Abnormal timing retard

[MrSpace]

I plugged in my OBD2 scanner today...

I got really wierd timing retard, it was like between -16 and -33, sometimes it went a little lower, but still always under zero.

This graph is from a little run (no WOT), you can see the RPM in blue and timing in pink...



Anyone knows why it's like that? Is it normal?

Thanks,

Etienne

[jnenad16]

are you using a generic OBD2 scanner, or does it have MB specific software? if its generic, that it may not be fully compatible with your cars CAN system. I know when I used a autoxray 3000 with my C280, alot of sensor values were way off, even though there was nothing wrong with the sensors, then I plugged my Baum CS2000 for mercedes and all the values were normal and within specs.

nenad

[MrSpace]

normal one (autoenginuity)

altough I tought my car wasn't CAN

I know autoenginuity makes a CAN version, but I didn't think it was necessary. If it is I'll sell it to buy a CAN compatible reader...

I am scanning my friend's car this week and see if it's the same for him.

Etienne

[speedybenz]

I am guessing that the negative numbers are confusing you. If so it is because it is telling the you degrees of timing before Top Dead Center. So the number would be negative.

What I see on my C43 as you see on your C230K is the -16 degrees timing which is just 16 degrees befroe TDC and that is not enough advance to make any power. It should be up around -25 degrees or so as a minimum number. At full throttle you see the timing advance up to -33 degrees or so where it needs to be for good power.

The ECU does some confusing things!!

Jeff

[MrSpace]

Thanks Jeff,

I've made a couple more runs today with the logger (to check fuel trim also, I'm all lost in the O2 sensors, I think I'll buy a complete A/F system with a guage and data logging system)

I made a test stopped, just logging RPM and Advance, there is what it gave (not driving, just giving gaz on Park)



So according to your reply, I shouldn't worry about those numbers?

Etienne

[jnenad16]

ethienne, according to the graph, it looks to me that you have some detonation issues. I know that the timing has to retard somewhat in the higher rpm's, but that can be fixed and you can gain some HP. you see how your timing retards shaprly after 5k rpm? try adding a good octane booster and run the test again. see if it changes anything.

nenad

[MrSpace]

I am going to log in my friend's stock C230k in about 1.5hour.

I will see if it gives him the same thing, if not it means either that my pulley changed something or the car is not running fine.

I'll keep you posted!

Etienne

[MrSpace]

Finally everything is fine, you were right Jeff!

My friend's stock had the same values as me, so from now on I'll compare values to the ones I got now.

BTW we were on the top floor of a mall parking, no ther cars, but the big light that lit us shut down probably because it was past 11pm.

Then as I was under the dash with a screwdrive, police arrived and checked all our papers The lady said "well you must admit this was fishy"

it was pretty funny.

Etienne

[Linh]

[QUOTE]Finally everything is fine, you were right Jeff![My friend's stock had the same values as me, so from now on I'll compare values to the ones I got now.
/QUOTE]


You could have ask me if you have any concern regarding the pulley kit. It normal that you're seeing negative degree of timing. That's the way reading record on the pre-2000 engine. On the post-2000 engine. Timing reading is showing the opposite (there's no negative).

[MrSpace]

well my concerns weren't about the pulley kit itself, but about the car, I wasn't sure if everything was going fine

Now I can install the air intake. I want to get a real wideband AFR reader/datalogger though.

Etienne

[Linh]

Now I can install the air intake. I want to get a real wideband AFR reader/datalogger though.

AEM has a wideband kit (Bosch 02 sensor and gauge) around $250-$300.

[MrSpace]

Yep I've looked in details about this, I will probably go with http://www.plxdevices.com/

I'll get the basic one, I don't need a gauge, only the capacity to plus it in the computer. And what's nice is that you plug this back into your ecu and it sends to the ECU the usual narrowband your OEM sensor would see.

I will look more in details, but it's on my soon to buy list.

Etienne