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

LinkBack Thread Tools Display Modes
Old 01-25-2007, 08:59 AM
Registered User
Join Date: Apr 2005
Posts: 136
Need opinion on fuel injector replacement

Hi guys,

I just need your experience on this idling issue I have. It's more a slight shake than a stumble. As you might have guessed I replaced 1 steel injector that fouled up when I previously had a burnt valve with a brand new brass kind.

When mixing old(steel) and new(brass) injectors, is the opening pressure difference great enough to cause irregular idling? I'm thinking that since the entire injection system has the same pressure from distributor to injectors, new injectors mixed in with the old actually causes fuel starvation for its assigned cylinder.

My issue is there at start-up then goes away during warm-up, but comes back at WOT. Vacuum lines have been checked and replaced those that needed it. Ignition parts checked/replaced. Air/fuel mixture at 50% with a new O2 sensor.

Thanks in advance.

'87 190E 2.3 8V

Reply With Quote
Old 01-25-2007, 02:35 PM
Registered User
Join Date: Aug 2006
Posts: 141
Miss at idle

Have you determined which cylinder is hitting light? Break loose injector lines at the fuel dist. one at a time and look for the one that the least RPM drop. Next swap the injector from the weak cylinder to another hole and test again. If the miss moves with the injector replace it, If not look for compression,ignition or fuel dist. problems at that cylinder.
Good luck Mike
Reply With Quote
Old 01-26-2007, 04:16 PM
Registered User
Join Date: Apr 2005
Posts: 136

Thanks for replying. How do you break the line while the engine is running without making a mess? Just the idea of 3bars of 93 octane spraying allover the engine frightens me.
Reply With Quote
Old 01-26-2007, 07:36 PM
Registered User
Join Date: Dec 2004
Location: Eugene, OR, USA
Posts: 121
uneven idle

The idle on my '86 300E smoothed out a lot when I replaced the injector seals. I identified the seals as leaking by spraying carb cleaner on each seal and listening for any change in the idle. If the idle changes, you know the carb cleanr is being sucked in around the seal.

My old seals were so hard they shattered like glass when I removed them. The new seals were nice and soft and inexpensive too. This isn't a hard job to do at all.
1986 300E
1993 Volvo 940 Wagon
1984 Volvo 240 (daughter's)
1976 Dodge 1/2T pickup, gas hog
Reply With Quote
Old 01-27-2007, 05:30 PM
Registered User
Join Date: Jan 2007
Posts: 242
you don't open the line while the engine is running, rather you let the engine run for a while till the pressure on the line has increase (say around 5 minutes in idling speed), then shut the engine and start with each line (top fo the the fuel distributor) slowly opening each line and see if there is pressure and fuel coming out from each line
Reply With Quote
Old 02-01-2007, 03:05 PM
Registered User
Join Date: Apr 2005
Posts: 136
Thanks for the replies.

I'll check the seals this weekend.

As for disconnecting the lines, I think this would be a good test for injector leaks. One question though, does each fuel line hold its own pressure? I mean if 1 injector is leaking (meaning pressure drop on this line) would the other non-leaking injectors maintain their pressure?
Reply With Quote
Old 02-08-2007, 08:36 AM
Registered User
Join Date: Apr 2005
Posts: 136
Thanks again.

It was definitely an injector seal problem. The new injector had a shorter seal and since the old seals were stiff, it didn't let the metal brackett go all the way down to seal the new one.

Engine performance is now at acceptable level, enough for me to move on to other issues.

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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 01:02 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, 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