95 sunfire se 2.2L emissions failed

[flycar]

In a nutshell...
About a month ago the car developed erratic idle, misfire and rattling during acceleration and climbing hills, loss of power, strange pinging sound from muffler usually during deceleration, sooty deposits around tailpipe, and fuel smell at idle.
Troubleshot the ignition, fuel, and exhaust systems and found #1 cyl plug was fouled out, looked like oily carbon, but the other plugs had normal deposits, and also oxygen sensor was completely clogged with white crust.
Changed plugs, wires, and O2 sensor... nope, that didnt fix it.
More troubleshooting... found and replaced bad ignition coil. Car seemed to run better. But still had a fuel smell during warmup and bump at idle, kinda like a harley.
The next day...
I took the car down for an emissions test. FAILED The test showed three times the hydrocarbon limit at 664 versus 220. CO levels were below limits at 1.10 versus 1.20.
More troubleshooting... removed and found catalytic conv nearly plugged.
Replaced catalytic conv and yipeeeee no more fuel smell. Car ran alot better. But still had the bump bump bump at idle.
Next emissions test. They could not get a good reading... CO was .94 and CO2 was 4.80... something about "diluted sample" during the idle test.The told me to go check for exhaust leaks. Of course, found none. Replaced the donut gasket on the exh manifold anyway just to be sure. Still had the bump at idle.
Third emissions test... readings were even lower... CO was .86 and CO2 was 3.12... again diluted sample ...now what?
More troubleshooting, pulled the IAC and found lots of sooty buildup on pintle. Cleaned pintle and installed IAC with new oring. Started engine, nope that wasnt it.
Pulled the EGR valve and of course it was closed as it should be. Installed EGR and started engine. Pulled vacuum line to EGR. No vacuum at idle. Good. Rev'ed engine. Vacuum came up above idle. Good. Pushed up on EGR diaphram. Car quit. Thats good I assume. That wasn't it either. Now what???
My tags expired yesterday and I've got thirty days grace period on the failed emissions. I know its got to be something simple. Any help would be appreciated at this point.

[flycar]

Also replaced the fuel filter during this process of troubleshooting...

Things I have not done:

• changed grade of fuel (price of gas these days)
• checked coolant temp sensor per the chart
• pulled codes from ECM (turns out that I have a hybrid OBDII ECM with OBDI codes)

OH... and no check engine light ever

[GTP Dad]

Try changing the PCV valve if it has one and the other issue is the MAP sensor. This can cause irratic idle and some of the other issues you describe.

[flycar]

Yup... I forgot to mention that I did change the pcv valve.... didn't really notice a change in idle performance... but it might help keep the oil out of the intake... probably what fouled out my plug in the first place.

I was starting to lean toward the MAP sensor... my thinking on this is when I pulled the IAC to clean the pintle... I noticed alot of buildup around the seat in the IAC housing... I cleaned as best as I could without removing the throttle body assy... but I'm suspicious as to how much gunk is on the interior and what air passages may be partially or fully clogged... sounds like a project for tomorrow.

Thanks for the advice... If you think of anything else, let me know. I'll post if I find something

[GTP Dad]

I think your fouling issues were caused by the plugged cat. The throttle body gets gunked up normally due to the emission controls and the recirculation of gases from that. High CO levels usually indicate poor combustion. You may want to pull the plugs again and check them for fouling and replace them with a little hotter range plug. This will give you a better spark and thus better combustion. Also clean the injectors with a bottle of injector cleaner. Finally, remove the EGR and clean the passageways from the engine to the valve. Also clean the valve. Use throttle body cleaner to spray everything. One last thing you may want to do is look to see if you have two O2 sensors. If so change the second sensor. I am not sure if this particular car has one or two sensor.

[flycar]

As I guessed...

The interior of the throttle body was gunked up... I cleaned everything with throttle body cleaner. There was a finger sized tube inside the throttle body (I assume part of the EGR system) that was nearly closed off with oily gunk... cleaned that too.

