Low boost
05-23-01, 08:20 AM
#1
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Low boost
Hey everyone,
I've been having boost problems for a while now and haven't been able to figure it out. I have a '93 touring with 37k miles. Normally, my boost will be 10-6-8. So it appears my primary boost is fine. However, every now and then (today on the way to work for example), my boost pattern drops to 8-4-6. Any ideas on what I should check for? I'm thinking it might be a clogged precat (I'm getting a downpipe one of these days!). I'm also curious as to why the boost isn't consistent. Why is it 10-6-8 most of the time, but 8-4-6 other times?
Thanks in advance!
Matt
------------------
'93 black/tan touring
I've been having boost problems for a while now and haven't been able to figure it out. I have a '93 touring with 37k miles. Normally, my boost will be 10-6-8. So it appears my primary boost is fine. However, every now and then (today on the way to work for example), my boost pattern drops to 8-4-6. Any ideas on what I should check for? I'm thinking it might be a clogged precat (I'm getting a downpipe one of these days!). I'm also curious as to why the boost isn't consistent. Why is it 10-6-8 most of the time, but 8-4-6 other times?
Thanks in advance!
Matt
------------------
'93 black/tan touring
05-23-01, 07:20 PM
#2
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Thats what mine is doing!!!!!!!!!!!!
I put a down pipe on and it did not fix it. I did the sillacone vaccuum lines still not fixed. Have it narrowed down to a selanoid, will find out real soon.Ive tried everything. At leat I know im not crazy now that I know mine is not the only one having this boost problem. What happens when you shift fast, do you get like 2 pounds of boost sometimes?
I put a down pipe on and it did not fix it. I did the sillacone vaccuum lines still not fixed. Have it narrowed down to a selanoid, will find out real soon.Ive tried everything. At leat I know im not crazy now that I know mine is not the only one having this boost problem. What happens when you shift fast, do you get like 2 pounds of boost sometimes?
05-23-01, 10:16 PM
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Yeah, I've noticed that too. It doesn't always happen, but sometimes when I just floor it and go through the gears quickly the boost is real low. Maybe not 2, but like 4. It will climb very slowly to like 6 or 7.
The thing that bugs me is that it is so inconsistent. Hard to narrow it down. Anyway, I also have the silicon hoses on my car, so I doubt it is one of them. Let me know how things go with the selanoid.
The thing that bugs me is that it is so inconsistent. Hard to narrow it down. Anyway, I also have the silicon hoses on my car, so I doubt it is one of them. Let me know how things go with the selanoid.
05-24-01, 09:00 AM
#4
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the really low boost you guys are talking about when you switch gears, etc. That is normal, and will disappear when you get the right boost pattern. I fyou are getting 10 and 8 sometimes on primary, it could only be a Primary leak from main tubing or a leaking actuator, like the bov. the slow creep to high 6 or 7, is common when scondaries are't wokring properly. I will tell the the key areas to look at. Obviously primary tubing & ducting. charge control,WG, TPC, and TC, and BOV systems(actuators, selenoids, hoseing for all the aforementioned) , pressure tank and vacuum tank storage abilities.
Check all that and you will find your problem. DOn't forget to check for falty actuators, My problem was in part due to a leaking TC actuator, not from loose hoses but from pierce diaphram.
Anyway, just thought I would throw some ideas at you guys.
Check all that and you will find your problem. DOn't forget to check for falty actuators, My problem was in part due to a leaking TC actuator, not from loose hoses but from pierce diaphram.
Anyway, just thought I would throw some ideas at you guys.
05-25-01, 02:35 PM
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Find a reputable rotary mechanic and go non-sequential. It eliminates all the vacuum lines and solenoids, cleans up the engine bay, and have no switch-over. The stock set-up is so complicated and they ALWAYS fail at sometime or another. They are amazing - if they're working that is. Your problem sounds like a solenoid. A lot of people are doing this nowadays because of the reliability issue with FD stock turbos and are loving it. You lose a hair of low end but it rips from 3000 rpm up with more consistency and power. It works like a small single turbo without spending $2000 or more. it only costs $150-200 for labor. Think about it.
