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 12-01-2014, 06:37 AM
Campbelljj's Avatar
Registered User
 
Join Date: Oct 2014
Location: Weeki Wachee FL
Posts: 160
M104 Hard start and high idle

I have a new to me 94 e320 with 74k miles with a hard start and high idle issue. I've searched and read everything I can get my eyes on. The obd1 blink code tester shows 6 which is idle speed control inoperative. The cruise is also inoperative. When it will not start, manually opening throttle on the engine results in starting but just a high idle 1400 neutral. Driving the car the engine responds well to pedal input. A few symptoms point me in the direction of the ETA. The main engine harness is new and has no issues that I can detect. Thanks in advance for any suggestions or information.

Reply With Quote
  #2  
Old 12-01-2014, 09:40 PM
oldtrucker's Avatar
BMW Mech (70's) Germany
 
Join Date: Jan 2014
Location: San Diego County
Posts: 131
It is hard to point someone into the right direction. You, already answered my first question, the harness.

By the symptom's you describe, it could be a vacuum leak somewhere, after the (MAS) Mass Air Sensor. Now, I know this is a very general statement and requires careful and systematical search and repair.
It could also be a bad MAS or dirty to a point it can't be recognized, but I doubt that.

If the harness was replaced, the unknown is, how long was it driven with the old ECO junk, possibly defective.

You can check if the Throttle body wiring is in good shape, most likely the TB's that where manufactured before 1995 or even early 1996, have the same junk as the engine harness. Unfortunately, you can't tell the date for sure, until you remove the TB and look at the date stamp, you can't really see while installed. There is a green label, that has the date imprinted too, but most likely is unreadable, because it fainted over the years.
If the wiring of the TB, is powderized or has cracked insolation, I would go onto e-bay and get one that is built after 1996 and replace it. Of course there is always the choice of a OE $1600 part or a rebuilt for around $900.
Depending on how severe the wiring damage may be, it has the ability to kill the input for the idle switch or other e-gas controller inputs. This would mean a replacement of the e-gas (mounted underneath the passenger foot compartment)
I had to replace mine since the previous owner didn't care much about high idle and what caused it. Luckily, you can find them on e-bay too.
But, don't start bying anything until you can definetively confirm it is broken.
__________________
Mostly, I don't know notin, I just know where to look.
I am looking back, to over 30 years in Electronics Design.
Electrons don't care if they move in a car, computer or relay!

95 W124 E320 M104.992 - Because, I love to repair, naaaah!
Over 221,000 Miles
Cheers,
Norbert
Reply With Quote
  #3  
Old 12-02-2014, 06:01 AM
Campbelljj's Avatar
Registered User
 
Join Date: Oct 2014
Location: Weeki Wachee FL
Posts: 160
Thanks. My next step was to pull the TB so you confirmed what I was thinking. I will post results
Reply With Quote
  #4  
Old 12-02-2014, 06:52 AM
oldsinner111's Avatar
once a happy man
 
Join Date: Nov 2008
Location: bristol,tn
Posts: 5,841
x2 on wiring of engine,and throttle body.Also check plastic hard vac lines under plug cover.Vac leaks can give you wrong idle too.
__________________
make america suck putin again
Reply With Quote
  #5  
Old 01-02-2015, 08:34 AM
Campbelljj's Avatar
Registered User
 
Join Date: Oct 2014
Location: Weeki Wachee FL
Posts: 160
Well I sourced a 2004 ETA non ASR for my 94 E320. I swapped units, new gasket and bellows. ETA removed was 1994 vintage so my guess was original to the car. Still have high idle. No hard start. Starts with barely a turn of the key. Runs and drives beautifully. Just has a high idle about 1400 in neutral 850-900 in gear. I need to clean MAS and manifold temp sensor. Also would a failed coolant temp sensor cause high idle. Seems to run a bit rich. Just changed O2 and it was caked with black sooty debris. I'm also thinking vacumn leaks but all I've checked looks great. Also where is the ICV on this car. Could this be stuck open. Sorry for all the random thoughts in this post. any help is appreciated.
Reply With Quote
  #6  
Old 01-02-2015, 02:13 PM
Campbelljj's Avatar
Registered User
 
Join Date: Oct 2014
Location: Weeki Wachee FL
Posts: 160
Viola! Cleaned MAF and manifold temp sensor and car now idles perfectly. Starts perfect just like before. I think we are in business on this M104. Thanks for your input and ideas.
Reply With Quote
  #7  
Old 01-21-2015, 01:51 PM
Campbelljj's Avatar
Registered User
 
Join Date: Oct 2014
Location: Weeki Wachee FL
Posts: 160
Well the high idle came back. No change when MAF harness pulled. Replaced with new MAF and car now idles around 800-850 neutral warm and a bit low in gear around 550-575. Should the idle be a bit higher. I'm guessing this is all controlled by the computer. Do I maybe have a lazy idle control valve. No stumbling on deceleration. The idle is low so it is a tad lumpy. No hesitation from idle when accelerating either. Need I keep looking or is this within the "norm."
Reply With Quote
  #8  
Old 01-21-2015, 04:15 PM
TnBob's Avatar
Registered User
 
Join Date: Dec 2009
Location: Shelbyville, Tn
Posts: 1,907
Next would be to pop your injectors and clean them.
Great time to replace all the seals there which are sold by the forum sponsor at the top of each page for under a buck each.
You typically wont need the plastic holder but the injector seals are probably history and leaking.
__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."
Reply With Quote
  #9  
Old 01-22-2015, 11:17 AM
oldtrucker's Avatar
BMW Mech (70's) Germany
 
Join Date: Jan 2014
Location: San Diego County
Posts: 131
Quote:
Well the high idle came back. No change when MAF harness pulled. Replaced with new MAF and car now idles around 800-850 neutral warm and a bit low in gear around 550-575. Should the idle be a bit higher.
This engine doesn't have an ICV.....

If the engine coolant sensor is signallig the wrong value, if it is higher (there is some mechanism that detects unrealistic values and may throw a code) meaning the temperature is too high, I would think the computer will run the engine richer and throw the CEL. If it is the other way, the external air injection pump might kick in, and thereby getting the O2 Sensor lean. So it also would run the engine richer. But in both cases, if the detection algorithm works correctly, it would switch on the CEL because these are conditions that can cause excessive pollution or engine damage.

No, the numbers indicated are fine as long as you don't feel excessive misses.
Also, the computer may not be done with re-adjusting the injection timing etc. needs to learn over about 10 trips.
If your engine idles smooth, your in. Nice going!!!

{Deleted since it was irelevant}

Also, if you haven't, built yourself a code reader, there are several posts with built instructions.
With this tool armed, you'll be able to get a little more insight what the computer complaint about previousely.
Check here post #3
__________________
Mostly, I don't know notin, I just know where to look.
I am looking back, to over 30 years in Electronics Design.
Electrons don't care if they move in a car, computer or relay!

95 W124 E320 M104.992 - Because, I love to repair, naaaah!
Over 221,000 Miles
Cheers,
Norbert

Last edited by oldtrucker; 01-22-2015 at 12:09 PM.
Reply With Quote
  #10  
Old 01-26-2015, 09:13 AM
Campbelljj's Avatar
Registered User
 
Join Date: Oct 2014
Location: Weeki Wachee FL
Posts: 160
Thanks for all the input and advice.

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 02:08 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