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Topic: Temporary rough idle warm & cold after starting Reply to Thread
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  Topic Review (Newest First)
Yesterday 11:09 PM
H.D. @JR420 & lesguy:

As I said, without knowing if the Lambda adjustment screw and/or EHA adjustment screw have/has been unprofessionally tampered with before, everything that has an effect on fuel combustion has to be checked before further touching the adjustment screw in order to reliably restore a proper condition of the system.

That, of course, does not mean that you should otherwise not further touch the adjustment screw. On the contrary, now that both of you know for sure that the adjustment screw has been tampered with (you did it yourself), you should at least check and, if necessary, readjust the duty cycle via the Lambda adjustment screw in order to help Lambda control to do the best it can do under the given circumstances.
However, without first checking everything that has an effect on fuel combustion or at least being sure that there are no further fuel combustion affecting problems, you‘ll never really know whether the system is in proper condition or not, no matter how well it subjectively perceived works.

I do recommend both of you to do at least a proper fuel pressure test (SP & LCP) though before you readjust the duty cycle (!) … in order to get more insight into (not only) both of your EHA‘s. …


Quote:
Originally Posted by JR420 View Post
... I have looked for videos and also posts on adjusting duty cycle. I haven't found yet anything other then using a multi meter that measures duty cycle on the diagnostic ports. Could it be that easy?
You‘ll find out (in detail) by reading post 2 of the Lambda control thread I‘ve mentioned several times in this thread. …

H.D.
Yesterday 09:31 AM
lesguy Wanted to update this thread with pics of my plugs condition after about 350 (300 highway) miles after install of rebuilt distributor, new Bosch injectors, and tinkering with the EHA adjustment and tower Allen screw. Also adjusted gap to .040 for each, as a test to see if larger gap smoothens idle a bit more. New Lemforder motor mounts go in on Monday evening if no rain
Yesterday 08:07 AM
JR420 Thanks, I have looked for videos and also posts on adjusting duty cycle. I haven't found yet anything other then using a multi meter that measures duty cycle on the diagnostic ports. Could it be that easy?
Yesterday 04:17 AM
H.D.
Quote:
Originally Posted by JR420 View Post
... Am I understanding correctly in that diagnostic will never be accurate issue if both have been tampered with ...
Yes … also if only one of them has been tampered with.

Quote:
Originally Posted by JR420 View Post
... meaning in order to correctly adjust I would need to start with a new EHA? ...
If the EHA has been tampered with and you really want to do it right … yes ... unless you know how to properly check the EHA‘s calibration (volume flow !) and, if necessary, how to readjust it to its original calibration.

That, BTW, is not explained in the video in post 53. … (See what I said about EHA adjustment in https://www.benzworld.org/forums/w12...e-driving.html) …

Quote:
Originally Posted by JR420 View Post
... feel confident there are no other ignition or fuel related issues ...
If you are sure that there are no more fuel combustion affecting issues, you should check and, if necessary (as very likely), readjust the duty cycle, respectively the EHA current.

Just don‘t overlook any issues, like fuel pressure problems or a leaky CSV, or vacuum leaks, or problems with the o2 sensor & other sensor input to the ECU, the ECU‘s Lambda control function, the EHA‘s electrical resistance, tiny dirt particles in the FD (which can easily get into it during reinstalation … you might be surprised about the effect a ≥ 0.3 mm particle can have), …
And let‘s hope that the FD was not only properly cleaned & refurbished, but also its calibration was correctly checked and, if necessary, readjusted after refurbishment. You might at least want to check for equal volume flow through each injector pipe port.

H.D.

P.S.: The man in the video in post 55 seems to have been taken in by one of the common misconceptions about the KE-Jetronic. He thinks that, with the difference between SP & LCP being above spec, his engine will run richer. That is not the case, at least not with the engine running at operating temperature, unless Lambda control is not working or the Lambda leaning limit is exceeded (duty cycle = 0%) … which, needless to say, should be prevented, of course. …
Yesterday 02:18 AM
Heikkif Another video:


On his channel there is a lot of material on KE-jet.
07-19-2019 01:09 PM
JR420 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.
07-19-2019 07:38 AM
Heikkif 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.
07-19-2019 06:52 AM
JR420 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?
07-19-2019 02:08 AM
H.D.
Quote:
Originally Posted by JR420 View Post
... the previous owners adjustment to compensate for something or somethings that should have been addressed need to be reversed. ...
That is exactly the point where you (and lesguy) are now … which should incite you to follow the advice quoted in post 44 (!) … first starting with:
“... 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.



H.D.
07-18-2019 08:18 PM
JR420 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.
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