Interesting/weird issue with boost
#1
Rotary!
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Interesting/weird issue with boost
For some reason in the last few days, my boost is tempermental. Under normal operation, the boost is normal, even when driving spiritedly...however...after driving it hard, once in a while there will be no boost produced.
I can't figure it out...all the hoses are intact and tight. It's odd that I 'll be driving along enjoying the ride, then all of a sudden I feel like I'm driving a yugo, then a couple minutes later, the boost comes back on.
Needless to say that when I bring it to my mechanic (who knows rotaries very well and owns three RX7's) the problem doesn't arise.
Very frustrating. If anyone has any ideas, it would be much appreciated.
TIA
By the way, my turbos are sequential
I can't figure it out...all the hoses are intact and tight. It's odd that I 'll be driving along enjoying the ride, then all of a sudden I feel like I'm driving a yugo, then a couple minutes later, the boost comes back on.
Needless to say that when I bring it to my mechanic (who knows rotaries very well and owns three RX7's) the problem doesn't arise.
Very frustrating. If anyone has any ideas, it would be much appreciated.
TIA
By the way, my turbos are sequential
#2
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Originally Posted by 3GRX7
For some reason in the last few days, my boost is tempermental. Under normal operation, the boost is normal, even when driving spiritedly...however...after driving it hard, once in a while there will be no boost produced.
I can't figure it out...all the hoses are intact and tight. It's odd that I 'll be driving along enjoying the ride, then all of a sudden I feel like I'm driving a yugo, then a couple minutes later, the boost comes back on.
Needless to say that when I bring it to my mechanic (who knows rotaries very well and owns three RX7's) the problem doesn't arise.
Very frustrating. If anyone has any ideas, it would be much appreciated.
TIA
By the way, my turbos are sequential
I can't figure it out...all the hoses are intact and tight. It's odd that I 'll be driving along enjoying the ride, then all of a sudden I feel like I'm driving a yugo, then a couple minutes later, the boost comes back on.
Needless to say that when I bring it to my mechanic (who knows rotaries very well and owns three RX7's) the problem doesn't arise.
Very frustrating. If anyone has any ideas, it would be much appreciated.
TIA
By the way, my turbos are sequential
#4
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Originally Posted by 3GRX7
I forgot to mention the sound after I let off the gas! It's so weird, it sounds like a a low pitched whistle or something, right?
Really weird
Really weird
#5
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Are you running stock boost? If so, maybe a bad TC solenoid. If you are running more than 10 psi, I will look further into my post of boost problem, and there is a fix, my car boost fine now. GOod luck
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do a full boost run... then when boost isn't built correctly - momentarily come off the throttle before going WOT again - if it builds normally it means the vacuum tank isn't holding vacuum due to the check valve.
it pretty much has to be a switching part/system, as all the mechanical parts would have that problem constantly.
it pretty much has to be a switching part/system, as all the mechanical parts would have that problem constantly.
Last edited by weetbix13; 03-09-06 at 05:39 PM.
#7
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sounds like for some reason the secondary turbo is not comming online, when you go wide open with this problem the whirring sound you are hearing when you lift off is the pressure from the primary turbo spinning the secondary backwards....not good...try not to do it till you fix the problem...look at the turbo control actuator, lines and according solenoids, also a leak in either the boost or vacumn chamber can cause this.
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#8
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OK, I'm a little confused....i looked into rotarypolo's boost problem post...is what sereneseven is saying essentially the same problem, or a totally different hypothesis?
Also, the fix that was done for rotarypolo's problem, could someone please try & explain it a little clearer? If I put the regulator on and set it to 10 psi, please explain how it "tricks" the turbo system. Is it possible to overboost by putting that on, potentially damaging the engine?
Also, the fix that was done for rotarypolo's problem, could someone please try & explain it a little clearer? If I put the regulator on and set it to 10 psi, please explain how it "tricks" the turbo system. Is it possible to overboost by putting that on, potentially damaging the engine?
#9
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The soleniods are spring loaded - too much pressure or vacuum and it will prevent the spring from opening/closing them. As well, age and dust can weaken or damage them. Even new solenoids have trouble switching at 14-15psi.
The pressure loaded into the pressure chamber easily exceeds 12psi in a stock car, and of course goes higher for higher boosted cars. This will lock the turbo control solenoid and slow the secondary response, unless you install a pressure regulator to keep the tank around 10psi. (It only needs about 8psi to work reliably).
I'll bet that your solenoids are going bad when hot or some other annoying problem.
