Hello, I am new to this forum, so if my question is a common one, forgive me. I have a 98 SL with 210000 miles. I acquired it when it had about 178000 and it has performed amazingly well and owes me nothing if it died tomorrow. However, I have become a bit spoiled by the fuel efficiency and would like to keep it going a while. Recently, with the cold snap here in Colorado, the car is very hard to start when the temps are below 30 or so, and will not remain running without holding the throttle full out for a while, while it coughs and sputters its way to where I can hold the idle at about 1200-1500 RPM. The plugs and wires are relatively new, but I know little else about the condition of many things about which I have seen posts.

I do get a "check engine" light at erratic times and have not had that checked, yet, which is likely the thing to do, but wanted to ask here, first. Sometimes if I get in it and drive it a few miles, shut it off and come back it will not start unless I hold the throttle to the floor and then nurse it back on the road. This is not how it has behaved previously.

It is likely unrelated, but the engine temp gauge nearly always shows just barely off the cold mark, but seems to put out plenty of heat in the car. I replaced the thermostat, when I first noticed this a couple of months ago, but it didn't make any noticeable difference.

Also, it is starting to use a bit more oil, perhaps a quart in 500-600 miles, and before was about a quart in 1200.

Again, the car owes me nothing, but if I can do a few things to keep it going, it would be great! Thanks for any and all feedback and I hope I have included enough information. I plan to get it scanned, as soon as I can.

 

Those symptoms are consistant with a faulty ECTS which is a 15$ coolant temperature sensor located on the drivers side of the head. It could be related to the erroneous temp gauge reading. Replace it and let us know the results. If it is running rich because of this I suppose it could result in excessive oil consumption by washing the pistons, but I think thats a stretch. Remember cars aren't like wine, they're more like a woman, and like a wife it's cheaper to keep her.

 

Thanks so much for the quick reply. Definitely worth a few bucks on the sensor. It does make sense that it is too rich, since only flooring the throttle will make it start. I will replace the sensor, and let you know what happens.

I agree about the woman analogy; however, I know there have been cases, in my life, where it might have been cheaper to keep her, but not worth the maintenance stress.

 

I have a 97 SL similar to yours with 229k still going strong, and still with the original clutch. Seems like the coolant sensor want bad around that 190K mark also. When you pull yours out, you'll most likely see a crack on the composite surface that was submerged in the coolant. That is why they go bad. The new ones are made of brass and last much longer. It's the same sensor that is in the air intake snout (that's on the dirty side of the air fillter) .....so if you want to see if it's the culprit, (right now, before your trip to the parts store), swap the two. The one in the air snout should be in better shape as it hasn't faced the extremes that the one in the coolant has. Still you will need to put the brass one in the coolant side eventually. This is how the ADD mind works. I need results right now.

 

Well, I got ambitious this morning and went out in the 25 degree weather to replace the ECTS. I had to hold my tongue just right to get the connector off, but finally got it off without breaking anything. Then taped, replaced, and started her up! Fired off nicely, idled nicely, AND the temp gauge came up after letting it idle for a few minutes!! The true test will be starting and restarting it after a couple of trips, but I really think this might do it!

Thanks so much for this forum and the replies! I will update this posting after trying it for a bit.

Oh, yes...got the brass replacement at Autozone for 9.99!

 

That was less expensive than I thought.You sure gotta love a story with a happy ending.

 

keep tongue away from sub freezing engine block

 

OK, I usually am very careful in saying something is fixed, but after putting it through a good run this morning, I would pronounce it fixed! 8 degrees this morning, started immediately, idled on its own, did not have to nurse it onto the road, idled flawlessly in traffic, and....when restarting after it had set about an hour, started immediately. Previously, would not idle on its own cold, would buck and snort trying to head out...obviously running way too rich because of false read.

I imagine my fuel mileage will go back up to previous levels. AND, the heat gauge is working now!

Again, my sincere thanks for this forum and the terrific help from hoseppi! Heck maybe there is another 200000 left.

Also, derf, thanks for the information on where to hold your tongue! ;-)

 

you're welcome -- gotta look out for the welfare of the pack

 

I didn't know whether to start a new thread or not, but I had my first chance to put a good run on the car since replacing the ECTS. This past weekend, I drove over 600 miles through Colorado mountains, passes etc. The improvements are very apparent in starting, idling, re-starting warm, etc. Those are apparently cured by the new ECTS.

However, I still have an erratic "miss" at times and watched it very carefully while driving to try to determine the exact conditions and I think it happens after decel, under compression. It also happens under anything resembling lugging the engine. (manual transmission)

The "miss" seems like an electrical misfire, similar to that experienced with bad plugs and/or plug wires. The plugs have less than 10000 miles and the wires have less than 5000 on them, so unless I got a bad set of wires, I don't think that is it. Also, once I am cruising along at highway speed, 50-75 mph, it purrs. Also, the mileage was over 42 for the tank I measured. So why am I bitchin, you say? I am really not bitchin and could live with it, but I don't want it to evolve into something worse.

Let me give you a scenario. A perfect example was coming down a fairly steep hill, shift down to 3rd to slow down, then to 2nd prior to entering the highway, trying to accelerate lots of missing until the engine could rev up to 3000 or so and level out, a little miss shifting up to 4th, then purred down the highway. Other times on slight decel, when hitting the accelerator again, 2 or 3 misfires.

It really doesn't seem fuel-related, but I guess it could be. Anyone experience anything like this? Thanks in advance.