What are you using to address the delayed PFC boost?
02-13-04, 11:06 AM
#26
You are correct, rynberg, mine is a different problem than what you're talking about... basically, i'm NOT getting that return at 3k (or whatever) like i'm supposed to. And it certainly shouldn't SOUND like it does.
... but i was reacting to someone's suggestion that this is a problem with ME. I dunno about BATMANs issue, maybe my longer description will help him sort it out.
... but i was reacting to someone's suggestion that this is a problem with ME. I dunno about BATMANs issue, maybe my longer description will help him sort it out.
Originally posted by rynberg
Ptrhahn: That is NOT the situation I am describing at ALL, though it may be Batman's problem. The phenomenon I am describing is not a mechanical problem but a design of the system. Once you cross the transition with the PFC, it will stay in non-sequential until you drop below 3k rpm. That is how it is SUPPOSED to function. I never have to return to idle or any other nonsense in order to get boost. My only point was that you have to drop the rpms below 3k to go back to sequential. This is really only noticeable in 5th gear and not normal driving -- in fact the only time I really notice it is merging onto the highway at 100 mph or so in 4th and then dropping it into 5th -- the car will still be in non-sequential in 5th gear, which is slow as **** as any non-seq people will verify.
Ptrhahn: That is NOT the situation I am describing at ALL, though it may be Batman's problem. The phenomenon I am describing is not a mechanical problem but a design of the system. Once you cross the transition with the PFC, it will stay in non-sequential until you drop below 3k rpm. That is how it is SUPPOSED to function. I never have to return to idle or any other nonsense in order to get boost. My only point was that you have to drop the rpms below 3k to go back to sequential. This is really only noticeable in 5th gear and not normal driving -- in fact the only time I really notice it is merging onto the highway at 100 mph or so in 4th and then dropping it into 5th -- the car will still be in non-sequential in 5th gear, which is slow as **** as any non-seq people will verify.
02-13-04, 11:36 AM
#28
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woah now, I mis-interperated as well. I thought it was just the system acting as it should be as rynberg was talking about. In that case its just a matter of staying in the correct RPM range as I was talking about. But yeah, yours is a different problem.
02-13-04, 12:11 PM
#29
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Originally posted by ptrhahn
This is nothing "inherant" in a twin turbo system.
The bottom line is, something is malfunctioning, and not returning the door inside the manifold to blow exhaust (almost) exclusively at the primary turbo when its supposed to, requiring you do do something "more" to trigger that action, like letting the car idle.
I'd even think that its something vacuum or mechanical in origin, because given the sound of the motor, i'd say your ECU isn't delivering fuel and timing maps consistent with what the turbos are doing... in other words, if you TUNED for a non-sequential car, it wouldn't sound like that... the maps your getting weren't intended for the conditions, because those conditions weren't intended.
Bottom line is, it's not "poor boost response" its poor or faulty system management... the door should be coming back, and its not... ergo, something isn't doing what its supposed to be doing.
This is nothing "inherant" in a twin turbo system.
The bottom line is, something is malfunctioning, and not returning the door inside the manifold to blow exhaust (almost) exclusively at the primary turbo when its supposed to, requiring you do do something "more" to trigger that action, like letting the car idle.
I'd even think that its something vacuum or mechanical in origin, because given the sound of the motor, i'd say your ECU isn't delivering fuel and timing maps consistent with what the turbos are doing... in other words, if you TUNED for a non-sequential car, it wouldn't sound like that... the maps your getting weren't intended for the conditions, because those conditions weren't intended.
Bottom line is, it's not "poor boost response" its poor or faulty system management... the door should be coming back, and its not... ergo, something isn't doing what its supposed to be doing.
02-13-04, 01:01 PM
#30
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It can be both a solenoid problem and the way the PFC operates.
Watch the TCA solenoid in the sensor section of the PFC. It will stay on after you back out of the gas until 3K RPM. If the PFC shows the TCA solenoid is not actived but it seems to be stuck in twin mode, then you have a solenoid problem.
