Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-25-2004, 12:13 AM
zorin's Avatar
Registered User
 
Join Date: Feb 2003
Location: Ottawa, Canada
Posts: 126
EHA current, Vacuum, poor throttle response

Problem: throttle not always responsive under engine load.
'88 260E

Hello,

In order to troubleshoot the intermittent problem of throttle not being responsive on my '88 260E, I meaured the EHA current while I was driving. I also hooked up a vacuum gauge to see vacuum use.

At engine operating temperature, key on , ignition off, I read +19 mA at EHA.

At idle speed, I get 0-4 mA . I think this meant that due to vacuum guage connections I was getting a bit of vacuum leak and the ECU was trying to correct it. The vacuum reading at idle was about 15 inHg. Is this normal?

As I started driving, the EHA current was moving between 0-8 mA. However, often, after a stop at any traffic light, or acceleration from a slow down, the throttle is not responsive. I the have to lift my foor off the pedal and depress even more to get the response I need.

I checked the readings of EHA and the Vacuum when I depressed the accelerator (but no immediate response). EHA current stays around 0-4 mA. The vacuum guage will go to zero, stays there for couple of seconds and then it goes to about 15 in-Hg or higher.

My understanding is that, under engine load, such as acceleration from a slow down or from a stop, or uphill, when the gas pedal is depressed, ECU, based on inputs sensors such as Air Flow Meter, O2 sensor etc, should increase the EHA current to 8-10 mA to cause more fuel flow to flow. I did see this increase in current at times when throttle response was OK. However, the current never reached +13 mA and the vacuum gauge always dropped to zero for a second or two whenever I depressed the gas pedal.

What would prevent the ECU from detecting the engine load? o2 sensor is new and I checked the Air Flow Meter for continuity. I also cleaned the throttle body and links. What else can I check?


Thanks.

__________________
Zorin

'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)

Last edited by zorin; 05-25-2004 at 12:31 AM.
Reply With Quote
  #2  
Old 05-26-2004, 12:04 AM
zorin's Avatar
Registered User
 
Join Date: Feb 2003
Location: Ottawa, Canada
Posts: 126
I am starting to think that EHA current has nothing to do with throttle position.

__________________
Zorin

'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 11:07 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page