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Hello guys. I’ve often thought my car was pulling timing on the top end. I haven’t been too sure what the timing advance should be under full load, but I’ve garnered that it should be somewhere around 15-18 degrees to run properly.
I’ve started to log my car via the obd2 port and here is what I’d consider useful information to my problem:
-logs on a good day showing about 11 degrees advance
-typically hovers between 5-11 degrees timing WOT
-confirmed lack of power at drag strip(110-112mph traps)
-doesn’t seem too affected by IAT. Logging on a very cold day with IATs no higher than 90 degrees. Timing still low(never above 11)
-tried 100 octane, same result
-only mod is a 76mm pulley and 010 pump
Now my Japanese tuner instincts tell me that I’m getting “phantom knock. This doesn’t seem to be a topic discussed often, but I can’t figure out any other possibilities. Kinda new to timing Mercedes so I very likely am barking up the wrong tree!
I’ve read reports of failing coils sending a frequency that could be read as knock?
Any thoughts gurus? I can’t live with this extreme loss of top end
Do you happen to know your 60-125mph (100-200km/hr) time?
Any other scanned errors which might be relevant?
I have had a tune flash sitting around for years, but have never gotten around to flashing it. There seems to be a debate as to it being “needed” as far as I can tell. I’m likely wrong, but I have seen reports of some impressive power from non-flashed pulley’d cars. I’ll be doing this soon regardless.
no ecu codes to speak of
I was doing some reading and I’m going to try and simply reset the ecu in case it has had a bug of sorts.
here are a couple of time slips. Not picking up big mph on the back end. Timing on the 112.5 mph never dipped below 8, but never above 11
i have seen false knock on these cars remember they are getting old and you can get that. simple to find out in a control envirement have him turm them off up till 4000 rpms see if timing changes. Or its something else your spinning that blower faster than stock making less power and the part throttle prob fells like garbage too.
Just wanted to share an update on this. Went to the track tonight with the only difference being a heat exchanger, new plug wires, and a renntech tune.
i am now a firm believer that these cars need a tune for a smaller pulley. I’m seeing 15-20 degrees timing at wot with very similar iat’s. I was seeing 145-150 degrees on every pass and my timing was still holding strong.
Only other possibilities just for informational purposes:
-I had replaced battery in the interim(there were no ecm codes)
-possibility of bad plug wires arcing thus giving false knock?(originals with 129k).
In either event, putting the tune on the car was definitely worthwhile, and I think it is a big reason for the power increase. I now believe that it is utter nonsense that the ecm can adapt to a 76mm pulley!
Why is the focus solely on the timing number and not including what the IATs are?? Timing is pulled starting at 120°
last time I was at the track, my IATs were nearly identical, but the computer was only giving me 8ish degrees timing. The 7 additional degrees of timing is why the car picked up 8mph.
last time I was at the track, my IATs were nearly identical, but the computer was only giving me 8ish degrees timing. The 7 additional degrees of timing is why the car picked up 8mph.
I believe that the stock timing maps can’t handle either or both:
1. the increased rate of airflow from the maf
2. the intake temps that the 76mm will certainly provide(unless winter driving)
I was also wondering if perhaps the computer considers the rate of change in intake temps? It seems like my temps raise at a slower rate after installing the new intercooler, and it doesn’t seem to aggressively pull timing at 145 like the stock map
very impressed with the renntech tune btw. Bought it for ease of use and I’m incredibly impressed
bigger pulley does not work without a tune, we all know that from 20 years, bigger pulley equal more boost then stock maps will dump lot of fuel that make afr at 9 if i remember, which lead to knock and retard timing.
and ecu start retard timing from IAT at 140F.
bigger pulley does not work without a tune, we all know that from 20 years, bigger pulley equal more boost then stock maps will dump lot of fuel that make afr at 9 if i remember, which lead to knock and retard timing.
and ecu start retard timing from IAT at 140F.
yea I mean that definitely seemed to be the consensus. My lazy *** was fooled by reading posts of people running 120mph on stock tunes and smaller pulleys.
just thought maybe this would reinforce the idea to those who may be considering doing the same
Timing pull starts at 90*.
501 you still have more power to be had as your timing is still on the low side.
On 100 octane you can throw another 2-4 degrees easy as long as your IAT stays low.
Timing pull starts at 90*.
501 you still have more power to be had as your timing is still on the low side.
On 100 octane you can throw another 2-4 degrees easy as long as your IAT stays low.
I’ll be going back when the weather gets crispy.
this tune was giving me about 19 with lower IATs so it should go faster. These cars are impressive and fun as **** for old beasts. Solid and predictable compared to the cars I used to modify. I thought with 130k on the clock she mighta been able to do 117ish mph or so, but now I know she just wants more mods!
06-15-2023, 09:39 AM
