Another female desperately needs help with..... ML320

[vml68]

I have a 1998 ML320 with 100,000 miles on it. The check engine light came on recently. I took it to a mechanic and he read the code and said there are several instances of engine misfires howver he was not sure if that was causing the check engine light to come on.
He changed the spark plugs and air filter. I also recently replaced one o2 sensor.
Now my truck is running badly, when idling it is really rough, sometimes there is a rattling sound that seems to come from under the car and the check engine light is still on. The mechanic thinks the rattling might be because of the catalytic converter or fuel pressure?? He says at this point he is just guessing because he cannot tell for sure what the problem is. I don't want to keep paying for useless repairs. It is getting really expensive. Any suggestions?

[RickT]

Originally Posted by vml68

I have a 1998 ML320 with 100,000 miles on it. The check engine light came on recently. I took it to a mechanic and he read the code and said there are several instances of engine misfires howver he was not sure if that was causing the check engine light to come on.
He changed the spark plugs and air filter. I also recently replaced one o2 sensor.

Spark plugs should be changed every 4 years or 100,000 miles (whichever is sooner). So, if they had not been changed, they were ready.

Misfires could be caused by spark plug wires. These are expensive to replace.

Originally Posted by vml68

Now my truck is running badly, when idling it is really rough, sometimes there is a rattling sound that seems to come from under the car and the check engine light is still on. The mechanic thinks the rattling might be because of the catalytic converter or fuel pressure?? He says at this point he is just guessing because he cannot tell for sure what the problem is. I don't want to keep paying for useless repairs. It is getting really expensive. Any suggestions?

The MAF sensor often goes bad and can cause reduced mileage and cause idle problems. This also causes the CEL to turn on.

The rattling could be the catalytic converter. These are a known problem on early model years. They crack at the weld. Cheapest fix is to have a muffler shop weld over the crack.

Fuel pumps are also a known problem on early model years. An updated fuel pump is available. Also, the fuel filter should be changed every 60,000 miles.

In summary, based on what you have indicated, your mechanic seems to be checking the correct items that are known problems. If you need to take the ML to the dealer and have them:
- troubleshoot the misfires and replace sparkplug wires as necessary;
- replace the MAF
- replace the catalytic converter(s)
- replace the fuel pump
you are looking at about $3,000 - $4,000. All of this can be done by a local shop (not the dealer for less). In general you should plan on spending an average of $1,000 per year to repair defective items, plus normal maintanence depending on how many miles you drive.

If you do a search you can learn much more about each of these issues, as all of them are known problems.

[ML320guy]

Originally Posted by vml68

He says at this point he is just guessing because he cannot tell for sure what the problem is. I don't want to keep paying for useless repairs. It is getting really expensive. Any suggestions?

OK, I understand avoiding the dealer's expensive prices when you can do a repair yourself. But, when you can't diagnose the problem, that's when (I believe) the dealer is worth the price. Be specific, say you want to know what's wrong and get an estimate before they do the repair. Then, armed with the information, you can decide if you want to look for aftermarket parts and/or do the repair yourself.

[vml68]

The mechanic I go to was recommended by a couple of different Mercedes/BMW dealers in my area. Apparently, he specializes in these cars. So while his prices are slightly cheaper than the dealership, they are still quite steep!

[ML320guy]

I think that it's good that the mechanic is admitting that he'd just be guessing but, I always feel like the dealer has the know-how & the special equipment required to determine what the problem really is. You can't just start replacing parts based on a guess, you need to determine what the problem is. Good luck.

www.Getaboyfriend.com

[Kevdog]

Just to give you an idea of some of the prices, I had my Mass Airflow sensor replaced at a cost of $534, fuel pump replaced for $400 and fuel lines replaced for $150 over the last couple of years.

Truthfully, the cost of operation over the 6 or 7 years I've had the car has not been bad. It probably averages $300-$400 per year(excluding fuel costs), but often comes in $1000+ bursts.

[Q]

As for the misfire, you can check each spark plug wire's resistance with a cheap ohm meter from RadioShack. No need to replace them all. You can buy individual wires and replace the one(s) that don't read close to 2.2k ohms.

[jfreezn]

Your mechanic had to remove the intake ducting to change the spark plugs. He may have left a tube unconnected. Or dislodged the one I speak of below.


Did he clean the EGR valve and the EGR tube that goes into the back of the intake manifold. EGR sets code 400. Mine was coked totally shut at the end of tube. Rough engine idle is a symptom.

Also, there is a a rubber vacuum distributor block which plugs into the intake manifold at the rear of the engine. This block has a Pitot tube which sends a signal to the Manifold Air Pressure (MAP). Mine had lost it's resiliency and crumbled when I removed it. The engine will run very rough if this block is not intact and properly inserted.

