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  #1  
Old 09-05-2002, 12:56 PM
Potomac German Auto
 
Join Date: Mar 2002
Location: Frederick, MD
Posts: 407
Question Defective EHA ???????

HELP !!!!! I am experiencing some problems w/ my fuel system. It is only happening after the car has been warmed up. It seems to hesitate when I step on the gas. I already replaced my fuel pump & filter last week. I am wondering if a defective EHA would cause this????
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1994 E500 (MY SUNDAY DRIVER)
1993 190E SPORTLINE LE W/ M104 SWAP
1997 C230
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  #2  
Old 09-05-2002, 03:06 PM
it leaks, its german
 
Join Date: Mar 2002
Location: raleigh nc
Posts: 1,111
what about the reference potentiometer (spl?) ?



Joe
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  #3  
Old 09-13-2002, 06:49 PM
Registered User
 
Join Date: Jul 2002
Location: Ojai, Ca.
Posts: 71
You might want to verify your fuel pressure regulator as well.
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  #4  
Old 09-16-2002, 09:22 AM
Potomac German Auto
 
Join Date: Mar 2002
Location: Frederick, MD
Posts: 407
Post Update....

Well a more than a week has passed and I have swapped out numerous components on my 16vlv. I started by replacing all of the units including the accumulator, fuel pump & filter. I thought that this remedied my problem. However, I was still experiencing severe hesitation. At this point I decided that I would do a complete tune up. To include, sparks plugs, wires, distributor cap and rotor. While in there I decided that I would swap out the EHA b/c I still felt it was a fuel delivery problem. Nothing again

I still am experiencing that same "surge" on deaccelaertion and in the 4k - 6k range on the Tachometer while accelerating. It puzzles me and I am wondering if it is now the poteniometer housed in the air flow meter. On start-up this morning I cranked it once and the engine settled into a high rev around 2200rpm. I tapped the gas and it fell back to around 900. This is second time in two days that I have seen this occur on start up?

Is there any way to test the poteniometer on the air flow meter? If I Ohm out the #1 & #3 pins on the side of the airflow and slowly push the "plunger" down, should there be a steady decrease/increase?
__________________
1994 E500 (MY SUNDAY DRIVER)
1993 190E SPORTLINE LE W/ M104 SWAP
1997 C230
2002 ML320
2000 BMW 528I (WIFEY'S CAR)

"Excuses are crutches for the unfounded."
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  #5  
Old 09-21-2002, 09:13 PM
Registered User
 
Join Date: May 2000
Posts: 376
Pat,

Welcome to 16V hell! Just kidding. But as these cars get more miles on them, they become more labor intensive. Seems they all get idle issues at some time.

To check the air flow meter, you need to check the #1 and #2 connector plug with the key on and the plug connected. Should read around 0.8-1.0 v at an idle opening of the air flow plate and increase smoothly to approximately 5.0v at WOT. No open circuits or spikes, nice linear voltage while you manually depress the flow meter.

Good luck and let us know what you find.

Tinker

Last edited by Tinker; 11-03-2002 at 02:03 AM.
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  #6  
Old 11-02-2002, 01:40 PM
Registered User
 
Join Date: Oct 2002
Location: Toronto, Canada
Posts: 700
I'm also having a similar problem Like Pat. I have started testign all electrical components to see if they match up with what the manual states the values should be at. Now I don't know about the Voltage in the air flow meter potentiometer, but when i check the resistance on pin #1 and pin #2, I get a steady increase from 0.98Kohm to 4.83Kohms. This is a bit off from what the Service Manaul states, which should be from 3.8Kon to 5.6 Kohm. I see this as a possible problem since it would make sense that the computer does not see the Air coming in until the air flow meter reaches at least 3.8Kohm, and it hesitates up to that point, however since the entire scale is way off, the engine never performs how it should and hesitates and misses cause of a bad mixture. I already tested my EHA and it works like a charm. I have a multimeter hooked up next to me when I drive and I see the current through it at all times. The car hesiatates when the EHA current is at 0 and stops hesitating as soon as it starts increasing, well the higher the current the less it hesitates. I have read that the current should be a from 0 to 12ma, or so, 7-8 being the middle where the car idles. 0ma occurs when you let go off the gas, and my car does this perfectly but does not recover from this stage until it reaches around 2000rpm.
If anyone has any suggestions regarding this, or ran into a similar situation, or simply knows what should be happening and when, please get back to me, I'm still trying to figure this out.

oh yes, it's an 85 190E 2.3 8vlv
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  #7  
Old 12-13-2002, 12:57 AM
psteinke
Guest
 
Posts: n/a
regarding xp190's hesitation

My 86 190E 8 valve hesitates all the time. It has very low acceleration and wont go over 60mph either. My EHA current is 0mA all the time. What was the thing that caused your eha current to stay at zero longer than it should have? Maybe mine has the same problem

Though, I setup to manually control the current through the eha and tweaked it around 8mA + - 4mA while accelerating and running at top end. No matter what current I had, the car ran the same miserable way. Bad eha I suppose?

Paul
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  #8  
Old 12-13-2002, 01:52 PM
Registered User
 
Join Date: Aug 2002
Location: Central Asia
Posts: 104
same problem different solution

This is a very good thread on the idle surge problems some of us are having.
My 1989 230E used to keep accelerating for 2-3 seconds after I release gas pedal. That was very a dangerous car to drive.
Interestingly when two months ago I have disconnected the electrical connection to the idle control valve and the car stopped surging . The car was surging because the idle computer was keeping the idle valve full open when surging(found this by monitoring the voltage to the idle valve). I think that the idle computer is reading false data from some sensor or switch. When I reconnect the idle valve the surging returns and idle goes down from 1100rpm to normal 800 rpm.
Right now I am driving the car with idle valve disconnected because it is better to have a higher idle than have the car accelerate by itself.
The so called "idle control computer" is actually called the Bosch KE fuel injection control computer. This computer:
-supplies EHA current and idle valve current,
-monitors the air mass meter, temperature sensor, idle microswitch, and EZL fuel octane corrector
-linked to the fuel pump relay, OVP
this is all according to the electrical scheme of the car I have on my pc.
Any of the above units can be a cause of the surge. It might be years before I find out what it is. However if we all think togeather and share our knowledge we can get to the problem faster than it seems.
Good luck everone.
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  #9  
Old 12-13-2002, 04:39 PM
Registered User
 
Join Date: May 2000
Posts: 376
As Hurshi states, the end result of all the sensors inputs is the voltage at the EHA. If you have no voltage at the EHA, your OVP relay is probably toast or a sensor is way out of line. For a correctly adjusted system, the voltage should be around 0 ma. From my understanding, the older systems adjust only positive ma, whereas the newer cars 1986+(?) adjusted either side of 0 ma (ie -10 ma to +10ma).

Tinker
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  #10  
Old 01-11-2003, 01:53 PM
Registered User
 
Join Date: Oct 2002
Location: Toronto, Canada
Posts: 700
my eha is acting weird

I noticed today that when I let go off the gas, and I'm going above 60kmph, the eha gets a current of 56ma, this is the eha with positive current only. Once the car goes below 60kmph, the current falls to 0 and stays there until the car goes over 2k rpm. Can any give any insight on this? Why would the eha richen the mixture when the decel switch is engaged?

xp
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