One thing I found out very recently is that this car is not officially-low-emissions-tagged. That means I can legally remove the catalytic converter.
This would probably happen by cutting the cat off the downpipes, and fabricating two parallel running pipes with an H pipe. The lambda sensor would go in the crosspipe. I need to work out whether this has been tried and tested by other M117 owners and then decide if I'm gonna go through with it.
I got the go-ahead to find any shop I like and have the exhaust tips refabricated. The shop where the current rusting ones were done are going to take care of the bill. When I start doing that, I'm going to have to decide whether I'm going to keep the rear muffler, or go with Magnapacks only. To be honest, the driving I'm currently doing on the Mercedes is largely just cruising for fun, so I might like some extra noise.
I went to a shop today to have a look at the A/C. Unfortunately my car has the large old-style valves in the A/C pipes, which is a surefire way of knowing whether a W126 supports R134a. So mine doesn't. Either I need to find a man with some R12 refridgerant, and the skills to put it in, or convert the car to the new stuff. The conversion is pretty expensive. Since I would hardly ever use the A/C I'm first going to try and revive the current system.
The trouble with R12 is that it's been illegal in Finland for something like a decade. I paid a visit to a shop who do maintenance on industrial refridgerators, air conditioners etc, and asked if they had any R12 laying around. Maybe they could've had some left over from emptying an R12 A/C unit in an old barn or something, since it's illegal to let that stuff into the atmosphere. But no, they hadn't seen any R12 in a while. I know a guy who might be able to smuggle some in from Russia, and that's pretty much the only option I've got left.
Jun 24, 2011
Jun 16, 2011
Fine Tuning
Been a while since last update. Nothing much to report, just little things.
Went to a shop with an exhaust gas analyzer to have a base fuel mixture setup done. Turns out the car was running way lean, which was causing a low-rpm misfire on a cold engine, and high-rpm misfire on a warm engine.
On a KE-Jetronic engine such as this M117, you're supposed to have the mixture on a good base setting, and the engine's electronic brain sets the mixture just so on all further rpm's. So, basically, it's very easy to set up, you just need the analyzer to do it. You're probably not going to get it right by feel. We hooked it up to the machine and enriched till it was producing between 0,5 and 2,0 % CO. Neutral idle RPMs went up 200 rpm, and in-gear idle stayed at 600-ish which is in the ballpark where it should be.
Went to the strip last Saturday. Did 15,53 sec on quarter mile. However, the car was still not running right. It should do a bit better on the quarter mile and I got a really bad misfire above 5000 rpm on WOT. This prevented me from going faster than 170 kph. I'm hoping new spark plugs and enriching the mixture further will fix this.
A few weeks ago I busted the accelerator pedal. Turns out a plastic hinge behind the pedal, which connects to the throttle assembly, has a habit of breaking even as often as every few years. It's not an expensive fix (15 EUR for an original part you can install yourself in 5 mins) but it was annoying till I got the new part. The pedal would slide off the throttle assembly, causing it to jam in a slightly open or completely closed position. Interestingly, the gas pedal is a W123 part, probably the same one used in all Mercs of the 70s through early 90s period.
Finally received my new license plate. The old plate had been bent into a V shape in two directions and was screwed directly into the front bumper. To be honest, it looked terrible. One of the screws was completely rusted and one looked new. My aim here was to bend the new plate as little as possible while mounting it slightly lower than the old plate. Above the spot in the bumper where the plate is supposed to go, there's a step where the plate "valley" ends and the top part of the bumper begins, IIRC the old plate was mounted over that step. I wanted the new plate to go a bit lower.
So, bought a plate holder, sawed off a bit where the EU flag is supposed to go, screwed the holder onto the bumper, and mounted the plate. There's about 15mm worth of padding between the plate holder and bumper, at each end. By taking off some of that padding I could adjust the V angle of the plate holder. I'm just not sure how much of that I can do without the plate and plate holder screwholes no longer lining up.
