W124 codes - PeachParts Mercedes-Benz Forum

speednjay · #1 05-10-2021, 08:27 PM

95 e320

I can’t shake these codes no matter what I’m doing. Pin 8 32,33.

-Timing chain and cogs are spot on.
-swapped out different cam adjusters with other functional e320
-swapped out knock sensors from functional e320
-main wiring harness upper and lower done
-throttle actuator updated
-o2 sensors are fresh
-fresh plugs/wires
-always filled with premium gas

What else do I need to check?

back-seat-driver · #2 05-11-2021, 03:39 AM

Always start with the OVP.

speednjay · #3 05-11-2021, 06:43 AM

Quote:

Originally Posted by back-seat-driver

Always start with the OVP.

Replaced

muller · #4 05-11-2021, 08:52 AM

What kind of scanner are you using?

Diseasel300 · #5 05-11-2021, 09:27 AM

More importantly, what the hell do these codes mean? Numbers without context are a guaranteed way to ensure you get little to no help.

speednjay · #6 05-11-2021, 10:35 AM

Quote:

Originally Posted by muller

What kind of scanner are you using?

Homemade blinking light scanner for odb1

speednjay · #7 05-11-2021, 10:36 AM

Quote:

Originally Posted by Diseasel300

More importantly, what the hell do these codes mean? Numbers without context are a guaranteed way to ensure you get little to no help.

32 is knock sensors and 33 is that a cylinder had a timing retard of more than 6 degrees

Diseasel300 · #8 05-11-2021, 10:49 AM

Have you checked for a vacuum leak? If you have a leak in one of the intake manifold runners, a lean mixture would sure account for knock.

nulu · #9 05-11-2021, 10:59 AM

Description in wis says open circuit knock sensors code 32 ,33 retarded timing, may be something loose causing knock sensors to activate , is it running too hot?, poor fuel , if it all checks out ,may be Hfm computer is faulty

speednjay · #10 05-11-2021, 11:10 AM

Quote:

Originally Posted by Diseasel300

Have you checked for a vacuum leak? If you have a leak in one of the intake manifold runners, a lean mixture would sure account for knock.

I checked visually and audibly. Everything seems ok. I’ll go over it again when I get home from work.
If a specific intake runner was leaking .. that spark plug would show up as lean right?

The car runs great except for a noticeable flat spot or two around 4K while at wot. Just drove 600 miles and got 25 mpg @ 80-90mph hwy speeds. I could take it in for a smoke test

Well the engine temps do spike a lot when in traffic. I think that might be more of a crappy clutch fan setup. All my Mercedes do exactly the same thing

Diseasel300 · #11 05-11-2021, 11:44 AM

Smoke test is your best bet for finding an intake leak. You can also spray brake cleaner around the manifold and head to see if you get ANY change in running behavior. Smoke test is more definitive.

Running hot can also cause detonation and knock. Crappy clutch fan will definitely contribute as can a dirty condenser/radiator blocking airflow to the thermostatic element on said fan clutch.

Keep in mind that retarding timing will greatly increase engine heat, so if you're already running hot and the computer is retarding timing due to knock, you have a "death spiral" of problems feeding into each other.

Usaguy · #12 05-11-2021, 07:05 PM

Quote:

Originally Posted by speednjay

...Well the engine temps do spike a lot when in traffic. I think that might be more of a crappy clutch fan setup. All my Mercedes do exactly the same thing

I think that the temp spikes might be causing these codes because the ignition module retards the timing depending on the engine temperature. Even the old ezl's do that. A good fan clutch will keep your engine temp at 87c in a 90f traffic and will disengage once you get up to speed.

Quote:

Originally Posted by Diseasel300

Have you checked for a vacuum leak? If you have a leak in one of the intake manifold runners, a lean mixture would sure account for knock.

It's a myth that running lean = running hot.

I don't think that a vacuum leak is contributing to a possible knocking condition and here's why:

These cars run at the hottest mixture setting from the factory (which is 14.7 or 0.068 fuel air ratio on the graph) anything leaner or richer than that runs cooler.

Left side is lean and the right side of this graph is rich.

The reason why they run at the hottest setting is because of emissions and fuel economy. That's where they try to keep the narrowband o2 that the w124 has.

If you have a modified engine you want it to run rich but you don't want it to get to 14.7 while under heavy load because that's the hottest mixture. Leaner than that is cooler.

Diseasel300 · #13 05-11-2021, 07:11 PM

Quote:

Originally Posted by christuna

It's a myth that running lean = running hot.

I don't think that a vacuum leak is contributing to a possible knocking condition and here's why:

I never claimed that running lean = running hot. I claimed that a leak in the intake manifold on a single runner can cause knock. This is very well documented since the single cylinder behaves differently from the rest. A lean mixture in a single cylinder can and will result in knock if the ignition timing is advanced, particularly if the engine is already running hot.