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335d No Power below 3000rpm?
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05-31-2016, 07:27 AM | #1 |
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335d No Power below 3000rpm?
3 years of trouble free motoring and the day I take my Eunos off the road for a turbo conversion, the 35 gets it knickers in a twist.
I've got no power below 3000rpm! Goes great when the big turbo kicks in, but the small un has stopped. On tickover the exhaust is also noticeably louder. I've swapped the pressure converters round to see if the fault moves (these were also replaced about 15 months ago for new ones), it didn't, I've also checked the vac lines (changed for silicone jobbies) and when sucking on the vac lines I can feel all 3 actuators move. I suspect the wastegate is stuck open due to not getting a vacuum, hence no boost from the small turbo and increased exhaust noise. Which actuator dumps to the down pipe? and any further pointers would be great! ps, no smoke from the exhaust, and no faults logged when checking with Carly... I guess this could point to the Pressure Converter on the inlet side, or there is another pressure valve behind the 2 pressure converters? |
05-31-2016, 08:41 AM | #2 |
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Bit more info.....
Just started the car and watched the large actuator between the turbos and inner wing. Now this should move on start up, as a vacuum is applied - It didnt.... With the car running, I operated the actuator rod by hand and the exhaust quietened down. |
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05-31-2016, 08:13 PM | #4 |
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OP, there is a sister thread going where Yozh explains in lots of detail what to check and why. I suggest you go give this a look if you haven't already. I think OmahaDZL started it. Good luck finding your issue.
By the way, who did your tune for the upgraded turbos? EDIT: JohnnyBravo1 is author of thread but OmahaZL is a strong participant. Thread is called "Low end boooost gone hmmm" Last edited by BB_cuda; 05-31-2016 at 08:19 PM.. |
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06-01-2016, 02:45 AM | #5 |
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Thanks, I did see that thread. Although the problem (no power below 3k) is the same, I think the symptoms are different.
There is another thread "code 4530" is really good for trouble shooting and working out how things work, although the thread title makes it a little less obvious when searching. Although I've already replaced the Vac hoses, I've ordered new again as I suspect a vac leak is causing the wastegate not to be pulled shut. Until the replacement hose arrives, there isn't any point taking the car apart just yet to inspect - I'll do it when I have the hose to replace everything again. Will keep this updated with my findings to help anyone searching with the same issue |
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06-01-2016, 08:17 AM | #6 | |
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06-01-2016, 09:20 AM | #7 |
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Yes, Ive been reading the other threads with interest.
Without a Vac supply the large wastegate actuator (easiest to access between turbos and inner wing) lies open - the vac closes it. ....mine is always open, so its missing its vac supply. I have put vacuum to it and it will hold shut, so its the supply in my case, not the hardware. If you manually operate the wastegate by pulling the rod with the engine running, the exhaust quietens as the wastegate shuts, which also rules out a sticking / broken flap in the exhaust. Im going to inspect all the Vac hoses again, but Ive ordered new just in case. As soon as the new hose arrives Ill inspect further, but without replacement hose theres no point disabling the car (as it still drives) just yet |
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06-01-2016, 03:24 PM | #8 | ||
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wasetgate actuator (easiest to access between turbos and inner wing)". If this is the large can you can see from above on the passenger side, it's a turbine switchover actuator and not for the wastegate. Wastegate one is below the LP turbo and you can not see it from above. If you remove all the heatshields, you can see the rod between the block and the turbo, but you need to have a good flashlight and know where to look. So, I think you are talking a turbine switchover vacuum actuator. Take a picture if in doubt and post here. Quote:
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06-01-2016, 03:41 PM | #9 |
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I was just thinking about it more. If we are discussing the actual wastegate, then it is normally closed and upon the application of vacuum it opens.
