190e 16v problem ???
 

hello,
i have a 86 190e -16v ,5 speed, when i come to a stop or when I am driving and push in the clutch the idle is staying at
3000 for few seconds then drops very slowly , or sometimes it just drops to 2k and stays there and at the next light it goes
back to 1k? , so i have been controling idle with the clucth , ouch,
I have cleaned the air flow sensor,(very clean), microswitch is clicking on , and is about a year old, ) 02 sensor is new with a catless system, If anyone has had this weird idle problem or
if you know what it is enlighten me please
thanks
1986 190e-16v
1974 IROC 911 rep
1984 benson gyrocoper

Have you also checked the idle control valve? I have read stories about clogged valves that won't do their job right. Just my 0,02

Dave, I've found that 90% of the time that problem is caused by the air-flow position sensor.
In fact I've had that problem on my street car & know that Benzmac also had the same problem.

Not a cheap OR easy repair

Is the air flow position sensor that whole unit under the fuel
distributor, or can i just bolt a new sensor to the housing?
You woundn't know the part # , i looked for airflow poisiton sensor with fastlane and didn't get anything?
thanks for your help
dave

Available only thru the aftermarket. BOSCH part number 3-437-224-035, very hard to calibrate.

MB part number 000-074-23-14 for the complete housing.

the temperture outside is 40 and warmer now , and the high idle
problem is GONE!!! It has not done it once???
Would the air flow sensor change in the colder minus 0 temps ?
any advice?
thanks

Dave,

Sounds like you had condensation and thus an ice build-up on the air-flow sensor or your linkage. Glad to hear it is back to normal.

Check the lube on your linkage and look and see if the sensor or the air boot going to it has moisture on or about it.

Haasman

today it was back to 20 deg out side, and the idle is back up to
2500, 3000? Any idea's I did clean up the air box, I did have some ice in it mixed with oil . I was almost thinging the
K&N air filter is letting water into the airmeter and and gumming it upon cold days, I fully cleaned it out, running with cleaner
but, still high revs
thanks

Perhaps the picture will explain things better.
Is there a procedure to calibrate it?
(we already know is hard, just out of curiosity)

Dave,

Disconnect the throttle position sensor on the side of the throttle body, not the decel switch, and report back.

Read here:
http://www.peachparts.com/shopforum/tech-help/52787-masking-faulty-air-flow-meter.html


Tinker

Hi Tinker:
I believe that your car is running VERY Lean at a duty cycle of 78%, not richer.
The MB manual clearly states:
"leaner = high ON/Off Ratio"
Since you find no difference in performance, may be the closed loop is compensating with enough fuel such that the performance is not affected, since the compensation goes from 10% to 80% (according to the graph below). I do not know how much this stresses the system.
Experts like stevebfl can give a better explanation.

Pesuazo,

I know, it seems completely opposite to what I have also read throughout this forum. BUT turning the mixture adjustment to the right (counter clockwise) results in lower % duty cycle reading on my car. Any thoughts? The only thing that crosses my mind is the cars attempts to compensate for the lean mixture but adding fuel through the EHA.

I had the car adjusted to the factory specified 50% duty cycle and near 0 ma at the EHA prior to its biannual smog check. It failed and they LEANED it out. I checked the duty cycle when I got it home and it was near 20%. Go figure. Completely inverse to what one would expect.

Look at the graph you just posted. 78% is on the left side of the graph, the rich side. Am I reading that right???

Tinker

??????????????/
 

Davect,

How is the performance of your 16vlv. Does it feel as if it is struggling to pull in the higher RPM range? Say like 4,000 on up?

My car has the exact same issue with it. I replaced the airflow meter w/ a known good one, but I still have that same problem. My car will not decrease idle from 3k, then all of the sudden it will drop back down to 900-1000 rpm.

My car feels like it is experiencing a lack of power. It in no way feels like a 16vlv should. When in 3d - 5th the car no longer wants to pull up through 6700rpm. She is acting like a dog.....!:confused:

pat

my 16v is sluggish at low RPM it sometimes bucks like a old 123 around 1500- 2000 rpm ,but high revs it really pulls about 4500-5000. Gas miles lately have been about 10 -15 miles a gallon?
thanks
dave

IDENTICAL ISSUE AS MY CAR !!

What you are explaining is almost identical to the problem which I have been chasing for a while. Please keep us posted !

:)

Yes, you are right. This graph has the lower duty cycle on the side that states rich. I think it is a mistake from its creator (whether the graph is right or wrong I am not to be credited, I just borrowed from one of the forum's member's website). According to the manual a low duty cycle means a rich mixture. The article from Stevebfl in the DIY section "Evaluating Electronic Engine Controls" mentions a duty cycle of 35% as rich.
Quote: "The value of 38% indicates a rich reading".
The fact that your duty cycle drops when turning CCW is waaaaay over my head.
Experts, please take me out of my ignorance, explain this matter.
:confused: :confused:

Pesuazo,

If you have a volt meter that reads duty cycle, we could settle this discussion. Maybe Pat or Dave could chime in here. Guys where is your duty cycle set? Would you mind terribly leaning it slightly to see which way the duty cycle readings go? You gents might discover why your cars are running so poorly. A fixed reading indicates a problem. Have you guys pulled the resistor (R16?) out of the wire harness to advance the timing???? It makes does make a slight difference on these 16V motors.

