PCH

Hi Guys,

I'm a new member on here, but have been driving a 96 ES300 with 188k mi on it, since new.
I have to do smog check here in CA for registration renewal.
I thought that it would pass easily, but the HC (hydrocarbon) figures were higher than max, at the 15mph and 25mph mark.
Anyone else have similar experience?
Smog guy said to do a tune up, but my mechanic says its a bad catalytic converter.
Just wondering if anyone has had similar experience & what the issue is.

Thanks in advance,
PCH

mdbrown

How is the car running? When was the last time it was tuned-up? What were the readings from the low speed and cruise test? It's possible that it needs a cat but it's also possible that it's a lean misfire. It could be a failing fuel pressure regulator... or arcing plug wires. Hard to make any kind of determination at all without at least the readings from the smog test. They'll at least get you a starting point...

GS4_Fiend

iTrader: (22)

Post the Full Results. All the 5 gases and Min, Max, and Measure.

PCH

The car is running fine. Only thing that I feel is the slow acceleration from stop, but everything else seems fine. Once it gets up to speed, I can't complain at all.

The numbers from the smog check are as follows:

15mph - C02 (%) meas 14.80, 02 (%) meas 0.04; HC (ppm) 51 max, 9 avg, 57 meas
25mph - C02 (%) meas 14.80, 02 (%) meas 0.02; HC (ppm) 35 max, 7 avg, 46 meas

The C0 (%) and NO (ppm) figures seem to be in line with the average, so I'm not posting those.

Lean misfire...intersting.

Thanks.

PCH

Thanks, I just posted the HC figures.
The CO (%) figure is virtually none.

NO (ppm) was

15mph - max 419, avg 57, meas 67
25mph - max 706, avg 50, meas 33

PCH

I think it's been a while since I did the tune up, probably 40k miles ago. I just had the oil change done last week, though.

I've had a sleugh of car issues lately & been getting them taken care of.
Most recent was a deteorating upper radiator hose that I had changed out. Part was only $16 at pep boys.

mdbrown

Sounds like a misfire to me. Your not getting too much fuel or your co numbers would be out of line. At the same time I doubt the cat is the issue as the co would be high as well. Check for unmetered air getting in behind the airflow sensor (cracked or loose intake boot or vacuum leak). That would explain the poor acceleration too. Looks to be a classic lean misfire condition...

TomS209

I also had maxed out in California for the hydrocarbons. I was as high as you could go and still pass on the dynometer. Figured I would need a cat the next test. Prior to the next test I drove it for about 15 miles and left it idling in the parking lot. They took it and did the test ( I thought it would flunk) and the tech came out commenting on what a clean vehicle it was. The hydrocarbons were less than half of what they were two years prior and it had 160000 miles on it. I recently took it in again for it's next test and it passed clean again. The catalytic converters can go bad but I would make sure the motor was good and hot when you take it in and let it idle until the tech takes it. It worked for me these last four years. Good luck. I did have to replace a cat on my Honda with 80,000 miles on it but the check engine light was on intermittently for about one year and the code pointed to the cat. That was about 5 years ago and after replacement I've had no problems. Went with aftermarket for about 300 installed.

Tom

GS4_Fiend

iTrader: (22)

Try cleaning your MAF sensor. It will help alot. Also, I notice the oxygen is at .2-.4%, looks like your car is still cold. As the oxygen content goes lower, the cat will work much efficient and all the emission will go down a tad lower. So before smogging it again, clean your MAF sensor, change air filter if dirty and drive the vehicle around for a good 30 mins then get it smog. Hope that helps.

PCH

Thanks for the reply.
I will try cleaning the MAF sensor.
Oxygen: yeap, car was still cold. The technician did run the car for about 5min, but I doubt that would warm the car up enough.
I will drive the car for the whole day the next time I take it in again for the smog check.

I got a quote for $225+tax for a catalytic converter (incl install). If I had to get a new cat, I was thinking of going with a hi flow cat & squeeze a few extra horses... anyone tried a hi-flow cat?

Car's not worth $ to sell, so I might as well keep it maintained and drive it as long as I can. It's a great daily driver.

PCH

Thanks for the reply Tom, I will try to run the car for a while before letting the tech re-smog the car.

My ES seem to run fine, except for the lack of acceleration....(or maybe i'm not as big of a leadfoot as i was before). Mine has close to 188k miles on it now.

mdbrown

FYI, the do a low speed and cruise test so the cat doesn't get cold. That's the reason for the dynomometer testing. Your readings don't point to the cat. High hydrocarbons means excess unburned fuel in the exhaust stream. Weak spark or lean misfire. If it were too much fuel then the CO reading would be off the board, if the problem was a weak/failing cat the O2 and Nox readings would be high.

Best bet would be if you hook your car to a scan tool with streaming data so you could see what's going on with the engine under load.

PCH

Thanks mdbrown!

Maybe I do need a tune-up (spark plug, wires & coil). I haven't done that in a while.
Scan tool: i might have to go to my local mechanic for that. I don't have a tool @ home.

As far as excess unburned fuel: you know, I do smell fuel smell....esp in the mornings when I'm warming up the car. I was getting high on it.

I've been getting 91 octange gas for the car, 95% of the time too...that's the best in CA. I'm sure other states have higher octane unleaded gas available. CA emissions is a PITA.

schan1w

Before you do anything, I would get it retested. Run the car all day and keep it idling before you hand it over. My tests have been ALL over the board each time. Some years, it barely passes, other years, it passes with flying colors. I don't think the machines are very well calibrated and also a lot depends on the gas / how hot the engine is, etc. I'd just retest and you very well may pass. Your numbers are that far away from max.

mdbrown

Don't let it idle too long before it's tested. Idling allows the cat to cool down which was one of the reasons for the loaded mode testing.