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Post by Stinger on Mar 27, 2015 20:15:00 GMT -5
Mass-air most likely won't fix it, it has issues with backflow as well. The only way I can think of to confirm it's what's happening would be to bypass the whole IC system and connect the turbo to the TB.
The only other thing it could be is the bypass valve malfunctioning (or just acting as that plastic valve acts). You could remove it, plug the hole, and see if it goes way.
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Post by Hueneme805 on Mar 27, 2015 22:40:59 GMT -5
Ill remove bypass valve n plug it first.
IC meaning intercooler and TB meaning throttle body right? In other words connect turbo straight to throttle body? Ill try that after if I still get same issue.
Will air going into motor be hotter if no IC is used. Will it run with less power/torque?
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Post by Stinger on Mar 27, 2015 23:04:21 GMT -5
Yes, that's what I mean.
Yes, it will be hotter and have less power. This shouldn't be an issue though since you don't need to test at it max boost, or under boost at all since the problem only exists when not in boost. I would actually suggest not running full boost when you don't have the IC being used since you've got a good chance of having a detonation issue if you try to run a bunch of boost with no IC.
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Post by filasfinest86 on Mar 29, 2015 1:12:18 GMT -5
mine does that too i think its what stinger suggested the vam is on that border line where it doesnt know wether to close shut or open my suggestion is to floor it or bring down the mphs a little bit.. mine does it too with the BIG intercooler in 5th youre either in it or your not.... this is probably why im going to get a PIMP bothers the crap outta me....
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Post by Hueneme805 on Apr 1, 2015 14:20:28 GMT -5
So this is what I found. I had a fitting that was loose on the bypass that was heading back to turbo, so I had that welded. I haven't drivin the car yet.
Going to drive it today to see results.
How important is it for turbo to use a bypass? Should I just delete it?
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Post by Stinger on Apr 1, 2015 15:33:17 GMT -5
It's important when you've got an FMIC. Regardless, a bypass isn't the cause of the backflow so deleting it won't fix the problem (unless the actual bypass valve is at fault).
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Post by Hueneme805 on Apr 5, 2015 16:01:41 GMT -5
Update on my research, so after welding the loose fitting for the bypass with bypass still attached and fmic the car still did the same thing. Bucking at same RPM and speed I have mentioned.
Then I removed bypass and plugged both ends of bypass fittings of fmic pipping and car drove worse with more bucking than usually.
So then I disconnected the fmic and connected turbo straight to throttle body. The car ran good with no issues at all during 4th and 5th gears at same RPM and speeds I have mentioned?
What does this mean. Check all my connections on my fmic starting from turbo to throttle body? Then try again with everything back on?
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Post by Stinger on Apr 5, 2015 17:27:07 GMT -5
It means it did exactly what I said it would do (bypass valve wasn't the problem and wouldn't fix it when deleted) and that it's what I said was the problem (VAM + FMIC = trailer hitching if you don't drive around the problem). So to fix the problem you need to delete one of the two items in that equation, or learn how to drive around it so it never happens when you're driving.
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Post by Hueneme805 on Apr 5, 2015 18:05:06 GMT -5
Will pimp ecu help with issue by deleting vam and keep bypass and fmic.?
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Post by Stinger on Apr 5, 2015 20:35:53 GMT -5
Yes, it will eliminate the problem by eliminating the VAM.
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Post by Hueneme805 on May 9, 2016 23:35:50 GMT -5
Found out the issue with problem. Vam door that opens and closes was rubbing on the inside of the housing. I disassembled the vam and shaved the door just enough for door to open and close without rubbing. Reassembled and No surging or bucking anymore. Pull's fine thru all rpms now. No AFR issues. Bad reman vam and fixed it at home.
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Post by Stinger on May 10, 2016 0:12:09 GMT -5
Nice!
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svokid
Boosted Newbie
Posts: 7
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Post by svokid on Jul 8, 2020 21:16:01 GMT -5
I have exact same problem, but not using vam. Running microsquirt in speed density. Any ideas
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Post by Stinger on Jul 8, 2020 21:31:34 GMT -5
Sounds like you need to adjust the fuel table.
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svokid
Boosted Newbie
Posts: 7
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Post by svokid on Jul 8, 2020 21:42:40 GMT -5
I tried that but it just made go a little richer then lean again. Tried to let auto do its thing and it pulled the fuel i added right back out
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