1990 420sel - PeachParts Mercedes-Benz Forum

just-n-time · #1 10-14-2006, 09:04 PM

just-n-time here, I got the chance to look into the car tonight,and found that I have great spark,at the distributor,coil lead.We can look to wards something else keeping it from firring. It just seems so strange that after changing the rpm sensor it ran with a little roughness but it ran,the only symptom that showed was an intermittent abs light and a slight serge at the time that the light would come on,then we got a flashing check Eng. light,it would soon smooth out and all the lights would go out and drove fine for a time and start up again,In my attempt to readjust the fuel did I mess up something? thanks for reading jnt.

jdc1244 · #2 10-15-2006, 12:22 AM

The slight surge with the ABS light sounds like engine management – might want to check the condition of the OVP relay as it provides power to the ECU.

just-n-time · #3 10-17-2006, 01:00 PM

Quote:

Originally Posted by jdc1244

The slight surge with the ABS light sounds like engine management – might want to check the condition of the OVP relay as it provides power to the ECU.

ovp is one of the first things replaced,update on testing,I went to the shop this morning and she fire up first time,let it run for five min.and it began that slight roll as if searching for a balance of air fuel ratio,I then unplugged the EHA and it smoothed out,I then plugged up the EHA and it stalled immediately,but fired up on demand[turn of the key]ran the same test again same result.just-n-time thanks for the look!

just-n-time · #4 10-17-2006, 07:31 PM

Quote:

Originally Posted by bribenz

did you try driving it with the eha wires unplugged ? when the throttle position sensor is faulty it can cause your symptoms [ surging ], and unpluging the eha will allow it to run better [ no surging ] ;; but it will change the idle speed and it will be slightly harder to start ;; this is just to eliminate the throttle position sensor as the problem not a cure ;; obviuosly

Will give it a try in a couple of days,my youngest son just informed me that I need to work on the work truck because of nose in the rear axel,don't you love being the owner,certainly not the boss,though I try.thaks for the reply just-n-time.

david s poole · #5 10-18-2006, 10:26 AM

have smoke test done on intake manifold to look for vac leaks[lots of little ones not one big one]with the age on these cars i'm finding that a complete o/haul of intake is almost mandatory.

just-n-time · #6 10-18-2006, 06:41 PM

Quote:

Originally Posted by david s poole

have smoke test done on intake manifold to look for vac leaks[lots of little ones not one big one]with the age on these cars i'm finding that a complete o/haul of intake is almost mandatory.

Hi Dave,I have thought as much my self,I have injector rubbers and a complete set of intake dough nuts and intake gaskets,I replaced part of the idle air lines,found a crack in one.
I have a bee keepers smoker think that will work? thanks j-n-t

just-n-time · #7 10-31-2006, 02:03 PM

Quote:

Originally Posted by just-n-time

Hi Dave,I have thought as much my self,I have injector rubbers and a complete set of intake dough nuts and intake gaskets,I replaced part of the idle air lines,found a crack in one.
I have a bee keepers smoker think that will work? thanks j-n-t

Well it is A week or two but after fixing the rear in our work truck,and a few dozen more things,I was able to get back to our beauty,and true to her temperament it would not start,though it did cough as if it wished to,so I unplugged the EHA to no avail,back to ground zero, I have it on my mind to remove the fuel screen from the tank and inspect that,is it a messy job and are there any tricks to it?I am going to start at the rear and come forward again,though I do intend to re build the intake system,soon as miss Debbie lets me have more money! Some more hints and thoughts are as always greatly appreciated,j-n-t

david s poole · #8 11-01-2006, 11:19 AM

i would lean out the fuel mixture.you must have richened it too far,because it sounds like it is choking on too much fuel.pull the oil dipstick and see if there is fuel in the oil.[by smell and also if fuel is present the mixture will pull back from the edge of the dipstick].

just-n-time · #9 11-01-2006, 07:22 PM

Quote:

Originally Posted by david s poole

i would lean out the fuel mixture.you must have richened it too far,because it sounds like it is choking on too much fuel.pull the oil dipstick and see if there is fuel in the oil.[by smell and also if fuel is present the mixture will pull back from the edge of the dipstick].

