Failed MOT on emissions, quite badly

Z22SE engine as fitted to various vauxhalls

failed emissions quite badly

fast idle test

CO Max Limit - 0.300 - actual 9.298 HC 200 - actual 1060

Lambda min 0.970 max 1.030 - actual 0.801

second fast idle test

CO 0.300 actual 9.946 HC 200 actual 1187 Lambda min 0.970 max 1.030 - actual 0.761

Natural Idle Test

CO max 0.500 actual 5.869

car has visible emissions, you can see soot when its running,

i changed the precat lambda this morning but still no luck,

cat is quite new, any suggestions on what it could be ?

cheers

mark

Reply to
luna
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With results like that I'd get an OBD2 reader on there soonest, or you'll be diagnosing it by the "replacing old parts with new parts until it's fixed" route!

JB

Reply to
JB

luna ("luna" ) gurgled happily, sounding much like they were saying:

Was it up to temp? That looks to me almost like it was stone cold - very high HC & CO, lambda very rich.

If not, then read the codes. If there's nothing there, I think I'd start by checking that the temp sensor for the injection was giving out the right resistances across a range of temps.

Reply to
Adrian

theres no fault codes showing and no eml light, used my OBD reader earlier :/

thats the issue i have, but those parts can get costly!

cheers

Reply to
luna

temp sensor is the same as the one on the dash i believe, and thats reading fine ?

Reply to
luna

luna ("luna" ) gurgled happily, sounding much like they were saying:

D'you mean the one for the temp gauge? It isn't always - I don't know this engine.

Reply to
Adrian

No different sensor and often diffeent location too.

JB

Reply to
JB

seems to be just the one sensor on this engine, and it also controls the cooling fan, which is working a the right temperature

Reply to
luna

Could be lots of things, but one that springs to mind is the fuel pressure regulator. If it sticks closed, the fuel rail gets full pump pressure = lots of fuel. I don't know this engine though.

I doubt it's a lambda sensor/airflow meter, as the fail-safe levels in the ECU should stop it before it ran *that* rich.

Reply to
Chris Bartram

Christ, for it to be running that rich it ought to stink of fuel and show visable black smoke! Replacing the o2 sensor is very very wishful thinking! You'll be needing to change it again and the cat from fuel poisoning if it goes much longer!!!

Don't know what OBD unit you used, but it can't be very comprehensive as it would show *massive* LTFT at off the scale besides the fact the ecu would still be in open loop mode. I am very very surprised that there is no fault code pertaining to an out of range o2 sensor, or even warmup period timed out, as the Simtec ecu on these knows how long the car should take to warm up and enter closed loop running, if this is exceeded, it will flag a code.

First thing, get a decent scan tool on it, in live mode and see exactly what sensor is calling for the massive fuelling! (9.9ish CO % is off the scale for most gas analysers)

More info is really needed here- has it been deteriorating, or did it suddenly go like this. Any work been carried out lately, whats the mileage and service history been like?

Tim..

Reply to
Tim..

There will be another one. That one doesn't talk to the ECU for fuelling control.. Possibly on the cylinder head or near the thermostat housing. JB

Reply to
JB

If its a Z22SE it could have had the chain snap in the past. As a consequence this sometimes knackers the rings when the pistons meet the valves (assuming temperature etc normal).

If you have not long bought the car the last owner may had the chain go then fixed it up quickly and sold it on. Whats its oil use like? They can be heavy on oil when running normally.

Go over to

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There are lots of very helpful people over there.

Paul

Reply to
Paul Edwards

should have added that the people over here are very helpful as well.

Reply to
Paul Edwards

Odds are the ECU thinks the engines cold, dead sensor or cable. Hook an OBDII scanner up & it'll tell you what temperature the engine thinks it's at.

Reply to
Duncan Wood

yeah cam chain snapped a year ago, but i've rebuilt the engine over the past year its had new pistons, valves,chain. its also been slightly tweaked with different cams etc injectors are brand new, ive tried 2 lambdas only thing not checked is the coil pack, either that or the timing is out on the cams, but ive photographic evidence that it isnt!

temp seems to be fine on the odb reader ?

Im really thinking its the coil pack, but i dont have a spare to test,

strange thing tho tonite when i changed the air temp sensor for a spare, the engine ran really really rough, misfires - and threw an engine code up p0340 which is cam sensor (the car doesnt even have one!) - so it could just well be the coil pack not firing properly (i've put a new crank sensor in)

cheers for the suggestions - very helpful,

Reply to
luna

A coil pack fault would show up on the ODB.

Reply to
James

One plug knackered?

Ian

Reply to
Ian

which i think is the PO340 error code, im just checking the TIS now

cheers

Reply to
luna

possible, but car ran fine on the way there with no misfires, plugs are new too, but could still be faulty (original GM)

Reply to
luna

luna ("luna" ) gurgled happily, sounding much like they were saying:

And this is the first emissions test since?

Reply to
Adrian

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