NCT Emissions

[ger]

Did the NCT this morning, everything grand apart from emissions.

My CO% was 8.39% way above the 3.5% limit and HC was 572ppm which came in under the 750 limit.

I recently fitted a walbro 190hp and up the boost to 8psi, ticks over ok and pulls really strong with no bogging but I seem to be idling very rich.

My guess is the walbro is over powering the stock reg but I thought this was only a problem with the 255 pump. Can the stock regulator get weak?

I could always change back to the standard pump for the NCT but would rather sort it out.

Any Ideas?

Set up is greddy turbo, 2.5 inch exhaust, decat, FMIC, Vortec FMU (8:1 disc), O2 clamp, walbro 190hp, 265cc injectors & forge valve.

[leamyj]

That's a pain alright Ger...Is there much of a difference between previous nct results and this one?? You gotta suspect that any changes in the fuel system since the last nct is likely to be a factor....i've no idea how you overcome this as I'm strictly NA..

[Steve]

I think you might be on the right track alright, you could try another stock reg but will prob have the same issue again in the future.
Have you a wideband? If so, what kind of AFR are you seeing?

If it t'was mine I'd either swop out the pump every year or seriously consider a megasquirt.

[ger]

Last NCT was less that 1.1%CO AFAIR so its a whopping 800% up, just remembered I had a spare engine underneath a load of crap in the garage and it has a reg on it so I will swap them out, see how it goes.

I have no wide band but a local mechanic is letting me use his emissions tester to sort this out. Its only a problem in vacuum. Once in boost my AFPR takes over the fueling.

Yeah a megasquirt would be good steve, but then comes the wide band and then the injectors and then I will need a new diff but that needs shafts and then I have to tune on a rolling road and the the brakes will be too small so I 'll need bigger brakes etc etc etc. That adds up to a lot of cash and in reality it goes pretty good at the moment, I have been driving this tune for about 3 yrs and turbo'd for 6 yrs and the engine is running fine at 305,000 km so I guess my tune can't be that bad.

Before I bought the pump I had read up and it only seemed to be the 255 that caused problems, at worst I will replace the stock regulator with a better adjustable one.
Once I get the idle sorted I'll go back for a dyno run to check the rest of the fueling.

Just found a guy selling these for the 5 on ebay. So I can hook up any adjustable regulator with a gauge and dial the pressure to stock for idle.

[ger]

I bought a fuel pressure guage and T'd it into the fuel inlet line going to the rail. Expected to see much higher than stock but it sat at 35psi. So it would seem the new pump is not overpowering the regulator at idle.

Found my last nct and my CO was 0.41%

My low idle CO at the latest NCT was 8.5% this is equivalent to an AFR of 11.36 when it should be 14.7

I need to be under 3.5% CO to pass

Could my O2 sensor be shagged?
Anything else that would cause very rich low idle?

Here is a handy CO to Afr chart

[Steve]

Other things, check air filter is clean, that you aren't running rich due to (ECM) temp sensor on the rear of the head dying, check for vacuum leaks between air flow meter engine, might also be worth running injector cleaner through too (you could pull out the plugs and see if they are all the same colour, one might be leaking).

[ger]

Thanks steve
My boost gauge is reading as always 21-23hg at idle and no loss of boost pressure, If I had a vacuum leak wouldn't the hg have dropped or an intake leak would have affected boost pressure?
It idles fine, not lumpy but does have a slight fall off after revving that picks up and settles at 900 rpm but its hardly noticeable.
My o2 sensor is in the down pipe, i'm thinking the turbo heat over the years could have fried it, I see there is a voltage test but i'm not great with a meter. The ECM is a good bet too, do you know any way test this for a fault.

I don't want to throw parts at it hoping for a fix. Also its hard to tell if its fixed without a gas analyzer.

[Steve]

Thats good vac, mine is 19 (think I've a leak).
How close to the turbo is the 02 sensor? It could be the issue alright if its close. If you do change it, consider upgrading to a four wire, v.easy to wire in.
Here's how to check (the 1.6 has a single wire so ignore the stuff about the heater wires)


Heres how to test the thermoswitch/sensor on the back of the head (lots of vids on how to use a meter on youtube ):
http://books.google.ie/books?id=8eNAb48 ... &q&f=false
I'd also bleed the cooling system incase you have an air bubble under that sensor, it happens.

Actually... check your timing too.

[ger]

Sorted, turned out to be a broken o2 sensor wire
In getting around to the problem I took off the air flow meter and gave it a good cleaning with some Isopropyl alcohol and checked the flapper door was closing properly. Cleaned and oiled the air filter. Tested the water temp sensor. Put in some new plugs as the old ones were pretty sooted up.

Running pretty good now, thanks for the help steve.

[Steve]

sorted, nice one!