State Emissions Failure where to start looking

[ab_slack]

As the title suggests my 87 BII 2.9L everything stock failed state emissions. Nothing really had indicated a problem although.

I could point to a steadily decreasing fuel economy from a high right after replacing O2 sensor of 20mpg down to 16mpg over 6 months, but I don't know how much to read into that with winter time gas, lots more idling time in the cold, more local rather than highway driving and much of the time driving in snow.

It did seem a bit unhappy in some recent warmer weather but generally has seemed fine in the cold. Today it was pretty cold.

The failure was low idle emissions with unburned hydrocarbons being just over 1000 ppm with an allowed maximum of 220 ppm.

From the test report:
Low Idle- Fail (sits around 800rpm on the tach)
HC 1040ppm - 220ppm allowed
0.38% CO - 1.2% allowed
12.9% CO2
2.4% O2

High Idle - Pass (sounds like they rev it up to close to 2000 rpm for this test)
HC 105ppm - 220ppm allowed
0.49% CO - 1.2% allowed
14.3% CO2
0.6% O2

It does have the occasional miss at low idle which may be the unburned HC and the high O2 level, but when I went thru two years ago it seemed to miss even more and HCs were at 190ppm.

So not sure where to start.

Should the cat use that excess O2 and burn the unburned HC?

Could there be an issue with the new O2 sensor? And if so what would make it go bad?

Any other ideas where to start looking?

 

[RonD]

Idle is always slightly rich, but yours is very rich.

Usually if HC is high from rich fuel/air mix you would expect to see high CO as well but yours isn't that high

Is your engine temp running at just below 1/2 way on gauge.
Lower engine temp causes computer to run richer mix.

Check MAP sensors vacuum hose, MAP sensor is located on firewall passenger side.

Check for leaking injectors
Engine warmed up
Key on engine off
Press gas pedal to floor and hold it there
Crank engine, it should not fire

The above is the "Clear flooded engine" routine, it tells computer to shut off injector pulses but leave spark on.
Intermittent firing would mean fuel is coming in.
Could be leaky injector, or leaky FPR

Check Fuel Pressure Regulator(FPR) on fuel rail, remove its vacuum line and smell it for gas smell, replace it if there is gas or gas smell.

Seafoam in the gas tank can clean injectors, I use it once a year and it does smooth out my 4.0l's idle

Replace PCV valve just because, and make sure Vent hose is clean and crack free.

Leaking EGR valve will raise HC at idle but not CO

Also the valve guide seals, pull spark plugs and check tips for how and what engine is burning.
At idle vacuum is highest, so that's when the most oil will be pulled into intake via the valve stem seals, which raises HC.

What is the oil use like?
Could be getting some extra oil in cylinder from rings as well


Could be new O2 sensor issue but I would expect to see the higher HC on high idle test as well


On older vehicles the Cat Converter often has to be running at 90% efficiency to pass emission tests, but again I would expect high idle test to also reflect Cat issue

 

[ab_slack]

Yes air temp was just under the half way mark. My temp tends to move around quite a bit, usually bumps from mid gauge to three quarters, but in this cold air (25 deg) its been sitting a bit lower.

Last time I put a fuel pressure gauge on, pressure held quite solid when I turned off the engine. I would tend to think a leaky injector and or fuel pressure regulator would have caused pressure to drop fairly quick. Now that was 6 months ago so it could have changed and is a very easy check to do.

TY for the other information. I have never messed with some of that so it probably is about time.

I just remembered something. I had filled it up with premium last time I got gas as a change and it seemed to run a bit odd after that. It seemed okay today. Don't know if that could have messed with things.

 

[RonD]

Fuel octane shouldn't matter, could have been extra water in the premium gas, usually they don't add ethanol to premium so you notice the water more, but that shouldn't change HC numbers.

