Overboost?
#1
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Overboost?
I am having some trouble with my car.
The car accelerates in second gear until the red line with no problems, but when I try in third the engine cuts just above 4.000 rpm mark. Same in fourth gear.
The car has the stock wastegate with 0.7 spring. Has cat bypass with a FVD diverter valve.
It seems I have a overboost issue. I did change the overboost switch with no improvement. I did rebuid the wastegate with new diaphragm.
I really don´t know where to start...any inputs?
Thanks in advance!
The car accelerates in second gear until the red line with no problems, but when I try in third the engine cuts just above 4.000 rpm mark. Same in fourth gear.
The car has the stock wastegate with 0.7 spring. Has cat bypass with a FVD diverter valve.
It seems I have a overboost issue. I did change the overboost switch with no improvement. I did rebuid the wastegate with new diaphragm.
I really don´t know where to start...any inputs?
Thanks in advance!
#3
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The did check the valve seal and guide, must be work ok.
However I will remove it and check; no many things left to check
Saw good reviews on the 46 Tial...is it worth the upgrade?
However I will remove it and check; no many things left to check
Saw good reviews on the 46 Tial...is it worth the upgrade?
#4
Firstly, having a boost gauge on this cars is a must. I recommend you to install one of them ( I have a zeitronix system with boost, EGT and AFR) just for piece of mind and to keep this important parameter monitored.
Perhaps you have a leak on the pipe that feeds the wastegate resulting on a a higuer than normal boost level.
Perhaps you have a leak on the pipe that feeds the wastegate resulting on a a higuer than normal boost level.
#5
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Firstly, having a boost gauge on this cars is a must. I recommend you to install one of them ( I have a zeitronix system with boost, EGT and AFR) just for piece of mind and to keep this important parameter monitored.
Perhaps you have a leak on the pipe that feeds the wastegate resulting on a a higuer than normal boost level.
Perhaps you have a leak on the pipe that feeds the wastegate resulting on a a higuer than normal boost level.
I am interested on the boost gauge with AFR display.
Do you have more information about this display?
Thank you
#6
I mean the pipe that feeds the WG with presurized air. The one that comes from the intercooler. You can have a damaged/blocked pipe or perhaps the banjo that connects this pipe to the WG is not properly tightened.
Zeitronix info:
http://www.zeitronix.com/Products/zt2/zt2.shtml
I have the ZT-2 + EGT sensor + boost sensor + LCD display. I also fitted the "alarm" system (ZAVT-1) to detect high pressure/low AFR situations. These cars dont have detonation sensors and ignition retarding systems so It's advisable to introduce additional security elements.
Zeitronix info:
http://www.zeitronix.com/Products/zt2/zt2.shtml
I have the ZT-2 + EGT sensor + boost sensor + LCD display. I also fitted the "alarm" system (ZAVT-1) to detect high pressure/low AFR situations. These cars dont have detonation sensors and ignition retarding systems so It's advisable to introduce additional security elements.
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#8
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Ok, I put a mechanical boost gauge and went for a spin. I found out that tge stock digital boost gauge is extremely reliable, matching the mechanical gauge readings.
The maximum reading was 0,7 bars, wich is 10 psi, so I assume the wastegate is working properly.
I was able to reach 6.000 rpm in second gear, but at 3rd and fourth (I did not check in fifth the engine cuts at 4.000 rpm.
Seems an overboost limiter switch issue...at 0.7 bars?
The maximum reading was 0,7 bars, wich is 10 psi, so I assume the wastegate is working properly.
I was able to reach 6.000 rpm in second gear, but at 3rd and fourth (I did not check in fifth the engine cuts at 4.000 rpm.
Seems an overboost limiter switch issue...at 0.7 bars?
#10
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Ok, I put a mechanical boost gauge and went for a spin. I found out that tge stock digital boost gauge is extremely reliable, matching the mechanical gauge readings.
The maximum reading was 0,7 bars, wich is 10 psi, so I assume the wastegate is working properly.
I was able to reach 6.000 rpm in second gear, but at 3rd and fourth (I did not check in fifth the engine cuts at 4.000 rpm.
Seems an overboost limiter switch issue...at 0.7 bars?
The maximum reading was 0,7 bars, wich is 10 psi, so I assume the wastegate is working properly.
I was able to reach 6.000 rpm in second gear, but at 3rd and fourth (I did not check in fifth the engine cuts at 4.000 rpm.
Seems an overboost limiter switch issue...at 0.7 bars?
Found the TSB. Number 9032 9307.
Reads:
Concern: The boost gauge in 1994 911 Turbos will only read 0.7 bar at max boost
General Information The boost pressure for 1994 3.6 liter 911 turbos is .79 to .85 bar. 1994 911 Turbos are equipped with a boost gauge that is only capable of registering 0.7 bar. For technical reasons, the software for the boost pressure gauge was taken from the 3.3 liter 911 Turbo.
Should a 1994 3.6 Liter 911 Turbo have a customer complaint or "car will only reach 0.7 bar boost," the complaint must be verified and boost pressure must be checked before repairs are performed.
If boost pressure is within specifications, no repairs are necessary.
Repair Information: 1994 3.6 Liter Turbo Max boost 0.79 to 0.85 bar 1992 3.3 Liter Turbo Max boost 0.75 to 0.81 bar
Damage code 903210 0002
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For your records this is the info from the TSB for the boost gauge which reads lower than max boost.
Found the TSB. Number 9032 9307.
Reads:
Concern: The boost gauge in 1994 911 Turbos will only read 0.7 bar at max boost
General Information The boost pressure for 1994 3.6 liter 911 turbos is .79 to .85 bar. 1994 911 Turbos are equipped with a boost gauge that is only capable of registering 0.7 bar. For technical reasons, the software for the boost pressure gauge was taken from the 3.3 liter 911 Turbo.
Should a 1994 3.6 Liter 911 Turbo have a customer complaint or "car will only reach 0.7 bar boost," the complaint must be verified and boost pressure must be checked before repairs are performed.
If boost pressure is within specifications, no repairs are necessary.
Repair Information: 1994 3.6 Liter Turbo Max boost 0.79 to 0.85 bar 1992 3.3 Liter Turbo Max boost 0.75 to 0.81 bar
Damage code 903210 0002
Found the TSB. Number 9032 9307.
Reads:
Concern: The boost gauge in 1994 911 Turbos will only read 0.7 bar at max boost
General Information The boost pressure for 1994 3.6 liter 911 turbos is .79 to .85 bar. 1994 911 Turbos are equipped with a boost gauge that is only capable of registering 0.7 bar. For technical reasons, the software for the boost pressure gauge was taken from the 3.3 liter 911 Turbo.
Should a 1994 3.6 Liter 911 Turbo have a customer complaint or "car will only reach 0.7 bar boost," the complaint must be verified and boost pressure must be checked before repairs are performed.
If boost pressure is within specifications, no repairs are necessary.
Repair Information: 1994 3.6 Liter Turbo Max boost 0.79 to 0.85 bar 1992 3.3 Liter Turbo Max boost 0.75 to 0.81 bar
Damage code 903210 0002
Yes, the point is the mechanical gauge (pressure checked) reads 0,7 bars at full boost, so there is no overboosting issues.
#15
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I know you say everything is new but usually that leads to a long mess of looking at other things that aren't the issue. I would start at square one and retrace your steps.