emission test failure, 400 pre-serpetine, cat-model

[LLantrisant]

pre-mot visit in my garage for testing emissions turned out the following:

engine warm:
2,8% CO, ~800 HC at idle-speed, fast idle (3000rpm) similar values

car is running fine, starts well, pulls well.

for a short test we unplugged the ECU.

after re-connecting, we started engine and Co/HC readings where suddenly quite low @idle...until throttle was opened the 1st time....than readings went up again and stayed high.

car is a 400, pre-serpentine, cat-model, pre-cats removed, ignition-leads and coil are new.

any ideas where to check first?

Edited by LLantrisant on Thursday 15th November 13:13

[QBee]

pure guess.....if you have an air leak between the AFM and the cylinders, more air will get in than expected, the lambda sensors will tell the ECU, and the ECU will chuck more fuel in.

Or your cat is buggered.

[LLantrisant]

i thought it might be more the coolant temp sensor giving too low readings, hence the ECU thinks that engine is on cold-start?

anyway....i found inside the documentation-folder of the car a rovergauge cd-rom and and USb cable....is this diagnostics tool suitable for testing all sensors`?

the problem is, the car has no registration at the moment, so i cannot drive in a garage to check with a emission tester....now it was just an exemption, as a freind of mine picked-up the car with dealer-plates for driving to the mot-station and pre-mot check in usually "emission" friendly garage


high CO & HC is usually indicating: to much unburnt fuel or too rich.--correct?
feedback for ECU is done by the oxygen sensors --> correct?

Edited by LLantrisant on Thursday 15th November 19:42

[mcosh]

Couple of unusual things to check as had same problem yesterday.
First car needs a really good run and clear out if it's not been used much.
Then the surprising one in this case......rotor arm....it was starting to fail and causing a barely detectable misfire but enough to shoot the readings sky high....new rotor fitted...good hard drive....and bingo...a pass😀

[TV8]

There are a bunch of things this could be. I would reset the ecu with an unplug of the battery, check the spark plugs for colour and also ignition set up. Blitz has a website to check the AFM and fueling side of the set-up. Another useful test is an infra-red thermometer on the exhaust outlets and look for big temp variations. One or two cylinders a lot cooler than the others could be extender problems assuming the car has them.

[blitzracing]

High CO and HC is basically unburnt fuel or over rich mixture. First thing to remember is if the ECU has been reset it needs to re learn is basic mixture setting at idle from the lambda feed back, but this only happens on a hot engine (over about 90'c ) at idle for about 3 minutes to allow the long term fuel trim to stabilise. If there is a fault, it could be a misfire, AFM reading high, incorrect fuel pressure,or faulty temp sensor. It could also be the catalyst is contaminated, so not doing its job. Best fix here is a good hot run for the engine with some catalyst cleaner additive in the fuel. This helps burn off any muck from the catalyst honeycomb.

[Sardonicus]

I would not be suspecting a CAT failure with a CO of 2.8 a working CAT will not squeeze that reading down to CAT limits if say you was seeing 0.8/1.0 that would be a different matter at the moment dismiss the CAT , try to loan or buy Rover-Gauge its a cracking bit of kit you can then monitor indicated coolant temps (possible failed sensor) see what the 02 sensors are saying etc , like mentioned already be clear you have no ignition faults/misfires etc 1st

[Steve_D]

LLantrisant said:

..........anyway....i found inside the documentation-folder of the car a rovergauge cd-rom and and USb cable....is this diagnostics tool suitable for testing all sensors`?.....

Yes the very bit of kit you need along with a temp gun.

The version you have on the CD may not be the latest/best so would be worth downloading the latest (free).

Start with the engine off and stone cold. RG should show you coolant temp and fuel temp both of which should be the same reading and around ambient. This is a good start to prove both those sensors they may fail higher up the temp range but it is a good place to start.
Other reading will be with the engine fully at temp with the fans cutting in and out.
When you have some readings come back to us or have a look at Blitz web site http://www.g33.co.uk/

Steve

[LLantrisant]

just to clarify: the car is not road legal....so i cannot do ANY test drives nore any "burn the cat-out of dirt" drives.

now back to rover gauge:

went to my car today, searched for the ECU and? it was underneath the dash!!! must have been altered from the former owner i guess

ok....nevermind i thought, but where the heck is this ECU-diagonostic plug no.2?



i can just find the black conector no.6

my car is a very early 1993 chimeara.......than i searched again the footwhell....and i was lucky to find the plug

Edited by LLantrisant on Saturday 17th November 12:25

[LLantrisant]

managed to connect rovergauge.....but there isnt any fault code shown.

but i guess this is due to the fact that i have disconnected the battery b4? isnt it?
if its like that....how long does the engine need to run ntil a fault code may appear.

please keep in mind, i can only run the engine in my home-garage as the car is not road-legal.

