Hi there folks. This is my first post over here and what would be greater then to start off with a problem i've been lurking around here for a while but decided to make a post by myself today.

I have an E420 1994 (w124) and my problem is as follows:
I cant rev the engine above 2500rpm with the MAF connected, it just cuts the ignition and dies if i push down the accelerator any further, i have to press it very gently to get it to 2500rpm. BUT If i disconnect the MAF i can push the pedal and rev the engine to redline without problems, and it will go pack to a smooth idle.

Ive looked down through the MAF and the hot wires are intact.

What the hell? anyone?

Best Regards from Sweden

 

You need to get it on a scope,could be a bad o2 sensor,or a bad maf or a bad cat.All would relay bad data to the ecu and any of the three could be your problem.
Unfortunately your model is to early for obd2,so you need a shop or someone with the early reader to diagnose your readings.Once you have it tho it should be an easy fix.
ohlord

 

Alright, the cats are located "after" the o2 sensor, and atm they have been cut down to be replaced by straight pipes, they were in bad shape anyways. I will try with the CRC MAF Cleaner today and if nothing happens i will take it to the mercedes dealer to read out the codes (just 1 km from me).

Best regards.

 

Cleaned today with the CRC MAF Cleaner but with no affect. Did'nt make any difference. I will unplug the maf and drive it to the dealer and have the codes read out before i go on and buy a new maf... Expensive

 

Today it was delivery date of my "new" MAF (used one, $300). Went off and grabed it, went to my garage and mounted it on the car.

And guess what, engine respons is MUCH better, no missfires AT ALL and with the pedal to the floor it revs to redline faster than ever before. The car now runs better than it have ever done.

I think i have to go cruising tonight

Edit: I forgot to wrote, I cleaned the MAF with CRC MAF Cleaner before mounting it.

 

Where are you located?
You removed the o2 sensors?pre cat they are the ones that send a reference signal to the ecu to tell the engine how to regulate rich/lean conditions.It may even run better if you replace those items.Gains in performance can be had without messing with that system.
ohlord
Glad the new old maf worked,the old one if you took it apart to clean,may work also.
more old model w124 info on mbworld.org or benzworld.org if you need more help in the future.

 

Thanks, i think the o2sensor was replaced not to long ago, it looks kinda new if you have a look at it from under.
I tried to clean the old MAF too before i ordered the new one, but it didnt help.

Im located in northern parts of Sweden.

Anyways im glad to travel in my benz again