K11 Misfire Problem

[porkpie700]

I have a 1999 1.0 insparation with a very bad misfire problem. So from cold when the choke is on it starts first time and ticks over just as it should, but after 2 - 3 mins it starts missin, the exhaust is popping like an old beetle or a twin cylinder motorbike. It's been a problem car for a while but i've fixed all it's glitches except this one.

I have checked just about everything that i can think of and even replaced the throttle body.
It gives good strong sparks,
Fuel pump is blasting fuel through no probs,
It's been fully serviced; oil, all filters, plugs and leads with dizzy cap & rotor.

The only thing i can think of now is maybe a stuck valve as when i changed the throttle body the manifold was full of oil, very dirty engine oil...
The puzzling thing is that if i disconnect the three plugs from the throttle boddy the engine will continue to run exactly the same but then die a little when i plug them back in. That ain't suppost to happen as every other micra i've known stalls instantly.

Anyone out there with experience of this same sort of problem or knows what it might be, you're ideas would be greatly appriciated. I've fixed just about everything that can go wrong on k10's and 11's but this micra has me well and truely scratching my head. fwn

 

[andy]

what about the dissy cap? is that ok inside and out?

 

[frank]

a pool of oil at the bottom of the mani is pretty common on a high miler porkpie, and if its running ok when cold maybe the coolant temp sensor is knackered and overfueling when warm ?

 

[porkpie700]

The dizzy is working 100% i've had it tested. frank; it's not a high miler really, just reached 70k recently and i've seen these things with 150k upwards on the clock. That said i did clean up the under-bonnet earths and check the sensor (the connectors were shabby so i clean em up). In doing so i managed to get rid of most of the misfires so thanks for that.

As a test i ran then engine with the temp sensor un-plugged and just like it said in the haynes manual the ecu went into safe mode and turned the fan on perminately, as it ticked over the occasional hiccup (that used to accompany the misfire) came back and each time it did, the engine died (almost stalling for like a half second) but the fan died with it, and came back with it too.

So i now supect that there is a hiccup in the power supply to the ecu, since it controls both the engine and the fan... So does anyone have any idea where the ecu gets its power from and where it earths to? If i can find and check/clean those and it still does it then it might just be a fault with the ecu itself.

 

[frank]

there are a number of earths porkpie (left arrow) and there,s a relay that supplies the ecu (right arrow)
it does sound like a dodgy connection somewhere eh (my ecu plug has to to cocked at a slight angle, else the car wont start )
http://www.micra.org.uk/attachment.php?attachmentid=13780&stc=1&d=1257514850

 

[porkpie700]

Thanks for that frank, i had to chop off the earth connectors and fit some fresh ends on them, they were shot. This helped to clear up the misfire some more, i took it out for a test drive and after 10mins it just cut out completely and the engine check light just kept flashing constantly.
I spoke to an ex-nissan tech and he believes that the key is at fault (it's one of those NATS microchipped keys).
The diagnostic test was giving me code 141, which isn't in any books or manuals but apperntly the nats keys do break after years of being chucked around. So since i only have the one key for it i'm going to get another one from nissan and if that sorts it i'll let y'all know. All these fickle electronics are why i prefer the k10, they're just so much easier to troubleshoot than the bubbles... (Y)

 

[Alienfish360]

1999 is a facelift correct?

OBD2 fault code 141 is an O2 sensor fault, caused by the 2nd sensor.
http://www.obd-codes.com/p0141

 

[matt1987]

if the key was at fault it wouldnt work at all im a current nissan tech and never heard of the keys breaking down, best bet is to check the ecu power for continunity and go from there

power comes from the relay down a green wire to ecu then out of ecu to dizzy cap, we have several which break down intermitten faults poor running and we trace it to the ecu power wire, hoodedreeper will tell you.

the relay is located in the engine bay left side of battery and is the first blue relay in the unit, we sometimes swap the relay to rule out the relay then do the wire check.

 

[porkpie700]

Thanks for that guy's. I swaped the two blue relays but this had no effect unfortunately, i personally suspect that the ecu is faulty.
The car has been turned over to a Nissan dealer, they had it on diagnostic this morning and found that the car had forgotten it's key code.
They have no idea why it did that but they coded it in and the car started up fine, only to hickup and then break down again 200 yards from the forecourt. :doh:

I pushed it back (on a busy duel carrigeway, oh what fun.) and the car has been left with them. I so badly want to kick the stupid thing but that wouldn't solve nothing so i'll just have to bite my tounge.

If it is the ecu and it needs to be replaced then i may end up with a small problem. You can bet the farm that a new ecu from the dealership will cost a fortune so if a replacement is needed then i will source one from a scrap yard.
What i need to know is, is the mileage stored on the ecu or in the clock-cluster? (it's the digital facelift model clocks, NO rev-counter).

If its stored on a chip in the clock then i can stick in a unit from pretty much any other 1 litre model, but if it's stored on the ecu then i'll have to get one from another facelift right?
Sorry for the lengthy post but this car's problems can't be solved in two words :laugh:.

