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Thanks very much HD. Great info. However, I had already jumped the gun and started diving in before your post. While I regret not seeing your post first, figured I’d share my experience: after carefully installing the 8 new Bosch injectors and the rebuilt distributor, I did follow the step to leave the lines (going to each injector) disconnected while all other fuel lines were connected to the distributor . I then jumped the proper pins on the fuel pump relay and slowly depressed the throttle plate and watched the fuel fill all holes. The hole at about the 9 o’clock position took slightly longer than the others at first, but all did fill and stayed full/kept pushing out fuel each time I depressed that throttle plate.

I then carefully connected and tightened the fuel lines to the distributor. After approximately 10 seconds of cranking she fired up and stayed running. Idle was very low (around 400 rpm) and even after warming up, she bogged down/stumbled at any attempt to give it gas. Got to end of my block and only by nursing the gas pedal was I able to make it back home and up my driveway. After a ton of reading many threads and posts, I removed the EHA and adjusted the adjustment screw 1/4 turn clockwise and then reinstalled it. The hesitation improved by about 20%.

I removed it again and turned it another quarter turn clockwise. Even more improvement and I could actually drive it out of my housing development successfully. But my idle was still low and the hesitation from about 500 rpm to about 1200 rpm remained. After 1200 rpm she ran flawlessly to redline and at all highway speeds. And starting on first crank after only 1-2 full seconds (at most) of cranking was now the norm. I then decided to carefully dremel off (horizontally) the top 1/4 inch of the tower in front of the distributor that contains the anti tampering ball/adjustment screw. That allowed me to remove the ball and easily access the adjustment screw with my 3 mm Allen wrench. With the engine on I turned that screw 1/4 CCW and my idle began to rise to about 550rpm and become much much smoother. Removed the Allen, drove around the block and Idol and drivability had improved drastically. But I still had the hesitation from 500rpm to about 1200. Went back home removed the EHA valve and turned the EHA adjustment screw 1/4 turn clockwise again. Reinstalled and test drove. More improvement as the hesitation was now only between 500rpm and 700rpm. A mild annoyance but dramatic shift from before making and adjustments.

So now I’m around 3/4 to maybe one full turn clockwise of the EHA adjustment screw and hesitant to overdo it. My initial thought is to leave as is, and find a local shop that can use guages, instruments and experience to really fine tune/properly adjust the lambda, mixtures, etc. But I may go back and give that EHA screw one last 1/4 clockwise turn to see if that will get rid of this last bit of hesitation. One thing I have noticed is that turning the EHA adjustment clockwise usually means adjusting the fuel mixture on the tower, a bit CCW to retain optimum idle. Thus far the EHA adjustments seem to mainly impact driveability, while the tower adjustment is mainly around idle.

I realize the above is all indirect conflict of HD’s professional guidance but again, the above was done prior to his post. I’m not suggesting that anyone follow my method, just sharing my reality.
 

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Thanks very much HD. Great info. However, I had already jumped the gun and started diving in before your post. While I regret not seeing your post first, figured I’d share my experience ...
I‘m sorry to hear that … especially in this case. It‘s not every day that one comes across a 30 years old CIS-E car who‘s Lambda adjustment screw & EHA adjustment screw have likely & fortunately never been tampered with. ... Wish I would have come across your post earlier which, with the forum properly working, I probably would have. And I wish the “ton of threads“ you read would have included the one I mentioned in post 19 (https://www.benzworld.org/forums/w126-s-se-sec-sel-sd/2720049-ke-jetronic-lambda-control-duty-cycle.html). That should have been sufficient to prevent you from jumping the gun too. … :wink_2:

... My initial thought is to leave as is, and find a local shop that can use guages, instruments and experience to really fine tune/properly adjust the lambda, mixtures, etc. ...
Here‘s a tip regarding shops / mechanics:
Ask them about the purpose of the adjustment tower next to your fuel distributor. If they say that it‘s used for mixture adjustments, ask them again if they‘re sure it‘s really for adjusting the “mixture“. If they say “yes“ … run !

If I had access to your car and you could tell me how far exactly you have turned both the Lambda adjustment screw and the EHA adjustment screw, I would first turn them back that far to their previous (original) positions. Then ... old-fashioned as I am when it comes to troubleshooting and a number of other things :D ... I would do what I usually do before I touch any adjustment screws or replace any parts, namely test & diagnose … in order to detect the problem(s) that is/are now apriori just masked by your “adjustments“.
Some FD related problems justify EHA adjustments, which should be carried out in a specific way & verified by specific tests. However, the reported improvements after your almost full CW turn of the EHA adjustment screw point to a number of possible problems that do not justify EHA adjustment !

