MOT fail - emissions

Just had the Hijet fail its MOT for high hidrocarbons and am a little skint at the moment so I'm going to try and fix as much as I can myself, bearing in mind that though I'm reasonably handy at most things, I have never messed about with engines before.

The first thing on the list is to do my first oil change which shouldn't be too tricky and the next on the list was probably new spark plugs (no idea how to do it but it cant be that hard) but after that I'm stumped. The Lambda and CO both seemed fine (can't remember Lambda but CO got to 0.6% max on fast idle test)

Any advice would be great as I really don't want to take it to a garage, it's high time I got my hands dirty and did more engine stuff.

Cheers

Possibilities are:-

Lambda Sensor
Map sensor
TPS sensor

Do a code scan job on it:-

http://www.daihatsuhijet.co.uk/hijet-diagnostic-engine-warning-light-flash-codes/

Lambda sensor might not give you an error code though.

Don't overlook the simple stuff either though - have a look at the plugs, inspect the air filter, check the exhaust for leaks as this can cause problems.

And if the timing is set wrong that will also make the exhaust gases wrong. All you need is a timing light.

Had the same on one of mine at about 95k miles - changed oil & filter, plugs and air filter and it sailed through. Doing it to the other right now for same reason.

As said above, also give it a damn good thrashing before the mot.

MattS wrote:high hidrocarbons

In case you don't know, high HC's means un-burn't fuel is going straight out of your exhaust pipe. Petrol I think is C8H18 thus it is made of 8 Carbon thingies with 18 hydrogen bits stuck to them.

You can get un-burnt fuel if:- (most likely first)

The lambda sensor is not tuning the fueling for you due to failure
The throttle possition sensor is telling the ECU the throttle is more open than it really is
The map sensor is telling the ECU the manifold vacuum is weaker than it really is, or a vacuum pipe to the MAP sensor is cracked somewhere
Your ignition system is failing to ignite the mixture (misfiring)
The ignition is way to retarded
The Catalytic converter is no longer burning away the excess fuel

As Logan says, once you carry out the rectification work, by thrashing the tits off it, you can burn away the residue from the inside of the cat giving it better efficiency for the test. A hot cat aways works better than a cold cat.

I worked on a civic no so long ago that had failed the MOT on emission test - for the two previous MOT's the car had been fitted with a new catalytic converter and lambda sensor each time it failed. Failing that year again, the garage wanted to change the cat and the lambda sensor again. Also it gave no error codes. I found that the TPS (throttle position sensor) was corroded inside thus telling the ECU the throttle was as 100% open all the time. After replacing the TPS the car accelerated better, cruised better, used alot less fuel, and passed the MOT two years on the trot.

Matt rant nearly over:-
fixing this fault you should see an improvement in MPG at very least.
Cheap lambda sensors are a waste of time - buy a denso one etc
Lambda sensors get permanently damaged if they get contaminated with oil or petrol

Thanks for all the info it is a massive help!

I've had a go at reading the diagnostic light however I'm pretty sure I didn't short the brown wire correctly (mine is a 1300 efi) as nothing flashed when the ignition was switched on. I shall have another go at the weekend when I'll have access to my mums sowing kit for thin pointy things to make a decent connection. In the mean time I'll be getting all the various bits I need to change the oil, filters, spark plugs and a couple of minor things at the end of the week.

Logi wrote:As said above, also give it a damn good thrashing before the mot.

I think John Cleese tried that - it didn't work

Our MPV (993cc) failed on the same thing and it was the MAP sensor had broken in the past and someone had bodged it back together and it had come apart again by the second MOT as passed the first one we put on it and on ours the map sensor is under the handbrake and the pipe goes through to the "engine bay" and it had broken the spout off.

Right,

Air filter, spark plugs oil and oil filter are on order for tomorrow, and while I'm under the van I'll check the exhaust system for any obvious leaks. I just had another go at shorting the brown wire with my multimeter so I know I definitely got voltage when I turned the ignition however the engine warning light did not flash, it just came on with all the other ignition lights. Is there any other way to check the lambda or other sensors (btw how much should a new lambda sensor cost? none of the parts places I went to could find a match). I had a gander for the MAP sensor as well but I don't really know what I'm looking for, by underneath the handbrake do you mean literally under the trim or in the engine compartment underneath the handbrake?

If I can get the basics done I'll book it in for a retest on Friday (after a good thrash on the motorway) and see where I stand. Is there anything else I could do before then?

Cheers

On a 1.3 the map sensor is part of the throttle body.

I don't know why your failing on the flash trick, what year is your van?

S reg 1998.

I even looked up the wiring for the plug in the manual to double check and you can see that it is pin 39 on connector B

That should work, are you grounding it out properly and getting a good contact on the pin?

If you have no error codes the light just flashes.

From it coming on and going off says the test pin is not grounded.

Your doing all the right things though, looking up the pinouts etc... worthy effort mate! I salute you

I've jammed a safety pin down next to the wire and then making sure I get continuity between the front of the plug and the safety pin. I've then just been using the multimeter to ground the pin on the bolt holding the EFI to the frame and checking that I get a voltage across it, which I do.

I might give grounding it on the ECU ground (pin 62 on connector A) a try. While I'm out getting parts tomorrow I think I'm going to get some crocodile clips for the multimeter as it would save a lot of faff!

