again and the garage won't exchange it again because they can't believe i've had two faulty brand new AFM's.

With the AFM disconnected the car is no different to how it is with it connected, and from what i've read on here that means the unit is fubar??

So my question is, why is my car eating AFM's for fun???

Many thanks in advance.

Bri

 

[jims-terrano]

Either the AFM is a very cheap replacment or it's not that that is faulty. Is there anything else that happens? just wondering if there is a fuel problem like sucking in air or fuel filter blocked. In the quick links section there is a workshop telling you how to read the fault codes, have a look at that as it may be of help.

Jim T

 

[Deleted Member S]

I take it your on about the Air Flow Meter which get called MAF units on here & by alot on Nissan dealers:thumb2 Was the unit replaced with a Nissan item do you know because if it's a Nissan one it would be covered under their warranty. why it's going through them I don't knowIIRC a few peeps I think have had probs with water getting into the airbox & contaminating the MAF units but a good clean with elec contact cleaner as solved the prob

 

[brianuk]

O.k, i'll check the codes and give it a clean tomorrow. But like i said both times it's been 100 miles or less. Are there wiring diagrams anywhere, so i can try and rule out any broken wires. As far as i know the parts came from APD but were bosch items i think.

 

[jims-terrano]

I wouldn't clean it just yet, it may void any warranty that it has. I'm sure somewhere in one of the recent threads there is a link to download a workshop manual, sorry can't remember exactly where though.

Jim T

 

[zippy656]

http://nissan4x4ownersclub.com/forum/showthread.php?t=3342


heres the link,

ive printed it out, well 90% so far.

have fun

 

[brianuk]

Right,

I downloaded the codes from the ecu.

I got 12, 34, 95 and 96

I see 12 is Maf sensor, 34 is injector needle lift sensor but 95 and 96 are not on the list i have.

I then erased the codes i think and all that was left was the 34 code which won't erase. Car still runs poorly.

Any ideas?

 

[wildbri]

This is just a thought, have you had a look at the air filter? is it the oily type. i have heard that oil can get on the sensor. I clean my maf wires about every six months when I change the oil and filter and have never had a problem.....mine is the hitach type.... bri

 

[brianuk]

I don't think it's the oily type, at least it's never looked oily and is fairly clean.

On the code 34 it says it could be air in the fuel. What's the best way to remove air from the fuel system??

 

[jims-terrano]

No you could be getting somewhere. Around the area of the injectors there are some small rubber pipes, these can crack or split. Also some people have fitted cheaper fuel filters and had trouble with them not sealing correctly. It's probably not a bad idea to run round with a spanner nipping up any fuel line unions.

Jim T

 

[brianuk]

O.k i'll try that. Can air get trapped in the fuel filter assembly, it's recently had the filter changed so i just want to eliminate that.

 

[jims-terrano]

When a filter is changed you will get air in the system, so yes this would need bleeding out but should of been done by the mechanic who fitted it. You should have a fuel primer pump on the bottom of the filter/housing, not sure if pumping this will help. Also on the bottom of the filter there is a drain tap to release any water that is sitting in there. Not done it myself but I've seen mechanics start a diesel up and then release the union on the injectors one by one to bleed air out.

Jim T

 

[Toolbox]

Some filters do not seal as well as they should, a very good place to start if its been changed

Code 96 is Engine control module (ECM)/ injector needle lift sensor - incorrect signal. That could be caused by System voltage low, needle lift sensor, ECM.

No idea what 95 is there seems to be any reference to it anywhere.

Some pattern part MAF sensors do fail prematurely and it’s always wise to fit a genuine Bosch one when they fail, but they do not normally put the engine check light on, even if disconnected.
Your problem seems to point to the sensor in number one injector I would start by testing it, disconnect it and test the resistance through the sensor, it should be around, 105 ohms. If the reading is ok then you can try and swap the 2 wires around in the plug to the sensor and see if the problem worsens or improves.

 

[Toolbox]

When a filter is changed you will get air in the system, so yes this would need bleeding out but should of been done by the mechanic who fitted it. You should have a fuel primer pump on the bottom of the filter/housing, not sure if pumping this will help. Also on the bottom of the filter there is a drain tap to release any water that is sitting in there. Not done it myself but I've seen mechanics start a diesel up and then release the union on the injectors one by one to bleed air out.

Jim T

If the engine has been running then it should be bled out or else it would not run, the only thing that it may be is that it is drawing air in when it is running

 

[brianuk]

The maf is a genuine bosch one not a pattern part.

By the sensor in no1 injector can you explain a little further what exactly i'm testing? Sorry it may appear more obvious when i'm under the bonnet.

Many thanks to you all for the help.

 

[Toolbox]

Number 1 injector (the fore most injector) contains what is known as a needle lift sensor, this is built in to the injector and is not serviceable other than fitting a new injector. The sensor is there so that the ecu can determine the exact injection of the fuel to alter the timing of the injection.

You will find a short length of wire attached to the injector, follow the wire from the injector and you will find a plug (2 pin) just to the left of the front of the cylinder head, (standing in front)
Test the sensor from this plug back through the injector.

 

[brianuk]

Thankyou for that. Very clear description, i'll give it a bash tomorrow.

 

[brianuk]

O.k, i have not tested the resistance yet, but when i pulled the two pin plug apart that you describe, it was very oily inside. It felt and smelt like clean engine oil, is this right??

Also anyone know a good online place for spares prices?

Thanks

Bri

 

[zippy656]

do as search for the parts department, Brian.. a few listing in there, if you find any other just add them too..

 

[brianuk]

I've tested the resistance and it seemed a bit hit or miss. Quite a few times there was no resistance shown at all, then i got a reading of 125ohms then nothing then 165ohms. Can i be happy knowing the part is wonky not my electrical tester??