Low Boost Pattern 8-0-4
09-23-03, 10:29 AM
#1
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Low Boost Pattern 8-0-4
My boost pattern is now 7-8 psi on the primary to 4500 rpm. At the transition the boost drops to 0, and rises again to a maximum of 4 psi to redline from 4500 rpm. Previously, the boost pattern was 11-8-11 psi (when boost was set to 11 psi target with Power FC).
I checked the secondary turbo compressor wheel's radial play. It's not usually high. The turbos are '99 Japan spec purchased new from SR Motorsports (Nov '02). They were installed on the car when the KDR motor was installed @ Rx7 Store (Columbus Oh) January of this year. Both motor and turbos have 9500 miles on them. There is no oil around the turbo housings. There is no oil smoke out of the exhaust, at throttle lift-off when shifting gears @ WOT.
In neutral WOT to redline, the boost gauge reads 0. It should read 3 to 4 psi. This apparently points to a boost leak.
I checked for leaks in the turbo and intake system. All hoses and piping are tight. All clamps are screw-type.
Below are the turbo control system parts I've replaced over the past few months during my diagnosis and repair of a previous secondary turbo problem:
-One way Check Valves (pressure and vacuum chamber, double throttle control)
-Solenoids (Turbo Control Actuator, Precontrol/Wastegate)
-Air Bypass Valve
-Charge Relief Valve
-New Vacuum Chamber
-New Pressure Chamber
-New Turbo Control Actuator
I've had trouble with oil pooling in my vacuum chamber. I still have that problem; I routinely pump out the oil from the vacuum chamber to keep the secondary turbo control system working properly. The oil in the vacuum chamber is still a mystery, and have wondered if my oil injector nozzles are bad (they are the original nozzles 112,000 miles now)?
Checked the C-clips on the precontrol and wastegate rods, and they are mechanically attached. Both rod lengths seem ok; the precontrol and wastegate doors don't seem to be "ajar".
Checked the Turbo Control Actuator C-clip, it's attached, and the rod length is ok.
Checked the Charge Control Actuator, and the CCA rod is pulled in when the motor is running, and releases when the motor is shut off...am not clear on whether this signifies a "good" CCA.
The vacuum hoses are all thick-wall silicone. Upon brief inspection, they all appear to be connected (none are popped off).
I checked the double throttle control actuator, and this appears to work fine. I disconnected the DTCA to release the DTC plates, and the boost pattern remained 8-0-4. If the DTC plates are stuck closed, you can only make 5 psi.
I'm not sure whether the turbos are bad, or if I have another turbo control issue? The main problem is the low boost. I cannot get higher than 8 psi on the primary turbo before transitioning to primary/secondary turbo operation. The primary turbo needs to make MORE than 8 psi for the secondary turbo to come online; my secondary seems to kick in, but only makes 4 psi from the transition rpm to redline.
I have an oil catch can installed on my FD3S. The oil filler neck oil vent nipples, primary turbo oil vent inlet (rat's nest), and PCV nipple (under the UIM) have all been plugged, so all oil venting goes through a modified oil cap, and into a vented/filtered catch bottle. This means the primary turbo doesn't get vented oil from the oil filler neck. The only route the primary turbo gets oil is through the oil feed lines in the turbos.
I have one bottle of CD2 oil seal in the oil mix. I have oil "sweating" from between the rear rotor housing and rear housing. The oil leak is not leaving any puddles, but there is enough oil to leave a residue on the rear rotor housing. The CD2 is not supposed to plug any oil lines. The CD2 is supposed to work with the rubber, so I don't think the CD2 would impact the turbos oiling.
I'm baffled and frustrated.
Comments, suggestions, ideas are welcome.
I checked the secondary turbo compressor wheel's radial play. It's not usually high. The turbos are '99 Japan spec purchased new from SR Motorsports (Nov '02). They were installed on the car when the KDR motor was installed @ Rx7 Store (Columbus Oh) January of this year. Both motor and turbos have 9500 miles on them. There is no oil around the turbo housings. There is no oil smoke out of the exhaust, at throttle lift-off when shifting gears @ WOT.