I had the same exact issue. Sometimes the twin mode stuck on even until I came to a stop and it was the solenoid. After replacing the solenoid the PFC still kept the TCA open until dropping below 3K RPM which I confirmed by watching the TCA solenoid indicator on the PFC.
To summarize: PFC says twin turbo mode then it wants it to be in twin turbo mode. If the PFC doesn't want it in twin turbo mode but it feels like it is, then you have a problem unrelated to the PFC.
BTW. I switched to nonsequential soon afterward.
Mark
Watch the TCA solenoid in the sensor section of the PFC. It will stay on after you back out of the gas until 3K RPM. If the PFC shows the TCA solenoid is not actived but it seems to be stuck in twin mode, then you have a solenoid problem.
I had the same exact issue. Sometimes the twin mode stuck on even until I came to a stop and it was the solenoid. After replacing the solenoid the PFC still kept the TCA open until dropping below 3K RPM which I confirmed by watching the TCA solenoid indicator on the PFC.
To summarize: PFC says twin turbo mode then it wants it to be in twin turbo mode. If the PFC doesn't want it in twin turbo mode but it feels like it is, then you have a problem unrelated to the PFC.
BTW. I switched to nonsequential soon afterward.
Mark
04-01-04, 11:39 PM
#34
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I agree with that notion.
If I am going to go non seq, i mine as well toss all the rats nest and other do dads and go single.
But, part of the charm of the FD turbo system is the low end power.
If I am going to go non seq, i mine as well toss all the rats nest and other do dads and go single.
But, part of the charm of the FD turbo system is the low end power.
08-24-04, 06:38 PM
#35
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Bump... I just found this thread after making a new post in the tech forum. I'm having the exact problem described here. My car didn't do it with the M2 ecu I had. Also, a couple of friends with almost identical setups don't have the problem.
Here's my post for reference:
I WILL figure this out, as its driving me nuts. I'll report back when I do. Personally, I think it may be a flakey solenoid that the PFC is more sensitive to, or a grounding issue. FWIW, my car had the 3K hesitation bad on the stock (M2) ecu.
- Dave Disney
http://rx7.voodoobox.net
Here's my post for reference:
My apologies if this has been covered before. I've searched the forum and found about three posts describing my exact issue, but there were never any follow-ups explaining a fix.
Anyway, I've got a weird problem and wanted to see anyone has run into it before:
Details: PFC, Downpipe, Hi-Flow Cat, RB Dual Cat-Back, M2 Intake, new plugs, good wires, vac hose job, running 12 psi. I just installed the PFC and Steve Kan tuned it for me (great work!). I didn't have this problem with the M2 Stage III ECU I had before. I'm hoping its just that the PFC is more sensitive to something or there is a setting I've missed.
It does this in any gear, but for example, if I punch it in 2nd gear at 2500 rpm, I get full boost quickly, it transitions quickly to the secondary at around 4200 or so, and makes great power to redline... everything works great. However, if I let out of the throttle and coast back down to a lower rpm, say 4000, and punch it again, the boost builds very slowy and the exhaust note changes (sounds different, but hard to explain... different pitch). It will do this until the rpms drop below 2800 (either by coasting down in gear, or just putting the clutch in). I can coast all day (refreshing the vaccum supply), but I won't get quick boost back until the rpms drops below 2800...
Looking at the switch/relay readout on the commander, when I pass the transition point under heavy throttle, the CCN indicator goes out and the TCN comes on. It stays this way until the rpms drop below 2800, when it switches back and I can get quick boost again. Basically, I can get normal turbo operation once with WOT under a gear, and then I have to clutch in and let the rpms drop below 2800 before it will work right again. If I don't do that and then go WOT, it will take two or three thousand rpm to built back up to full boost.
I've tried replacing the turbo control solenoid (mounted on the ACV) and I also replaced the two solenoids mounted on the front of the upper intake (wastegate solenoid and pre-control) since they were easy to get to and those made no differences. I've also confirmed that all my checkvalves are good and my vacuum and pressure tanks are holding vac/press overnight.
Have you ever seen that behavior before. Any ideas?
