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 ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-25-2001, 09:03 AM
Registered User
 
Join Date: May 1999
Location: Calgary, Alberta, Canada
Posts: 190
I have an 1988 300e that has a rough idle at initil cold startup that lasts for about 3 seconds and then it is fine. I have replaced wires, cap, rotor, plugs and it is still there. The car uses no oil or antifreeze as that was my first thought that might be causing an idling problem (fluid in one cylinder). Also, occasionally I will feel a very slight miss at idle. Car runs and drives perfect except for at idle. Any ideas?
Reply With Quote
  #2  
Old 01-25-2001, 10:18 AM
Crowe's Avatar
Benz Enthusiast
 
Join Date: Apr 2000
Location: Atlanta, GA
Posts: 366
'88 300E

I have the same situation with my '88 300E. This appears to be a fairly common problem. I replaced the plugs and have used some fuel injector cleaner which did seem to help for a while. In my case the problem seems to be worse at times, and then almost go away at other times.
__________________
  • 2001 E320
Reply With Quote
  #3  
Old 01-25-2001, 12:11 PM
yal's Avatar
yal yal is offline
Benz-smart
 
Join Date: Oct 1999
Location: New York, Long Island
Posts: 2,705
Same here...I am seriously considering changing the injectors seeing as they are cheap and its a pretty simple DIY job.

ps I hope its not unique to 1988
Reply With Quote
  #4  
Old 01-25-2001, 10:06 PM
Registered User
 
Join Date: Dec 2000
Posts: 368
This definitely sounds like bad injectors to me. Had a few cars with the same problem. Putting in new injector should take care of the problem.

However, new injectors have to be pressurized. You wouldn't belive how many people just put in the new injectors. Sometimes it's fine, but most of the time you end up with the same problem or make it even worse.

CIS injectors have a certain pressure at which they open and close. In order to get them to work right (when brand new) you need to put a lot of pressure on them to open them up. The car fuel system pressure doesn't go this high. You need to take it to someone that has a pump or you can take it to your dealer. I don't think they charge that much to change injectors.

Vin
Reply With Quote
  #5  
Old 01-26-2001, 12:07 AM
terryloh
Guest
 
Posts: n/a
Hi Vinamg,
I'm just curious bout the new injectors needed to be pressurized stuff. Is it in the mB manual or is it thru experience. I've just replaced my injectors and never heard of this from my mech???
1987 300E
Thnks
Reply With Quote
  #6  
Old 01-26-2001, 12:29 AM
Registered User
 
Join Date: Dec 2000
Posts: 368
I'm pretty sure it's somewhere in the manual.
I didn't know about pressurizing the injectors either.
Anyway, I was working on a 88 560SEL about a year ago. The car was in real bad shape. I changed the plugs, wires, distributor, rotor and injectors. The car ran perfectly except for a slight hesitation from a dead stop. I knew the problem was fuel related. I checked the whole fuel system, checked for vacuum leaks etc. The car was driving me crazy.

Finally, I decided to ask my friend about it at the local Mercedes dealership. I told him about the problem and about the parts I changed. Without hesitation he asked me if I pressurized the fuel injectors. To make a long story short. He pressurized (opened) them, I installed them and my problem was gone just like that.

I am pretty sure the techs on the forum know about this.
ALL NEW MECHANICAL INJECTORS HAVE TO BE PRESSURIZED (OPENED) AND CHECKED FOR CORRECT OPEN/CLOSE PRESSURE AS WELL AS SPRAY PATTERN.

Vin
Reply With Quote
  #7  
Old 01-26-2001, 12:38 AM
terryloh
Guest
 
Posts: n/a
Hi Vinamg,
thnks for your reply. As for pressurizing the injectors, would using an air gun work? Or how do the experts do that?
Thnks again
Reply With Quote
  #8  
Old 01-26-2001, 02:28 AM
Registered User
 
Join Date: Dec 2000
Posts: 368
They have a small Bosch pump with a fuel container. It's the same pump that they use to test the injectors. I think the pump can go all the way up to 10 bar. Normally you don't have to go over 5 bar to open them up and have a nice spray pattern.

