MIL after limp mode

[Lazy-Ferret]

Over the time I have had my car, I have managed to get it to go into Limp mode a few times, but have never seen the MIL come on.

After fitting my Boost valve yesterday, and having a play, tonight, pulling away hard from the Dartford crossing tolls, and the car went into Limp mode. Not a problem, just carried on coasting, switched off the ignition, and then re-started, and carried on. Only trouble was, I had lost a bit of speed, so put my foot down,and stuffed it back into limp mode. After a second re-start, and a bit of careful driving it was fine for the rest of the journey...

OK, so I know how to fix this, but my question is, why does my MIL not come on when this happens? The only way I know, is the engine just goes lifeless, and has no power, but nothing on the Dash to tell me. Is this right?

 

[bud]

Questions.
By what do you mean boost valve.

A excess boost dump valve or a boost control valve

What boost is it running
Is it a mechanical injector pump or electronic.
manual or auto

IF it is in the truck in your pic, and is a computer controlled pump it will throw it into limp mode and cut fuel to protect the engine to predefined map settings.
if you had a mechanical pump, you can throw all the air and fuel in there you like.

 

[AlexD333]

Yep mine will do this, has done several times, would be interested to know :thumb2

 

[Banshee]

Got to admit I've never experienced this :S but will be watching closely to see what it is guys.

You running veg Clive?

 

[Lazy-Ferret]

Got to admit I've never experienced this :S but will be watching closely to see what it is guys.

You running veg Clive?

A mix of Veg and Diesel. More Diesel than veg normally though.

As I said, I know why it's going into limp mode and how to sort it, I just thought that when it goes into limp mode, I should get a light come up on the Dash.

The boost controller has a preasure valve that stops the waste gate opening premiturely, and also a way to bleed off the preasure to delay it and increase the boost. The Valve works a treat but I decided to have a play with the bleed valve to see what would happen. Now I know the answer to that.

sent from my phone, sorry for any typo's.

 

[rayf3262]

[FONT=Calibri, Verdana, Helvetica, Arial]The ECU range checks the inputs from the sensors attached, the sampled value is checked against a map which is a table that holds acceptable values for the sensor for a given set of conditions RPM, speed, control sleeve position (target fuelling), etc. Basically they are all cross checked against each other.

If a sensors value falls outside of the pre established limits by a small margin the sensor output is deemed to be unfeasible, the ECU will normally fail over to a safe fueling map with no MIL indication.
If, on the other hand the sensor value is off by a larger amount then the safe map will be selected and the MIL switched on.
In both cases there will normally be a fault code or DTC stored, giving a clue as to what the cause may be.

In your case LF I would think the additional boost you have achieved is being interpreted as an OVER-BOOST condition. Whilst the ECU has no absolute manifold pressure sensor it looks at the inlet airflow (the MAF) to determine this condition.
Too much inlet air at a given engine speed = too much suck from the turbo!
Might be worth seeing if any stored DTC's confirm this.
[/FONT]

 

[Lazy-Ferret]

Cheers Ray. So basically it depends on how far out the level is to whether the MIL actually turns on or not.

I am just making up a plug and lead with a push button on so I can go and have a play at reading the codes.

How many codes does it store and how far back does it remember as I have never cleared or read them in all the time I have had it?


sent from my phone, sorry for any typo's.

 

[rayf3262]

Cheers Ray. So basically it depends on how far out the level is to whether the MIL actually turns on or not.
Thats about it.

I am just making up a plug and lead with a push button on so I can go and have a play at reading the codes.

Good plan!

How many codes does it store and how far back does it remember as I have never cleared or read them in all the time I have had it?

I don't know how many, but it will store the DTC's indefinitely, if reading with Consult it will also tell you how many engine starts since fault was logged too.

 

[Lazy-Ferret]

I don't know how many, but it will store the DTC's indefinitely, if reading with Consult it will also tell you how many engine starts since fault was logged too.

Thanks, I will only be using the "Check" feature, so wont have that, but I know there are going to be a few in there, as I had the fun of fitting the MAF amp, and a couple of leaky pipes on the IC, plus the ones from this, so could be there some time clearing them all...:augie:lol

 

[rayf3262]

Thanks, I will only be using the "Check" feature, so wont have that, but I know there are going to be a few in there, as I had the fun of fitting the MAF amp, and a couple of leaky pipes on the IC, plus the ones from this, so could be there some time clearing them all...:augie:lol

I forgot to mention that in the vent of numerous DTC's, it might pay to clear them and then see what pops up.

 

[Lazy-Ferret]

I forgot to mention that in the vent of numerous DTC's, it might pay to clear them and then see what pops up.

I downloaded and printed out the "Workshop 29. Accessing, Reading & Erasing Engine trouble codes" from the down loads section, and armed with my new Code reading cable, which has a 14 pin plug on one end, and a push button on a length of wire bridging the Ign and Chk pins, I connected up to the car....