I just used a length of wire with the ends stripped back, one shove up the connector and the other touching the case - well you've seen my picture above!

Well I've change the oil and filters and the spark plugs, it looked like she was in dire need of a service. The oil that came out was like tar and there was oil on two of the sparkplugs and crud on another. Hopefully this is all she will need to pass her retest tomorrow.

Is the oil on the spark plugs an indicator that they just really needed changing or is there something more serious that needs checking/replacing? also as it looks like she needs some tlc where else should I look for wear and tear?

Cheers for all the help.

btw I've given up on the ecu diagnostic, I've had a third go at it and it's still not flashing at all

if the plugs are oily then it can mean valve seals or rings are knackered but if the plugs were dying you can get a residue build up that looks like oil try setting fire to it if it is build up then it will not light with out a flame assistance but if it is oil it should burn for a few moments unaided.

It passed! CO was apparently still high enough to fail it (0.6%) but the guy still let it though as it wasn't by much. Cheers for all the help guys its very appreciated

I would get to the bottom of it as you'll be wasting money on excessive fuel and be losing out on performance.

I would like to sort this out myself however I think this is starting to reach the limits of what I can do myself. If I could get the bloody diagnostic to work then I'd have some direction but I feel like I'm flying blind at the moment. Should I fork out for a new Lambda (I've looked online and can't seem to find anyone who sells one for a hijet) on the offchance that its gone or should I try and find a garage that will be able to find the problem straight away?

I think you shouldn't give up on diagnostics of one form or another... back to multimeter warfare

The 1 wire lambda sensor outputs a signal between 0 and 1 volt depending on air fuel ratio, so you can connect a multimeter up to it and watch it work. It needs to be hot, so the engine must have been ticking over for 5 minutes or so. Rich fuel conditions are about 0.8 volts to 0.95 - Ok is about 0.25 to 0.75 - and lean is - 0 to 0.25 Expect it to bounce around abit - engines are crude affairs.

Throttle position sensor is dead easy to test, shove your black multimeter wire on a ground somewhere, and spike the red probe in to the middle wire on the TPS sensor. Turn the igntion to ON. With the throttle closed you should get between 0.4v and 0.8v then press the accelerator pedal to the floor and you should get over 3.5v . As you gently press the pedal up and down the voltage should slide nicely.

Coolant temp sensor is tested in a similar way, you set your multimeter up to ohms, then put your probes on the temp sensors connectors - this graph should help you determine if yours works - so at cool ambient day temp, the water will be about maybe 14 degrees - so about 2.5k ohms to 3k ohms



We can also test the intake air temp sensor too - thats in the air intake ducting - white thing if I remember correctly - but I'll save that description if you get this far. They never tend to fair on anything (famous last words ahoy)


(p.s. graph for temp sensor is from 993cc - but probably same thermistor inside - most likely - but not definite)

Temp sensors - if in doubt, connect your multimeter, put sensor in pan of water, turn cooker on, watch the resistance creep up. Don't want to take it out huh? Connect up your multimeter and start the engine, let the coolant become "hot-ant"

If open circuit, or short circuit - temp sensor is dead - if resistance stays still - dead

MattS wrote:however the engine warning light did not flash, it just came on with all the other ignition lights

Just had a thought, you may have a van that's been "tinkered with"

Newish MOT law states all warning lights have to work.

What rogues do, is wire up the engine warning light to the oil pressure light or something else.

That way is isn't on all the time, but it still lights up and goes away when you start the engine.

That might be why you can't get diagnostic mode to "work" - it may be working - but you can't see it.

Once upon a time, people took the bulb out to sell a dodgy car or whatever - now you can't MOT them with a warning light on all the time.

So pop your dashboard clocks out which is very easy, just pull the trim off, then I think 4 screws, and unplug the cables by pressing the buttons on them, and the speedo cable by pulling the sheath back. Then inspect for fowl play.

Also before you take it out, the engine warning light should do this:-

Turn ignition on, don't start the engine
Engine warning light comes on,
About 5 seconds later goes off,

If it doesn't go off, until after you start the engine, then its connected to the oil pressure light.
If it comes on and goes off before the engine has been started then I think its OK.



Also, if you brought it to me in Crewe, I would have a look at it for you, and I have spare sensors knocking about so I can show you some tricks and most likely fix it in not alot of time.

Wow thanks for such a detailed response HJ!

I've just had a play around with sticking pins on the ECU and the throttle and pressure sensors are giving the correct voltages. I also tested the oxygen sensor and though it was jumping about a lot (probably due to my cheap multimeter not being stable at low voltage) it was alternating between around 0.2 to 0.8 but occasionally hanging around 0.15 for a few seconds so I'm not too sure what to read into this. Sorry to be dim but where is the water temperature sensor?

Here is the voltage table from the manual if anybody else has similar problems


All this being said I realised that I am a complete plonker and left the oil filler cap off the van over the weekend and during the MOT, could this be a contributing factor?

On the warning light front your right, something is amiss as the light does not switch off until the engine is running but I had a look at the back and I can't find anything that looks out of place (photos below), am I missing something or has it been bodged somewhere else?









From looking at the circuit the wire for the engine light is the third up (green and yellow) on the longest connector

I was wrong, light stays on and goes off just before oil light after starting.