Hi,

I've got 2 different reports as to what's wrong with my ML320 and I'm trying
to determine which one is correct.

2001, ML320 w/143,000 miles. Check Engine light's been on for a while,
intermittent at first, then on solidly. When its cold the low speed is quite rough
and hesitates alot. Once the engine is up to temp, its much better, although it
is idling a little rougher than it used to.

Took it to shop 1 and they said:
they pulled error codes PO173(Fuel Trim, bank1), P2043 (Misfire detected),
and P2046(Misfire cylinder 3). They recommended plug wires for cylinders
2,3 and a Ox Sensor of the left side. I didn't do it then because there wasn't
time.

Then took it to shop 2:
They claim error codes PO173 (Fuel Trim Bank 2), PO170 (Fuel Trim Bank 1),
P2085 (Partial Load Limit Bank2 Fuel Trim), P2016 (Bank 1). Shop 2
recommends replacing Mass Air Flow sensor and Air filter.

Anyone have any thoughts as to which one of these assesements is more
likely correct? Would the Ox Sensor have much effect immediately after
starting the engine, before it is up to temp?

Thanks much.

__________________
dac

Go with the second diagnosis....air mass sensor failure is the most likely problem.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I agree, that is a MAF. Air filter is up to you, sounds like they may just want to run it up a bit, and that is something you can easily do yourself for probably half the price as they markup up many times on filters. You can also do the MAF yourself, as it is pretty straightforward, and instructions were posted here before.

OK, sounds like a good idea. Im going to do it myself. I've changed Mass
Air Flow sensors before - on other cars. So I don't think it will be a problem.

Thanks much for your feedback.

__________________
dac

I have your problems,,,replaced the spark plugs, mass air flow sensor and cats. Still have the problem.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles