My car still hold back at high rpm?
23 June 2010, 09:53 PM
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My car still hold back at high rpm?
Hi i have had this on going problem with my car for some time now where the car hesitates and hold back at high rpm. Also the car feels a bit laggy. Also when the car is cold if you hit boost the car starts to misfire like its flooded
and if you give it a rev it clears. Now since this i have changed the following parts but still the same?
1 set of coils
3 sets of NGK 7 plus
cam pulleys
cam & crank sensor
Timing belt
and now the igniter
The cars spec is wrx engine with
TD05 16G
Forge motor sport actuator
Front mount intercooler
Lateral 740cc injectors
Simtek ecu mapped by JGM
Greddy boost controller
Any one on here had the same problem of have any clue to fix this on going problem?
and if you give it a rev it clears. Now since this i have changed the following parts but still the same?
1 set of coils
3 sets of NGK 7 plus
cam pulleys
cam & crank sensor
Timing belt
and now the igniter
The cars spec is wrx engine with
TD05 16G
Forge motor sport actuator
Front mount intercooler
Lateral 740cc injectors
Simtek ecu mapped by JGM
Greddy boost controller
Any one on here had the same problem of have any clue to fix this on going problem?
23 June 2010, 10:00 PM
#2
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are you sure the boost controller is set right , what you got both settings set to ??????
did the print off a , fuel print of the dyno to ?
perhaps the map is wrong .
did the print off a , fuel print of the dyno to ?
perhaps the map is wrong .
Last edited by richgreenscooby1; 23 June 2010 at 10:01 PM.
23 June 2010, 10:01 PM
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Did you make sure the gap on the plugs was the specified distance (0.7mm i believe)
I've seen the PFR7B's come out of the box with anything from no gap to about 3mm.
I've seen the PFR7B's come out of the box with anything from no gap to about 3mm.
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23 June 2010, 11:52 PM
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Hi,
It sounds like a maf issue. Simply remove the maf clean it with brake cleaner and refit.
If this does not fix the problem I would suggest you replace it with a new one.
I hope this helps.
It sounds like a maf issue. Simply remove the maf clean it with brake cleaner and refit.
If this does not fix the problem I would suggest you replace it with a new one.
I hope this helps.
24 June 2010, 01:06 AM
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When I mapped it the first time it was on an Apexi PowerFC and the issue was far worse.. it is not a misfire, it is not det, now on the SimTek it is far less obvious and just a dip in the power curve.. previously it was a real restriction at the top (do you have the graphs from the Apexi?)
It's an issue with engine or turbo imho, but all the obvious checks came up with nothing. I wonder if it maybe a valve seat issue and compression at higher rpm is changing.. engine has no untoward noise or obvious issue when listenned to with microphone attached etc..
Simon
It's an issue with engine or turbo imho, but all the obvious checks came up with nothing. I wonder if it maybe a valve seat issue and compression at higher rpm is changing.. engine has no untoward noise or obvious issue when listenned to with microphone attached etc..
Simon
24 June 2010, 01:53 PM
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i have basically the same problem and have basically replace evrything except the whole engine itself. i also have a hunch with jolly green that it could be the valve seat leaking at high rpm but cant confirm unless we open the engine up and check it
24 June 2010, 07:38 PM
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OK today i had a bit of time to kill at work so i changed the PCV breather but still no change i just don't understand as the car idles and runs so nice. On my way home i gave it some stick in first gear and it just held back and felt so flat and started to miss like the engine had flooded so i gave it a couple of
revs and it cleared then i opened it up again in first and it seem to hold back more when there is no load?
Here are the dyno graph from when it was mapped with the Apexi power FC and Z32?
revs and it cleared then i opened it up again in first and it seem to hold back more when there is no load?
Here are the dyno graph from when it was mapped with the Apexi power FC and Z32?
Last edited by greekpeterfromlondon; 24 June 2010 at 08:12 PM.