Hi Dave,will check on the gas in the oil in the am,just changed every thing accept the brake fluid and trans,fluid,when I get to the intake I will have to save the antifreeze its all new not even 50 miles on the change. let me try to remember clock wise to lean yes? well I will look it up latter.Good to here from you again,We never made it over to see you now that school is back in full swing Miss Deb will be tied up so if I can get things balanced,We will get together. j-n-t

david s poole · #10 11-02-2006, 09:26 AM

ccw to lean,cw to richen.i would try a half turn just to start.pull one or two plugs to check,they will be black if you are too rich.

just-n-time · #11 11-03-2006, 06:44 PM

Quote:

Originally Posted by david s poole

ccw to lean,cw to richen.i would try a half turn just to start.pull one or two plugs to check,they will be black if you are too rich.

Oh yes indeed I will check to see if any are blackened! CCW, yes I looked it up and knew I was wrong as soon as I wrote CW, Thought I would get to the fuel strainer in the tank this wknd but my Friend has a Ford that blew a plug out so I will spend my time getting them back on the road,I think there son has to much torque in his arms. Well I shall keep every one posted,concerning the MB. Thanks again Dave,Always good to here from you,j-n-t

Minnet · #12 11-03-2006, 07:12 PM

I noticed, that you mentioned, that it would run smoother with the EHA disconnected.

In that case, you should not attemt to adjust the mixture screw. With the EHA disconnected, the fuel distripbutor will operate in its "native" mode (as it did before the "E" version), where the fuel pressure increased proportional to the airflow by the mechanical control (air flow meter plate will move the plunger inside the fuel distributor). The mixture screw is adjusting this linkage, and since it appears to run OK with EHA disconnected, the adjustment must be close to the correct position.

The EHA is connected in parallel to the plunger to fine adjust the mixture according to the feedback from the oxygen sensor.

So, if it works well with EHA disconnected and ill when connected, the problem must be in the electronic loop. Either it could be the EHA itself (it does fail sometimes), or it is the control by the ECU, which basically gets input from oxygen sensor, air mass sensor, altitude sensor (if provided), coolant temperature, rpm, speed and throttle position switches.

just-n-time · #13 11-05-2006, 08:41 PM

Quote:

Originally Posted by Minnet

I noticed, that you mentioned, that it would run smoother with the EHA disconnected.

In that case, you should not attemt to adjust the mixture screw. With the EHA disconnected, the fuel distripbutor will operate in its "native" mode (as it did before the "E" version), where the fuel pressure increased proportional to the airflow by the mechanical control (air flow meter plate will move the plunger inside the fuel distributor). The mixture screw is adjusting this linkage, and since it appears to run OK with EHA disconnected, the adjustment must be close to the correct position.

The EHA is connected in parallel to the plunger to fine adjust the mixture according to the feedback from the oxygen sensor.

So, if it works well with EHA disconnected and ill when connected, the problem must be in the electronic loop. Either it could be the EHA itself (it does fail sometimes), or it is the control by the ECU, which basically gets input from oxygen sensor, air mass sensor, altitude sensor (if provided), coolant temperature, rpm, speed and throttle position switches.

I did reset or adjust the fuel when I had it running so I might have over richened the system I will pull 2&6 just to look,The ox is new,Not more than 20 mile on it,Though I have no idea of all the other switches and sensors you mention. Fuel system has nearly a complete revamp we only have the tank screen to replace and I will then be certain of the fuel system having good supply to the main filter and the pumps,Well onward and upward thanks for your input all is greatly appreciated j-n-t

just-n-time · #14 12-03-2006, 06:51 PM

well I have a few new things to post,Intake got a complete update all new gaskets and all rubber including the air duct housing,after this job was complete the Idle had to be reset it seems that the Eng.had such a bad intake leek that some one had the fuel linkage set so that after the rebuild it ran at 4000 rpm,after all that has bean cured we are now at the point of needing a new ICV to regulate the Idle and some new plug wires.
We will update all the sights as the job is progressing.jnt

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