|Topic Review (Newest First)|
|Today 01:09 PM|
Thanks and great video! Seems like best place to begin would be with EHA fuel pressure measurement then going about HD's recommended procedure.
Need to procure proper fuel pressure gauge fittings next.
|Today 07:38 AM|
A competent person can tune EHA to original settings by using a pressure gauge. That has been explained in MB manuals and also for example on this video:
Manuals can be found in the stickies of this forum section. If the car has no other problems causing misfires than KE -jetronic bad tuning and has no leaks on exhaust at front of O2 sensor then all that is needed for tuning it is pressure gauge and digital multimeter.
|Today 06:52 AM|
Thanks HD, I have reviewed all of posts previously mentioned above and feel confident there are no other ignition or fuel related issues other than restoring lambda adjustment to original settings with the unknown being previous potential EHA adjustment.
Am I understanding correctly in that diagnostic will never be accurate issue if both have been tampered with meaning in order to correctly adjust I would need to start with a new EHA?
|Today 02:08 AM|
Originally Posted by JR420 View Post
“... without at least knowing exactly how far in which direction the adjustment screw has been turned, valuable diagnostic information is gone for good (!) and everything that has an effect on fuel combustion (see examples under “Please note“ in post #2) has to be checked first before further touching the adjustment screw, in order to reliably restore a proper condition of the system. ...“
Without following that advice your issue(s) will not be properly taken care of, no matter how much subjectively perceived improvement tampering with the Lambda adjustment screw and/or the EHA adjustment screw brings.
And when that is done, proceed to the third quote in post 44, where I said:
“… Only if all respective potential fuel combustion affecting causes [for duty cycle deviation] (which already a simple duty cycle check can point to) are checked and, if necessary, fixed, changing the setting of the Lambda adjustment screw (solely according to duty cycle or, better, EHA current !) is in order. ...“
Which advice you follow is up to you, of course. … However, as an engineer who was involved in several MB CIS-E engines (before they went into mass production) I warmly recommend to generally be very careful about online CIS-E info & advice. Most of it reveals substantial lack of understanding this (least understood & most underestimated) injection system … which leads me to another warm recommendation , namely to follow the advice in https://www.benzworld.org/forums/w12...uty-cycle.html. … Those who love their CIS-E engines and do not know or understand what's posted there (like probably more than 95% of indy‘s) I recommend to stay away from the Lambda adjustment screw and/or the EHA adjustment screw and to let someone who understands these things assist you … again: no matter how much subjectively perceived improvement tampering with these screws brings !
BTW … contrary to common believe, these adjustment screws should not be turned based on what an exhaust gas analyzer reads and an oscilloscope is not necessary to do adjustments, both of which you will find out in detail by following the above link. … And if someone tells you that the purpose of the Lambda adjustment screw is to adjust the “mixture“ or exhaust gas emissions, I recommend to keep him away from your engine bay.
|Yesterday 08:18 PM|
After reading additional info is it even possible to bring car back to original settings if EHA and tower adjustment screw was changed or do I need to replace EHA before shop does fine adjustments on tower adjustment screw?
Seems like if both have been adjusted (not certain again on EHS, but wouldn't be surprised) that it would be very difficult to attain with so many variables.
|Yesterday 05:46 PM|
Yes thanks HD, I should have paid more attention to the tower, but I did not know what tamper proof cover looked like until researching. It became clear that it was previously removed and already adjusted unfortunately for me.
I suspect this was done to pass am emission failure (recorded on carfax).
Now with renewed fuel system the previous owners adjustment to compensate for something or somethings that should have been addressed need to be reversed.
Thinking I might be better off going to an indy who can use an oscilloscope and exhaust analyzer to properly adjust?
Additional info - I have not adjusted EHA, but have no idea if previous owner did. I do know they messed with idle mixture screw though or a tamper proof cap would still be in place. I don't intend to touch EHA as it pulls strong, but idle is off. Seems to me as mentioned above that the exact science of it would use an exhaust gas analyzer/oscilloscope and then proper CO output could be achieved.
Neither tool do I own and good ones are costly thus my thinking is an indy that knows what there doing should be able to properly adjust in an hours time? Don't like the idea of engine running rich or lean.
|Yesterday 04:43 PM|
My (personal) experience with adjusting the rather sensitive Allen in the tower, is that with a poorly tuned vibrating engine runs, the engine movement can make it a bit challenging to achieve minute adjustments while simultaneously knowing precisely how much you’ve adjusted that Allen.
Again, just my experience. Not a substitute for doing things the “right” way.
|Yesterday 02:10 PM|
Gentlemen, maybe you should really contemplate doing what I said in post 19:
Originally Posted by H.D. View Post
You say that, from all you have read “the lambda screw should not be turned with the engine running“. That tells me that you've probably not read my Lambda control thread that I mentioned in posts 19, 22 & 32. … In that thread I explained under “Adjustment procedures“ in post 2, that the adjustment is always done while the engine is running at idle speed ! …
Before touching that adjustment screw, I warmly recommend to follow the above quote ! … But this is not my thread and what you (suggest to) do is up to you, of course. I‘ll not further interfere. …
|Yesterday 12:26 PM|
JR420: From what I see in the pic, the anti tamper portion was removed from the tower, so yes, appears at some point and adjustment was made via that adjustment allen head inside the tower.
HD is giving you the correct guidance. And rumb's guidance is good as well
I'd suggest not touching the EHA screw
I also suggest that IF you touch the towers allen, you do it with engine off and make a TINY change that you track. That way if the results arent positive, you can easily put it back to where it was before you touched it.
Also, after you make any change? I suggest driving it for a few miles, turn ac on, turn ac off, go on the highway, go in stop and go, etc. Let the system fully adapt to the tiny change you make. Then make your decision as to whether any improvement, was made.
|Yesterday 11:06 AM|
From all I have read the lambda screw should not be turned with the engine running. adjust in 1/8th or 1/16th turns and then measure again.
Personally I would put the EHA back where your found it and then read and adjust your duty cycle until that is in spec.
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