I turned on Ignition... MIL comes on and stays on.
I press button on cable, MIL goes straight off, and while I am still pressing and waiting about 2 seconds the download says, the light starts to flash slowly..
I release the button, and the light comes straight back on...

After playing around, it would appear that my car only gives the fault codes while the button is actually pressed, and even then, in my case it is just giving 55 (No fault found)...

No I am pleased my car has no faults, but I did think that after all the playing around I have done, and the number of times I have put it into limp mode, it would have something in there. So I guess mine does not store minor fault codes... or am I seriously over looking, or doing something wrong.

Can anyone spot my mistake?

 

[AlexD333]

I have to say actually that I get this from time to time, and even after my plug in, it only ever reads code 55.

Lazy Ferret, next time you get this, pull over if you can and leave the engine on, see what it does, does it only rev to about 1700rpm and is it too gutless to move?

these are my rough symptoms.

engine purrs away still.

 

[Mobieus_uk]

I can only think that if you mod the engine in any way shape or form and you do not remap to take into account the new ranges the sensors will see you may get the odd mil light flash up every now and then

 

[Lazy-Ferret]

I have to say actually that I get this from time to time, and even after my plug in, it only ever reads code 55.

Lazy Ferret, next time you get this, pull over if you can and leave the engine on, see what it does, does it only rev to about 1700rpm and is it too gutless to move?

these are my rough symptoms.

engine purrs away still.

Exactly that...

I can only think that if you mod the engine in any way shape or form and you do not remap to take into account the new ranges the sensors will see you may get the odd mil light flash up every now and then

The problem is, for some reason I don't get a MIL, and that is what I was expecting to get... My MIL has only ever come on when I turn the ignition and it does the light check, other than that, despite several times, putting it into Limp mode, the MIL has never once come on. Thats what I do not understand.

 

[bud]

have to remember too that most nissan diesel hot wire 3 pin afm's will only read volume up to a full value of 16 psi. once there it says im at capacity and thats all the fuel i will put in.

you will need a maf amp or a bigger maf from a petrol 3L 6 cylinder to get any further gain.

 

[Lazy-Ferret]

have to remember too that most nissan diesel hot wire 3 pin afm's will only read volume up to a full value of 16 psi. once there it says im at capacity and thats all the fuel i will put in.

you will need a maf amp or a bigger maf from a petrol 3L 6 cylinder to get any further gain.

I don't think I was anywhere near 16psi... assuming my gauge is correct, I was just about 11. I do have a MAF amp, but again, any more than the bare minimum amplification, and the car goes into limp mode. Having said that, there is a big difference in power from the MAF amp being on and off, so even that small amount makes a lot of difference.

Not sure I want to go down the "Proper tune up" route, as my engine is probably not really up for it, I only wanted the waste gate valve to stop the it opening prematurely, but for the same price, I could get the whole controller, so I got that. Then, since I had the controller, I was playing with it to see what it did.

I think if I ever want to really up the power, I will take it to one of those places that does the re-map etc, and let them work it all out.

 

[bud]

You dont need any controller to stop wastegate creep. Just a new spring. And the engine will take 25psi but the factory turbo will only handle 18 psi. Before it falls to bits.
My daily around town driving is 18psi at the inlet manifold on a mechanical injector pump and r32 skyline turbo with aftermarket internals. Out in the bush its on its limit 25 up to 28 psi when at full loud pedal..... oh and the noise from the turbo sucking down air drowns out the exhaust note. Lol

 

[Thomas-the-Terrano2]

I have to say actually that I get this from time to time, and even after my plug in, it only ever reads code 55.

Lazy Ferret, next time you get this, pull over if you can and leave the engine on, see what it does, does it only rev to about 1700rpm and is it too gutless to move?

these are my rough symptoms.

engine purrs away still.

Hi, just found this thread, funny as my terrano showed the exact symptons that day.

Differences no mods to my knowledge and always pump diesel bought.

Generally does restart ok from limp, but has been know to take 3 to 5 restarts.

Get it from cold, running cool, or sometimes warm at speed. If enough speed has
recovered without restart, coasting til recovers.

Never a mil light, 2 mot testers have pulled code of turbo boost or over boost despite
everyone saying a 2.7tdi cant give overboost.

Have had suggestions of TPS but when mot guy witnessed it still thinks its more
turbo related - has suggested a new turbo!

Any thoughts please, had suggestions of #1 injector, egr etc totally confused, Mrs
won't drive it in case does it, I know can restart it,

 

[solarman216]

As there is no sensor to read pressure on the TDi ECUit can only be calculated from the maf and other data the ECU recieves, very unlikely to be the turbo as cannot see it over performing, Rick

 

[AlexD333]

Nice to know it's not just me. One morning i tad it 6 times on way to work, a40 loss of power is not fun :doh