Fail Smog Check at idle and car start slow

[Ted]

I took the 94 Q45 in for the smog check yesterday. And it fails at idle, but at 2500RMP - it is fine. Lately, the car starts a little sluggish between 1000-1800RPM. So I am not surprise that it fails. The car has 88K miles on it. The last time I took it to the dealer was at 75K and they did not do much except for lubing and checking the parts. I want to do the maintenance this time around. I have read a few post about maintenance for the Q45. Some of you gave very good advice in the previous posts. Here is what I know I can do:

1. Change the spark plugs2. Change the oil, oil filter and air filter.

But some of the previous post suggested:3. TB Cleaning4. Plenum Cleaning5. Intake Cleaning6. Rail Flush/Injector cleaning7. MAF cleaning.

How do you do these? Are there any diagram or pictures that you could post here so I can have an idea.

I appreciate all of your advices.

Ted.

[maxnix]

Ted, welcome to the board. Where are you located? How does your car fail at idle? HC? NOx?

3. - 5. and 7. on your list are mostly manual labor and are detailed in the posts. 6. requires a machine and solutions, as detailed also in the previuos posts.

Don't forget IAC and EGR valves. How long have your O2 sensors been installed?

[elwesso]

Take a few days to do searches on those things, and you can decide what you can/cant do.......

[90Q45blue]

Don't forget IAC and EGR valves. How long have your O2 sensors been installed?

I agree w/ Brian. EGR is *very* important for emissions. Just clean the Tube and the Backpressure Valve and while you're in there replace the Valve Gasket ($1.12 from Joe). Also, O2 Sensors are a must. go to http://www.sparkplugs.com for a good price.

Nick

[elwesso]

Will the new o2 sensors increase performance???

[90Q45blue]

Will the new o2 sensors increase performance???

Yes, very much so. Loss of original power on a Q engine can be attributed to many things but two of the most common are:

old/worn O2 Sensorsbad MAF/MAF connection

Nick

[elwesso]

are the sparkplugs.com o2 sensors cheaper than Joe??

[Ted]

"Ted, welcome to the board. Where are you located? How does your car fail at idle? HC? NOx?"

I live in San Jose, CA. Here is the result of the smog check:

%CO2 %O2Test RPM MEAS MEASIdle 789 13.6 02500 RPM 2474 14.4 0

HC (PPM) Test MAX AVG MEASIdle 100 17 1882500 RPM 130 12 2

CO% Test MAX AVG MEASIdle 1.00 0.00 2.092500 RPM 1.00 0.10 0.01

ThanksTed