From the exhaust sound change, I'm wondering if the wastegate or the other flapper door in the turbo manifold (prespool door) isn't functioning properly, but I can't figure out why it would work normally one time and then be screwed up until the rpms drop below 2800.
Is there any chance my PFC is bad? Everything else seems to work just great.
I'm going to take the upper intake off and check all the lines for kinks. I think I'll also replace the other turbo control solenoid (the one in the rack) while I'm in there.
Thanks for your time!
Anyway, I've got a weird problem and wanted to see anyone has run into it before:
Details: PFC, Downpipe, Hi-Flow Cat, RB Dual Cat-Back, M2 Intake, new plugs, good wires, vac hose job, running 12 psi. I just installed the PFC and Steve Kan tuned it for me (great work!). I didn't have this problem with the M2 Stage III ECU I had before. I'm hoping its just that the PFC is more sensitive to something or there is a setting I've missed.
It does this in any gear, but for example, if I punch it in 2nd gear at 2500 rpm, I get full boost quickly, it transitions quickly to the secondary at around 4200 or so, and makes great power to redline... everything works great. However, if I let out of the throttle and coast back down to a lower rpm, say 4000, and punch it again, the boost builds very slowy and the exhaust note changes (sounds different, but hard to explain... different pitch). It will do this until the rpms drop below 2800 (either by coasting down in gear, or just putting the clutch in). I can coast all day (refreshing the vaccum supply), but I won't get quick boost back until the rpms drops below 2800...
Looking at the switch/relay readout on the commander, when I pass the transition point under heavy throttle, the CCN indicator goes out and the TCN comes on. It stays this way until the rpms drop below 2800, when it switches back and I can get quick boost again. Basically, I can get normal turbo operation once with WOT under a gear, and then I have to clutch in and let the rpms drop below 2800 before it will work right again. If I don't do that and then go WOT, it will take two or three thousand rpm to built back up to full boost.
I've tried replacing the turbo control solenoid (mounted on the ACV) and I also replaced the two solenoids mounted on the front of the upper intake (wastegate solenoid and pre-control) since they were easy to get to and those made no differences. I've also confirmed that all my checkvalves are good and my vacuum and pressure tanks are holding vac/press overnight.
Have you ever seen that behavior before. Any ideas?
From the exhaust sound change, I'm wondering if the wastegate or the other flapper door in the turbo manifold (prespool door) isn't functioning properly, but I can't figure out why it would work normally one time and then be screwed up until the rpms drop below 2800.
Is there any chance my PFC is bad? Everything else seems to work just great.
I'm going to take the upper intake off and check all the lines for kinks. I think I'll also replace the other turbo control solenoid (the one in the rack) while I'm in there.
Thanks for your time!
- Dave Disney
http://rx7.voodoobox.net
08-24-04, 08:32 PM
#36
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You have eliminated any issue other than the way the powerFC operates if the Turbo Control Solenoid indicator is on when the boost takes a while to build and off when it doesn't. This is an output indicator, so the powerFC wants to do what you are complaining about. Contact someone with the datalogit to change the transition. You may want to call Chris Ott at rx7.com. He can explain what needs to change.
Mark
Mark
08-24-04, 08:51 PM
#37
from the autosportracetech.com site
Vacuum Chamber
This is a black plastic tank that is buried between the alternator and power steering pump. Kind of difficult to see, removing the Pressure Chamber helps to see it, has one hose connection, and should have a hose attached, (Engine View Picture). This hose comes from the rats nest of metal tubes, and there is a one-way check valve between the rats nest of tubes and the Intake, (the only check valve located between Throttle Body and the Firewall). This one-way check valve can start to leak after a while, causing loss of vacuum to various controls when under boost for a while. A way to troubleshoot this one-way valve leaking is to note a gradual loss of boost and then drop the throttle long enough for your boost gauge to indicate at least 20 inHg of vacuum then slam the throttle back down again. If boost isn't back up to what it should be then replace this one-way check valve. Basically what this does is "recharge" the vacuum chamber when you let off the gas, allowing actuators to operate properly while the vacuum is still present.
What about checking this one-way check valve they talk about above and seeing if that's the culprit.