Tested the MAP sensor by backprobing as follows:
Car on, engine not running : pins C-A 5.36 volts, pins B-A 5.13 volts... hmmm
Engine running: pins B-A 2.15 volts.... hmmmmmm
Throttle wide open: pins B-A voltage drops to 1.90 volts... that can't be right

According to the book, with the car on and engine not running, there should only be about 0.5 volts btwn pins B-A; and voltage should be about 1.5 volts above that with engine at idle... And, the voltage should be about 4.5 volts higher with throttle wide open...

Bad MAP sensor ???

The IAC did reset itself, however, idle really sucks now since i cleaned the inside of the throttle body...

I am going to try to clean the rest of the EGR system. And, yes, the car only has the one O2 sensor. Later models had the second sensor after the cat. thanks

[flycar]

well... I checked the coolant temp sensor against the chart... good at ambient and engine operating temps... guess that's not it.

Backprobed the MAP sensor again just to be sure... same readings as before... some web surfing kind of confirms that my sensor is not doing what it is suppoed to... new sensor is only $39.56 at Autozone... so it wouldn't hurt too much to throw that part at it, even if it doesn't change anything...

I tried pulling the vacuum line off of the fuel pressure regulator with engine running... nothing changed... that might be something to pursue... $64.99 at Autozone

I'm running out of ideas

[hotbug1776]

it's the cat probably, mine just went, I have a 95 as well, I replaced just about everything else last year. No PCV or EGR, but the MAP died, and the IAC needed cleaned. Now the CAT died, so, living in a nice area with no emmisions, I now don't have a CAT. I lost a little power at Idle, but that loss is nothing compared to the gains at mid/upper throttle. OMG the car hauls tail now even more than before.

so check the CAT as well, since it had also turned my tips black with soot when it started breaking down.

[GTP Dad]

Hotbug1776, he replaced the cat already. Still has problems.

[flycar]

Thanks hotbug... but as GTP said, I already changed the cat... as well as my plugs, wires, coil, pcv and O2 sensor... and cleaned and tested the EGR valve and IAC valve

Meanwhile.. more troubleshooting of the fuel pressure regulator, I found fuel residue inside the vacuum hose to it... possible ruptured diaphram in the regulator.. another good reason to change the regulator

My next project is to pull the injectors and check for fouling... I have a sonic cleaner and varsol to clean any deposits, if any... some reading on this revealed that if an injector gets plugged... the computer could get a false lean mixture signal and enrichen the other three injectors... and cause the whole system to act stupid... hence the high hydrocarbon reading on my first emissions test...

Still, any more advice is appreciated. Thanks in advance

[hotbug1776]

I guess I need to not stay up so late LOL.

[maxwedge]

Originally Posted by flycar

Thanks hotbug... but as GTP said, I already changed the cat... as well as my plugs, wires, coil, pcv and O2 sensor... and cleaned and tested the EGR valve and IAC valve

Meanwhile.. more troubleshooting of the fuel pressure regulator, I found fuel residue inside the vacuum hose to it... possible ruptured diaphram in the regulator.. another good reason to change the regulator

My next project is to pull the injectors and check for fouling... I have a sonic cleaner and varsol to clean any deposits, if any... some reading on this revealed that if an injector gets plugged... the computer could get a false lean mixture signal and enrichen the other three injectors... and cause the whole system to act stupid... hence the high hydrocarbon reading on my first emissions test...

Still, any more advice is appreciated. Thanks in advance

High hc's are raw unburned fuel from say an dead miss or an injector loading up a cylinder or the regulator leaking fuel into the vacuum hose. The pcm trys to lean the mixture down but reaches it's limit to trim the fuel pulse width. Make sure to change the oil, if gas diluted this can be a problem also, as well as a loaded up vapor cannister.

[Young Chuck D]

jesus man what did you do to the car...?

[DonTam]

Just something else to check, the intake manifold gaskets tend to leak on the 2.2 and cause irradic fuel mixtures.

[Tech II]

DonTam......check the date......