Found something in oil change

[560slsteve]

thanks rocky,


i was thinking of that sensor, and it probably needs changing, and i will get my mechanic's CD and check the voltages after the holidays. it does seem like it is doing it now earlier than before, when it ran like a sewing machine at idle and then got rougher when it got warm. that is telling me the warm up injector is getting the right mixture, and then it leans out when the car warms and that injector turns off. i did pull the wires off that engine temp sensor and the idle really went to crap, but i guess if its a little off the effect will be slighter.

i will check that closely and follow your advice about the ALLDATADIY service--sounds like something very helpful. I agree with the diagnosis idea as the part throwing will be expensive.

I just replaced the dash wood and console with teak after getting the AC completely redone, and got new seats. when i feel the car is mechanically sound i am going to replace all the light lenses, the glass ,and put a great paint job on it, even thought the original is still good. with the new CAFE standards just adopted, this car should really be unique around 2020 when everyone will be driving a Leonardo DeCraprio motorized phone booth and worrying abpout carbon credits. i hope they grandfather this thing in, because i burned enuf carbon credits today to make ALGORE proud!!!

thanks

[rocky raccoon]

Steve:
I hope not to be a pain in the ass but something else occurred to me irt your idle miss. If you are sure you are going to lean instead of rich and you checked all the usual vacuum suspects, one more simple check is in order.

Once I fixed the driveability issue with the temperature sensor, I did find a rough idle which felt like a classic vacuum leak. I found a vacuum hose that originates on a spigot at the rear of the passenger side intake manifold. It is easily overlooked since it is hard to see and access. It is between the rear of the engine and the firewall. This hose runs along the upper firewall and provides vacuum to a three-way connection entering the passenger compartment through the firewall in front of the driver's position. That three-way feeds the "Economy" indicator, the driver door power lock and something else I'm not sure of. In my case the flexible rubber section at the manifold output rotted and split probably from exposure to oil. I replaced it with a piece of thick wall plastic tubing.

The big clue for me was that the "Economy" indicator not going full range and the driver door lock being intermittent. I mean who cares about "Economy" with these things anyway. I did not associate those problems with my rough idle until studying the vacuum diagrams in alldata. The result was everything works and the idle smoothed out at all temperatures.

One caveat with ALLDATA. It is not very user-friendly. It can take patience to dig through it for the information you need and some of the photos are terrible. I still believe it to be an excellent investment. I was very unsure of maintaining this overcomplicated car before using it and now I feel much more confident.

Merry Christmas to You!

[ctaylor738]

It sounds to me like you have two problems: 1) a miss on #8 when warm, and 2) a general problem with the computer unable to get control of the mixture.

WRT 1, if you have done the plugs, wires, and injectors, there's not much left besides the FD or the line, but you might want to re-check the seating of the injector. You can also try switching the line on the FD and see if the miss moves to another cylinder.

WRT 2, change the oxygen sensor and see if that helps. You can find a generic heated sensor for less than $40 and connect to the existing harness. The other thing that might be happening is that the electro-hydraulic actuator aka EHA is not working right, so the computer is sending the signal, but the EHA can't change the mixture.

You can check the mixture with a DMM with a duty cycle reading by connecting to Pins 2 and 3 of the diagnostic socket. Lots of posts on how to do this.

[nobby]

We had a military Karcher pressure washer come in the shop for repair. The engine was seized. Upon disassembly, we found a connecting rod broken. Why, do you ask?
Well it seems as though some one at the factory had misplaced an 18 mm socket in the crankcase and it had taken 120 hrs of service to finally do some damage.

These things do happen.

[560slsteve]

thanks for the replies rocky. i appreciate any suggestion on this car.....some people on here have probably forgotten more than i will ever know about this car, so every little bit helps.

i did check that 3 way vacuum hose--hooked the hand held vacuum pump to it and it held a vacuum back to the engine and into the passenger compartment, so i figured no leaks there. beofre this happened, i did find a few deteriorated hoses and replaced them , but no help onthe idle miss. like i said, the car runs greta at speed and has plenty of pickup, but just seems todrop a cylinder at idle, which aggravates me to no end. it used to run very smooth at idle.
about the economy, or lack of economy gauge, it seems now that the needle doesnt bottom out at idle like it used to. it may never have, and i am just now noticing it. i thught at idle it used to rest onthe pin, and now it stays about a needles width tot he right. it goes all the way to the right when you put your foot into it. when i am coasting downhill at speed, the needle goes to the left and stays on the pin, and the car will sometimes surge like its trying to breathe. goes back to normal when i throttle up.

Ctaylor,

i have replaced all the wires (with correct resistance), and rechecked the #8 injector seal. took it back out and re-installed, thinking it may have been cocked or something---no dice. i will check on that O2 sensor--was thinking about that, but i have an O2 sensor light on the dash which i thought was working--it comes on when you turn on the ignition, and goes out once the engine starts.

i have read about switching the lines on the FD, and when i took #8 off and cleaned the line, i was scared to replace it with a different one--it seems they are cylinder specific and i didnt want to bend or crack one---i am guessing i need to make up a flexible line of some sort to do this? that way i will really isolate the problem and be sure its the FD clogged in that port.

I wish the FD was something to take apart and clean and rebuild, but from what i have read on this forum and some porche forums, it may be better to leave it to the pros. i read about a place called Jaytan industries that rebuilds these things, but have to research them further. what i read, they will take the old one apart and tell you what they find, which is what i am interested in--not just changing out a part. if everything else fails to solve the problem, that will be my next step in this process.

now if i can just keep crap from showing up in the oil pan!!ha just anther SL deal--i also replaced the speedo cogs , like everyone else has, and got that fixed, but now it sounds like a bomb ticking everytime the 10th of mile number ticks over---guess i need to grease that!!!! at least its reading the proper mileage now. another SL learning curve, plus i now know how to cuss in german, which also seems to help sometimes while working on this car.

thanks for the replies.