Edited by LLantrisant on Saturday 17th November 21:23

[Belle427]

I cant answer the code question but you need to run it up to temperature as suggested first to let it all stabilise again.
It would benefit you to drive it and blow the cobwebs out of it, a friendly mot tester would help get it through and then you can fault find and drive.
I found a new tester this year and he was very friendly, pm me if you are in South Wales as im in Blackwood and its just down the road from me, obviously i cant guarantee him but im sure he would help.

Edited by Belle427 on Sunday 18th November 10:09

[Steve_D]

Don't worry to much about fault codes as they are not very reliable and are pretty basic.

main things are, as I said before, start with temp readying on an 'overnight' cold engine.
Then get the car up to temp with the fans cutting in and out.
Work down the list and record (or post a screen shot) all the readings at idle. If the ECU has been powered down the 3-4 minutes at hot idle should see all the long term trims set and possibly any fault codes.

With those readings the experts on here will hopefully spot something for you.

Steve

[LLantrisant]

ok...here we go.

cold start in garage (winter arrives):
ignition ON, engine NOT running:



engine is warming up (idle):



engine becomming warmer (idle):



engine becoimming warmer (throttle a bit open)



engine now warm (idle):



engine warm but off, ignition ON:




Fault-Codes: None
but se thing seems not ok with1 of the oxygen sensors?

Edited by LLantrisant on Sunday 18th November 13:21

[Steve_D]

First off your temperature readings look to be good so that is not your issue. It is worth noting for yourself the temperature the fans come on and go off and compare those with the gauge on your dash. I'm betting they read significantly different and is why we include this comparison on our customer car service records.

You need to do some more results but this time show or tell us what the long and short term o2 sensors are reading.

When up to temp the ECU will be reading the sensors and adjusting the fuel/air mix accordingly. The engine has a map which says how much fuel to use. Then if the o2 reading are high or low it will adjust the fueling this it known as 'trim'. The short term trim should have the readings dancing around zero as it makes fine corrections. To achieve these fine corrections it uses long term trim for coarser corrections.
So, to advise you we need to see both the long and short term corrections.

Steve

[LLantrisant]

at the moment its quite cold here...so takes ages until the fan´s kick-in....and my neighbours are not so amused when i´m reving the car for so long time.

what i can see, with engine at 2000rpm that 1 oxygene sensor is at 6% , the other at 100%.
and the CO & HC readings are extreme high...means the oxygen sensor says "lean", the ECU is giving more fuel...and CO& HC is going up.

in theory this should mean the oxygene sensor is giving wrong info...or am i wrong?

[Steve_D]

May also be a misfire.
This is where the heat gun comes in.
Point it in turn at each of the manifold ports. You are looking for one or more cylinders running cooler than the others.

Steve

[Belle427]

Blitz mentions here the affect of a misfire.
Are you still running the extenders?
https://www.pistonheads.com/gassing/topic.asp?h=0&...

[LLantrisant]

yes...i have the plug- extenders, new lucas leads (no fancy silicon, hocuspocus-internet-aftermarket-raceleads) and new ngk plugs, but.....the car was only started in my garage, multiple times in the past months, but never driven...only just recently pre-mot it was driven n trade-plates for 30km to a local-garage for emiision test and the other day back.

as said, car is NOT road-legal.....all tests/investigations can only be done in my home-garage

[blitzracing]

As mentioned the short term trim should be moving all the time, so if its not and stuck at 100%, you may have a dead probe, as no voltage means a lean mixture, so the ECU adds fuel to try and get the probe to switch. Try swapping the probes over if you can undo them.

[BIG DUNC]

LLantrisant said:

yes...i have the plug- extenders, new lucas leads (no fancy silicon, hocuspocus-internet-aftermarket-raceleads) and new ngk plugs, but.....the car was only started in my garage, multiple times in the past months, but never driven...only just recently pre-mot it was driven n trade-plates for 30km to a local-garage for emiision test and the other day back.

as said, car is NOT road-legal.....all tests/investigations can only be done in my home-garage

Other than no MOT, is there any other reason why it is not legal.

Even without an MOT (& tax) you can legally drive on the road if you are taking the car to a garage for an MOT test or for work relating to an MOT test.

Obviously, this should be booked in advance (you cannot just drive around and claim to be on your way to a test if stopped) and of course you need to be insured.

However, going to a test centre in order for them to monitor emissions with their equipment is clearly work relating to the MOT.