how many miles are on the car and how old are the 02s?

 

In summary: SOTP dyno?

A scanner is nice for diagnostics.

 

A lot or just a bit?

I thought if you wrap your lips around the hose and blow it should not let air through?

Must have missed it. Sorry

 

About 168,000 miles on car and the O2s are probably original since I put about 108K on it .

So driving to my meeting tonight it was harder to feel the hesitation. Also the fuel trim numbers were different. The long term numbers were now in the 121 to127 (or so) area idle or cruise. No more numbers under 120. Don’t know if I influenced any of the symptoms by playing with the gasket and making the cover tight. Got a few ideas going to play around with to see if I can change the trim numbers. When I looked at the downstream O2 sensor at idle it was about 50mv and in cruise was about 1/2 volt varying. I think that’s normal.

Also just for the heck of it I looked at some of my other OBD2 vehicles downstream O2 sensor with a scanner. The response is much different than the upstream as I remembered.

 

Downstream should be relatively steady. Both should be about the same or you have a bad cat somewhere. That or you have massive emissions down one side. Knowing what I know now, I'd change all 4 just because they are that old and see where we go. Big alarm to me would be front to front comparisons and rear to rear comparisons. IF one is bad, all 4 go unless they are relatively new.

 

the 94 has three two up one down.

 

I'd change all 3 to be certain

 

About 168,000 miles on car and the O2s are probably original since I put about 108K on it .


02s should be replaced at 60,000 as normal mantiance. they seem to be a bit neglected. you will see a big improvement if you get around to changing them. how long do you let your oil go between changes?

 

I have been suggesting this for two differant posts now. you can lead a horse.

this is a ob1 car being set up for a ob2.

 

I hear you and have not dismissed you suggestion on the O2s. Just not ready to go there quite yet. My past effort has been working the vacuum system to see if anything is leaking as is how I found the leaky booster.

I'm installing the new PCV today and expecting the top gasket sometime today.

Agreed and stated in my previous post as the 94 was a cross over year with some OBD2 software built into it but running solid OBD1.

Doing Mobil1 oil every 5 thousand miles. Only have 4K at this time.

 

you should be on your 3rd set of 02s for proper maintance.

it would be a good time while your under there to pull the knock sensors and do a proper flush. I put new ones in I could not bring myself to put back 20 year old parts. they come with the proper dope and torque is important. just pinch the connectors with your fingers to remove. might have to run a wire in there to dislogde the crap.

 

I do dump the fluid ever couple years and flush the block with a hose attached to the fitting for where the O2 sensor is. IIRC, Mercedes makes a citric acid flush of some sort to soak the crap out? IDK. AUto parts store with some sort of flush might be good. Just drain, fill with water, put flush, drive and drain and fill. Run for a bit, drain and fill again.

 

If the sensor is a 94 vintage with over 100K on the clock, what exactly are you waiting for?

As to the oil, I don't know if you should extend the oil change that far out without getting a lab test. According to my tests, the oil was fine for 6000 and I change it at 5000 for easy counting interval. If I go past 3000 to save a buck, I'd at least send it for testing to see how much further instead of guessing

 

might want to correct this before someone makes a c4 fountian.
the flush you can buy now is a waste thanks to the epa.
and buy full strength antifreeze an distiled water 50 50

 

You may want to check for leaking injectors.

 

http://www.benzworld.org/forums/w124...tem-flush.html

Never had to flush that way before but I never had oil in the coolant or let the thing sit for forever. I did it on another car and did notice that even after the water was clear and we soaked the crap in it, the water came out dirty so IDK

 

you always have good info but you drunk fingered this one.

I think you missed my point I have never done a flush in a 02 port.

 

DOH!! Knock Sensor port on passenger side, coolant nipple on driver side. My bad.

 

I just never got around to doing the O2 since the car always runs well. It still runs good just has that little annoyance I'm playing with currently. New PCV installed today.

Well right now I'm still working the vacuum system and not done yet. Received the gaskets for the throttle body however the bag was correct, but the gasket was wrong. Even my second source had the wrong gasket for the top of the TB.

The 94 is unique as the gasket is a solid rectangle. All other years use an open gasket which is the one I received. It seems to be a packaging problem by AC Delco. Currently working the problem, not a lot of choices around town. I think I have it handled and will know tomorrow.

I need to evaluate everything again once I get the gasket installed and happy with the vacuum system. At that point I will move forward.

 

Got a chance to do a 120 mile trip so I could really look at allll the numbers on the Tech1 for a long time especially the O2 and L and S fuel trim. The long term stayed pegged at 123 and short term varied around the 128 mark seeing 130 at times but was moving fast.

So that’s what I saw pretty much around town also. Shows slightly rich or 3.9% of the 128 mark. Short term trying to make up for it my leaning it out.

Got that Throttle body gasket installed. Finished with the vacuum system and happy with it now. Went around the engine 4 times with propane especially near the booster and EGR valve so looks good. Verified MAP with vacuum vs. voltage from a chart and is right on. Can't really verify MAF, no codes and historical data same as 5 years ago.

So no argument for not changing the O2 as ya'll are technically correct. Got under the car and wanted to just loosen the O2s just to see if I could after all this time. As I first did not have a optimistic attitude especially with no space to work in. Turns out got them loose with not too much trouble and just snugg them up again. Probably will zero in on the Denso 234-4012 sensor and get a couple of them.

Should be interesting to see if it affects my hesitation. Moving forward.