77 450sel cold starting problems
 

I have inherited a 1977 450sel with 156,000 miles on it. My uncle gave it to me and he bought it new. It was extremely well cared for: no rust, great paint, new interior, etc. It has been driven less than 500 miles in the past 7years. I have changed the oil and filled the tank with fresh gas. It runs great, but is hard to start when cold. When it starts, it hesitates and just runs poorly until it gets warmed up. It had a major tune up at 150,000 in 1998. Once warm it starts fine. What do you all think? Does it just need to be driven, does it need "Deep Creep" spray, or something else? Thank you in advance!!

Greg
Hendersonville, TN
1955 Ford Fairlane
1977 450sel
1995 E320 wagon
1998 E320

I suggest you put a bottle (or two) of injector cleaner in the tank, and then take it for an extended highway drive with lots of hard-driving for a half-hour or so. These cars suffer greatly when you only drive them 500 miles in 7 years! The fuel system probably has crud all inside it and a nice hard run might help clean that crud out. Once you've done that, if it continues to act up, report back!

I have added a 1/4 of a bottle of Marvel's Mystery Oil, a bottle of STP fuel injector cleaner, and a bottle of Octane booster. I thought that would have covered all the bases. I have driven the car about 100 miles. Maybe I am not being patient enough. What has me puzzled is how good it runs when it is warm.

Have driven the car about 200 miles. Still having a hard time starting when cold. I sprayed a half a can of "Deep Creep" through the throttle body lots of smoke, but not better. Could it be the "cold start valve" or a vacuum leak. When it starts cold it has no power at all until it gets warm. Is there a way to clean the csv. It also has a fairly high idle on occation

TG:

Get yourself over to Costco and buy a four-pack of Techron FI cleaner. It is only $10. Add two bottles to the tank, drive like hell in one direction, and when the tank is empty, add the other two, fill'er up and drive back. You should have all the crap cleaned out by then. If it isn't running much better after all that you can start looking for other ways to spend your money on this car. There are plenty...

I have an early 107 that doesn't get used as often as it should, so I do the double-shot of Techron trick to keep the innards clean. Works. The strong dose Techron will also help to clean the cold start valve and the idle air valve if they are gummy.

230/8

My $.02...
 

...what they said. 7 years of sitting is an eternity.

Do the Techron thing a couple of times before you start tearing into things. New oil & filter was smart- tranny fluid & filter change out is a real good idea too (no relation to your stated problem - just a good idea)

If that doesn't resolve most of the problem, come on back here - we'll point you to lots of prior threads dealing with this particular item and help get you running smooth.

I don't think octane booster will do anything to help especially if you are using 91 or better - smarter guys/gals than me can weigh in on that here.

Actually, I think the octane boost might hinder your quest - doesn't it simply reduce the volatility of the gas by raising the flashpoint thereby retarding ignition?

Keep us posted and welcome to the world of W116 stewardship.

Kevin

I would check out the cold start valve for starters. Below 50 degrees F, it provides a quick spray of fuel to get the engine started. You can pull it out, plug the hole, reconnect the wire and fuel line, stick it it a jar and watch for a spray when the starter is cranked.

If that is OK, then see if the warm-up compensator has power and check for resistance across the pins where the power plugs in. Make sure the vacuum line is connected.

If that's good, then you may have a fuel distributor problem or an overly lean mixture setting. The next tests would be to test the CO at hot idle, and hook up a gauge and test the control pressure as the engine warms up from a cold start.

I have gotten the car running better. I have replaced some of the vacuum lines and replaced the spark plugs, but it is still not running good when cold. It wants to start first thing, but as soon as it hits it will die. After a few tries it will start, but only idle at about 800rpm and when I feather the gas it wants to die. The good thing is after 5-10 minutes its fine. It also starts better when the ignition key is turned for a few seconds. Could the fuel pump be getting weak? It will not do the warm up idle at 1300rpm. I think this is unrelated, but the egr valve has been disconnected and the vacuum lines pluged. Should I leave it or hook it back up?

Sure sounds...
 

like the warm up regulator/compensator(?). Follow ctaylor's direction. If its starting OK cold, I wouldn't suspect the CSV.

