High emissions

[doommachine]

Hey guys,
OK so my car has been emission tested, and I have done all that I can think of to lower the emissions. I am getting very high HC and mid-high CO readings (900 and 3.5% approx). My base timing is 5 degrees, my idle AF is about 14. All I can think of now is the fuel pump (walbro, in the process of changing it), FPR, and lack of spark.

How do I test the spark? Would getting larger gapped plugs increase the amount of spark? Is there some way of testing the actual output of the coil without causing myself huge amounts of pain?

Anything else anyone can think of?

 

[AUSVR4]

Wouldn't closer gapped plugs increase the spark?

Do you need a stock fuel pump?

 

[brisvr4]

Did you make sure that your cat was good and hot when they did the test?

 

[doommachine]

Yeah I just installed the stock fuel pump (my knuckle is bleeding from the MOTHERF&&*ING 14" nut.. they're right on the VFAQ. Vice grips help). Car seems to be a lot better, the idle is dead smooth, and so if the vacuum at idle. Black water is now shooting out of my exhaust pipe, which I assume is a good thing (it doesnt smell like raw fuel, it smells like dirty water).

I did want to pre-heat the cat but I had to wait to get tested, and when I suggested it, the guy said it wasn't what regency were interested in, just the emissions at cold idle or something. I thought it sounded BS, next time I go I will definitely heat it up.

Edit: with the plug gaps, surely if the gap is further, then more potential difference is required to make a spark happen, and the spark would be bigger + have more energy? I thought the point of closing the spark plug gap on high compression applications was to minimise the time the spark is there to get more ignition accuracy at high RPMS?

I could be wrong, that is just how it works in my head

 

[JAP63]

Edit: with the plug gaps, surely if the gap is further, then more potential difference is required to make a spark happen, and the spark would be bigger + have more energy?

Correct.

 

[doommachine]

So new plugs as well, another set lol...

 

[Entaran]

So new plugs as well, another set lol...

Oh no. not seven whole dollars.

 

[matress]

try putting hotter plugs in there too... 5's or something maybe

hydrocarbons are unburnt fuel aren't they?

 

[doommachine]

Hahah.. seven bucks, where are you getting plugs from? Yeah HC is generally unburnt fuel, especially if the CO content is high. Apparently you can have high HC and low CO if the mixture is too lean as well.. complicated... I will get hotter plugs too, I asked the mechanic too but he reckons it makes no difference...

 

[doommachine]

Blurb, still bad. Going to have to pay someone to look at it

Anyway.. the mechanic suggested that the injectors could be damaged due to the high flow of the fuel pump..and also the FPR.

Any easy test of the FPR that anyone can think of? Are damaged injectors obviously, visibly damaged?

 

[TMP73N]

in order to have good emissions a few things have to be taken into consideration. firstly how good is your compression? secondly if your factory computer is still running standard and you have modified the fuel system it will be very hard to bring the emissions down automatically. if you have 900 HC's ppm and a dangerous 3.5co then your vehicle is running way too rich. try putting smaller injectors, reducing fuel pressure, check your air filter, get your mechanic to check your O2 sensor operation. once you modify things like the fuel system on standard management systems, it will never run as good as factory because its out of the computers hands. all things modified must be considered.

 

[doommachine]

Compression is great, the engine is close to new condition (already checked).

Fuel system is now pretty stock.. but I didn't consider the air filter, I have noticed it runs crappy now that I have the airbox over the filter... I dont have the intake pipe, so it would stand to reason that hot air is getting sucked in...

 

[blackvr]

I do a lot of emission testing for Regency, a lot of diagnosis, and a lot of Mitsi work. Firstly, 3.5%CO in itself is no where rich enough to cause 900ppm HC's. High HC indicates in general engine combustion inefficiency.With your example, things to look at may include incorrect cam timing ( dont assume the TDC marrk is accurate in Mitsi's, keyways wear!!), Air leaks for individual cylinders ( ie lean misfire). Air leaks may include inlet manifold gasket leaks from shrunken gaskets. Richish mixtures sort of hide this , so unclip injector wires one at a time to find the "lazy" cylinder after disabling the IAC motor.