Besides wishing that the forum would work properly again, I wish I had enough time to assist you with detailed test instructions. I hope that someone else can do that, or that you're lucky and find an experienced mechanic.

H.D.
 

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Thanks H.D. Appreciate all of your knowledge sharing. And I do understand (now) that the proper way to address issues like I encountered after installing the rebuilt distributor/new injectors, is to avoid touching either the EHA adjustment/3mm adjustment in the tower adjacent to the fuel distributor (incorrectly known sometimes as the "mixture" adjustment) and to follow the detailed troubleshooting process to include (but not limit to): fuel pressure, ignition performance, vacuum leak detection, ICV values, duty cycle/lambda values, A/F ratio values, etc. And ONLY after confirming that all systems are functioning correctly, does one consider touching either of the adjustment screws.

However, I also wanted to follow up on my own experience for those that may simply be interested.

Despite better judgement, went home yesterday and removed the EHA and adjusted the screw 1/4 more turn clockwise. Reinstalled, let engine warm up via a 10 mile test drive, came back home. Results? The hesitation from 500rpm to about 700rpm reduced noticeably, but not 100%. But the idle became a bit more unsmooth and dropped to about 475rpm. Adjusted the tower screw 1/8th of a turn CCW, started engine, went out for another drive, and idle smoothed back out (but not silky smooth..but definitely liveable for sure) and went to about 575rpm in park, maybe 525rpm in drive/neutral. Outside temps were in the 94F range, very humid. At any other speed abouve 700rpm, the engine pulls/runs flawlessly. Zero hesitation anywhere, strong pull. At idle (or when driving with windows down) I smell no excess fuel, and I've never seen any black smoke from the tailpipe (before or after fuel system work) nor excess soot on my garage floor by the tailpipe from coldstarts. Fuel economy gauge is pegged full left when (for example) cruising with cruise control set to 50mph on flat/level highway.

Actually drove it to work this morning. Cold start took maybe..2.5 to 3 seconds to fire up, (a bit longer than before), but once she starts, she's fine. Idles at about 800rpm for about 3 seconds, then drops back down to about 550-575rpm and stays there. Shifting into gear and backing out of garage is eventless. Going from R to D and pulling off, there was zero hesitation at all. Zero.

Parked the car this morning, let it sit for 4 hours (still 94 degree + heat today) and just did a quick start and rev test. Started fine, idled fine (but not flawless...but never was flawless), and when I revved 3 times...rolled on first time, slammed to the floor next two times..zero hesitation at all in the RPM's. Zero. Wonder if the cold start valve/injector is injecting a bit more fuel (even with hot ambient temps?) during this start/rev testing, thus temporarily killing any hesitation?

Will pull the plugs later and examine to check for evidence or richness, lean-ness, or just right.
 

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Update today:
Didnt get a chance last evening to pull the plugs, but started and ran fine on the drive home from work. Could be mental (or could be the 98f outside temps and high humidity sucking out some HP/Torque) but seems like Im down just a bit on overall horsepower/torque. But again, could easily be the heat combined with running the A/C. She still pulls very nicely, smoothly at all ranges, BUT the ever so slight hesitation between 500 and about 700rpm is there after the engine is fully warm.

When I combine that with the fact that the hesitation is 100% gone when the engine is cold/not warmed up (and I assume, naturally running a bit rich since its cold start condition), Im thinking I need to richen a bit via either the tower or EHA adjustment. But my first step is to check the condition of all of the plugs.
 

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What would you say if someone suggested checking duty cycle ratio? After all it reveals among other things if EHA valve or lamda screw have been adjusted in a way that control unit can't correct fuel/air ratio. If control unit can correct fuel/air ratio engine is most of the time neither running rich nor lean but only when load conditions change or engine hasn't t reached running temperature. Here is a short description of what can be tested on KE -jetronic in addition of HD:s posts:

https://vdocuments.site/ke-jetronic-diagnosis-eha-pot-testing-etc.html
 

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Thanks for your appreciation, lesguy. :)

... I do understand (now) that the proper way to address issues like I encountered after installing the rebuilt distributor/new injectors, is to avoid touching either the EHA adjustment/3mm adjustment in the tower adjacent to the fuel distributor (incorrectly known sometimes as the "mixture" adjustment) and to follow the detailed troubleshooting process ...
Correct … and not only issues like you encountered now after installing the rebuilt FD / new injectors, but CIS-E engine issues in general should be addressed by respective troubleshooting processes instead of by tampering with the Lambda adjustment screw, let alone the EHA adjustment screw. … Only if all respective potential fuel combustion affecting causes (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.

