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 05-01-2002, 05:00 PM
Registered User
 
Join Date: Dec 2001
Location: Gig Harbor WA.
Posts: 69
Please!!Need tech advice on strange problem

I have seen alot of great advice shared on this forum and I hope someone might have be able to help me on this one. Thanks in advance for any suggestions!

I have a strange problem with my '88 560SL that I need some advice on.

During normal driving (below 4,000 RPM) the engine runs strong and accelerates smoothly. But on occasion (like most of the time) if I really get on it say from 60 mph it will downshift to 2nd and the tac will jump to about 4000 rpm's and it's almost like the timing gets retarded or the fuel flow is reduced and there is a slight vibration coming from the engine. When this happens it will continue to accelerate to redline but at a reduced pace. When it shifts to the next gear and the rev's drop below 4000 rpm's it begins to feel strong again. It's almost like a governor or rev limiter kicks in slightly. I can also cause this to happen if I put it in a lower gear and gradually accellerate past 4000 rpm.

I bought the car about 6 months ago and have already replaced the following:

Sub frame mounts and motor mounts
rear flex disk
both fuel pumps and filter
idle air valve and hoses
new copper spark plugs, rotor, disributer cap, plug wires and air filter
air distributor hoses that connect to the fuel injector's.
timing chain and tensioner

I have also checked for a vaccume leak and ther doesn't seem to be any.

Is it possible that a coil or EHA could cause this????
Any help or suggestions would be greatly appreciated. Thanks in advance...
__________________
Hud

88 560SL
97 E320

Last edited by Jerry Hudson; 05-03-2002 at 03:46 PM.
Reply With Quote
  #2  
Old 05-02-2002, 12:59 PM
Registered User
 
Join Date: Dec 2001
Location: Gig Harbor WA.
Posts: 69
any ideas???
__________________
Hud

88 560SL
97 E320
Reply With Quote
  #3  
Old 05-02-2002, 01:15 PM
moedip
Guest
 
Posts: n/a
four suggestions
1) is air filter clean?
2) have you changed the fuel filter?
3) run some injector cleaner in the fuel
4) check the OVP relay - I believe it also is a rev limiter (doubt if problem - but maybe)
I take for granted that your spark plugs and distributor cap and rotor are good. If all the above does not help - check the output of your coil. - sorry I lied - FIVE suggestions
Reply With Quote
  #4  
Old 05-02-2002, 02:10 PM
Registered User
 
Join Date: Dec 2001
Location: Gig Harbor WA.
Posts: 69
Thanks Moedip for the suggestions, but the air filter nad fuel filter are new and I have run injector cleaner through several times. The fuese on the OVP is new also. I have considered the OVP, but it doesn't exibit any of the common symptoms of a bad OVP. It idles smooth and no ABS light. Is there a way to check the OVP. I don't want to just start swapping parts. The strange thing is that it run great around town and only has this problem above 4000 RPM. I may have been mis-leading when I said there was a slight vibration coming from the engine when this happens. It is more like change in the harmonic frequency of the engine.
weird huh....
__________________
Hud

88 560SL
97 E320
Reply With Quote
  #5  
Old 05-02-2002, 02:27 PM
moedip
Guest
 
Posts: n/a
Have you checked the dist. cap and rotor, plugs and coil - at high rpm they have to perform flawlessly. Check for a crack inside your dist. cap - stranger things have happened on new product. Have you metered your spark plug wires - they should read- I believe - 700-1200 ohms. They should all be about the same in resistance. Like I said - could be a bad new wire - just cause they are new - doesn't mean cannot be bad. - Is you idle nice and smooth?
Reply With Quote
  #6  
Old 05-02-2002, 02:54 PM
Registered User
 
Join Date: Dec 2001
Location: Gig Harbor WA.
Posts: 69
As stated in my original post all those items are new. thanks
__________________
Hud

88 560SL
97 E320
Reply With Quote
  #7  
Old 05-03-2002, 03:49 PM
Registered User
 
Join Date: Dec 2001
Location: Gig Harbor WA.
Posts: 69
???
__________________
Hud

88 560SL
97 E320
Reply With Quote
  #8  
Old 05-03-2002, 05:19 PM
Registered User
 
Join Date: Mar 2002
Location: Venezuela
Posts: 40
Mine does something d¿similar to that, i was thinking O2 sensor
__________________
89 560SL
78 172N
01 CBRXX
98 EV11
Reply With Quote
  #9  
Old 05-03-2002, 07:07 PM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
How about a partially plugged catalytic converter.
__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote
  #10  
Old 05-03-2002, 07:26 PM
Registered User
 
Join Date: Dec 2001
Location: Gig Harbor WA.
Posts: 69
Thanks for the suggestions.

A blocked Cat or O2 sensor are both on my list of suspects. Any idea on the best/quickest way to test to be sure?? I guess I could disconnect the O2 sensor and see if there is a change...I was also thinking that the coil may be breaking down. Does that sound possible?? It almost feels like the timeing doesnt advance..
What is really strange is that it runs so strong right up to 4000 RPM, and sometimes will go all the way to redline and seem OK. Thanks ...
__________________
Hud

88 560SL
97 E320
Reply With Quote
  #11  
Old 05-04-2002, 10:27 AM
Registered User
 
Join Date: Mar 2002
Location: Venezuela
Posts: 40
a partially plugged catalytic converter, not in my case I don't have one, I would say the O2 sensor, don't you have to replace it after so many milles any ways?
__________________
89 560SL
78 172N
01 CBRXX
98 EV11
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 05:12 AM.


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