93 300e 2.8 failed emissions ..need help

[Argospete]

My 93 300 e just failed.emissions for the 3rd time in one year. Hydrocarbons are too high at idle??. It passes the other testing. What do I need to do to pass?? Cat has been replaced and plugs only have about 5k on them. I need help?? Cant renew registration without passing

[liquiddog]

I have passed several times by putting CRC Guaranteed to Pass in the tank and running it down close to empty. Then refill and run the crap out of the car to get the cat hot. Get tested right away.

That has worked for me in Texas. Cali has tougher standards I think.

[Argospete]

Tried the guarantee crc to pass and did not work. At idle the hydrocarbons are double and the co level is above the limit at idle...I have spent a lot of money on this car in the past 2 years and dont want to let it go. Need help people!!!!

[97 SL320]

Does this have electronic FI or CIS?

If CIS, engage the adjusting allen screw and pull the plate up and down to see if the idle smooths out.

If electronic FI, pull the vacuum hose on the pressure regulator and see if liquid fuel is leaking out.

With either, a tired oxygen sensor can cause problems.

[MAVA]

Maybe check live readings with a scan tool

[Argospete]

I think I am going to go ahead and replace the oxygen sensor and see if it passes. I have had two mechanics look at the car already and cant give an answer without trial and error and start replcaing parts which can be costly.

[Argospete]

I just changed the oxygen sensor and put some fresh 93 octane gas and a bottle of injection cleaner. I take test and I failed.....The hyrdocrabon levels are still too high at idle..the normal is 220 and I reading 290.. at idle.... I went twice for test and failed twice this week, second time I failed hydrocarbon at cruise as well for first time...I have been driving the car for 3 days straight now....need help!!!!!! What next???

[jcyuhn]

You need to pull the codes from the ECU. To do this build the Arthur Dalton code reader. Use search or Google to find the directions and parts list here. Used to cost 10 bucks at radio shack. Then pull codes from pins 8 and 14 and post them up here.

How does the car run? Smooth idle? Good power? What's the mpg?

[Lucas]

I've gross polluted here in Cali and had to go to the referee. It was actually great. We went through the whole motor and he showed me what to fix.

I don't know your car, but almost all the electronics can usually be tested for resistance values. Like the oxygen sensor. I've always had luck cleaning stuff as opposed to replacing. Toyotas have that sensor kinda like a MAF, right after the airbox. Those can always be cleaned up and run.

Just some thoughts. If not, it's usually about $250 to pass 😏


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[C.Doner]

high CO and HC at the same time usually points to excess fuel. Not just a rich mixture. You could have vacuum leaks as well which will lean the system out. If your ECU compensates for the lean mixture with more fuel you get high emissions all over the place. The first place after the tune up parts to be positive about, is the vacuum system. Make sure all vacuum hoses are in order. Then from there look at the fuel injection. Make sure all injectors are working properly. Start with the simple things then move on to complex parts.

[oldsinner111]

if you have high mileage they won't pass,as you are burning a little oil.

[Argospete]

I am getting high hydrocarbon readings at idle and co levels are passing. Car runs smooth at idle. It was a cold rainy day today and the fumes and smoke from the exhaust were strong. But once I put on the highway and drove for about an hour the car was not smoking from the exhaust. Yes, it does burn a bit of oil as it has 178, 000 miles.

[Stretch]

Originally Posted by C.Doner

high CO and HC at the same time usually points to excess fuel. Not just a rich mixture. You could have vacuum leaks as well which will lean the system out. If your ECU compensates for the lean mixture with more fuel you get high emissions all over the place. The first place after the tune up parts to be positive about, is the vacuum system. Make sure all vacuum hoses are in order. Then from there look at the fuel injection. Make sure all injectors are working properly. Start with the simple things then move on to complex parts.

With reference to this ^^^^

I'm not sure if this will be a wild goose chase (or not) but I was reading about tuning my M102 engine and there was a bit in the FSM about disconnecting the fuel tank vent from the system when checking idle speed and the behaviour of the fuel injection system. My M102 (for emissions) has a carbon filter system for the fuel tank that eventually leads to the air intake - essentially after a bit of cocking about the nasty vapours from the fuel tank end up going into the air intake. This can raise the idle and make the mixture too rich.

I wouldn't be surprised if that was also the case for the OP's car - this is just one way in which a mixture might end up with excess fuel.

[Hirnbeiss]

High HC alone could just be a bad cat. With your mileage not a crazy possibility. You know your O2 sensor is good.
Common Reasons for Failure | EnviroTest
Otherwise, I would get some good diagnosis before throwing parts at it.

[oldtrucker]

What state?
I have an E320 221,000 miles first cat, still going strong.
Maybe different with yours, unless they get treated badly, they will be good for a long time.
Aftermarket, is a different story.
I would see if there isn't any un-metered air going in. (could tell how, but most would discourage, because they think it's too dangereous)
If you know how long your O2 Sensor is in, you can guess, or take it out and check visually.
However, HydroCarbon is high and not the carbon dioxide, if I remember right, meaning too much water content.
When was the last oil change?
Do you have, at operating temperature water discharging at the pipe?
Is the inside of your oil cap clean or foamy?

Most important is to check for vacuum leaks, broken vac lines, disconnected couplers, make sure the rubber couplers are in good shape all around, not just at the top. Also, make sure they fit snug.
Vacuum leaks can cause all kinds of problems.