air in injector

[piddler]

I posted earlier about the 230sl idling rough. I finally had a little time to work on it today.

I cracked the connections on each injector starting with #6. #6 and #5 had a lot of air bubbles when I cracked the connection. The other cylinders did not seem to have as much if any. Can anyone tell me where the air could be coming from? It would seem to me that if there was air leaking in then there should be gas leaking out since this is a pressurized system from the tank. Could it be a small leak in the line in the gas tank?

Any and all help appreciated, Pete

[ja17]

Hello piddler,

My first suspect would be an injector not closing all the way. Try switching it with another cylinder and see if the problem moves.

Next, the 19mm fittings on your injection pump (at the end of each injector line) should be torqued to 18 ft. lbs. No more and no less.  You may want to check these next.

Joe Alexander
Blacklick, Ohio

[rwmastel]

quote:Originally posted by piddler

I posted earlier about .....

Pete,

Hi.    A little forum hint:  It's easier for everyone reading or referencing your troubles and successes if you just reply to the thread you started before.  It's best to keep all the information in one thread.  If you can't find it because it's old and not on the front page, then you can use the Search feature and include specific terms and even search for posts by your own user name.

Thanks and good luck with the idle issue.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[piddler]

I found out that you can not adjust the idle mixture with the engine running. This should be mentioned somewhere.

We did get the idle mixture adjusted to get the idle much better. There is a hose that runs from just above the air filter directly to the intake manifold with an adjustment at the manifold end. We adjusted this and helped the idle more.

I know that the engine is running rich because the plugs have a lot of carbon after just a short run.

At this point the car will idle but the RPM fluctuates 100 to 200 RPM at times. We have the idle set at about 800 RPM. Also the car stalls  some times when I put it in drive or reverse. Could this be vacum leak?

I pulled the plug wires one at a time and all seemed to affect the idle so I don't think the problem is confined to one cylinder.

Help and thanks in advance, Pete

[J. Huber]

Hey Pete. If you mean don't adjust fuel mixture while running, you are so right. This has been emphasized many times -- even my manual puts it in bold I think. I guess it can't be said enough.

It sounds like you are getting closer. I would suggest you take a good look at your linkage. It needs to be perfect and with little or no play. There are some very good step-by-steps here and Dorian's site. I can find the links if you can't.

Once you have the linkage correct, you can check the vacuum and then you may need to go back to air/fuel adjustments to get the idle right. You also have to watch the Constant Speed Solenoid -- making sure it responds when the car is put in gear.

Good luck.

James
63 230SL

[rwmastel]

You CAN and SHOULD adjust the air input to the idle when the car is running.  This is the metal screw near the intake manifold where the small (3/4" diameter?) hose runs from the air filter housing to the manifold.

You CAN NOT and BETTER NOT adjust the fuel mixture when the car is running.  This is the screw adjustment on the back of the fuel injection pump unit.

For further troubleshooting, James is exactly right.
1.  Adjust all linkages to specified lengths/positions.
2.. Adjust venturi flap (on intake manifold) to proper closure fit.
 (Ask for help on these two things if necessary.)
3.  Ensure the linkage ball/socket connections are all tight - no slop!
4.  Disconnect the large main linkage rod that goes across the valve cover.
5.  With the car running, you can now manually add throttle (fuel) input with the linkages to the fuel injection pump or add air on the intake manifold linkages (venturi unit).  Giving extra air or fuel and watching the RPM response will tell you if you're running rich or lean.
6.  Make proper adjustments to the fuel pump misxture screw with the engine OFF.
7.  Keep repeating adjustments until you get the best tune.

Other things:
Make sure your ignition is good from the battery to the spark plugs.
Check your engine compression.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[piddler]

I have Chiltons manual and a MB manual. Neither of them mention having not setting the fuel mixture with the engine running. I appreciate the information. I did try to make this adjustment with the engine running. I hope I didn't break any thing.

For what I have done/checked so far: The linkage seems to be in good shape. There does not seem to be any slop. I changed the plugs and condenser and set the points with a dwell meter to 40 degrees. I could not get a set of point locally. The points that are in the car look good. I pulled the plugs and checked the fire on each plug and there is a good blue spark. The idle was all over the place but it was still better than when I started. When I screwed up on the fuel mixture. I counted the notches on the adjustment and set it at center and started making adjustments to get it where it is now. I drove the car about 5 miles today. When I got home the it was idling at about 1400 RPM but it seemed to be a little smoother. The compression is low but it is about the same on all 6 cylinders.

I would like more information about the linkage lengths and positions. Also more about the adjustment on the venturi flap.

Thanks for all the help. I will be out of town for a few days but I hope to get to work on the car some more Friday night.

Thanks again, Pete

[J. Huber]

Some good reading to do before you get back to the car...

A search here on "linkage tour" will yield a fine thread by Joe A. and some related ones near by.

Also take a look at this:

http://pagoda113.com/eve/forums/a/tpc/f/3296041521/m/7246004272

James
63 230SL

[piddler]

James, thanks for the link to G. Davis' instructions on the idle adjustments. I could not find the link to Joe A. that you mentioned. I set the linkage and idle air as per instructions. My problem is that I cannot adjust the idle fuel to get the RPM down to where it needs to be.  It idles at about 1100 RPM and adjusting the fuel adjustment does not affect the idle.

The manuals that I have did not mention that the fuel adjustment should not be made with the engine running and guess what!!!? I did it. Could it be that I damaged the adjustment when I tried the adjustment with the engine running?? If so, can the adjustment mechanism be replaced without replacing the fuel injector pump?

I could use some positive feed back here.

Thanks, Pete

[J. Huber]

Hey Pete. George's instructions are always fantastic. Here is the thread by Joe.

http://index.php?topic=5003,tour

As for questions about the pump -- I'll let the heavyweights have this one. I always heard you can damage the pump and yourself if you turn the idle with engine running. But since you are still here -- maybe you didn't engage anything? Did you push, turn and click the screw? Anyway, since you are up and running -- even if you are revving a bit high, I think you'll be alright...

Did you make sure the CSS or idle compensator is out of the way of linkage? A long shot but I think it could hold the idle high if its misadjusted. Also -- when idling at 1100, what happens if you pop off the ball socket on the pump rod at the main linkage?



James
63 230SL

[piddler]

Thanks for the other link. It looks like it has a lot of information I can use.

I removed the idle compensator while making the adjustments. I am going to be gone for a couple of days and maybe when I get back to the car I will have a clear mind.

Thanks, Pete