Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 08-03-2003, 04:00 PM
Meza's Avatar
Registered User
Join Date: Jan 2003
Location: SC
Posts: 148
Throttle position switch and the way transmission shifts

Main question: If the TPS is not working properly, would that cause the car to accelerate slow and tranny shifts hard?

At low speed the car is slow and once I get it above 60 Miles/hr it has plenty of power. I did the following tests:

1. The on/off ratio is at a fixed 50% when engine is started and then will fluctuates around 50% after warm up (O2 sensor is working properly)
2. EHA current fluctuates around 0 mA like it should (-0.40 to +0.34 mA ).
3. Idles good except for a slight miss that I can't still figure out where it's coming from. I have changed the ignition wires 2 days ago as #3 ignition wire had an infinite resistance. The engine miss was reduced, but it is still there.
3. The cylinderhead was rebuilt about 800 miles ago.
4. I get no more than 300 miles on one tank. Yesterday I refilled after about 260 miles.
4. Spark plugs, cap, and rotor are all new and look normal after the 800 miles.
5. The OVP relay is new.
6. I adjusted/lubricated the throttle linkages.
7. Injectors were replaced about 50K miles ago and no difference is driving power.
8. I checked the ignition coil for resistance and it is within the MB manual specification.
9. The idle valve was cleaned (was fairly clean) and WD-40ed.
10. I don't have a check engine light (I can't see one in the car).
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer
Reply With Quote
Old 08-03-2003, 05:51 PM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
Old 08-03-2003, 07:11 PM
Meza's Avatar
Registered User
Join Date: Jan 2003
Location: SC
Posts: 148
Thanks Steve. Good short answer.

I have just finished changing my transimission fluid and filter that I did immediately after posting this question. The car seems to be shifting about 80% better. I guess my modulator will need adjustment and may have to take it to a shop or the dealer. It is hard to get to or maybe there's a trick to get to it. I have a new updated one in case the old one is leaking. I suspect I have a vacuum leak in the modulator. The vacuum line going to it is not leaking. I used a vacuum pump and it held vacuum alright.
Thanks again,
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer
Reply With Quote
Old 08-04-2003, 10:08 AM
Registered User
Join Date: Jul 2001
Location: SoCal
Posts: 1,303
If shifting is smooth under some conditions - e.g. gentle acceleration - you might try adjusting the bowden (sp?) cable to get the shifts to occur at a higher rpm. You might also pull the airflow sensor potentiometer to check its condition (scribe-mark its position first!). If the element is worn through, you won't get proper low-speed enrichment on acceleration.

'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
Reply With Quote


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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 11:20 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page