993 turbo engine problem
08-17-2003, 10:41 PM
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993 turbo engine problem
My problem with the 993turbo is that under hard acceleration in 4th or 5th the car seems to hesitate and cough between about 4000-5000 rpm. I think the ecu is limiting boost. After 5000rpm it clears up and feels ok. What do you think?
There was a thread here before with the same problem. I think that car's problem cleared up itself. Although there was a theory that it was a case of bad gas. Do you think my car is also suffering from bad gas?
BTW my car has an FVD ecu, FVD K24, FVD cams, 102mm p&c, Carillo rods and cat bypass.
PhD, do you have any ideas?
Thanks
JW
'86 930
'96 993tt
There was a thread here before with the same problem. I think that car's problem cleared up itself. Although there was a theory that it was a case of bad gas. Do you think my car is also suffering from bad gas?
BTW my car has an FVD ecu, FVD K24, FVD cams, 102mm p&c, Carillo rods and cat bypass.
PhD, do you have any ideas?
Thanks
JW
'86 930
'96 993tt
08-18-2003, 02:43 PM
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DV: Mine was the car that also had/has this problem. I can still get it sometimes. In my case it only happened in 3rd gear if I floored it at 3000 rpm. It doesn't happen if I shift at or near redline in the previous two gears. Basically it was a case of "Dr. it hurts when I do this" So don't do that!
I quit doing it so I don't see the problem any more.
I quit doing it so I don't see the problem any more.
08-18-2003, 02:56 PM
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Re: 993 turbo engine problem
Originally posted by DV 993tt
My problem with the 993turbo is that under hard acceleration in 4th or 5th the car seems to hesitate and cough between about 4000-5000 rpm. I think the ecu is limiting boost. After 5000rpm it clears up and feels ok. What do you think?
My problem with the 993turbo is that under hard acceleration in 4th or 5th the car seems to hesitate and cough between about 4000-5000 rpm. I think the ecu is limiting boost. After 5000rpm it clears up and feels ok. What do you think?
you mean like this......
Your description accurately matches my power run.
I attributed it to the knock sensor.....
Q
08-18-2003, 07:27 PM
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The first thing I would do is take a OBDII log of the problem. See if anything is showing up in the ECU. The problem I remeber with the FVD mod to the ECU is they shut the engine light down. You may have a DTC and not even know it. The issue you have can be many things ranging from an intake leak to a bad 02 sensor. I would start with some basics then work out toward the other components of the system. Not sure this helps.
08-18-2003, 07:29 PM
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Q, that does look like perhaps you are overboosting a bit and the car is pulling large amounts of timing to protect. What kind of things have you done to the car?
Last edited by PorschePhD; 08-18-2003 at 11:13 PM.
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08-18-2003, 10:41 PM
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Q
That looks like exactly what I am feeling. Have you done anything to remedy this?
PhD
Thanks for the suggestion? I'll take it in to have my mechanic look at the log and go from there.
That looks like exactly what I am feeling. Have you done anything to remedy this?
PhD
Thanks for the suggestion? I'll take it in to have my mechanic look at the log and go from there.
08-18-2003, 10:59 PM
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PorschePhD
NO MODS ! ....the car was standard when this dyno run was done.
I attributed the hiccup to hot ambient temperatures and cr@p australian fuel pulling in the knock sensor.
As you stated ....timing being removed.
I had another 993TT [also standard]
It displayed similar traits....
It was not obvious on the road, unless it was an extremely hot day.
DV 993tt
Hopefully the above has clarified my situation.
Since these dyno runs were done, I have fitted intake, mufflers, hybrid K24's and prog management.
The car is being tuned today
...I will post the resulting dyno sheet tonight.
Lets hope the hiccup is gone.
Q
NO MODS ! ....the car was standard when this dyno run was done.
I attributed the hiccup to hot ambient temperatures and cr@p australian fuel pulling in the knock sensor.
As you stated ....timing being removed.
I had another 993TT [also standard]
It displayed similar traits....
It was not obvious on the road, unless it was an extremely hot day.
DV 993tt
Hopefully the above has clarified my situation.
Since these dyno runs were done, I have fitted intake, mufflers, hybrid K24's and prog management.
The car is being tuned today
...I will post the resulting dyno sheet tonight. Lets hope the hiccup is gone.
Q
08-19-2003, 12:39 PM
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PorschePhD
you started me thinking about the "hiccup" being caused by an overboost situation.
I went back to the dyno logs for the run.
Nope. - wasn't an overboost situation
here is a copy of the log from 4000 rpm - 5000rpm :
On another note, I was at the tuners tonight
The 993TT isn't finished, but all is progressing well
It has started to show some good consistant numbers on the dyno
Will post the sheet when finished.
cheers
Q
you started me thinking about the "hiccup" being caused by an overboost situation.
I went back to the dyno logs for the run.
Nope. - wasn't an overboost situation
here is a copy of the log from 4000 rpm - 5000rpm :
ษอออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออ อป
บ Speed Power Tractive Roller RPM Ignition Temp Air/Fuel Vacuum บ
บ KPH kW N AIR ๘C Petrol (Atmos)บ
ศอออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออ อผ
104 170 5899 4021 0 19.8 11.4 10.29 PSI
106 171 5819 4099 0 19.8 11.4 10.11 PSI
108 174 5803 4176 0 19.8 11.3 10.08 PSI
110 176 5762 4253 0 19.8 11.1 9.96 PSI
112 178 5713 4331 0 19.8 11.2 10.07 PSI
114 179 5660 4408 0 19.8 11.3 10.03 PSI
116 185 5750 4485 0 19.8 11.1 9.81 PSI
118 190 5810 4563 0 19.9 11.0 9.55 PSI
120 195 5857 4640 0 19.9 10.9 9.27 PSI
122 197 5820 4717 0 19.9 10.8 9.06 PSI
124 198 5759 4795 0 19.9 11.8 8.89 PSI
126 198 5669 4872 0 19.9 12.2 8.71 PSI
128 199 5597 4949 0 19.9 12.5 8.53 PSI
130 200 5539 5027 0 19.9 13.1 8.36 PSI
132 200 5461 5104 0 19.9 13.9 8.40 PSI
บ Speed Power Tractive Roller RPM Ignition Temp Air/Fuel Vacuum บ
บ KPH kW N AIR ๘C Petrol (Atmos)บ
ศอออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออออ อผ
104 170 5899 4021 0 19.8 11.4 10.29 PSI
106 171 5819 4099 0 19.8 11.4 10.11 PSI
108 174 5803 4176 0 19.8 11.3 10.08 PSI
110 176 5762 4253 0 19.8 11.1 9.96 PSI
112 178 5713 4331 0 19.8 11.2 10.07 PSI
114 179 5660 4408 0 19.8 11.3 10.03 PSI
116 185 5750 4485 0 19.8 11.1 9.81 PSI
118 190 5810 4563 0 19.9 11.0 9.55 PSI
120 195 5857 4640 0 19.9 10.9 9.27 PSI
122 197 5820 4717 0 19.9 10.8 9.06 PSI
124 198 5759 4795 0 19.9 11.8 8.89 PSI
126 198 5669 4872 0 19.9 12.2 8.71 PSI
128 199 5597 4949 0 19.9 12.5 8.53 PSI
130 200 5539 5027 0 19.9 13.1 8.36 PSI
132 200 5461 5104 0 19.9 13.9 8.40 PSI
On another note, I was at the tuners tonight
The 993TT isn't finished, but all is progressing well
It has started to show some good consistant numbers on the dyno
Will post the sheet when finished.
cheers
Q