Look into your fuel pressure regulation system (don't know that engine well enough to define that - can somebody chime in?).

Keep us posted - I have two M100 engines (the legendary and scary 6.9) that I will be diving into this spring and both have similar problems. I'll be interested in your findings.

Kevin

The fitting at 7:00 on the pic attachment can be removed from the fuel distributor. Inside is a metal screen filter that can get clogged. Undo the fitting and spray your deep creep in there.

It is possible the pump is on the way out. Search this forum for the various tests.

If the car has sat up for awhile you can crack open (not remove) each fuel line at its junction with the FD. Be really careful because the fuel is under real high pressure and it could put out your cigarette. Use a rag to catch the fuel. Yours may look muddy. That's rust. Do each line in turn and take your time. Use deep creep or similar an hour or two before attempting to unscrew the connections. Don't remove them or get close to it, just loosen enough to let the gunk out.

Twist too hard and you are messed up bad. The steel lines and fittings are in the softer metal of the FD and you really don't want to strip out the threads in the FD.

The warm up regulator also has a metal screen that collects rust and crud in it. This really sounds like you since you say the car runs fine when warm and the warm up regulator is pretty much out of the equation by then. It provides enrichment when cold by reducing the pressure on the top of the control piston in the FD, allowing the piston to rise and expose more of the fuel outlet slits. An obstruction in the WUR could produce the symptoms you describe.

It is softer metal than the two steel lines that feed/empty it, so you'll want to use the deep creep similarly. On my 6.9, I got too frisky in twisting off the supply fuel line and I snapped the fuel line. There were none in the US, so I got one from Stuttgart where they had only 12 more on the shelf and they aren't making any more is what they told me. So take your time and make sure it's ready to remove before you start getting aggressive.

It is easier to clean the WUR with it removed. What you want to do is backwash the filter screen to get the crud out. There's only a small volume like less than a thimble full of fuel in the part of the WUR that sees fuel. There's an almost microscopic port between the inlet and outlet sides of it. You'll need some high pressure air to flush this passage out. Anyway, with the WUR out, you can get your solvents out and give it a good soaking and then try and blow it out.

If this doesn't fix the WUR and it has checked out electrically as suggested earlier, you can take the device apart, but do some reading before you attempt this. There are some good links to Bosch CIS which have been posted before. I believe I have posted several, so you could search on my name. Porsches and Volvos, etc used the same Bosch system and Bulletin Boards for them have plenty of troubleshooting procedures.

Let us know how far you get.

I am betting on the WUR.

cold start problems
 

All of the above are probally good advice. But start with the simple items first. Check the engine temperture sending unit, if it tells the computer that the engine is hot the fuel mixture will not be correct til the engine actully warms up.

Here's a link for you:

http://www.w116.org/

and the service manual:

http://handbook.w116.org/matrix6.htm

Pick the engine FI system you have and delve in.

Good luck and keep us posted.

I don't think that there is a temp sending unit on this engine. Enrichment by the WUC is controlled by the resistance/heat internal to the unit. You need to check the CO at hot idle and put a set of pressure guage between the WUC and FD and see what control pressure you are getting when the egine is cold.

Another possibility is that the auxiliary air valve may be sticking, and you are not getting enough air to keep it going at cold idle.

Thanks for all the replies. I have opened all the fuel lines to make sure they were not pluged and they were fine. I am having starting problems while both hot and cold(cold every time; hot if it sits more than 5 min.) It almost seems like a fuel pump problem. Since I got the car 8 weeks ago I have put about 2000 miles on it and I has not gotten any better while running all kinds of FI cleaner. I did pull the injectors and they seemed fine, just wiped the injectors and reinstalled. I can only hear the pump when I am right next to the back wheel. I am not sure what to try first since it has a hard time starting when warm. Oh, and the ACC decided to quit working all of a sudden. What do you all think Vacuum leak.

Before you invest in a fuel pump, expensive and messy to install, try the following:

- Raise the idle a little by turning the giant screw on the idle air valve ccw.

- Check the system and control pressure.

- Check the CO at hot idle.

You did replace the seals when you pulled the injectors?