Vin
Reply With Quote
  #9  
Old 02-03-2001, 10:04 PM
Registered User
 
Join Date: May 2000
Posts: 317
pressurizing injectors

I want to change my injectors and the sleeves soon. I believe you about pressurizing the injectors(which just made it a NON-DIY for me). If at all possible could any of the moderators or more experinced techs go more into detail about this? Vinamg, if you are a more experienced tech I do apologize for the oversight.
__________________
Richie
1986 300E
Reply With Quote
  #10  
Old 02-04-2001, 07:45 AM
Registered User
 
Join Date: Dec 2000
Posts: 368

I was hoping that one of the techs from the forum would confirm the info. However, my friend that told me about it has been a certified Mercedes tech for 8 years.

I've changed injectors in a few "CIS" cars and never had a problem. Once I found out about it I always do it. With the proper pump it can be done in 5 minutes. I'm not sure what they would charge for it. I just take it down to my friend at the dealership and he does it for me.

If done and you still have a problem, at least you can eliminate the injectors. I just don't want anybody repeating my mistake. I eliminated the injectors because they were brand new. The car drove me crazy until I talked to my friend about it.

Vin
Reply With Quote
  #11  
Old 02-05-2001, 03:07 PM
Bigshot
Guest
 
Posts: n/a
Have the same problem with 89 560. The dealer found a antifreeze leak and had to remove intake or some ****. I have a bag of black plastic tubes that were replaced then too. Since then the car shutters at start up most of the time. Do used injectors have to be pressurized as well or just reinstalled?
Reply With Quote
  #12  
Old 02-05-2001, 07:54 PM
Registered User
 
Join Date: May 2000
Posts: 317
Re:pressurizing injectors

You take your injectors to have them pressurized before you install them yourself? Or,does the shop do this as a favor to you? Larry, Jeff, Benzmac, Donald, Stevebfl, M.B.D.O.C is anyone there to confirm this? We need to know before I go to a shop and make a fool out of myself.
__________________
Richie
1986 300E
Reply With Quote
  #13  
Old 02-05-2001, 08:18 PM
engatwork's Avatar
busy
 
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,774
hmmmmm, I have never heard of

doing anything other than turning the ignition to "on" for a couple of seconds and not starting the car. May have to do it a couple of times. It is my opinion that the system will then be pressurized.
Jim
'95 E320
'97 CRV
Reply With Quote
  #14  
Old 02-05-2001, 08:24 PM
Member
 
Join Date: Jan 2000
Location: Indpls.,IN. USA
Posts: 84
The largest problem from my point of view, with K-jet and KE injection is leaking injectors. This has been a problem with these systems since they were introduced in the mid 70's. The rough start is caused by excess fuel leaking out of the injector and causing an rich cylinder, another problem is that it takes a second or two for that fuel circuit to refill and acheive opening pressure. As far as presurizing new injectors prior to installation, I don't. I have probably installed a thousand or more. However there certainly would be no harm in testing a new injector with the proper solvent. The most important thing to keep in mind is cleanliness. Take the time to blow the dirt from around the injector fittings and leave the caps on until you are ready to screw on the lines. The pressurizing is cleaning out contamination. It would have no effect on the mechanical operation of the injector.
Reply With Quote
  #15  
Old 02-05-2001, 10:08 PM
Registered User
 
Join Date: May 1999
Location: Calgary, Alberta, Canada
Posts: 190
Would it make any difference taking them out and having them cleaned to see if they are leaking or anything or are they just bad injectors (quality) to start with.
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mercedes (and BMW) straight sixes have a rough idle "by design"?! sanchezc Tech Help 32 12-22-2014 07:01 PM
Rough Idle & Cruse Control Problem 1988 300E billw7 Tech Help 1 09-27-2004 06:58 AM
87 300E runs rough at idle & low speeds, lamda sensor? Mateo Tech Help 3 09-29-2002 06:31 AM
300E rough Idle sugar8 Tech Help 2 06-08-2002 06:01 AM
Rough idle on 300E... just got worse PCU2000 Tech Help 24 01-07-2001 02:25 PM



All times are GMT -4. The time now is 06:36 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, 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