Ot - mb

[Phil S]

Any MB owners / experts onboard ? 99 S420 with 151k on the clock...OBDII codes = P0170 and P0173 = r/lft bank fuel something. All service up to date, but I did find a worn-through vacuum hose from valve-cover to intake that could have lead to a MAF malfunction. Thought's, suggestions ? She's never skipped a beat, but cold start = rough idle lately.

With kind regards,
Phil S.

[dsparis]

Remove the MAF and clean it with MAF cleaner. Make sure its dry before re-installing it. If I remember correctly you'll need a security torx bit to remove it.

[DonziJon]

Any MB owners / experts onboard ? 99 S420 with 151k on the clock...OBDII codes = P0170 and P0173 = r/lft bank fuel something. All service up to date, but I did find a worn-through vacuum hose from valve-cover to intake that could have lead to a MAF malfunction. Thought's, suggestions ? She's never skipped a beat, but cold start = rough idle lately.
With kind regards,
Phil S.

(For 1999 MB) These codes seem to be generic. Other codes are sometimes Mfg Specifc.

P0170: "Fuel trim malfunction bank #1"
P0173: "Fuel trim malfunction bank #2"

I got those codes off my Bran New Actron CP9180 AutoScanner. Got it from Amazon Saturday. It took two days to my door. Havn't hooked it up to a car yet...still getting familiarized. :yes: DJ

[HOWARD O]

Here's an idea: http://www.benzworld.org/

[mrfixxall]

Fuel trim codes,,

do what dan said first,clean the mass air flo meter..if it still acts up in the am starting suspect the lower intake gaskets.to test the cat will need to be cold with no coolant temp's..get some flammable brake cleaner (non chlorinated) and rite after you start the engine lightly spray the lower part of the intake where it meets the cylinder head,if you notice a change in the rpm's then the o'rings in the gaskets are leaking..if you find no leaks and the code exist still them replace the mass airflo sensor..BTW make sure you have a clean air filter after cleaning or replacing the maf.

[Phil S]

Interesting.....pulled MAF body from intake & cleaned it with CRC MAF Cleaner. Let it sit to dry for a couple of hours and re-installed. Everything went back together fine. Cranked it up....and wa-lah....perfect idle and smooth as silk ! Pulled it out of garage to let her warm up...nice & smooth low-idle. Drive it around the block a couple times and all seems normal. The MAF cleaning worked !...until, I shut if off and re-started it. Then I started it and now it seems it's running on half of the bank of cylinders ! Showing a code P1580 and not happy about it apparently ! She might need a visit to the Star machine.

Anyway, thanks for all your help as always !
Phil

[DonziJon]

Code P1580 is a Mercedes specific DTC. My scanner says "See Service Manual." I'd Google it.

BTW: My wifes '05 Camry has had the Check Engine Light on for over three years. The car runs fine. The night before the every two years State Inspection, I disconnect the battery overnght to clear the computer. The car was just inspected a couple of weeks ago and passed as usual. Yesterday the light came back on after a 193 miles since the inspection. My scanner manual says "some" codes have diferent "Duty Cycles"...a certain number of startups and engine/catalytic temperature cycles.

Todays cars were never meant to be worked on by mere mortals. It's prolly a Left Wing Plot to make us wards of the government. :nilly: DJ

[dsparis]

Re-check your work. Make sure the throttle valve is plugged in and no leaks after maf.

[Phil S]

Well, I decided to re-visit my work as I really wasn't looking forward to the invoice from a star diagnosis with Christmas bearing down.

I didn't have the torx-size security bit I needed to remove only the MAF insert, so instead, I removed the whole body of the MAF housing in order to clean it. It's held on to the intake with screw-type hose clamps....but getting to the screws took me a 1/4" driver with 2 universal swivels and a 7mm socket to get to the lower one. Finally got it out, cleaned it as mentioned, & re-installed. Here's where I thought I was being smart, but instead, really screwed it up royally.....my typical mo. :bonk:

Seeing as how difficult it was to "reach" the dang screw on the clamp to get it off, during the re-install, I thought well heck, why not just slide this sucker around a bit so I can reach it a lot easier the next time...and so I did, and sure enough it was a heck of a lot easier to tighten back up. See how smart that was ?! Unfortunately, where I had placed the screw perfectly for easy access was in the direct path of the electronic throttle cam just below it ! Needless to say, it quickly became out of sync with the computer which obviously confuses the heck out of them when things aren't where they are supposed to be in relation to the accelerator pedal, etc. Had to take it back off and put the hose clamp screw back where it was, clear the codes again, and presto...running smooth again. I put about a 100 miles on it today through probably 10-15 full cycles, and knock on wood, so far so good.

But thanks again for your expert help. A thorough MAF sensor cleaning was all it took. Ordered the breather / vacuum hose that's worn out, so I still need to do that else I think it will just foul it up again in short order.

Again, thanks. :yes:
Phil

[Phil S]

DonziJon -

Agree with your purchase. OBDII scanner or better is a necessity these days if you try to do any of your own maintenance on just about any car these days. I think you can pay just about anything you want for them, but they are definitely worth it. I have an el-cheapo one which gets me by most of the time, but those brand-specific codes.....well...I have an opinion of them. :mad:

Thanks again for your help, and Mr. Fixxall, DSParis, & Howard O !

With kind regards,
Phil S

[Cuda]

Code P1580 is a Mercedes specific DTC. My scanner says "See Service Manual." I'd Google it.
BTW: My wifes '05 Camry has had the Check Engine Light on for over three years. The car runs fine. The night before the every two years State Inspection, I disconnect the battery overnght to clear the computer. The car was just inspected a couple of weeks ago and passed as usual. Yesterday the light came back on after a 193 miles since the inspection. My scanner manual says "some" codes have diferent "Duty Cycles"...a certain number of startups and engine/catalytic temperature cycles.
Todays cars were never meant to be worked on by mere mortals. It's prolly a Left Wing Plot to make us wards of the government. :nilly: DJ
A warning light came on my new '05 F 350. I was driving by the Ford dealer where I bought it, so I pulled in and asked a tech. He said the light would come on for a myriad of things. One being one tire was a couple psi from the others.

You're right, an engine is impossible to work on. Give me a distributor and a carburetor anyday.

[Cuda]

You can take your car to any Autozone and they will scan it for free. It will spit out a bunch of codes, most which don't refer to your car. When you take it to a mechanic, they are just making their best guess at it. I took my van down to be worked on. The mech said he spent all day looking for a short. I told him he wasn't very good at this. I took my van home and never looked back. The codes said it was a cam sensor, but I could look at the sensor and tell it was new, and there is no adjustment on it. The mech said often when it says the cam sensor, it could be the crank sensor. It ran too good for any of that to be a problem, so I put new plugs in it, which didn't make a difference, so I just drive with the light on.

[McGary911]

Glad you got it fixed. Cleaned the MAF on my CLK a few months back and it really smoothed out the idle. I did the same, took off the whole cylindrical intake to get to the MAF.

One thing I've learned about these cars, is that all the seemingly illogical things (like your clamp alignment) are actually there for a reason. I tend to let them be.