Tim
Vacuum Chamber
This is a black plastic tank that is buried between the alternator and power steering pump. Kind of difficult to see, removing the Pressure Chamber helps to see it, has one hose connection, and should have a hose attached, (Engine View Picture). This hose comes from the rats nest of metal tubes, and there is a one-way check valve between the rats nest of tubes and the Intake, (the only check valve located between Throttle Body and the Firewall). This one-way check valve can start to leak after a while, causing loss of vacuum to various controls when under boost for a while. A way to troubleshoot this one-way valve leaking is to note a gradual loss of boost and then drop the throttle long enough for your boost gauge to indicate at least 20 inHg of vacuum then slam the throttle back down again. If boost isn't back up to what it should be then replace this one-way check valve. Basically what this does is "recharge" the vacuum chamber when you let off the gas, allowing actuators to operate properly while the vacuum is still present.
What about checking this one-way check valve they talk about above and seeing if that's the culprit.
Tim
08-24-04, 09:37 PM
#38
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The stock system low set point is closer to 3400 rpm, dropping below that will get single mode. At this point, the vac and pressure at the TCA is released/vented by the solenoids and TCA slams door shut, which is naturally assisted by pressure in the exh manifold. When I let rpms drop to 3500 still in twin mode in 3rd gear, the pull is still quite good and boost jumps. In 4th the rpm climb after decel is slower, so boost rise in twin mode will be sluggish up to 4k or so.
The usual PFC settings lower the twin on and off rpms, vs stock. This helps transition spike control by getting it done before torque peak, esp with high boost settings. But 3k sounds too low for an on point .... i'd start increasing the low rpm setting (and high if a min delta is needed).
As others said, make sure a slow-when-hot solenoid is not delaying the low point venting for the TCA. Also need to be sure CCV is closing near the y-pipe for single mode.
The usual PFC settings lower the twin on and off rpms, vs stock. This helps transition spike control by getting it done before torque peak, esp with high boost settings. But 3k sounds too low for an on point .... i'd start increasing the low rpm setting (and high if a min delta is needed).
As others said, make sure a slow-when-hot solenoid is not delaying the low point venting for the TCA. Also need to be sure CCV is closing near the y-pipe for single mode.
08-24-04, 09:48 PM
#39
Junior Member
Originally Posted by almost99
You have eliminated any issue other than the way the powerFC operates if the Turbo Control Solenoid indicator is on when the boost takes a while to build and off when it doesn't. This is an output indicator, so the powerFC wants to do what you are complaining about.
Mark
Mark
I going to give the check valves another look and test them with a vac. pump. If that doesn't turn up anything, I'm putting a remote camera in the engine bay and watching the actuators and compare them to a car that operates properly. I'll report back on what I find.
09-22-04, 08:42 PM
#40
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Anyone figure this out?
I am actually having this problem as well. I've posted under another topic a week or so ago that stated after I get into the 2nd turbo and shift I am only getting 2-3 psi. Well I read this and had to go out and do some testing and if I push in the clutch and let it get to below 3k and floor it again my boost is fine. Just letting off the throttle to allow vacuum to build back up doesn't help at all. I have to wait till the rpms get back down.
I am leaning towards a sticky actuator but I must admit I am not sure which one but I do know what its not.
All vacuum/pressure lines are fine. Pressure and vacuum chamber are fine. All solenoids are fine, I've even swapped them out with others and I get same results(Hot ones is the only thing I haven't tested). I have replaced the TCA since the old one did have a problem but it didn't fix this issue. I have tested all other actuators and when the car is cold they work within specs. CRV and ABV are also fine.
Since my TCA is new I am ruling that out.
So does anyone think that either the pre-control, wastegate, or charge control could cause this? If someone can give a good argument for one I'll buy it to test. I'd love to get this system working properly.
I am actually having this problem as well. I've posted under another topic a week or so ago that stated after I get into the 2nd turbo and shift I am only getting 2-3 psi. Well I read this and had to go out and do some testing and if I push in the clutch and let it get to below 3k and floor it again my boost is fine. Just letting off the throttle to allow vacuum to build back up doesn't help at all. I have to wait till the rpms get back down.
