Failed NCT!

tomo92

Failed nct today on emissions,
Oil temp:104℃
Low idle: 690 rpm
CO:0.00%
HC:8ppm

High idle: 2380rpm
CO:0.00%
HC:8ppm

Lambda: 1.09

I only bought the car it a 1.8 opel vectra, I've had a code thrown up 2 weeks ago p0170, and the mechanic said it was the 02 sensor as he put it on the analyzer and it was 1.11 and the car stutters and hesitates from cold, so I had to get a scrap yard lambda sensor as I couldn't get one in time from the auto factors, so I put that in and a different code came up p0130 and that basically means lambda sensor, I would just like to know if by looking at this nct report it is the sensor,

Atlantic Dawn

P0130 could be a hole in the exhaust too, I would check there's no holes before replacing sensors.

Renegade Mechanic

Problem with scrapyard parts is the likelihood they were bad when the car drove in.. Scrappies are great for mechanical parts, that you can see and inspect, but hit and for anything electronic.

The code is another code for lambda sensors - specifically the circuitry. As mentioned, it could be a hole in the exhaust, but the nct should pick up easily on that, I'd imagine.

I'd still try a new one. They make a good difference to fuel consumption and driveability, too.

tomo92

Renegade Mechanic wrote: »

Problem with scrapyard parts is the likelihood they were bad when the car drove in.. Scrappies are great for mechanical parts, that you can see and inspect, but hit and for anything electronic.

The code is another code for lambda sensors - specifically the circuitry. As mentioned, it could be a hole in the exhaust, but the nct should pick up easily on that, I'd imagine.

I'd still try a new one. They make a good difference to fuel consumption and driveability, too.

I had it up with a garage yesterday to have the mounting welded back on to it as that was on the fail sheet too, and the mechanic said there was a pin hole and he'll seal it while it's up in the air, and code is still being thrown up

jimgoose

Hmm. I'd expect it to be blowing more HC/CO than that if the Lambda sensor had failed "high" causing the ECU to richen up. P0170 is a fuel-trim fault. I'd suggest a good look for vacuum leaks in the vicinity of the intake, hoses etc. as well as exhaust leaks.

tomo92

jimgoose wrote: »

Hmm. I'd expect it to be blowing more HC/CO than that if the Lambda sensor had failed "high" causing the ECU to richen up. P0170 is a fuel-trim fault. I'd suggest a good look for vacuum leaks in the vicinity of the intake, hoses etc. as well as exhaust leaks.

To be honest I sprayed the intake hoses with carb spray and car didn't rev at all and I had it up the garage yesterday getting 2 brackets on the exhaust welded to it and the fella found a leak and filled it but I'm still getting code and high lambda, what's the chances of the MAF I'd need to be sure as there over a 100 quid and not a part I'd want to change unless I had to.

jimgoose

tomo92 wrote: »

To be honest I sprayed the intake hoses with carb spray and car didn't rev at all and I had it up the garage yesterday getting 2 brackets on the exhaust welded to it and the fella found a leak and filled it but I'm still getting code and high lambda, what's the chances of the MAF I'd need to be sure as there over a 100 quid and not a part I'd want to change unless I had to.

I'd find a garage with a gas analyser, disconnect the MAF, and see if that improved the Lambda reading at the tailpipe. When running closed-loop under no load I would expect the ECU to play it safe and run on the rich side. In short, if the MAF is causing this you will see Lambda at around 0.98.

tomo92

jimgoose wrote: »

I'd find a garage with a gas analyser, disconnect the MAF, and see if that improved the Lambda reading at the tailpipe. When running closed-loop under no load I would expect the ECU to play it safe and run on the rich side. In short, if the MAF is causing this you will see Lambda at around 0.98.

If I disconnected the MAF sensor and turn the ignition to on and it cuts out should it run or cut out, as I've done this and the car did run not better or worse the same as before, I have already spent 400 on the car and it's 12 years old, don't get me wrong I want the problem fixed as the car is ideal right now, but I'm being charged every time I go to get it analyzed, and the funds are getting low now.

jimgoose

tomo92 wrote: »

If I disconnected the MAF sensor and turn the ignition to on and it cuts out should it run or cut out, as I've done this and the car did run not better or worse the same as before, I have already spent 400 on the car and it's 12 years old, don't get me wrong I want the problem fixed as the car is ideal right now, but I'm being charged every time I go to get it analyzed, and the funds are getting low now.

Most of them will start and run fine with the MAF disconnected, albeit inefficiently. It's hard to say what's going on without getting an analyser up it's jacksie with that sensor offline.

tomo92

jimgoose wrote: »

Most of them will start and run fine with the MAF disconnected, albeit inefficiently. It's hard to say what's going on without getting an analyser up it's jacksie with that sensor offline.

If I could get a tech2 diagnostic machine would u know what values the MAF should be by any chance.

jimgoose

tomo92 wrote: »

If I could get a tech2 diagnostic machine would u know what values the MAF should be by any chance.

I'm talking about a tailpipe emissions analysis while the MAF is disconnected. The youngfella in a bit of a shed around the corner from me here has a gas-analyser, they're not that scarce!

tomo92

jimgoose wrote: »

I'm talking about a tailpipe emissions analysis while the MAF is disconnected. The youngfella in a bit of a shed around the corner from me here has a gas-analyser, they're not that scarce!

I know the gas analyzer, but the only one that has one is a mechanic up in gorey, and every time I go up it's 20 quid with out giving me some useful info as how to sort the problem, I ordered a tech2 diagnostic it should be here in a couple of days and it can tell all the live data for the sensors , I know the 02 sensor should be between 0.1 and 0.9 and the second one on the exhaust should be 0.45 and switching slowly, but I don't know what the MAF sensor should read, I'm not a mechanic I can do some basic jobs on the car service, plugs, clean the throttle body bits like that, but when it comes to emissions I don't have a clue only what I've been reading and funny enough there's a handful of mechanics in gorey but none want to have anything to do with it, only the fella that charges me 20 quid for the use of his emissions tester, he said the first time it was the front 02 sensor to buy 1 from a scrap yard as the nct was due on a Monday and this was a Friday and I couldn't get a new one from the auto factors in time so I went the scrap yard they gave me a 1.2 corsa 02 sensor still reading high then went back I got a 1.6 zafira one and then failed the nct with that one so that's €40 I'm down for 15 mins work checking emissions and information that's no way useful from a person that is supposed to be a mechanic that learned his trade with a number of years experience working on cars, (sorry for the rant I'm just a little pissed of as I need this to pass the nct with all the check points now a days and I'm trying to get my C truck license I don't need to have any points on my license)

jimgoose

tomo92 wrote: »

...but I don't know what the MAF sensor should read...

The MAF will have three wires - 12V, ground and signal. The signal should be between 1 and 1.7V, varying smoothly and in linear fashion as revs/throttle increase. You shouldn't see any sudden, bonkers fluctuations.

tomo92

jimgoose wrote: »

The MAF will have three wires - 12V, ground and signal. The signal should be between 1 and 1.7V, varying smoothly and in linear fashion as revs/throttle increase. You shouldn't see any sudden, bonkers fluctuations.

And would that be on the tech2 scanner or a multi meter

jimgoose

tomo92 wrote: »

And would that be on the tech2 scanner or a multi meter

Meter, ideally with a pin-prick probe.

tomo92

jimgoose wrote: »

Meter, ideally with a pin-prick probe.

You wouldn't know what it should read on a tech2 diagnostic by any chance as I wouldn't be the handiest with a multi meter