BTW wifes 87 16V auto usaully runs right around 20mpg. With a 5 speed I would expect a bit more.

Tinker

Thats why I am so confused, I do own a meter with duty cycle. I have the CD manual with the codes and all the diagnostic testing. I have become somewhat profficient at diagnosing my lambda control.
When I go CCW, I see my duty cycle go up, CW it goes down, just like the manual states.
For what I understand the Duty Cycle (in an ideal system) should oscillate between 45-55%, at idle and at 2500 RPM.
There is an acceptable 10% difference. ie. 40-50% idle and 50-60% 2000 RPM is OK
Mine normally oscillates at 41-48% idle and 49-57% at 2500 RPM. And those values were achieved "tinkering", just like your name. ;)
Obviously all the inputs are OK, since I have no fixed duty cycles.
Except when cold, I get 50%, when it warms up it oscillates (which only makes sense, since closed loop happens only in a warm engine)

Pesuazo,

I don`t doubt you. I wish the other 16V owners would chime in.
Although it would be a bit strange, perhaps the 16V`s CIS program was designed differently??? I doubt it. Bad computer?

Scratching my head.

Tinker

I calibrated the air flow meter on my 190
 

Calibrating the air flow meter is not that hard at all, it just seems this way

all you need is a good multimeter and LOTS of patience.

Mine was glued on and I decided to rip it off and put it back the way it should be, why it was done this way I dont' know but it's fixed now

What I did is set it to it's lowest possible reading, this takes micrometer precision so make sure you got a steady hand.

also don't let it be too lose when you are adjusting it because the slightest movement will set it to some catastrophic value.

that's all there is to it really, worked for me at least.

stupid guy told me I would need the entire air flow meter asembly which is $800 or more

took me an hour to fix the problem.

xp

Hi xp:

Did you purchase a new pot or just cleaned the old one?

Did you take pictures by any chance?

I read somewhere (stevebfl?) that a pencil eraser can be used to clean "something" inside. I am dying of curiosity. I don't want to open mine up for fear of getting stranded. I only have one car, this one, and the word catastrophic does not help either.
I certainly don't have micrometer accuracy with my hands.
I searched and searched the net, but could not find a seller of the pot by itself.

Calibrating the Mixture on a 16 V
 

I have been struggling with my cars drivability for the last 8 months after replacing my car's potentiometer to fix a stumble on acceleration. The stumble ended up being a defective distributer cap so I reinstalled the original pot after cleaning it with alcohol.

When reinstalling it the only procedure check that I have was to get the unit to increase continuously to approx 5 volts when the sensor plate is deflected, per my MB manual. Is this critical? If so why does my CD rom manual so vague?

Since this time I have been unable to get the car to idle reliably. Sometimes it idles fairly good with just a slight dither between 950-1100. Other times it will stall repeatidly at idle. Still other times it hangs at 2000-3000rpm. I am very suspect of the CIS control unit being bad from my tinkering, but based on some of the other posts I am not alone in my problems. So maybe the Control Unit is OK, just the system is out of adjustment.

I took the car into a shop to fix and they simply drilled out the mixture adjustment plug and tampered with that and then concluded that they could not fix it either. Now I have no idea what is right anymore.

I do have the MB manual and have checked a number of the devices and have found everything to be within spec in terms of resistance values and the EHA when checked seemed to be at the proper duty cycle at idle.

The car is currently running rich based on fuel mileage 17mpg and black soot coming from the tailpipe. but when I adjust the mixture screw the idle has a tendancy to oscilate violently and stall repeatidly.

Currently I have my multimeter hooked up to the O2 sensor and am curious about the signal from that. Once the car warms up the signal is around .8-.9 volts most of the time, but then occasionally it will oscilate from .1 to .9 as I think it should but then a few minutes later it again hangs at .8 or .9.

Any suggestions would be appreciated.

Zeilekd,

What kind of car? 16V? You checked the duty cycle at the X11 plug? And what was the duty cycle? What is the ma at the EHA? That will give you an idea if your mixture is close and if the O2 is functioning.