25 June 2010, 02:30 PM
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If this is a 93-96 car with hydraulic heads then the problem is the hydraulic followers/valvetrain playing up.
The symptoms will be worse with increasing boost (increased loads on the valves themselves) and increasing RPM. You will not see a significant change, if at all in AFR, boost, airflow or det resistance, but feel a very obvious hole in the power band. On the dyno pushing the problem can result in the power dropping 50-60hp in just a few hundred RPM.
The graphs above suggest exactly this problem, and if it's a pre 97 car or has a pre 97 engine, this is for sure your problem.
The only 100% fix IMHO is to move to non hydraulic heads.
The mechanics behind the problem are exhaust back pressure getting behind the exhaust valves, boost pressure on the inlet valves, soft OEM springs and most important of all tired hydraulic followers pumping up and ultimately opening the valves.
The symptoms will be worse with increasing boost (increased loads on the valves themselves) and increasing RPM. You will not see a significant change, if at all in AFR, boost, airflow or det resistance, but feel a very obvious hole in the power band. On the dyno pushing the problem can result in the power dropping 50-60hp in just a few hundred RPM.
The graphs above suggest exactly this problem, and if it's a pre 97 car or has a pre 97 engine, this is for sure your problem.
The only 100% fix IMHO is to move to non hydraulic heads.
The mechanics behind the problem are exhaust back pressure getting behind the exhaust valves, boost pressure on the inlet valves, soft OEM springs and most important of all tired hydraulic followers pumping up and ultimately opening the valves.
25 June 2010, 02:42 PM
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If this is a 93-96 car with hydraulic heads then the problem is the hydraulic followers/valvetrain playing up.
The symptoms will be worse with increasing boost (increased loads on the valves themselves) and increasing RPM. You will not see a significant change, if at all in AFR, boost, airflow or det resistance, but feel a very obvious hole in the power band. On the dyno pushing the problem can result in the power dropping 50-60hp in just a few hundred RPM.
The graphs above suggest exactly this problem, and if it's a pre 97 car or has a pre 97 engine, this is for sure your problem.
The only 100% fix IMHO is to move to non hydraulic heads.
The mechanics behind the problem are exhaust back pressure getting behind the exhaust valves, boost pressure on the inlet valves, soft OEM springs and most important of all tired hydraulic followers pumping up and ultimately opening the valves.
The symptoms will be worse with increasing boost (increased loads on the valves themselves) and increasing RPM. You will not see a significant change, if at all in AFR, boost, airflow or det resistance, but feel a very obvious hole in the power band. On the dyno pushing the problem can result in the power dropping 50-60hp in just a few hundred RPM.
The graphs above suggest exactly this problem, and if it's a pre 97 car or has a pre 97 engine, this is for sure your problem.
The only 100% fix IMHO is to move to non hydraulic heads.
The mechanics behind the problem are exhaust back pressure getting behind the exhaust valves, boost pressure on the inlet valves, soft OEM springs and most important of all tired hydraulic followers pumping up and ultimately opening the valves.
25 June 2010, 02:43 PM
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i ve had this type of problem on wifes jdm o1 bugeye for past 5 years gave up trying to find problem just drive with it now dont know about yours but you can drive through it its flatish about 77 to 90mph then after higher speeds than that, also if you hold it bout 50 to 60 for 4-5seconds in 5th then take your foot of accelerater the cars revs take another 2 to 3 seconds to drop hope you get joy would be interested if u sort it
25 June 2010, 07:51 PM
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I suppose it makes sense now the engine came out of a WRX that was smashed but was left in a farm for a few years so now i need to get in gear and get my new engine ready but first i have to say thanks to Simon JGM for
all you help and good advice and for making a good job of mapping the car even with the issues that the engine has and thanks Paul from Zen for a fantastic write up and diagnoses.
all you help and good advice and for making a good job of mapping the car even with the issues that the engine has and thanks Paul from Zen for a fantastic write up and diagnoses.
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