------------------
Barry
93 RX7 TT
Greddy Intake w/ heat shield
M2 medium Intercooler
Unorthodox Underdrive Pulley
Apexi N1 catback exhaust
SS downpipe
Random Technologies Hi-Flo Cat
Non-sequential turbos
New Mazda engine blueprinted
with all reliability mods (KD Rotary)
Street Ported engine (KD Rotary)
Fluidyne Radiator
Silicone vacuum hoses
ACT Heavy Duty Clutch
SR Motorsports #9.5 flywheel
Apexi Power FC tuned by KD Rotary
SR Motorsports Fuel Pump
AST Eliminated
Pettit front sway bar
Greddy turbo timer
Autometer boost guage
Redline Oil in trans and rear
18 inch ICW chrome racing wheels
Warrior wing
------------------
Barry
93 RX7 TT
Greddy Intake w/ heat shield
M2 medium Intercooler
Unorthodox Underdrive Pulley
Apexi N1 catback exhaust
SS downpipe
Random Technologies Hi-Flo Cat
Non-sequential turbos
New Mazda engine blueprinted
with all reliability mods (KD Rotary)
Street Ported engine (KD Rotary)
Fluidyne Radiator
Silicone vacuum hoses
ACT Heavy Duty Clutch
SR Motorsports #9.5 flywheel
Apexi Power FC tuned by KD Rotary
SR Motorsports Fuel Pump
AST Eliminated
Pettit front sway bar
Greddy turbo timer
Autometer boost guage
Redline Oil in trans and rear
18 inch ICW chrome racing wheels
Warrior wing
05-26-01, 12:28 AM
#7
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I have the same problem. My car was 10-8-10 and all the sudden it dropped to 10-5-7, sometimes 10-5-8. I've been through all the hoses and found nothing. I'll be spending time on it this weekend. Please let me know if you find your problem and I'll do the same.
By the way, when I first got my car I had a similar boost problem and found that the wastgate and turbo pre control wiring harnesses were on backwards. Common problem that dealers didn't hook them back up correctly after fixing a recall or something. The white dots have to match. These are under the pressure chamber. I know this is not my current problem but it may be yours if the problem isn't new.
By the way, when I first got my car I had a similar boost problem and found that the wastgate and turbo pre control wiring harnesses were on backwards. Common problem that dealers didn't hook them back up correctly after fixing a recall or something. The white dots have to match. These are under the pressure chamber. I know this is not my current problem but it may be yours if the problem isn't new.
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05-29-01, 06:23 PM
#8
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Just wondering if anyone solved their problems. My primary boost has been fine lately (I tightened the clamps on the y-pipe hose, they were a little loose), but secondary is still low.
On a side note, I tried to take off my extension manifold to check out some hoses and also to replace a sensor. Couldn't quite get it off. Do I have to disconnect some hoses to do this? They are ty-wrapped, so it is kind of a pain.
On a side note, I tried to take off my extension manifold to check out some hoses and also to replace a sensor. Couldn't quite get it off. Do I have to disconnect some hoses to do this? They are ty-wrapped, so it is kind of a pain.
09-04-01, 11:34 PM
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It's been a while. Has anyone found a solution to this? I haven't worked on it much, mainly because the car was my only car until a few days ago. Didn't want to risk screwing something up without any backup transportation. But I'm going to start looking into it again soon.
09-05-01, 03:00 AM
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My advice is to lean toward what KZ1 is saying, test the control system and look for the basics.
My additional advice:
1. Look for loose hoses and couplers.
a. The Y-Pipe hoses (the 1" hoses should not turn")
b. Tighten hose clamps on all the couplers.
c. Test drive.