Dave
The pressure loaded into the pressure chamber easily exceeds 12psi in a stock car, and of course goes higher for higher boosted cars. This will lock the turbo control solenoid and slow the secondary response, unless you install a pressure regulator to keep the tank around 10psi. (It only needs about 8psi to work reliably).
I'll bet that your solenoids are going bad when hot or some other annoying problem.
Dave
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Originally Posted by 3GRX7
OK, I'm a little confused....i looked into rotarypolo's boost problem post...is what sereneseven is saying essentially the same problem, or a totally different hypothesis?
Also, the fix that was done for rotarypolo's problem, could someone please try & explain it a little clearer? If I put the regulator on and set it to 10 psi, please explain how it "tricks" the turbo system. Is it possible to overboost by putting that on, potentially damaging the engine?
Also, the fix that was done for rotarypolo's problem, could someone please try & explain it a little clearer? If I put the regulator on and set it to 10 psi, please explain how it "tricks" the turbo system. Is it possible to overboost by putting that on, potentially damaging the engine?
#13
3GRX7, PM Saxyman - he recently held a GB on replacement solenoids with all new check valves, basically all new parts for turbo control. It also relocates the solenoids and makes them easier to work on. He may still be able to make you up a kit, although im nto sure.
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Originally Posted by dgeesaman
4 important solenoids at $60/ea. Def. do the check valves too.
Worthwhile, IMO.
Dave
Worthwhile, IMO.
Dave
that'll be awhile before I get to that.
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Originally Posted by dgeesaman
Used ones are $10-20/ea, and with a Mityvac you can test and sort out the good ones.
I do think it's worthwhile to buy new turbo control solenoids - they all eventually go bad, and for $120 it's well spent.
Dave
I do think it's worthwhile to buy new turbo control solenoids - they all eventually go bad, and for $120 it's well spent.
Dave
....$240 for 4 solenoids at $60/ea just isn't looking good in my book, i'd rather ride around and stay out of boost before I spend that much on new solenoids....
#19
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There are about 10 in the area of the rats nest. There are two that fail first - the turbo control solenoids. Then there are two more that are turbo-related which are a pain to change if they fail - the charge control and charge relief solenoids.
The last two turbo-related solenoids is the green wastegate/precontrol pair, which is not cheap to buy new but very easy to access. And plenty of used ones out there. They don't tend to fail that often IME.
There are even more solenoids that I have not mentioned because they aren't for turbo control. So really, 2-4 is a very economical solution to the problem.
Dave
The last two turbo-related solenoids is the green wastegate/precontrol pair, which is not cheap to buy new but very easy to access. And plenty of used ones out there. They don't tend to fail that often IME.
There are even more solenoids that I have not mentioned because they aren't for turbo control. So really, 2-4 is a very economical solution to the problem.
Dave
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Originally Posted by weetbix13
do a full boost run... then when boost isn't built correctly - momentarily come off the throttle before going WOT again - if it builds normally it means the vacuum tank isn't holding vacuum due to the check valve.
it pretty much has to be a switching part/system, as all the mechanical parts would have that problem constantly.
it pretty much has to be a switching part/system, as all the mechanical parts would have that problem constantly.
Also I heard that I might have a boost leak, my car is suppose to build boost when I rev itup at idle? It doesn't boost any at all now.....but before it use to build 2psi or so...
I think I'm going to go ahead and replace all of the turbo control solenoids / check valves......& hope that that is my only problem currently preventing me to boost correctly.
Last edited by TrevorC; 03-11-06 at 03:06 PM.
#22
Can you keep this thread informed of your progress Mate, I have the same problem after having larger injectors, HKS RS Induction kit and a boost controller fitted. From cold the car will boost fine, its only when it gets warmer that I have the problems where you accelrate hard past 5000rpm then let off and accelerate again only to get 0.5 and then the weird noise.
Driving me mad now !!!
Cheers,
Gareth
Driving me mad now !!!
Cheers,
Gareth
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unfortunately I don't have $200 right now to spend untill I get paid the next friday after this week......and unfortunately I don't have alot of time to work on my car as I work alot.
since then I've followed up on some threads such as:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/rx7-poor-accelaration-497716/page2/
but I haven't got around to checking that out yet to see if my solenoids are good, also I've PM'd "saxyman990" about a solenoid / check valve package / group buy he is doing for pricing (dunno the price yet) if it does tun out my solenoids / check valves are gone bad.
since then I've followed up on some threads such as:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/rx7-poor-accelaration-497716/page2/
but I haven't got around to checking that out yet to see if my solenoids are good, also I've PM'd "saxyman990" about a solenoid / check valve package / group buy he is doing for pricing (dunno the price yet) if it does tun out my solenoids / check valves are gone bad.