Severe boost creep and ECU not hitting overboost protection? FML
12-28-2010, 08:15 AM
#23
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On a side note, my exhaust note was retarded loud with the WG wired open. Oh since I can still drive with everything hooked up, I put some preload on the WG actuator and am getting 5-6psi at 2k rpms...the thing is crazy responsive with some preload.
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12-28-2010, 08:30 AM
#24
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Sent this to ATP Turbo to see if they have any insight to all of the madness:
Hi guys!!
I am running a Garrett 2560R on my 1.8L Miata. The turbo is 5+ years old. Recently the CHRA failed and I replaced it with a new CHRA via Garrett's CHRA exchange program. Previously I was running 13-14psi with no issues (using a Hallman MBC). Since the CHRA replacement, I have had a big problem with boost creep/overboost. Through a battery of tests, I've narrowed it down to the IWG port not seeming to handle the flow of the new CHRA. With the IWG flapper wired as far open as it would go, I am still able to see boost climb to 15+psi in higher gears (minimum of 5psi seen in all gears).
OK, now that you have some background information of my issue, let me get to the question. Is it possible that since my turbo was manufactured, Garrett has since updated the design of the 2560R and the new CHRA is simply flowing too much for the old IWG housing I have? Might getting a new exhaust housing help with my boost creep problem?
Any help to solve this problem would be greatly appreciated!
Thanks for your time,
Mike.
I am running a Garrett 2560R on my 1.8L Miata. The turbo is 5+ years old. Recently the CHRA failed and I replaced it with a new CHRA via Garrett's CHRA exchange program. Previously I was running 13-14psi with no issues (using a Hallman MBC). Since the CHRA replacement, I have had a big problem with boost creep/overboost. Through a battery of tests, I've narrowed it down to the IWG port not seeming to handle the flow of the new CHRA. With the IWG flapper wired as far open as it would go, I am still able to see boost climb to 15+psi in higher gears (minimum of 5psi seen in all gears).
OK, now that you have some background information of my issue, let me get to the question. Is it possible that since my turbo was manufactured, Garrett has since updated the design of the 2560R and the new CHRA is simply flowing too much for the old IWG housing I have? Might getting a new exhaust housing help with my boost creep problem?
Any help to solve this problem would be greatly appreciated!
Thanks for your time,
Mike.
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12-28-2010, 07:07 PM
#26
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I'm definitely not experienced with these things, but I could understand if the limited travel of the wastegate was causing boost creep (since it's not able to open fully and the pressure could start to build against the restriction). Could you lengthen the swing arm where the wastegate actuator rod connects to it (which would effectively give it more travel)? I'm not sure what could have changed to prevent the wastegate from having full travel though?
Disclaimer: If anything I have said here is stupid, please kindly disregard it.
Disclaimer: If anything I have said here is stupid, please kindly disregard it.
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12-28-2010, 07:16 PM
#27
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This post will help you more than me.
Yes the actuator arm is adjustable. But it has a range and that range isn't the same as what the flapper assembly is. To bleed off excess exhaust, the IWG doesn't need to open all the way, just some of the way. Now, in my case, I get boost even with the actuator disconnected and the flapper opened all the way....way more then it would be if the actuator was at it's "all the way open" position. If I am getting boost with it wired open, no amount of adjustment in the actuator is going to help.
Yes the actuator arm is adjustable. But it has a range and that range isn't the same as what the flapper assembly is. To bleed off excess exhaust, the IWG doesn't need to open all the way, just some of the way. Now, in my case, I get boost even with the actuator disconnected and the flapper opened all the way....way more then it would be if the actuator was at it's "all the way open" position. If I am getting boost with it wired open, no amount of adjustment in the actuator is going to help.