Changing the EHA‘s adjustment is an option that can be taken into consideration if there is a problem with the FD or with the EHA itself and the car is not worth fixing/replacing these components.

In your specific case … with the reported improvements after turning the EHA adjustment screw CW by a full turn or even more … there is a number of possible (now inadvisably masked !) problems. Besides non-FD/EHA related ones, there could be a mechanical problem with the EHA itself or maybe its adjustment was changed CCW by a PO. Or there could be a FD refurbishment related problem (e.g. incorrect calibration). Or dirt might have gotten into the FD‘s lower cambers via EHA port(s). It often happens that a tiny dirt particle gets in there during EHA reattachment … and if it‘s 0.3 mm in size or bigger, it can easily cause the symptoms you reported.

BTW, be aware of the fact that blindly turning the Lambda and/or EHA adjustment screw(s) CW can easily lead to an air/fuel ratio that‘s rich beyond the Lambda control function‘s leaning limit. … ;)

H.D.
 

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Heikfiff and H.D.
Very appreciative of the guidance and information sharing. Digesting the info in that link now. Based on these posts, along with re-reading H.D's original long/detailed thread, going to hold off on any more adjustments. Leaving well enough alone for now. (It's a weekend driver, so minimal miles are put on her) Will make a path towards checking the duty cycle ratio. Thanks again
 

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As promised, updates: Simply have not had a chance to pull all of the plugs to check their condition yet. Nor have I had a chance to get out the voltmeter do some reading and try to check the duty cycle. But have been able to take a 560 on a couple of errands during the evenings. More observations:

Once fullly warmed up and in this 96 degree 90% humidity weather, idles at stoplights (in drive but stopped) right at about 500rpm even with no AC on. Slight vibration but that was there since I bought the car. Also, still has the slight acceleration stumble/hesitation at around 500 to 650 rpm when accelerating from a stop. Will recheck plug gap while they are out

With ac on under same conditions, D or P idle is about 600rpm and smoother. And minimal acceleration hesitation.

However, I have noticed the following behavior that I don’t think I’ve noticed before but can’t 100% confirm: at very low speed or from stop, when I floor it she pulls with no issue. Kickdown works fine, but at the top of second gear, she will not upshift unless I let up off the accelerator just a bit. If I just keep the pedal to the floor, she hits the rev limiter at around 5500-5600 and just bounces off the limiter. If I drive the car leisurely, all shifts occur just fine.
I tried adjusting the Bowden cable a bit, but to no avail, so I put the Bowden adjustment back to its original position where there is only a tiny bit of slack.

Any suggestions as to why she will not upshift under full throttle condition?
 

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Not a positive difference. It had green paint lines on the adjustment bar to show where my starting point was. I noticed a tiny (2mm?) bit of slack in the cable so I first tried removing the slack. Test drove and that took the shifts higher in the rpm range and made shifts harsh. Both opposite of what I needed/wanted. Returned to original position and tested. Got it back to original. Under anything but full to the floor throttle, up and down shifts are perfect.
Then decided to add a bit more slack to the cable. Made the 1-2 shift occur too early under full throttle but didn’t give me the 2-3 upshift with pedal to floor. Just kept bouncing off of the rev limiter.
Again: not 100% positive this symptom wasn’t already there ( i’m not sure I’ve done pedal to the floor acceleration starting at 0 before on this car. Higher speeds yes, but I may have lifted off pedal before 5000 rpm) but either way, would like to resolve.

For now, she’s running well but based on HD’s post, now I’m too curious to not know what my lambda and duty cycle numbers are so I’m sure I’ll be digging in more over the next couple of weeks
 

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... based on HD’s post, now I’m too curious to not know what my lambda and duty cycle numbers are so I’m sure I’ll be digging in more over the next couple of weeks
After you mentioned (in post 17) that the adjustment tower was still in its tamper-proof condition, my suggestion (in post 19) to check the duty cycle after reinstallation of the refurbished FD was based on the assumption that neither the Lambda adjustment screw nor the EHA adjustment screw had been tampered with.