I would pull the spark plugs and have a look at what they tell you, keep track of which plug came from which cylinder, it can be helpful

 

[adsm08]

Running premium fuel in a Ranger could cause high HC.

High octane fuel is meant for high compression engines, it is resistant to ignition. A Ranger engine doesn't have the compression ratio to properly burn 92 or 93 octane. They are best left to run on 87.

 

[ab_slack]

RonD, adsm08, thank you for the info.

I tried the WOT test, and it just started up normal and revved. Either this doesn't have WOT logic or however it determines WOT isn't working be it a switch or just throttle position sensor.

Fuel octane shouldn't matter, could have been extra water in the premium gas, usually they don't add ethanol to premium so you notice the water more, but that shouldn't change HC numbers.

Interesting, I would have suspected potentially more ethanol since that boosts octane. Regardless I suspected that maybe cause premium doesn't move as much that I could have hit the station with tanks low and got some real crap.

Running premium fuel in a Ranger could cause high HC.

High octane fuel is meant for high compression engines, it is resistant to ignition. A Ranger engine doesn't have the compression ratio to properly burn 92 or 93 octane. They are best left to run on 87.

The fact that it seemed a bit odd after the fill (and the tank was near dry, took over 21 gallons) supports you here. It was explained to me long ago that octane refers to the point at which fuel will self ignite and since operation was a controlled burn, as long as octane is high enough to prevent pre-ignition higher octane isn't a problem. I can see however that there could be interaction with compression, the resultant temperature and ability to ignite.

My experiment with the higher octane was related to some really positive results I have had recently with some older 2-cycle engines which pre-date the ethanol in the fuel that have been cranky for many years. So looks like maybe a failed one.

I also had another thought. I didn't watch them closely. I heard them start my BII a couple times. It used to be they never turned off the vehicles, but they changed procedures some time ago for safety and environment to turn off vehicles. If vehicle is warmed up when I get there, if they let it sit for 5 minutes, start and test immediately is there risk they measure before entering closed loop?

 

[Andy D]

You need to take the test with the temp on the hot side. How old are the ignition parts? Air filter and oil ? I'm surprised NJ emission tests pre OBDII cars, MA doesn't anymore

 

[tmcalavy]

Tune it up...new plugs, rotor, maybe wires, etc. after you drop a can of sea foam in the tank and use another can to degunk the top end. After you sea foam it, then change or clean the plugs and run the snot out of it at road speed for 30 minutes or so. Sounds like it been eatin' a steady diet of winter gas and lots of around town driving...time for an engine enema.

 

[ab_slack]

You need to take the test with the temp on the hot side. How old are the ignition parts? Air filter and oil ? I'm surprised NJ emission tests pre OBDII cars, MA doesn't anymore

Ignition parts are less than 2 years old and have less than 10K miles on them. Same with air filter.

I suspect NJ will stop doing emissions testing on the pre-OBD2 stuff when the first model year where everything was required to have OBD2 reaches 25. At that point anything they fail can always get antique plates.

Tune it up...new plugs, rotor, maybe wires, etc. after you drop a can of sea foam in the tank and use another can to degunk the top end. After you sea foam it, then change or clean the plugs and run the snot out of it at road speed for 30 minutes or so. Sounds like it been eatin' a steady diet of winter gas and lots of around town driving...time for an engine enema.

Yep already dropped seafoam in the tank tonight. Everything you mentioned are pretty much the top things I would turn to. I posted the query mostly because, as I mentioned above, the ignition stuff isn't very old. Also I felt it was out quite a bit.

I'll check those things anyways cause something can always be going on and plugs can highlight that.

Anyways I appreciate all the ideas. There are a number of items on my todo list to check out and those which also got mentioned here get bumped to the top.

 

[ab_slack]

Okay, got her re-tested today....and FAIL

Again low idle, again for unburned HC. HC were reduced from 1020 in the prior test to 339. The standard is 220.