In neutral WOT to redline, the boost gauge reads 0. It should read 3 to 4 psi. This apparently points to a boost leak.
I checked for leaks in the turbo and intake system. All hoses and piping are tight. All clamps are screw-type.
Below are the turbo control system parts I've replaced over the past few months during my diagnosis and repair of a previous secondary turbo problem:
-One way Check Valves (pressure and vacuum chamber, double throttle control)
-Solenoids (Turbo Control Actuator, Precontrol/Wastegate)
-Air Bypass Valve
-Charge Relief Valve
-New Vacuum Chamber
-New Pressure Chamber
-New Turbo Control Actuator
I've had trouble with oil pooling in my vacuum chamber. I still have that problem; I routinely pump out the oil from the vacuum chamber to keep the secondary turbo control system working properly. The oil in the vacuum chamber is still a mystery, and have wondered if my oil injector nozzles are bad (they are the original nozzles 112,000 miles now)?
Checked the C-clips on the precontrol and wastegate rods, and they are mechanically attached. Both rod lengths seem ok; the precontrol and wastegate doors don't seem to be "ajar".
Checked the Turbo Control Actuator C-clip, it's attached, and the rod length is ok.
Checked the Charge Control Actuator, and the CCA rod is pulled in when the motor is running, and releases when the motor is shut off...am not clear on whether this signifies a "good" CCA.
The vacuum hoses are all thick-wall silicone. Upon brief inspection, they all appear to be connected (none are popped off).
I checked the double throttle control actuator, and this appears to work fine. I disconnected the DTCA to release the DTC plates, and the boost pattern remained 8-0-4. If the DTC plates are stuck closed, you can only make 5 psi.
I'm not sure whether the turbos are bad, or if I have another turbo control issue? The main problem is the low boost. I cannot get higher than 8 psi on the primary turbo before transitioning to primary/secondary turbo operation. The primary turbo needs to make MORE than 8 psi for the secondary turbo to come online; my secondary seems to kick in, but only makes 4 psi from the transition rpm to redline.
I have an oil catch can installed on my FD3S. The oil filler neck oil vent nipples, primary turbo oil vent inlet (rat's nest), and PCV nipple (under the UIM) have all been plugged, so all oil venting goes through a modified oil cap, and into a vented/filtered catch bottle. This means the primary turbo doesn't get vented oil from the oil filler neck. The only route the primary turbo gets oil is through the oil feed lines in the turbos.
I have one bottle of CD2 oil seal in the oil mix. I have oil "sweating" from between the rear rotor housing and rear housing. The oil leak is not leaving any puddles, but there is enough oil to leave a residue on the rear rotor housing. The CD2 is not supposed to plug any oil lines. The CD2 is supposed to work with the rubber, so I don't think the CD2 would impact the turbos oiling.
I'm baffled and frustrated.
Comments, suggestions, ideas are welcome.
Last edited by SleepR1; 09-23-03 at 10:36 AM.
09-23-03, 11:25 AM
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Not sure what your mods are, but judging from what you said about controlling the boost on your PFC, you're probably still running your stock duty control selenoid. Try installing a profec, AVC-R, AV-VCR or maybe even just a home depot MBC to bypass the stock boost control selenoid. You might be pleasantly surprised.
09-23-03, 12:06 PM
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Originally posted by SERIES7
Not sure what your mods are, but judging from what you said about controlling the boost on your PFC, you're probably still running your stock duty control selenoid. Try installing a profec, AVC-R, AV-VCR or maybe even just a home depot MBC to bypass the stock boost control selenoid. You might be pleasantly surprised.
Not sure what your mods are, but judging from what you said about controlling the boost on your PFC, you're probably still running your stock duty control selenoid. Try installing a profec, AVC-R, AV-VCR or maybe even just a home depot MBC to bypass the stock boost control selenoid. You might be pleasantly surprised.
