What causes weak low end boost?
#1
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What causes weak low end boost?
I have had this problem since I finished this build.. But my car does not start to boost well until about 5K+ RPM's. I read posts of people with similar setup's saying they hit 10 PSi in 2nd gear at 3k!!! I have been searching and searching for a problem but everythigg checks out okay. I have checked the wastegate operation a trillion times, so it has to be somthing besides that.
I am open to any and all causes of this.
Mods listed in Sig. On the dyno I was boosting over 13PSI at 8.5K the high end boost is great! And it was still not dropping off. I just don't quite get why I have such weak low end boost.
Thanks,
Robert
I am open to any and all causes of this.
Mods listed in Sig. On the dyno I was boosting over 13PSI at 8.5K the high end boost is great! And it was still not dropping off. I just don't quite get why I have such weak low end boost.
Thanks,
Robert
#2
my fc broke
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maybe its your primary and secondary's being to differnt. because i know a guy with the simlar setup but hes just running avcr instead safc but he has a FMIC and hes only running 800 secondary's only and his runs fine
#3
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I am still runing the stock IC, but if anything this should increase boost responce. I keep thining about a aftermarket IC, but I need to figure out whats up with this first.
I don't think the injectors are a issue; I played on the dyno for 2 days (infact I will try to post pics of the boost curve on the dyno later, I am at work right now) And I have the fuel curve dialed in perfect, that should be the only thing the injectors would effect, I assume.
I don't think the injectors are a issue; I played on the dyno for 2 days (infact I will try to post pics of the boost curve on the dyno later, I am at work right now) And I have the fuel curve dialed in perfect, that should be the only thing the injectors would effect, I assume.
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Here is my day 1 Dyno sheets. Notice the low end boost. I ended up with much higher boost after I set my second stage boost control config, But the curve is about the same (still looking for my day 2 sheets, I will try to post them also)
#5
Hks Ownz Me (
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1. compression
2. exhaust
3. check to make sure you have the air diffusers and all the little nefty stock gadgets that mazda put there
4. check for leaks
but its most likely going to be number 1
2. exhaust
3. check to make sure you have the air diffusers and all the little nefty stock gadgets that mazda put there
4. check for leaks
but its most likely going to be number 1
#6
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More details, and lots pictures of the problems in this link
Check this post
I know it's not motor compression ... the motor only has 2600 miles on it, and I have a compression gauge.
I am very lost on this problem, there is nothing on this car I have not been able to solve ... until this.
-Robert
Check this post
I know it's not motor compression ... the motor only has 2600 miles on it, and I have a compression gauge.
I am very lost on this problem, there is nothing on this car I have not been able to solve ... until this.
-Robert
Last edited by Rpeck; 10-11-03 at 11:52 PM.
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#10
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I have the same problem with boost. I know its from huge exhaust leaks cuz i can hear them. I also have a streetport which could be adding to the problem, cuz the engine could be outflowing the stock turbo. I make about 3psi MAX in first, in second it makes only 3 till about 5k, then goes up to 6.
#11
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Originally posted by 2a+RoN
I have the same problem with boost. I know its from huge exhaust leaks cuz i can hear them. I also have a streetport which could be adding to the problem, cuz the engine could be outflowing the stock turbo. I make about 3psi MAX in first, in second it makes only 3 till about 5k, then goes up to 6.
I have the same problem with boost. I know its from huge exhaust leaks cuz i can hear them. I also have a streetport which could be adding to the problem, cuz the engine could be outflowing the stock turbo. I make about 3psi MAX in first, in second it makes only 3 till about 5k, then goes up to 6.
Question; at what point does your TII gauge go from vacuum to 0 (equal pressure) My guage shows vacuum till past 3k. .. then it just starts to get to 0. then finally boost .... I boost great pressure 10PSI+, but it ust kicks in so late i have to shift once it starts to boost good ...
#12
Rotary Motoring
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Check your other thread and please try to link duplicate threads
-edit-
https://www.rx7club.com/showthread.p...hreadid=231522
-edit-
https://www.rx7club.com/showthread.p...hreadid=231522
Last edited by BLUE TII; 10-13-03 at 12:18 AM.
#13
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Originally posted by BLUE TII
Check your other thread and please try to link duplicate threads
-edit-
https://www.rx7club.com/showthread.p...hreadid=231522
Check your other thread and please try to link duplicate threads
-edit-
https://www.rx7club.com/showthread.p...hreadid=231522
thx.
#17
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No cat, Free flowing 3"-4" All the way through. I still have the problem right now. But at the moment I have the whole UIM, and half of the rest of the car apart, I am starting back over from step 1 if you know what I mean.
-Robert
-Robert
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I have the whole UIM opened up right now, I don't see anything wrong with the throttle body at all. I did have the TB mod done.. where the first set of plates are removed, I am in the process of putting that back to normal. It is NOT the wastegate, trust me, and I have looked at almost everything on this situation.... this is by far the most stuped I have ever been with this thing .
-Robert
-Robert
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