2. Look at the control system
****Highly recommend getting the Sop Manual*****
a. Replace vacuum lines if you haven't already (all of them!)but first see note below step 2-f
b. Test drive. If not cured, go to the next test.
c. Cut to the chase. Test the Turbo Control Actuator (TCA) by applying manual pressure and vacuum to the two metal tubes that shoot straight up between the coolant filler neck and alternator. Look under the car for movement of the Turbo Control when you release the pressure or vacuum. The rod should stay fully retracted for as long as there is pressure or vacuum present. No exceptions! If good then go to step "d" but if not, then try hooking up your vacuum pump directly to the TCA to bypass the metal tubes and hoses. If still bad, replace TCA.
d. Test to see that pressure holds in the black plastic pressure chamber next to the upper intake manifold by removing one of the two hose and tapping directly into the chamber leaving one of the hoses still attached and add pressure. Trade the leftover hose out with the one still attached to the chamber and test again. There should be no pressure loss with either hose still attached.
If there is a loss of pressure while one hose is attached and not the other then you can narrow the pressure loss to the hose that was leaking and then further determine if it is a check valve, or a leaking solenoid or hose.
e. Do the same test on the vacuum chamber found next to the power steering. There should be no vacuum loss with the tank hooked up directly to the vacuum pump only. Note: The tank will take a few pumps to remove the air in it. Test
the hose that was attached to the chamber that leads to the solenoid rack by applying vacuum to it. There should be no loss of vacuum. If so, then there is a possible bad check valve, hose, or solenoid leak. Test the check valve first and if good then move on to test f.
f. The vacuum chamber is shared by the Turbo Control Actuator (TCA) solenoid, Charge Control Actuator (CCA) & solenoid, and the Charge Relief Valve (CRV).
A quick end-of-the-line test for leaks with the CCA is to pull the vacuum line off the CCA and hook it to a vacuum tester and then turn the car on. You should see vacuum around 15 to 22 inches. Leaving the tester connected, turn the car off but leave the key on "run". You should see vacuum stuck between the tester and the vacuum tank via the solenoid. There should be no vacuum
loss until the key is off. The Charge Relief Solenoid is similar in testing with the exception that there should be vacuum held at the CRV even while the car is off. If you see vacuum loss here then you have either a bad hose connection between the CRV
and solenoid, a leaking solenoid, or a leaking vacuum side hose between the CCR Solenoid and CRV Solenoid. As for the TCA vacuum solenoid, there should be no vacuum loss when you hook your vacuum pump to the opposing metal tubes that we used in test “C”. Simply pump out the air in either hose and look for any vacuum loss. If there is a loss in vacuum then you either have a bad hose connection to the respective solenoid or you have a leaking solenoid. Repair hose or replace solenoids as necessary.
Note: Remember, if you have access to any of the solenoids, you should test the solenoids for vacuum loss and switching capabilities by applying 12 volts directly to the switches while vacuum is present. There should be no loss of vacuum or pressure between the “L” like nipples on the solenoid when there is no voltage. There should be flow between the nipple pointing up, and the metal nipple pointing to the rear of the solenoid when there is no voltage present and no flow when voltage is. Replace the solenoids if defective.
g. Repeat step 1.
Why bother? Because the control system is the number one suspect for improper secondary boost. Some people have posted on the possibilities of cross interference between the signals of both the wastegate solenoid and the prespool solenoid, and perhaps this is an avenue to be further looked at, but the prime problem with these cars can be generalized as poor control management. Too many switches goofing around and too many hoses popping off. To find the cure of problem you must methodically eliminate every possibility. With these cars there are several, and you will only be doing yourself a favor by carefully eliminating each one, one by one.
Or you could pay someone else who knows what they are doing to do it for you. Ughh!
My additional advice:
1. Look for loose hoses and couplers.
a. The Y-Pipe hoses (the 1" hoses should not turn")
b. Tighten hose clamps on all the couplers.
c. Test drive.