Last edited by SleepR1; 09-23-03 at 12:10 PM.
09-23-03, 12:10 PM
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Actually, I'm not too sure how the profec works, but I've got my AVC-R controlling boost totally independant of my PFC. The AVC-R comes with it's own pressure sensor and boost control selenoid so your stock poot no more workie. It's great to have when it comes to diagnosing boost problems, you know, the process of elimination...
09-23-03, 12:14 PM
#7
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The way I understand it, the wastegate duty cycle solenoid doesn't control boost until you're @ the transition rpm. Boost control below 4500 rpm is done through the precontrol solenoid. It's worth a shot to replace that solenoid pair. I'll put my old one back on, and see. I replaced the old pair thinking it was responsible for my secondary turbo not coming online properly. Thanks, dude! Hey where's that pic of you and that cute g/f?? 
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09-23-03, 12:15 PM
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Originally posted by SleepR1
Oh, no...you're not down too are you, Greg??
Oh, no...you're not down too are you, Greg??
https://www.rx7club.com/forum/showth...hreadid=225390
09-23-03, 12:25 PM
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09-23-03, 01:23 PM
#13
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Have you tried pressure testing your system? A visual inspection many times won't reveal boost leaks - this is hands down the FIRST thing that needs to be done when troubleshooting boost problems.
Plug any air inlets into the motor, and use a pressurized air source that's at 10-15psi to pressurize the intake tract. Listen and feel for air escaping. I've found boost leaks in the most surprising places using this tactic.
Dale
Plug any air inlets into the motor, and use a pressurized air source that's at 10-15psi to pressurize the intake tract. Listen and feel for air escaping. I've found boost leaks in the most surprising places using this tactic.
Dale
09-23-03, 01:48 PM
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Originally posted by SleepR1
The way I understand it, the wastegate duty cycle solenoid doesn't control boost until you're @ the transition rpm. Boost control below 4500 rpm is done through the precontrol solenoid. It's worth a shot to replace that solenoid pair. I'll put my old one back on, and see. I replaced the old pair thinking it was responsible for my secondary turbo not coming online properly. Thanks, dude! Hey where's that pic of you and that cute g/f??
The way I understand it, the wastegate duty cycle solenoid doesn't control boost until you're @ the transition rpm. Boost control below 4500 rpm is done through the precontrol solenoid. It's worth a shot to replace that solenoid pair. I'll put my old one back on, and see. I replaced the old pair thinking it was responsible for my secondary turbo not coming online properly. Thanks, dude! Hey where's that pic of you and that cute g/f??
With an aftermarket boost controller, you will still use the stock pre-control solenoid. You are just replacing the wastegate solenoid action. When running a separate boost controller, set the controller to the boost you want and then make sure the boost setting on the PFC (which will no longer do anything) is higher than what the boost controller is set too. This will prevent the PFC from fuel-cutting on you.
09-23-03, 02:52 PM
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Originally posted by dcfc3s
Have you tried pressure testing your system? A visual inspection many times won't reveal boost leaks - this is hands down the FIRST thing that needs to be done when troubleshooting boost problems.
Plug any air inlets into the motor, and use a pressurized air source that's at 10-15psi to pressurize the intake tract. Listen and feel for air escaping. I've found boost leaks in the most surprising places using this tactic.
Dale
Have you tried pressure testing your system? A visual inspection many times won't reveal boost leaks - this is hands down the FIRST thing that needs to be done when troubleshooting boost problems.
Plug any air inlets into the motor, and use a pressurized air source that's at 10-15psi to pressurize the intake tract. Listen and feel for air escaping. I've found boost leaks in the most surprising places using this tactic.
Dale
09-23-03, 03:13 PM
#16
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Originally posted by SERIES7
Try installing a profec, AVC-R, AV-VCR or maybe even just a home depot MBC to bypass the stock boost control selenoid. You might be pleasantly surprised.
