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07-31-2013, 07:48 AM | #1 |
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Dyno trouble shooting session of Z4M ESS VT - 525
So I finally got the old girl on the dyno to sort out my limp mode issue and lack of top end. The limp mode after installing the VT-2 525 has been very different than before and despite not having any leaks during leak testing the car didn't feel as strong as it should. The dyno clearly shows oscillating boost which is consistent with belt slippage, with corresponding glazing on the belt as well. The belt is also noticeably looser than after install. I believe my hydraulic belt tensioner has given up the ghost as well as my belt is not tight due to an incorrect crank pulley. Annoyingly during the install my shop installed the wrong crank pulley (the VT-1 pulley) which means that even without my belt slipping I was not making full boost. I can't believe I made 398 whp at 5psi lol. Ignore the boost spike after let off this sampling system for this dyno does that on all cars for some reason. My peak boost was barely over 5psi at 8,000 rpm.This explains why my car has felt consistent but weak and the limp modes that all of a sudden were not temp related. The tensioner failing added belt slip on top of the pulley issue and thus my problem worsening as of late.
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07-31-2013, 12:22 PM | #2 |
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Ouch. Welcome to the club with the boost. I am only hitting 6psi at 8000 rpm's, but I am hitting 5psi at 5500 rpm's. We are going to smoke test it tomorrow and check the pulley size that was sent. ESS said I should rule out belt slippage if not hearing it and because it is a new unit. We will see. Keep us update.
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07-31-2013, 12:49 PM | #3 | |
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07-31-2013, 01:40 PM | #4 |
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How much torque were you putting down?
hehe, not to laugh at your misery, but this makes me feel a tad bit better about my current situation as well (as we're both currently putting out the same whp) jkjk Hopefully we all have full power in the coming month or two edit: on a side note, I was able to record a conservative 4.4s 0-60 even without the full 470rwhp and 330rwtq that I should have. And it was able to smoke the tires through 2nd gear. I wonder what full power is like |
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07-31-2013, 02:48 PM | #5 | |
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07-31-2013, 03:00 PM | #6 | ||
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07-31-2013, 06:15 PM | #7 |
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Welcome to the club of the underpowered!
Replace your belt tensioner ASAP, everyone here. See my build thread. My old tensioner was weak, evidenced by the belt coming off-center one time. Eventually, it ripped out the mounting point on the oil filter housing, so I had to replace that. $1k+ total repair job Also, my replacement belt isn't the same brand as ESS used, and its slipping badly. I just ordered a new Contitech 6PK2315 belt, I think thats what I had before
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07-31-2013, 07:28 PM | #8 | |
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07-31-2013, 10:45 PM | #12 | |
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Not sure if you're asking me, or saying that you fixed something similar... I'm still down on power, waiting for a new belt to arrive. Going catless today or tomorrow. Custom tune hopefully soon after
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07-31-2013, 10:46 PM | #13 |
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between 400-420rwhp. really sensitive to ambient temperatures..
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07-31-2013, 10:59 PM | #14 | |
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So, you don't know that your belt was slipping? Last edited by seank; 08-01-2013 at 12:35 AM.. |
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08-01-2013, 01:55 AM | #15 | |
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What are the odds of that haha Well, here's to better times ahead! |
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08-01-2013, 06:28 AM | #16 | |
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08-01-2013, 07:06 AM | #17 |
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08-01-2013, 08:38 AM | #18 |
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The number one issue with these kits (in general) on the Z4M is pulley slippage? Seems like I read more and more topics regarding this. Don't the vendors supply the proper hardware so that this isn't a drawback?
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08-01-2013, 10:16 AM | #19 | |
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08-01-2013, 11:15 AM | #20 | |
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My car only has 50,000 miles and only 1 track day. It is not like reading the threads where some of the e46m3 guys have 120,000 miles on the tensioner. I also don't want to throw parts at it. Well, not yet anyways. |
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