I am leaning towards a sticky actuator but I must admit I am not sure which one but I do know what its not.
All vacuum/pressure lines are fine. Pressure and vacuum chamber are fine. All solenoids are fine, I've even swapped them out with others and I get same results(Hot ones is the only thing I haven't tested). I have replaced the TCA since the old one did have a problem but it didn't fix this issue. I have tested all other actuators and when the car is cold they work within specs. CRV and ABV are also fine.
Since my TCA is new I am ruling that out.
So does anyone think that either the pre-control, wastegate, or charge control could cause this? If someone can give a good argument for one I'll buy it to test. I'd love to get this system working properly.
09-23-04, 09:46 AM
#43
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having similar issues myself.
I managed to get the car to run great for about 2 days then its back to running shitty.
I have terrible boost response int he lower rpms and i also have this dreaded transition problem as well. Its almost always something stupid and miniscule.But to find its a bitch indeed.Let me know what you guys find as any clue would be quite helpfull.Im thinking at this point that its probably a leaking vacuum chamber or perhaps a bad check valve.But how would this affect my primary boost?
especially at low rpms? i thought the system was quite simple as far as primary boost is concerned.
I managed to get the car to run great for about 2 days then its back to running shitty.
I have terrible boost response int he lower rpms and i also have this dreaded transition problem as well. Its almost always something stupid and miniscule.But to find its a bitch indeed.Let me know what you guys find as any clue would be quite helpfull.Im thinking at this point that its probably a leaking vacuum chamber or perhaps a bad check valve.But how would this affect my primary boost?
especially at low rpms? i thought the system was quite simple as far as primary boost is concerned.
09-23-04, 10:12 AM
#44
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It's kinda scary when it hardly boosts in lower RPMs and then wildly shoots up towards the top.
When the boost character was normal it was easier to let off on the throttle if the engine starts to knock.
When the boost character was normal it was easier to let off on the throttle if the engine starts to knock.
09-23-04, 07:32 PM
#45
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Update:
Decided to check things while they were hot. So I ran the car for a bit and then dug into it.
All turbo related solenoids checked out ok. Both the 12v test and the ohms.
First actuator I tested is sticky. CCA. Previously I did the kokoko test and the vacuum test and it never appeared to be bad so possibly it being hot made the difference. Problem is I have a funny feeling this isn't the problem but I hope so. At least it will probably fix my jumpy transition. I'll order one tomorrow since its bad and will report back once I get it on. Sometime next week probably.
Pre-control and wastegate actuators appear fine. Didn't check the TCA since its new, or if I am more truthful, I was too lazy to get under the car.
Decided to check things while they were hot. So I ran the car for a bit and then dug into it.
All turbo related solenoids checked out ok. Both the 12v test and the ohms.
First actuator I tested is sticky. CCA. Previously I did the kokoko test and the vacuum test and it never appeared to be bad so possibly it being hot made the difference. Problem is I have a funny feeling this isn't the problem but I hope so. At least it will probably fix my jumpy transition. I'll order one tomorrow since its bad and will report back once I get it on. Sometime next week probably.
Pre-control and wastegate actuators appear fine. Didn't check the TCA since its new, or if I am more truthful, I was too lazy to get under the car.
10-12-04, 12:55 AM
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My comment might be out of place because I might not be sure of what's happening here for many of you but I have great turbo response at all RPM ranges (except in 1st gear, a little slower response). I have manual controllers and bypassed the solenoids all together. I couldn't believe the difference when I made the change. I watch the boost gauge jump almost instantly. I do have the PFC but my boost is mechanical now.
10-12-04, 08:26 AM
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No pics at the moment. But there are two metal tubes coming from the TCA area up behind the airpump. The sections that these are connected to with a hose are right beside and a little under the small coolant hose which is under the pressure chamber.
These are all just in front of and to the right of the wastegate/pre-control soleniods if looking at them from the front of the car.
These are all just in front of and to the right of the wastegate/pre-control soleniods if looking at them from the front of the car.