The behaviour is similar to the turbine switchover valve. It is normally closed and upon the application of vaccum it opens. If looking at the long rod that comes out from the vacuum actuator, when at rest an no vacuum is applied it is in a closed position and the exhaust pathway to the LP turbo is closed. When vacuum is applied the vac actuator pulls/retracts the rod and then opens the pathway to the LP turbo. May be we are confusing rod retraction with the closing action here, where it is the opposite. If your retracts with the hand vaccum and holds that vacuum, then it is either the vacuum leak elsewhere, a bad pressure converter, reversed vac lines or the vac pump. Also, check the electrical supply to the pressure converter. |
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06-01-2016, 05:12 PM | #10 | |
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That aside, on rest it's wide open, and stats wide open with the engine and vac supply running. Now I know where the problem is I can run backwards in the vac supply once the replacement hose arrives. I don't want to strip it down whilst the car is running and take it off the road for longer than needed only to find in waiting on some replacement vac hose The pressure converters were new about 12-15months ago and I have also swapped them over with no change to the issue, so the vac loss is further back in the system and not related to the pressure converters - unless one has a leak... |
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06-01-2016, 07:38 PM | #11 | |
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Are you certain about the changeover valve orientation? I always thought it was opposite of what you are saying. It just doesn't make sense that the vehicle would hold the actuator 'open' when idling, starting and stopping. It would make more sense that it behaves much like a vgt turbo, default position is 'open' and when vacuum is applied, it would close the change over valve, resulting in the HP turbo being on line. This would also give the car a safety net for the hp turbo. If the default position was 'closed' then if something happened to the vacuum supply, the hp turbo would overspin and grenade itself. I may very well be wrong, I'm just trying to make sense of it. |
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06-01-2016, 08:39 PM | #12 |
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I can not say that I'm 100% sure as I do not have proof, but from the BMW technical info: http://www.e90post.com/forums/showpo...95&postcount=1
We know that at lower rpm the turbine control bypass is mainly closed and most of the exhaust goes to the HP turbo. As rpm increases the bypass is increasingly open. One thing is for sure is that the application of the vacuum to the actuator will retract the rod. That is normal as the design of the vacuum actuator is such that vacuum will pull on the rod and no vacuum will release it. What is not certain is whether pulling on the rod opens or closes the turbine bypass. We know that when we shut down the car the rod will retract back. This points to the fact that the bypass is possibly open in the position of rest and closes on application of vacuum. This also may point in the direction of, when vacuum actuator has failed, loss of power is experienced at the lower rpm range as bypass remains open. The same is when the vacuum actuator is leaking then bypass can not be closed fully and loss of power is experienced at the low rpm range. I think I have just contradicted myself. I suppose for anyone who has pulled the HP turbo, would be able to determine the default position for sure. You guys are right, the default is open. |
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06-01-2016, 09:07 PM | #13 |
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When I was porting the LP turbo's wastegate, I had to disconnect the waste gate actuator rod from the waste gate linkage. I recall that to open the WG, the rod had to move aftward.
I may have likely mentioned something unrelated but just in case it pertains, I thought I would share. |
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06-01-2016, 10:11 PM | #14 |
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So, at rest, is WG open or closed?
I'm so curious now that I'm going to be under the car on the weekend checking. We know how vacuum and control work. But which way the linkage is setup may be different. Too bad they do not mention anything in tech docs. |
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06-02-2016, 12:52 AM | #15 | |
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Now, just need to confirm what is the wastegate and compressor bypass valve mechanical behavior. |
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06-02-2016, 04:57 AM | #16 | |
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Later while doing short drives with the gauge in the cabin turbine control and compressor bypass plate work. Wastegate was odd. Whenever it was triggered there was big vacuum loss, the dial flew all the way around. In fact also when monitoring system vacuum after the accumulator the wastegate' vacuum need brought down the total system vacuum by 50 percent or more. Is this normal? |
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06-02-2016, 06:36 AM | #17 |
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I'm not familiar with the system at all, Mark, but that sounds like a leak. Unless BMW designed that actuator to move really quickly, atmospheric vents would be small enough to maintain adequate vacuum for the rest of the system.
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06-02-2016, 07:55 AM | #18 |
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Yeah, before I can theorize further, I would like to know is the Waste gate open to atmosphere only when vacuum is applied meaning by default it is closed, or is it by default open, and application of vacuum closes it to enable boost build up.
My gut is telling me, that they would have engineered it such that it is open without vacuum thus protecting the turbos in the event of a vacuum loss. But my testing contradicted this. The mityvac had shown zero vacuum to the WG until heavy fueling or abrupt throttle lift. And then it was LOTS of vacuum quick, even robbing from total system vacuum for ~3-5 seconds until the pump could recover. Testing further in the garage (engine off) I could not detect any leaks in the WG vacuum lines or actuator. The pressure converter is still a mystery at this point or maybe this is correct behavior for the WG, it would need to move fast to maintain correct boost. |
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06-02-2016, 07:59 AM | #19 |
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So does anyone know the purpose and function for the engine mount and swirl flap vac lines? I just saw this when looking at the vac manifold this morning. Those are the only two we did not touch...
So far no reappearing codes or faults from before. |
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06-02-2016, 08:35 AM | #20 |
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I have also checked and confirmed that upon the start-up the actuator pulls the rod back. Quote from Yozh.
When you say back, do you mean rod moves aftward or forward? |
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06-02-2016, 09:07 AM | #21 |
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WG is closed at rest, and with vacuum supplied it opens the WG. I remember this from DP install and porting the WG. I remember adjusting the flapper so there was a slight preload on it upon re-assembly...so that means its closed.
BB-cuda, I'm not 100%, but I do believe the turbine change over vacuum can retracts the rod with vacuum, so that would be aft, toward the rear end of the car. |
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06-02-2016, 09:27 AM | #22 | |
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Thanks for the confirmation on WG behavior! Also, confirmed, the turbine control valve at rest is extended allowing exhaust into the both HP and LP turbos. With vacuum it retracts directing exhaust to the HP turbo. Likewise, at rest the compressor bypass plate is closed directing air to the HP turbo. With vacuum it opens. |
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