O2% dropped from 2.4 to 1.0 so that is saying to me more is getting burnt

High Idle showed some improvement with unburned HC going from 105 to 67. O2 didn't change on that one.

Idle seems someone smoother now than it was when tested the first time. When it passed two years ago idle was worse than it is now.

They shut the vehicle off for 10 minutes before testing. The start it up for 2 minutes and started the test. I don't know if that is enough time for it to get past its start up drama and get back into closed loop.

The only real issues I spotted going thru were ACT sensor, thermostat, horrible PCV system, and an EGR sensor (and EGR not opening). I know the EGR is closed however and since this testing is at idle I didn't resolve the EGR not opening issue. The EGR control solenoid is not getting vacuum to it so it can't deliver vacuum to the valve itself.

MAP sensor tested good, TPS tested good, ECT sensor tested good. Could still be a wiring issue I suppose but no codes for KOEO or KOER tests other than the EGR not opening.

Plugs all looked the same, good gap. Wires, cap and rotor I didn't look at too closely.

So other than it just being cold, I am thinking maybe the cat isn't being efficient, or at least at low idle it doesn't get warm enough to work.

 

[Mark_88]

If the cat is OE I'd suggest putting on a new one...and fix the EGR vacuum situation...that should get it passed.

EDIT: I guess they don't have a Repair Cost Limit or similar...in Canada they set the repair at $450 and if it fails the test you get a diagnostic ($125) and if they see that the RPL is exceeded you get a Conditional Pass...my truck has NEVER actually passed the test...7 conditional passes later...

You could probably petition the government to get that implemented...

 

[ab_slack]

If you can demonstrate, I think it is $500 they will give a conditional pass. I am not near that yet. I am closer to $240 even if I include that MAP sensor I got because I diagnosed it wrong. When new one also showed failed too, found my mistake, went back and checked the original and it was good.

I guess the other thing that crosses my mind as potential issue is fuel injectors. I am fairly confident they aren't leaking since fuel rail holds pressure very well, they my not be making good spray pattern or providing the correct volume despite cleaner.

 

[Mark_88]

I guess I've been fortunate then. They always find something worth more than the RCL. Last time it was the carburetor, which in Canada costs somewhere around $500 to replace.

Having the HC drop as much as it did since the last test indicates you are doing something right. Still sounds like the cat.

I've heard numerous stories of people going through similar situations only to replace the cat and have it pass with no problems.

 

[ab_slack]

Fuel injectors are on the list of things to address. Cat has been on the suspect list just from age. I am pretty certain it is the original.

I've been reluctant to do something with the cat mostly because I was uncertain about other items. Didn't want to put a new one to have it degrade because something was dumping too much fuel down the exhaust...but I am guessing from these numbers which aren't too far off and some residual O2 it isn't overly rich.

 

[ab_slack]

I've heard numerous stories of people going through similar situations only to replace the cat and have it pass with no problems.

It passed after pulling the initial timing setting back from 11 deg to 8 deg and by...replacing the cat.

Pulling back the timing was suggested as a "trick" that is generally helpful, but didn't do too much, left it there. Put a new cat on it and it came down pretty radically. Went to local shop which still had something to measure tailpipe output to check things before going back to the state inspection. Unburned HC after driving was down around 10ppm. Over a period of time at low idle it would creep up to 40ppm.

I expect the engine still is putting out the unburned stuff and the cat is just converting it. Probably not the best of situations. I actually think at the retarded timing it runs a bit worse so will probably tweek that back to 10 deg.

Ironically when I went for the test today, unlike previous times where they had me turn it off the ignition immediately, and there was a 10 minute gap before they turned it on. They had me keep it running and only asked me to turn it off immediately before they had me get out and the guy got in to do the test. It was off for less than a minute. It probably would have passed last time had they done that.

I wonder if my bitching last time got into the ear of someone and they looked up how they were supposed to treat older cars. I dunno. Different people this time than before.