Try installing a profec, AVC-R, AV-VCR or maybe even just a home depot MBC to bypass the stock boost control selenoid. You might be pleasantly surprised.
I thought I saw a pic of you standing next to a cute blond? Maybe it was someone else with the a similar avatar?
09-23-03, 03:54 PM
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sleepr1 before one year i had the same exactly promb i bought from mazda a complete new core, turbos, and all the sol valves! ........after two weeks of searching and having 100miles trying to find at road what is happening i decide to take out my dp [before selling my 10 years love] to see the color inside and guess it was white, i have a faulty omp, cutting fuel at 4500''' the big
mystery was that my stypid stock ecu didnt produse any code' thats my small idea
dimitris
mystery was that my stypid stock ecu didnt produse any code' thats my small idea
dimitris
09-23-03, 04:12 PM
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Dimitris, your oil metering pump was bad, and the ECU was cutting fuel? Why was your downpipe white, and how does that relate to the bad oil metering pump? I'm confused...
09-23-03, 04:48 PM
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SleepR1, the best way to pressurize the intake is with an air compressor - like one you run air tools with. If you don't have one, and don't want to buy one, you can get a tank that holds compressed air that you can fill with air at a gas station (just like filling a tire).
You need an air nipple that goes right to the manifold - best bet is the one that you typically use for a boost gauge. Might need to get a regulator for the air to turn the pressure down to 10-15 psi - running really high pressure will likely just pop stuff off, not a good idea.
Also, for plugging the inlet, I've seen people use empty soda cans - stuff it in the rubber inlet pipe to the turbo, then clamp down. Looks ghetto, but this is for testing purposes.
Saw this trick a long time ago in an Option video from Japan - they were doing it on a 240sx (Silvia). Found a leaky blow-off valve that was bigtime hampering performance.
The OMP is another possibility, but I doubt that would be an issue with the PowerFC, moreso with the stock computer.
Dale
You need an air nipple that goes right to the manifold - best bet is the one that you typically use for a boost gauge. Might need to get a regulator for the air to turn the pressure down to 10-15 psi - running really high pressure will likely just pop stuff off, not a good idea.
Also, for plugging the inlet, I've seen people use empty soda cans - stuff it in the rubber inlet pipe to the turbo, then clamp down. Looks ghetto, but this is for testing purposes
.Saw this trick a long time ago in an Option video from Japan - they were doing it on a 240sx (Silvia). Found a leaky blow-off valve that was bigtime hampering performance.
The OMP is another possibility, but I doubt that would be an issue with the PowerFC, moreso with the stock computer.
Dale
09-23-03, 05:23 PM
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What about an exhaust restriction? Could a clogged high-flow cat affect boost, such that my boost pattern is 8-0-4 psi? What about a leak between the turbo and the motor? Is it easy to snug those bolts down between the turbo assembly and the motor?
09-24-03, 04:10 PM
#22
Manny,
What's the PFC showing in regards to boost? Also what's the duty cycle associated with the 1st turbo since it's controlling the pre-control solenoid, maybe its set wrong and venting to much boost out the CRV from the second turbo.
Just some ideas.
Tim
What's the PFC showing in regards to boost? Also what's the duty cycle associated with the 1st turbo since it's controlling the pre-control solenoid, maybe its set wrong and venting to much boost out the CRV from the second turbo.
Just some ideas.
Tim
09-24-03, 04:24 PM
#23
Originally posted by SleepR1
How is the oil metering pump affecting anything regarding boost??
How is the oil metering pump affecting anything regarding boost??