 

[kakawak]

just thought i would quote the price of a new key since i enquired about it today from the local nissan garage............£115

as the saying goes "at least **** turpin wore a mask!"

regards me

 

[porkpie700]

Indeed he did; the dealer rang me up today and told me that after some more testing it's apparently a Mass Air Flow stall. £660 i was told for a new throttle body inc. fitting. But i know that the throttle body that i put on it was working fine on the doner car so i personally don't think it's the MAF on that one. Two throttle bodies with the same fault, not likely especially since they both worked last week.

I asked them to test the circuits & wiring in that system and apparently it all checks out fine, but i still suspect the ECU to be at fault. A tiny fault in the ECU can cause several other faults and easily knock out the engine. If the part of the ECU that deals with the MAF had a glitch then surely it's possible that it could give the diagnostic tool a false reading, i.e. saying it's the MAF when it's the chip that deals with the MAF...

 

[porkpie700]

Problem Sorted

After two weeks of testing and replacing the problem has finally been sorted. It turned out to be an intermittant fuel pump together with a faulty distributor. The old fuel pump must have shredded something because the bottom of the tank was covered with iron filings! Shiney metal fragments all over, never a good sign.

So if anyone out there ever gets the same problem as i did, change the distributor, i paid £20 at my local scrap yard and i got the distributor with it's cap and it's genuine nissan spark plug leads. Much cheaper than the £120 fuel pump i had to fit. :grinning:

 

[Rory the Red Micra]

Hi guys ,can anyone help. I have a 1.3 k11 1995 with 98k on the clock . I have a misfire on cylinder 2 . I've changed plugs , dizzy and leads, now giving a strong spark on all leads. I have done the throttle body resolder trick , to no avail. I'm now suspecting it's a fuel issue , so I popped out cylinder 2 injector and swapped it with the working one from cylinder one . The misfire still occurs on cylinder two.
The only two things I can possibly change is the ECU and the O2 sensor.
Can anyone either confirm the ecu could indeed cause this and is it worth changing the o2 sensor as my inclination is to change this 21 year old ecu.
The other 3 cylinders are strong and a compression test saw 140 across all four cylinders.
Thanks guys for any posts .

 

[h701micra]

Maybe a weak connection at the injector plug?
@frank may have other ideas to add

 

[Rory the Red Micra]

Maybe a weak connection at the injector plug?
@frank may have other ideas to add

Thanks h701micra for taking the time to reply , I checked the connections visually as I went through all the other attempts , however it could be but without a meter I can't tell . I've wing led the wire around whilst it running .... To no avail again ! I'm thinking more and more it's the ECU ? eBay or breakers I am thinking . Not sure of the part number without getting the old one out first but does anyone have an idea ?
Cheers

 

[frank]

ecu problems are very unusual on k11,s eh, has yours got the nats immobiliser rory ?

 

[fuzzy-hair-man]

There's a trick of putting a screwdriver against the side of the injector whilst running, other end against your ear and allows you to hear if the injector is working...
If you have a test lamp you could check for 12v at the injector.

 

[Rory the Red Micra]

Maybe a weak connection at the injector plug?
@frank may have other ideas to add

There's a trick of putting a screwdriver against the side of the injector whilst running, other end against your ear and allows you to hear if the injector is working...
If you have a test lamp you could check for 12v at the injector.

Thanks Fuzzy, I have tried that and the injector is not working . Even when I changed it with cylinder one. So , I am thinking it's the injector not being told to perform . That being the possible case , I am working back to the ECU ? It's on order so fingers crossed. I'll certainly be keeping you guys updated.

 

[Rory the Red Micra]

ecu problems are very unusual on k11,s eh, has yours got the nats immobiliser rory ?

Not sure Frank?? I don't think so . No stickers on the windows and the immobiliser is a scorpion . The keys are not encoded . I changed both door barrels as a key broke in half in the drivers lock earlier this year. A pair from eBay got me back on the road. So I'm puzzled with the possibility that the ECU 's are normally good. I'll try the one on order and let you know . Thanks bud .

 

[fuzzy-hair-man]

Thanks Fuzzy, I have tried that and the injector is not working . Even when I changed it with cylinder one. So , I am thinking it's the injector not being told to perform . That being the possible case , I am working back to the ECU ? It's on order so fingers crossed. I'll certainly be keeping you guys updated.

The injectors are triggered on earth so there should be a 12v live at one of the 2 wires that plug into the injector that may narrow down where the problem is... If you have 12v then it could be wiring(back to the ECU) or ecu, but as frank said I'd guess wiring...

 

[Rory the Red Micra]

The injectors are triggered on earth so there should be a 12v live at one of the 2 wires that plug into the injector that may narrow down where the problem is... If you have 12v then it could be wiring(back to the ECU) or ecu, but as frank said I'd guess wiring...

Thanks Fuzzy, that's helpful. You two could so be so right. I'm off tomorrow afternoon so I'll be on it and let you guys know.
Thanks again guys . Fingers crossed !!

 

[Rory the Red Micra]

It's done guys !! A knackered fuel injector . I found a replacement from Abbey Breakers in Erith. Top guys. Rory runs like a dream .
Thank you Fuzzy and Frank for all your comments , opinions and ideas. All gratefully received and valued.
Cheers guys