As I explained in my Lambda control thread, the purpose of a duty cycle check is to get diagnostic information. Unprofessional tampering with the Lambda and/or EHA screw(s) distorts and ruins that information. Thus, if you know exactly how far you have turned these screws, you should first turn both of them back to their exact previous positions, hoping that they have never been tampered with before … which, with the adjustment tower still having been in tamper-proof condition, seems to be the case with the Lambda adjustment screw. But can you be sure that the EHA adjustment screw was still at its original setting when you changed it ? … Only if both of these screws have never been unprofessionally tampered with, the duty cycle provides reliable & valuable diagnostic information !

If you don‘t know whether one or both of these screws has/have been tampered with, a deviated duty cycle either points to specific fuel combustion affecting problems, or it shows that one or both of these screws has/have been tampered with. The problem is that you can not tell which of these two is the case … which takes you to that point in post 40 of https://www.benzworld.org/forums/w126-s-se-sec-sel-sd/2720049-ke-jetronic-lambda-control-duty-cycle.html, where I said:

“... 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. ...“

H.D.
 

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Thanks HD. Understood. My original EHA was leaking, so not long after buying the car last fall, I replaced it with a used unit that a forum member sold me. The assumption was that the EHA screw was untampered with, but obviously no guarantees on that assumption. I do have written down my total number of clockwise turns I’ve made to the EHA, but I’m not 100% confident on number of turns made to the mixture screw under the tower as I found that initially I wasn’t pressing the Allen far down enough to engage the actual adjusting screw. So in the end, with car at idle, I adjusted counter clockwise until it stalled, turned clockwise just a bit to restart, then clockwise until it stalled. Then for final adjustment turned the screw to halfway between both stall points

Lucky mike: Unfortunately i do not have a spare FPR to test with. I’ll try to get video footage today of the no upshift issue in action to post
 

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... with car at idle, I adjusted counter clockwise until it stalled, turned clockwise just a bit to restart, then clockwise until it stalled. Then for final adjustment turned the screw to halfway between both stall points ...
Doing that may sound somewhat logical, but it‘s a bad idea !

As explained in my Lambda control thread, with the Lambda adjustment screw … (I recommend to not even think of it as “mixture screw“, for reasons I explained in that thread) … turned according to anything other than EHA current (respectively duty cycle) without knowing what the EHA current (respectively the duty cycle) was before it was turned or how far exactly in what direction it has been turned, the duty cycle‘s diagnostic information is gone for good.

With this (unfortunately) being your situation now … if you place value on things to be reliably in proper condition & properly adjusted ;) … install a good EHA who‘s adjustment screw setting is without doubt original. Then check and, if necessary, fix everything that has an effect on the fuel combustion. Don‘t forget what I said (in post 26) about dirt particles getting into the FD‘s lower chambers ! … Then check and, if necessary, adjust the duty cycle as described in post 2 of my Lambda control thread.

H.D.
 

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Thanks H.D. I appreciate your knowledge sharing and guidance. I’m learning from it. Question: is my full throttle no upshift from 2-3 possibly related to my fuel system? Or is that most likely a coincidence? Doesn’t concern me excessively because I don’t redline this engine as a matter of routine. But still, one likes to have their drivetrain in top order.
 

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Maybe the rev limiter cuts in too early as fuel pump relay should shut off kick down at 5800 RPM. Anyhow fuel pump relay should shut off kick down if that was your question. As one releases pedal from kick down there is not happpening anything at the bowden cable or throttle linkages before kick down switch is released.
https://www.startekinfo.com/StarTek/outside/12253/disc 2/program/Engine/107/M117_56/073-165.pdf
https://www.startekinfo.com/StarTek/outside/12253/disc 2/program/engine_560SEC.htm

At the top of the W126 forum page stickies there is link to service manuals.
 

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... is my full throttle no upshift from 2-3 possibly related to my fuel system? ...
Only in as much as the fuel pump relay is involved, since it contains the kickdown shutoff function. As Heikkif mentions, it could be that either the rev limiter (fuel pump power cut-off) cuts in too early or the kick-down shut-off does not take place as it should 200 rpm below the rev limit.

You could either do what luckymike suggests, or you could check (easiest at terminal 9 of connector X26) if the (battery)voltage disappears at about 5600 rpm.

H.D.
 
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