Next, mitsis work in closed loop operation at idle when they warmup. Expect to see 0.2%CO and 150ppm at idle in closed loop. If your sensor doesnt have a heater circuit to bring it up to operating temp, then holding the revs at 2500 rpm for a couple of minutes will do the trick... until a couple of minutes when it cools down and falls out of closed loop, and goes back to the base richness. Many mitsis I see have dead or very lazy O2 sensors, especially those in excess of 150K on the odometer. I use my oscilloscope to confirm the O2 sensor operation. The base mixtures of the ECU before the O2 sensor adds its correction is approx 3.0 % CO......

Dont get too hung up on spark plugs at idle , the mitsis are pretty tolerant on that front.

Best luck... cheers Mike

 

[3zercrowd]

Man you should be telling the MGEC guys this sort of information :wink:

They HATE regency down there. :lol:


Not that they are having a personal attack on you of course.

Join up the forum and help them out

Cheers, good information :wink:

 

[doommachine]

Thanks for the info, very useful. There is a guy looking at it for me now, he should be able to fix it .

Edit: Actually you do raise some very interesting points.. so the CO, though high, isn't in line with the high HC... so one cylinder could be misfiring, or running lean.. certainly the car runs fine, drives fine, it's just the idle that is messy. Throttle response is good, the car doesn't knock (I still have the knock link installed, I will pull it before regency) under load.

I have a fairly new O2 sensor, it seems to work well. It does have a heater. The voltage at idle generally swings wildly from 400-800 mv... when the idle drops and goes funny, it goes down to 86 mv... which would be inline with what you're saying, the car has a leaning out error.

Maybe one cylinder is running particularly rich (having pulled the spark plugs, it is probably the one closest to the transmission, that spark plug was black as night, the rest got better as they got further away from the input side of the fuel rail), and the closed loop operation drops fuel to the point that it leans out on the other 3 cylinders. The cylinder on the timing belt side was a little grey around the edges. Maybe it is my FPR?


Sound reasonable? I am just guessing

 

[blackvr]

Hey, I'm one of the good guys ! I run a dyno, and a lot of my work involves emission reports for guys needing to go to Regency RTA. You guys need all the help and tricks to get past the very blinkered authorities.

Doomsday, your spark plugs are telling the story. Note that 86 mv is a very normal number. You really need to see it oscillating on the scope to get a better idea. Next trick is to hook a fuel pressure gauge and make sure it is ok. then pull the vacuum hose and confirm the ( higher ) base fuel pressure as per manual ( 3 to 3.5 bar ?) Maybe the FPR is faulty, or if you have a hi volume fuel pump, it cant return the excess fuel and consequently the pressure goes up. Got a spare set of injectors if you have a crook injector sqirting to hard ?

Also, you can get air leaks into individual cylinders from hard shrunk injector seals. Took me ages on my VR4 to work out why I had idle issues. If you "cheat" the AFM ie air leaking past the seals, that can give overall richer mixtures. A water squirt bottle is great for finding manifold vacuum leaks. You'll hear the engine go down a cylinder as the water kills combustion.

However, if the sparkplug as black, better work out why ! That blackness will most certainly cause hi HC's. A definitve test of which cylinder is wobbly, is to stick the 4 gas analzer probe up the exhaust, disable the IAC, and one by one unclip the injector plug. 100% sure way of finding which cylinder is contributing to the HC's !! Pulling the injector plug means no fuel and that means zero combustion ! that is no HC's for that cylinder.

Cheers Mike

 

[doommachine]

Hmm.. you make my head hurt with all of the awesome info.. well hopefully this guy can work it out and make it alright.. hehe.. should find out tomorrow! But it definitely sounds like a faulty injector or something like that.

 

[AUSVR4]

Mike,
I know your one of the good guys!
If only you had access to a AWD dyno...
The guys I was reccomended were farkwits

Cheers
Dan

 

[blackvr]

Dan, I have got access to an AWD dyno......

 

[AUSVR4]

Well then we need to talk