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12-28-2010, 10:22 PM
#29
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Will need to buy a new exhaust housing before doing that, when I replaced the CHRA I found some very small/fine hairline cracks around the IWG port on the exit side. It was also seen by the show that did the reassembly and was given the A-OK that it shouldn't be a problem. At that point I did put a new exhaust housing on the to-do list and I guess I'll be getting to that sooner than I thought. I do not attribute those cracks to the problem with boost creep as they were there long before the old CHRA **** and if they were a problem, they would have been a problem before as well. I don't feel it's worth porting a housing that has cracks of any size. With that said, i'd like to get conformation that it would be the final solution to the problem...which I think it is...because to me, that is the only factor in the boost creep problem.
On a side note- I can still pound some ricer *** even with the IWG wired open
Some punk kids in some shitty beat-*** EG hatch tried to **** with me on my way home....poor, slow *******.
On a side note- I can still pound some ricer *** even with the IWG wired open
Some punk kids in some shitty beat-*** EG hatch tried to **** with me on my way home....poor, slow *******.
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12-29-2010, 11:08 PM
#31
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I think you need to compare the wheels from the old CHRA and the new one. Perhaps there are some differences. No bearing style differences?
Other than that I don't see how keeping everything else the same could cause your problem even with the WG wired open.
Other than that I don't see how keeping everything else the same could cause your problem even with the WG wired open.
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12-30-2010, 05:12 PM
#32
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An odd thing I noticed on my way home today. Since I've been driving the car around, boost comes on strong and hard betweem 2k and 3.2k rpms...it's great...spools like a TDi. Boost is quick to build to 10psi too. But if I go up to 6k rpms and shift and go back WOT right away, boost suddenly becomes vrey slow to build....like when the wastegate was open. Interesting. Not that it helps me get any closer to a solution. I'll be taking it off the car sometime soon....
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12-31-2010, 01:26 AM
#33
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I ******* hate this ****. I should have just tried to get my hands on a brand new ******* turbo rather than a replacement CHRfuckingA. At least in that case I wouldn't have to worry about wondering what the **** has changed between the 5/6yr old turbo I had and the brand new replacement center and driving myself crazy thinking that is the only logical ******* answer to this mess.
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01-02-2011, 07:06 PM
#34
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OK. So today I spoke with the owner of a reputable tuning shop and started to explain what I've done and the symptoms of what has been going on. Before I could even finish he said "Garrett has updated the design since yours was made. No doubt about it". I trust his word too, as they know what's what. I mean, they did wax One Lap America last year with a 911 GT2, and waxed the Red Line Time Attack series with a GC8 Impreza a couple years ago. Anyway, I'll be ordering a new exhaust housing and having it ported.
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03-03-2011, 08:06 AM
#37
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For the reason of aynone using the search functin in the future*
I have resolved the boost creep issue.
I ordered a new exhaust housing and had BEGi port it. I also added an updated wastegate actuator. All is fine now as there is no more boost creep issue. Problem fixed!
I'm going to say the problem was indeed that the turbine was simply flowing too well and exhaust gas wasn't wanting to divert through the IWG port. Car pulls hard now.
I have resolved the boost creep issue.
I ordered a new exhaust housing and had BEGi port it. I also added an updated wastegate actuator. All is fine now as there is no more boost creep issue. Problem fixed!
I'm going to say the problem was indeed that the turbine was simply flowing too well and exhaust gas wasn't wanting to divert through the IWG port. Car pulls hard now.
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03-03-2011, 12:44 PM
#39
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A problem that made no sense given that I just changed out the CHRA with an "identical" unit. No one could confirm that Garrett has made any changes to the design on the 2560R...which it's clear they have otherwise I wouldn't have had a IWG flow problem. Turbo and 3" exhaust were on the car long before the turbo failed so it wasn't a problem that could have even been a possibility with the old CHRA. It least you weren't suggesting things like something in my exhaust causing a blockage or that having a 3" exhaust was the cause 
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03-03-2011, 01:54 PM
#40
No one suggested you having a 3" exhaust was the cause. It was stated that having an updated turbo design coupled with your 3" exhaust resulted in flow that was overcoming the IWGs ability to control boost properly. Same diagnosis, port the wastegate. And look what it was.
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