Tinker

Tinker,

86 2.3-16 190e

Since the shop adjusted my mixture and my potentiometer is out of adjustment I have to ask which one to adjust first and what the procedures are. Is it wrong to assume that the O2 sensor either works or it does not? My biggest frustration with the car is that nothing seems consistent. I do not understand how a Potentiometer or Mixture being out of calibration would cause different operational problems when all other operational conditions (outside temp, engine warm up time etc.) are the same. This is why I question the CIS control unit. Something is arbitrarily causing the ECU to send bogus signals to the rotory idle air valve. Can this be the potentiometer? Also what about my O2 sensor hanging at .9 volts then a minute later adopting the oscilating voltage with an average at .5?

Kurt,

I don`t think the shop you took your car to was very knowledgeable. Did you mention to them that you reset/cleaned the potentiometer or did they come to the conclusion that the air meter was out of adjustment on their own? I know some other posts indicate you can set these by yourself. From what I have read, the concensus seems to be that you can not.

Also, from what I have read/been told, the CIS computers almost NEVER go bad.

The voltage from your O2 sensor should fluctuate. They can get fouled or burned out. If you are seeing mv in the 0.1 to 1.0 range from the O2 WITH the heater wire hooked up, it more than likely is alright. If it is stuck at 1.0 mv, I believe that is a rich condition. Where did the shop set your mixture? Did they say it was lean or rich? If the air flow meter/piotentiometer is messed up, the voltage signal it sends to the ECU will be off causing the computer to make attempts to correct. Have you monitored the voltage coming out of the air flow meter?? You can disassemble the connector on the #4 runner so you can monitor the voltage while your driving. I did this for a weekend and could not find any spikes or open curcuits in mine.

Do you own a volt meter with a duty cycle function? As Stevebfl writes about, you can check the system by monitoring the EHA amperage and the duty cycle readings. You will get a much better idea as to what is going on. If you get fixed duty cycle, the number provides you a hint where the problem lies.

Let us know.

Tinker

today I took of the air mass potentiometer and the part number
is 3-430-591-017 , this part is wasted worn down to silver metal
I can not find this number any where on the web to buy a new one
the numbers you guy's gave me is 3-437-224-035
is this the new number?? I can find this one everywhere
any thoughts on this??
thanks
Dave

Dave, if your part# is different, the part may not be the same. However, if it looks identical to the ones I pictured, then chances are good it is the same. The resistance measured between the outside circuit board solder tabs is about 4000 Ohms. The 'low' end of the board has a trimpot wired in series from the solder tab to the connector pin. The other two solder tabs connect directly to the other two pins.

Steve

Classic problem
 

This is such a classic problem to all of us the 16V owners. Since the calibration procedure to this air mass sensor assembly is so intend and not so sucessfull.
I have the same problem with my car too and nothing seems to have fixed, so one day I adjusted the hex key about an eight of a revolution clockwise and the car seems to love it. It becomes very responsive thru out the whole RPM spectrum and no more getting stuck at high idle.
I have to admit that this is all luck.

Alex

I think, though, that a mixture adjustment cannot substitute well for a worn-out pot. Since that adjustment is a calibration for the mechanical action of the airflow meter on the fuel distributor, it should need to be made if the airflow meter body (i.e. the MB part) is replaced, or it there has been enough mechanical wear. The procedures described on this site involve measuring the EHA current to determine how much it is compensating for an incorrect mixture.

I was surprised by how easy replacing the worn pot was. I was careful, and pre-adjusted the new one to be as close as identical as my DVM could resolve. That done, it was plug-and-play. No mixture adjustment should be needed.

I don't know why the bad pot was causing the idle speed fluctuation and decel surging, but I have a theory:

[WAG] At steady throttle, and demand of the engine is essentially constant, the pot sensor return to the ECU is a fluctuating voltage where the wiper hits the worn spot. The ECU interprets this as 'leadfoot' and tells the EHA to go rich. Since this wasn't actual demand, the Lambda sensor tells the ECU 'very rich', and since we are signalling 'throttle closed' too, it compensates by opening the idle control valve more. [end WAG]

I stress - I really have no source that tells me this is what happens, but it seems reasonable for the symptoms.

Steve

ya I'm only getting 1400 ohm on the outside pins, plus it 's much more worn out than yours in the pictures, but it is exactly the same .(not the #'s though).

Ordered a 3-437-224-035 from Phil with new injectors,seals housings, see if this does the fix?, If not new governer then?

Ha! had no idea you could get a Bosch generic part through FastLane. I guess if you don't ask....

Anyway, I am concerned about the large value difference you measure from what I believe I did - double check the two when you get the part. I wrote what I remembered, but since I was only conerned with comparing new/old, I didn't write it down at the time.

If you do see such a large difference, though, measured right at the board tabs, then you may have a problem directly substituting the part. Bosch used a different value for a reason, probably due to the source requirements in the ECU. If somebody can supply new/rebuilt Bosch complete airflow meters, the correct pot must be available somewhere.

Look for subtle differences between the boards - jumpered pads, a separate resistor (about 2200 Ohms) connected between outer board tabs, etc. Maybe they only make one board, but change the part# as they mod the installation.

Steve