W124 problem
12-13-2017, 09:28 AM
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1987 W124 300e - current. Use to own W140 S500, W116 280s, W124 230e, W115 230.4, W115 240d
W124 problem
I recently bought a 1987 300E. The car is in a good condition and I use it as my daily driver. However, from the get go I noticed that the car seems to hesitate if the RPM's go over 3000 and the car had no power. This meant that on highway driving, I could barely reach 110km/ph. Also, if going up an incline (Pass) the car would only do about 40-50 km/ph. In town the car seems okay though.
I noticed that if you start the car, all warning lights would be off until you drive a few km's then the oil and or the washer light would go on. It's also then that the car seems to lose power.
After a lot of digging on here, I found out about a possible culprit being the OVP relay. After sourcing one, I put it in and the car had the exact same problem. I took both relays to an auto electrician who 'welded' both. But that still didn't resolve the issue. Very recently I sourced another relay. It still does the same thing e.g. Warning lights go on, lack of power etc.
The above mentioned electrician did a diagnostic's test on the car earlier today and said that he can't pick up any problem, so finally my question is this: What else could it be? No one here seems to know including a reputable mechanic who owns 2 w124's. They've adjusted the air/fuel mixture etc and nothing works. Could it possibly one of the fuel pumps? If so, how could that effect the warning lights?
Oh, and as a side note, I regularly check the car's oil, coolants etc, so the warning lights don't come one due to any low levels. Also, the warning lights don't go on for a while until you travel a couple of km's so I doubt that there are any problems with the sensors themselves.
Sorry for my almost biblical sized rant but any and all replies will be greatly appreciated.
Regards from South Africa
I noticed that if you start the car, all warning lights would be off until you drive a few km's then the oil and or the washer light would go on. It's also then that the car seems to lose power.
After a lot of digging on here, I found out about a possible culprit being the OVP relay. After sourcing one, I put it in and the car had the exact same problem. I took both relays to an auto electrician who 'welded' both. But that still didn't resolve the issue. Very recently I sourced another relay. It still does the same thing e.g. Warning lights go on, lack of power etc.
The above mentioned electrician did a diagnostic's test on the car earlier today and said that he can't pick up any problem, so finally my question is this: What else could it be? No one here seems to know including a reputable mechanic who owns 2 w124's. They've adjusted the air/fuel mixture etc and nothing works. Could it possibly one of the fuel pumps? If so, how could that effect the warning lights?
Oh, and as a side note, I regularly check the car's oil, coolants etc, so the warning lights don't come one due to any low levels. Also, the warning lights don't go on for a while until you travel a couple of km's so I doubt that there are any problems with the sensors themselves.
Sorry for my almost biblical sized rant but any and all replies will be greatly appreciated.
Regards from South Africa
12-15-2017, 11:44 PM
#2
Member
A few issues here to clarify and check further:
1. The dash warning lights should all light up on engine start, and then go away once the engine is running, Is this not the case in your car?
2. Engine speed failing to rise beyond 25K or 3K rpm usually has a leak in the air inlet system. Check all air hoses and casing.
3. If engine loses power after warming up, a high suspect will be the temperature sensor feeding wrong data to the ECU and resulting in fuel being too lean for acceleration.
4. Is there any problem at lower engine speed like hesitation? If so, it could be a failing fuel pump relay, a heavily clogged fuel filter, or a dying pump (there are two).
5. A bad fuel pressure regulator might give rise to problems in poor acceleration.
6. Apart from all fluid level checks, have you looked at the air filter, spark plugs, distributor cap, distributor arm, ignition coil and cable?
On warning lights acting weird, please check all wiring, grounding points, connectors, cables, etc. are in good working order. A weak battery or bad voltage regulator in the alternator may give rise to problems of all sorts.
Last area to look is the airflow sensor (rarely fails in the W124), engine harness and the ECU.
1. The dash warning lights should all light up on engine start, and then go away once the engine is running, Is this not the case in your car?
2. Engine speed failing to rise beyond 25K or 3K rpm usually has a leak in the air inlet system. Check all air hoses and casing.
3. If engine loses power after warming up, a high suspect will be the temperature sensor feeding wrong data to the ECU and resulting in fuel being too lean for acceleration.
4. Is there any problem at lower engine speed like hesitation? If so, it could be a failing fuel pump relay, a heavily clogged fuel filter, or a dying pump (there are two).
5. A bad fuel pressure regulator might give rise to problems in poor acceleration.
6. Apart from all fluid level checks, have you looked at the air filter, spark plugs, distributor cap, distributor arm, ignition coil and cable?
On warning lights acting weird, please check all wiring, grounding points, connectors, cables, etc. are in good working order. A weak battery or bad voltage regulator in the alternator may give rise to problems of all sorts.
Last area to look is the airflow sensor (rarely fails in the W124), engine harness and the ECU.
