94 S 420 Loss of power!!Help! - PeachParts Mercedes-Benz Forum

eddie a · #1 03-20-2008, 05:55 PM

Hi Guys, Just bought my second Benz two days ago,It was running perfect until today...seems like its running on 4 cyl.I made it home but,dont know where to start looking first..The check engine light has been on and off a few times.. Any advice?????

bobs · #2 03-20-2008, 10:27 PM

Get access to a scanner and pull the fault codes. That will save you a lot of guesswork.

Larry Delor · #3 03-20-2008, 11:12 PM

Sounds like limp mode. If you have the LED & button, you can get some basic codes that way. Else, do like Bob says.

BMG · #4 03-23-2008, 08:21 PM

This vintage has a pulse readout that provides the codes. reader cost $20 for the parts at Radio Shack. Plenty of threads on reading these codes.

Do you have a 30 day warranty or sinilar on your purchase.

94's all had bad wiring harnesses which could easily be causing the problems your describing. In addition to the wiring, the Electronic THrottle Actuactors also had the same wiring and need rebuilding or replacement.

Do some reading and check your warranty.

stevebfl · #5 03-23-2008, 08:24 PM

The dual distributor ignitions also have a common problem with dist caps and rotors that will drop 4 cylinders.

jcciem · #6 03-24-2008, 08:51 AM

Drivers side ignition coil

'87 560SL 150,000
'94 SL500 40,000
'91 350SD 515,000

eddie a · #7 03-24-2008, 09:32 AM

You guys are great!! I got the car away from the machanic and was charged 2 hours.. I guess it could of been worse.As the car was being loaded on the ramp truck it smelled really rich... I could smell gas out of the tailpipe. I didnt mention that earlier..Its going to the dealer.. wish I could get this knot out of my stomach.... Thanks for all of the replys.. Ill post the outcome on Wenesday 26th 08...

Dee8go · #8 03-24-2008, 09:47 AM

Quote:

Originally Posted by eddie a

Hay Thanks for the reply.. Like I said before ,Its my second Benz,The first never gave me trouble.. Im not really excited about going to a dealer.. But I guess I must.. My mechanic said the car was to old and cant be hooked to a computer ..Is he alright??? After he told me that I called a dealer... They told me it can be hooked to a laptop to find out whats wrong...Ill be talking it out of his shop on Monday to have the guess work haulted.. Can anone straighten me out on the computer issue Id love to print this and bring it to him... Thanks so much...cant wait to hear back...eddieA

I am assuming that you must have the right software and connectors to do this. What does that cost?

Larry Delor · #9 03-25-2008, 10:49 PM

140 posts? I'm afraid I have more than that. Are you talking private messages? Those you can erase, to make room for new ones.
When you go to the Shack, get pins that will fit into the hole (unscrew that cap, and get an idea). I wasn't thinking, and got large "banana" connectors...useful for getting power, but not for interrogating.

eddie a · #10 03-26-2008, 05:13 PM

Just got the car back... it was the drivers side Ignition coil.. jcciem hit it on the head.. I never would of thought..I smelled gas so I thought Fuel system.. They also said I need control units= $ 3000 I read something on replacing parts in them, Im I correct ?If so can anyone guide me to the info?? Thanks again guys....

BMG · #11 03-28-2008, 09:49 PM

You might consider starting a new topic on the response from the dealer regarding the Control Units.

Were they suggesting the computers needed replacement?

As mentioned earlier, you should check to make sure this car had the harness replaced along with the leads to the ETA's. Its likely its been done if the car was well cared for but one can never be too sure.

JimF · #12 03-29-2008, 11:53 AM

Quote:

Originally Posted by eddie a

Just got the car back... it was the drivers side Ignition coil.. jcciem hit it on the head.. I never would of thought..I smelled gas so I thought Fuel system.. They also said I need control units= $ 3000 I read something on replacing parts in them, Im I correct ?If so can anyone guide me to the info?? Thanks again guys....

Make the home-brew (h/b) reader yourself and use it to read the DTCs from your car. Post them here and we can help.

Many of the codes can be read from my pages since my S500 is a '94 also.

The details of a R/S compatible reader is in MENU#2 if you want to see what one looks like (at bottom of the page).

BMG · #13 03-29-2008, 09:50 PM

Eddie_A sent me a copy of the estimate. They wanted him to replace the ABS/ASR/ESP Control Units.

I recommended he follow JimF's lead, make the code reader and pull codes on the units.

I have attached a portion of the document he sent me. I expunged any personal information as well as obvious dealer identification. Perhaps JimF and or Arthur Dalton can make more sense of it.

JimF · #14 03-30-2008, 10:43 AM

Quote:

Originally Posted by BMG

I have attached a portion of the document he sent me. Perhaps JimF can make more sense of it.

No, I can't . . . . other than $1050 for a coil, fuse and oil change!

Tnx for reminding me why I don't go to a dealer . . .

eddie a · #15 04-02-2008, 08:25 AM

Im back again.. I built the scanner and I tried to get the fault codes.. I turned ignition in the on position,Plugged in the banana plugs,black to 1..Red to three.and yellow to desired module.. The LED stays on constantly, even in every socket. The car does have the built in LED also, and that also stays on. I dont know why this would happen.. I need guidance , Thanks