Ask spoautos on the forum about lim gasket leak symptoms
you could try unbolting the hfc from the downpipe to see if that was the problem. It's just 2 bolts and a gasket and you can leave it attatched to the cb still just leave the dp open enough.
also a little more about the pressurizing the system technique. The way I did mine was I went to a gas station. I parked as far away as I could from the compressor but still having it reach the uim. I took off the place where the boost gauge goes and I had bought an adapter to fit perfectly on that nipple without letting air escape. It was some kit at walmart a small blue package for like 7 bucks that contained the piece I needed. Any way then I took off the air filters on my ntech intake and I put 2 tennis ***** in the plastic intake hoses. Then started putting air in and immediately i heard a leak and then found it with my hand at the back of the y pipe.
I think if you can't get this figured out afterwards then it's time to buy a set of block off plates and do the turbo simplification mod. It will help a great deal in the end and im sure you'll solve your problem in a weekends work.
good luck
-Snook
09-24-03, 08:19 PM
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Snook,
I see now. FWIW, I can redline the engine, so I don't think it's OMP.
RE pressurizing the system...sounds like an idea. I found a loose nut on the CCA air pipe that connects the second turbo to the CCA pipe/Efini Y-pipe. After snugging this nut, there was no change in the boost pattern.
I will check the turbo assembly's attachment bolts to be sure the turbos are securely attached to the exhaust manifold.
The engine torque brace transmit too much vibration/harshness to the motor and accessories, which leads to stuff loosening. I removed the ETB a couple of days ago. It's nice to have the cabin be smooth and (relatively) vibration-free once again.
My strategy is to rule out mechanical causes, and then look at the solenoids, namely the CCA and turbo control solenoids (TCA solenoid--already replaced-- is different from the TC solenoid). CCA and TC solenoids are numbers 2 and 3 on the solenoid rack if you count number 1 solenoid as the one up front.
I see now. FWIW, I can redline the engine, so I don't think it's OMP.
RE pressurizing the system...sounds like an idea. I found a loose nut on the CCA air pipe that connects the second turbo to the CCA pipe/Efini Y-pipe. After snugging this nut, there was no change in the boost pattern.
I will check the turbo assembly's attachment bolts to be sure the turbos are securely attached to the exhaust manifold.
The engine torque brace transmit too much vibration/harshness to the motor and accessories, which leads to stuff loosening. I removed the ETB a couple of days ago. It's nice to have the cabin be smooth and (relatively) vibration-free once again.
My strategy is to rule out mechanical causes, and then look at the solenoids, namely the CCA and turbo control solenoids (TCA solenoid--already replaced-- is different from the TC solenoid). CCA and TC solenoids are numbers 2 and 3 on the solenoid rack if you count number 1 solenoid as the one up front.
Last edited by SleepR1; 09-24-03 at 08:23 PM.
09-24-03, 11:08 PM
#25
I've had it happen a few times where I was possitive I found the boost problem and then went for a drive and no change so that wasn't it. Exciting but it really lets you down after.
Yes the tca solenoid should be attatched to the air control valve on the inside of the lim. The other tc and cca are on the rack as you mentioned and all of those solenoids are interchangeable as long as they have the same number of nipple on them you can just switch the connectors and it becomes that solenoid. Right now I have a feeling you are using all of them but if you do the simplification which rids of all engine bay emissions then you will have 3 I believe extra to play around with.
That's dissapointing to hear about the etb because I've had a couple and always was curious to see if it would make the car feel more solid. If it's going to do that then I'll just forget it I'm fine with how the car feels inside. Once I get a short throw shifter I will be in love. That should have been my first mod but more important things came up....
let us know whats up man
Yes the tca solenoid should be attatched to the air control valve on the inside of the lim. The other tc and cca are on the rack as you mentioned and all of those solenoids are interchangeable as long as they have the same number of nipple on them you can just switch the connectors and it becomes that solenoid. Right now I have a feeling you are using all of them but if you do the simplification which rids of all engine bay emissions then you will have 3 I believe extra to play around with.
That's dissapointing to hear about the etb because I've had a couple and always was curious to see if it would make the car feel more solid. If it's going to do that then I'll just forget it I'm fine with how the car feels inside. Once I get a short throw shifter I will be in love. That should have been my first mod but more important things came up....
let us know whats up man