Good luck

Jim in Phoenix

[Darkmann]

it's worth the $$ to visit the dealer - but, just for diagnosis. They'll probably charge you $85-$100 for the diagnostics, but they have the best chance of nailing the problem. Then what you do is order the parts yourself. Infact, work a deal with your service advisor - you get the parts cheaper by yourself and they install. They may say you get no warranty - but, hey if the parts are OEM, they have the OEM 1yr warranty on them, and the shop has to warranty their work anyway. Bottom line, you win in both cases and your SA wins also, somewhat.

[vml68]

Originally Posted by Darkmann

it's worth the $$ to visit the dealer - but, just for diagnosis. They'll probably charge you $85-$100 for the diagnostics, but they have the best chance of nailing the problem. Then what you do is order the parts yourself. Infact, work a deal with your service advisor - you get the parts cheaper by yourself and they install. They may say you get no warranty - but, hey if the parts are OEM, they have the OEM 1yr warranty on them, and the shop has to warranty their work anyway. Bottom line, you win in both cases and your SA wins also, somewhat.

Got the diagnosis done. Apparently both catalytic converters need to be replaced and they recommended all 4 oxygen sensors be replaced too!
All of it adds up to some serious $$$$. I have never ordered parts over the internet before but there is such a big difference in price, I am considering it. Any suggestions?

[ML320guy]

Wow, it just amazes me that the catalytic converters go bad in these vehicles. If I were you, I'd ask them exactly which converters reported the error codes, and replace just those with aftermarket sensors. Then, see what happens. The CC's are big bucks.

[Darkmann]

Originally Posted by vml68

Got the diagnosis done. Apparently both catalytic converters need to be replaced and they recommended all 4 oxygen sensors be replaced too!
All of it adds up to some serious $$$$. I have never ordered parts over the internet before but there is such a big difference in price, I am considering it. Any suggestions?

I don't have my owner's manual here, but remember that the converter is part of the emissions control system and it may be under warranty in your state. I know you have 100K, but read your emissions warranty agreement first before buying anything. You may have it repaired under warranty!!!

If that doesn't pan out, remember your mechanic guy mentioned the converter? Now's probably the time to go back to him and cut the deal - you get the parts and he puts them on. The dealer will definitely be too much $$$ for this, compared with your mechanic guy - make sure you give him a good smile!!!

Now, as for buying on the net, there are several outfits and a lot of them advertise here and on other sites. You will find a large difference in prices of different parts on different sites - don't forget to consider S&H; it adds up!!!. For starters, begin here. Click on the Buy Parts button above to see what prices you get. Then try some other sites. For respect to this site, I will not post other vendors' addresses here. But if you are not happy with the prices you get here, e-mail me (or send me a PM) and I'll direct you to some other sites. Good luck.

[vml68]

Originally Posted by Darkmann

I don't have my owner's manual here, but remember that the converter is part of the emissions control system and it may be under warranty in your state. I know you have 100K, but read your emissions warranty agreement first before buying anything. You may have it repaired under warranty!!!

If that doesn't pan out, remember your mechanic guy mentioned the converter? Now's probably the time to go back to him and cut the deal - you get the parts and he puts them on. The dealer will definitely be too much $$$ for this, compared with your mechanic guy - make sure you give him a good smile!!!

Now, as for buying on the net, there are several outfits and a lot of them advertise here and on other sites. You will find a large difference in prices of different parts on different sites - don't forget to consider S&H; it adds up!!!. For starters, begin here. Click on the Buy Parts button above to see what prices you get. Then try some other sites. For respect to this site, I will not post other vendors' addresses here. But if you are not happy with the prices you get here, e-mail me (or send me a PM) and I'll direct you to some other sites. Good luck.

No such luck!. The warranty was 8years/80,000 miles whichever come first.
Since the shop that I use for the ml320 charges just a few dollars less than the dealer, I am actually going to take it to another mechanic who has worked on other cars of mine. And, he has no problem installing parts that I buy.

I was also told that while they are pretty sure that the converters are causing the problems with the car, it is not a guarantee. So after I change the catalytic converters and the oxygen sensors, the CEL might still come on and they might find additional problems!!
What's confusing is that if both were in such bad shape, why didn't my check engine light come on sooner? And why didn't the oxygen sensors detect any problems?

[tok2457]

Sorry, i just receive a call from the dealer because of the same problem that you're having. My pastor car is having the same problem. The car started moving very slow and the mileage is @ 98,000. I was told that the catalytic converter is bad. The quote i got is $2000 just for the CC not including everything else that i need to do on the car. The total cost to bring the car back to life is $3900. The car is also a 1998 ML320..




Tony