84 944 stumbles at partial throttle more so when cold
08-26-2022 | 03:03 PM
#1
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84 944 stumbles at partial throttle more so when cold
I would like to get the discussion going with this one, so will throw it out and see what thoughts everyone has. I will not give away what we have checked so far initially as I would really like pure input. Here is the problem
very low mile (78,000) original mile one owner 84 944. The problem is that the car when revved even standing still falls on its face. If the car is slowly revved it will be ok, and by the time it gets to higher rpms it is ok. When the engine is hot the problem lessens but is still there. The car really cannot be driven in a normal way because of this. Again if given spirited throttle when starting off the engine falls on its face. What does everyone think please?
very low mile (78,000) original mile one owner 84 944. The problem is that the car when revved even standing still falls on its face. If the car is slowly revved it will be ok, and by the time it gets to higher rpms it is ok. When the engine is hot the problem lessens but is still there. The car really cannot be driven in a normal way because of this. Again if given spirited throttle when starting off the engine falls on its face. What does everyone think please?
08-27-2022 | 09:13 AM
#2
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From: New York & Indiana
I would like to get the discussion going with this one, so will throw it out and see what thoughts everyone has. I will not give away what we have checked so far initially as I would really like pure input. Here is the problem
very low mile (78,000) original mile one owner 84 944. The problem is that the car when revved even standing still falls on its face. If the car is slowly revved it will be ok, and by the time it gets to higher rpms it is ok. When the engine is hot the problem lessens but is still there. The car really cannot be driven in a normal way because of this. Again if given spirited throttle when starting off the engine falls on its face. What does everyone think please?
very low mile (78,000) original mile one owner 84 944. The problem is that the car when revved even standing still falls on its face. If the car is slowly revved it will be ok, and by the time it gets to higher rpms it is ok. When the engine is hot the problem lessens but is still there. The car really cannot be driven in a normal way because of this. Again if given spirited throttle when starting off the engine falls on its face. What does everyone think please?
The symptoms indicate probable high fuel pressure, too much fuel being injected.
The fuel pressure regulator,FPR, fails closed leading to higher fuel pressure than spec.
Consult CG for test procedure.
Another anecdotal indication that is not always present is a fuel vapor smell in the vacuum hose connected to the FPR
Last edited by T&T Racing; 08-27-2022 at 09:16 AM.
08-27-2022 | 12:04 PM
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Thank you for the first two observations. Having an unlimited parts supply here we have done a bunch of things to the car and the problem persists.
We have installed a brand new fuel pressure regulator and the fuel pressure is good. When the problem happens, the pressure rises to 37 lbs
We have installed four NEW injectors
Please if I could have more suggestions
We have installed a brand new fuel pressure regulator and the fuel pressure is good. When the problem happens, the pressure rises to 37 lbs
We have installed four NEW injectors
Please if I could have more suggestions
08-27-2022 | 01:49 PM
#6
Drifting
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From: New York & Indiana
[QUOTE=Dr. 914;18327969]Thank you for the first two observations. Having an unlimited parts supply here we have done a bunch of things to the car and the problem persists.
We have installed a brand new fuel pressure regulator and the fuel pressure is good. When the problem happens, the pressure rises to 37 lbs
We have installed four NEW injectors
Please if I could have more suggestions[/QUOTE
Check Clarks Garage. I would suggest if the pressure rises to 37 psig, then there is a vacuum leak in the vacuum tubing that is preventing the FPR to slightly adjust to lower pressure as the vacuum increases in the intake and is not sensed by the FPR.
We have installed a brand new fuel pressure regulator and the fuel pressure is good. When the problem happens, the pressure rises to 37 lbs
We have installed four NEW injectors
Please if I could have more suggestions[/QUOTE
Check Clarks Garage. I would suggest if the pressure rises to 37 psig, then there is a vacuum leak in the vacuum tubing that is preventing the FPR to slightly adjust to lower pressure as the vacuum increases in the intake and is not sensed by the FPR.