Also, I had the old issue with the sunroof switch, where the up and down (sunroof tilting) directions would not work. The way to get the sunroof in that position was to keep pressing the switch in the "closed" direction till the tilt-position was up. And repeat to close the tilt position. Problem with this, in addition to it not working like it should obviously, was that it was impossible to know for sure when the sunroof was completely sealed, since there was no noticeable stop between the two "open" positions.
I'd prepared myself for a wiring issue, but this turned out to be as simple a fix as resetting the sunroof motor in the trunk. You put it in neutral, spin a wheel and put it in gear until it works right from the switch. The wheel was a couple revolutions wrong. Like I said, easy fix thanks to the internet.
As for other things in the near future:
Went to a shop with an exhaust gas analyzer to have a base fuel mixture setup done. Turns out the car was running way lean, which was causing a low-rpm misfire on a cold engine, and high-rpm misfire on a warm engine.
On a KE-Jetronic engine such as this M117, you're supposed to have the mixture on a good base setting, and the engine's electronic brain sets the mixture just so on all further rpm's. So, basically, it's very easy to set up, you just need the analyzer to do it. You're probably not going to get it right by feel. We hooked it up to the machine and enriched till it was producing between 0,5 and 2,0 % CO. Neutral idle RPMs went up 200 rpm, and in-gear idle stayed at 600-ish which is in the ballpark where it should be.
Went to the strip last Saturday. Did 15,53 sec on quarter mile. However, the car was still not running right. It should do a bit better on the quarter mile and I got a really bad misfire above 5000 rpm on WOT. This prevented me from going faster than 170 kph. I'm hoping new spark plugs and enriching the mixture further will fix this.
A few weeks ago I busted the accelerator pedal. Turns out a plastic hinge behind the pedal, which connects to the throttle assembly, has a habit of breaking even as often as every few years. It's not an expensive fix (15 EUR for an original part you can install yourself in 5 mins) but it was annoying till I got the new part. The pedal would slide off the throttle assembly, causing it to jam in a slightly open or completely closed position. Interestingly, the gas pedal is a W123 part, probably the same one used in all Mercs of the 70s through early 90s period.
Finally received my new license plate. The old plate had been bent into a V shape in two directions and was screwed directly into the front bumper. To be honest, it looked terrible. One of the screws was completely rusted and one looked new. My aim here was to bend the new plate as little as possible while mounting it slightly lower than the old plate. Above the spot in the bumper where the plate is supposed to go, there's a step where the plate "valley" ends and the top part of the bumper begins, IIRC the old plate was mounted over that step. I wanted the new plate to go a bit lower.
So, bought a plate holder, sawed off a bit where the EU flag is supposed to go, screwed the holder onto the bumper, and mounted the plate. There's about 15mm worth of padding between the plate holder and bumper, at each end. By taking off some of that padding I could adjust the V angle of the plate holder. I'm just not sure how much of that I can do without the plate and plate holder screwholes no longer lining up.
Also, I had the old issue with the sunroof switch, where the up and down (sunroof tilting) directions would not work. The way to get the sunroof in that position was to keep pressing the switch in the "closed" direction till the tilt-position was up. And repeat to close the tilt position. Problem with this, in addition to it not working like it should obviously, was that it was impossible to know for sure when the sunroof was completely sealed, since there was no noticeable stop between the two "open" positions.
I'd prepared myself for a wiring issue, but this turned out to be as simple a fix as resetting the sunroof motor in the trunk. You put it in neutral, spin a wheel and put it in gear until it works right from the switch. The wheel was a couple revolutions wrong. Like I said, easy fix thanks to the internet.
As for other things in the near future:
- Spark plugs soonish
- Monday I'm going to have the A/C inspected. It's not blowing cold, so first need to make sure it's not completely broken and then fill it up.
- Also on that date, will arrange for the tailpipes (last 30 or so cm of the exhaust) redone
- Car is going in for a machine buffing on July 6th.
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