2. Look at the control system
****Highly recommend getting the Sop Manual*****
a. Replace vacuum lines if you haven't already (all of them!)but first see note below step 2-f
b. Test drive. If not cured, go to the next test.
c. Cut to the chase. Test the Turbo Control Actuator (TCA) by applying manual pressure and vacuum to the two metal tubes that shoot straight up between the coolant filler neck and alternator. Look under the car for movement of the Turbo Control when you release the pressure or vacuum. The rod should stay fully retracted for as long as there is pressure or vacuum present. No exceptions! If good then go to step "d" but if not, then try hooking up your vacuum pump directly to the TCA to bypass the metal tubes and hoses. If still bad, replace TCA.
d. Test to see that pressure holds in the black plastic pressure chamber next to the upper intake manifold by removing one of the two hose and tapping directly into the chamber leaving one of the hoses still attached and add pressure. Trade the leftover hose out with the one still attached to the chamber and test again. There should be no pressure loss with either hose still attached.
If there is a loss of pressure while one hose is attached and not the other then you can narrow the pressure loss to the hose that was leaking and then further determine if it is a check valve, or a leaking solenoid or hose.
e. Do the same test on the vacuum chamber found next to the power steering. There should be no vacuum loss with the tank hooked up directly to the vacuum pump only. Note: The tank will take a few pumps to remove the air in it. Test
the hose that was attached to the chamber that leads to the solenoid rack by applying vacuum to it. There should be no loss of vacuum. If so, then there is a possible bad check valve, hose, or solenoid leak. Test the check valve first and if good then move on to test f.
f. The vacuum chamber is shared by the Turbo Control Actuator (TCA) solenoid, Charge Control Actuator (CCA) & solenoid, and the Charge Relief Valve (CRV).
A quick end-of-the-line test for leaks with the CCA is to pull the vacuum line off the CCA and hook it to a vacuum tester and then turn the car on. You should see vacuum around 15 to 22 inches. Leaving the tester connected, turn the car off but leave the key on "run". You should see vacuum stuck between the tester and the vacuum tank via the solenoid. There should be no vacuum
loss until the key is off. The Charge Relief Solenoid is similar in testing with the exception that there should be vacuum held at the CRV even while the car is off. If you see vacuum loss here then you have either a bad hose connection between the CRV
and solenoid, a leaking solenoid, or a leaking vacuum side hose between the CCR Solenoid and CRV Solenoid. As for the TCA vacuum solenoid, there should be no vacuum loss when you hook your vacuum pump to the opposing metal tubes that we used in test “C”. Simply pump out the air in either hose and look for any vacuum loss. If there is a loss in vacuum then you either have a bad hose connection to the respective solenoid or you have a leaking solenoid. Repair hose or replace solenoids as necessary.
Note: Remember, if you have access to any of the solenoids, you should test the solenoids for vacuum loss and switching capabilities by applying 12 volts directly to the switches while vacuum is present. There should be no loss of vacuum or pressure between the “L” like nipples on the solenoid when there is no voltage. There should be flow between the nipple pointing up, and the metal nipple pointing to the rear of the solenoid when there is no voltage present and no flow when voltage is. Replace the solenoids if defective.
g. Repeat step 1.
Why bother? Because the control system is the number one suspect for improper secondary boost. Some people have posted on the possibilities of cross interference between the signals of both the wastegate solenoid and the prespool solenoid, and perhaps this is an avenue to be further looked at, but the prime problem with these cars can be generalized as poor control management. Too many switches goofing around and too many hoses popping off. To find the cure of problem you must methodically eliminate every possibility. With these cars there are several, and you will only be doing yourself a favor by carefully eliminating each one, one by one.
Or you could pay someone else who knows what they are doing to do it for you. Ughh!
Last edited by KZ1; 09-06-01 at 06:50 AM.
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