'02 GT Intermittent problem (Reward for help)
08-19-2009, 10:51 PM
#1
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Join Date: Jul 2003
Location: United States
Posts: 50
'02 GT Intermittent problem (Reward for help)
OK. I’m going to sweeten the deal for anyone who helps me. I’ve got an ongoing problem with my stang and I’m so desperate that I’m willing to send anyone who helps me resolve this problem $50 either by Paypal or by check.
Let me start by specifying everything done to my car and then the symptoms.
I’ve got an ’02 5-Speed SOHC 4.6L. It has the following mods:
MAC Long-Tube headers
MAC Off-Road Pro-Chamber
Flowmaster 40-Series mufflers
Typhoon Intake Manifold
Steeda Dragon Plenum and Throttle Body
MAC Cold-Air Intake with 90mm MAF housing
Steeda Underdrive pulleys
Ford Motorsport 3.73 gears
Walbro 255 LPH fuel pump
Alrighty, onto the problem. I’m going to describe what the car feels like as best as I can. When you begin driving in first gear, immediately, you feel a subtle vibration in the engine, almost exactly the same as you feel when traction control kicks in. If you keep the gas at the same pressure, you feel this vibration throughout all the gears. If you get to a certain point in the RPM range in any gear and you ease off the gas to a minimum, the car feels like it jerks very little and the vibration disappears and it feels normal. It stays normal until you press the gas any harder than you were holding it before. Sometimes, the car will have the same vibration when you’re idling, and other times it won’t. There is no difference in response from the car whether the A/C is on or off. Obviously, this vibration is impacting acceleration a lot and it will take twice the time to get through the RPM range with this problem than it took when the car was driving normally. Sometimes, it will throw a code, but the codes vary so much that there is no rhyme or reason. I’ve gotten a code for lean in either bank and then the next time rich in either bank. Then I’ve gotten a code for a cam sensor but no matter what the code is, once I reset it, it never comes back. The latest was for incorrect reading in the upstream O2 sensors. I played with the EGR recently through my hand-held programmer and I thought it may have been stuck in the open position, but the problem persisted even when I turned the EGR system off and installed a small piece of aluminum between the EGR and plenum to block any possible leaks. Currently, there are no codes. One thing worth mentioning is that I’ve never once gotten a code for a misfire, which is the first thing I thought this could be when it originally started.
The following things were done/installed in effort to fix the problem:
Ford Motorcraft 255 LPH fuel pump and assembly
Ford Motorcraft fuel filter
Ford Motorcraft 19lb injectors
Cleaned/oiled MAC filter and let stand for 24 hours before re-installing
Cleaned the MAF sensor with carb-cleaner followed by electrical contact cleaner
I’ve pulled the wires off each injector and coil one by one but every single one produced the same result, the engine would idle even rougher.
In one final play of desperation, I played with the timing and A/F mixture through my programmer all to no avail.
One more problem I’m having is with the ABS system. A year ago, it started intermittently turning on and off until a few months back it turned off completely and never came back. I should point out that the main problem started happening before the whole ABS problem and the ABS has been off even when the other problem went into remission a few times.
Any input will be greatly appreciated.
Let me start by specifying everything done to my car and then the symptoms.
I’ve got an ’02 5-Speed SOHC 4.6L. It has the following mods:
MAC Long-Tube headers
MAC Off-Road Pro-Chamber
Flowmaster 40-Series mufflers
Typhoon Intake Manifold
Steeda Dragon Plenum and Throttle Body
MAC Cold-Air Intake with 90mm MAF housing
Steeda Underdrive pulleys
Ford Motorsport 3.73 gears
Walbro 255 LPH fuel pump
Alrighty, onto the problem. I’m going to describe what the car feels like as best as I can. When you begin driving in first gear, immediately, you feel a subtle vibration in the engine, almost exactly the same as you feel when traction control kicks in. If you keep the gas at the same pressure, you feel this vibration throughout all the gears. If you get to a certain point in the RPM range in any gear and you ease off the gas to a minimum, the car feels like it jerks very little and the vibration disappears and it feels normal. It stays normal until you press the gas any harder than you were holding it before. Sometimes, the car will have the same vibration when you’re idling, and other times it won’t. There is no difference in response from the car whether the A/C is on or off. Obviously, this vibration is impacting acceleration a lot and it will take twice the time to get through the RPM range with this problem than it took when the car was driving normally. Sometimes, it will throw a code, but the codes vary so much that there is no rhyme or reason. I’ve gotten a code for lean in either bank and then the next time rich in either bank. Then I’ve gotten a code for a cam sensor but no matter what the code is, once I reset it, it never comes back. The latest was for incorrect reading in the upstream O2 sensors. I played with the EGR recently through my hand-held programmer and I thought it may have been stuck in the open position, but the problem persisted even when I turned the EGR system off and installed a small piece of aluminum between the EGR and plenum to block any possible leaks. Currently, there are no codes. One thing worth mentioning is that I’ve never once gotten a code for a misfire, which is the first thing I thought this could be when it originally started.
The following things were done/installed in effort to fix the problem:
Ford Motorcraft 255 LPH fuel pump and assembly
Ford Motorcraft fuel filter
Ford Motorcraft 19lb injectors
Cleaned/oiled MAC filter and let stand for 24 hours before re-installing
Cleaned the MAF sensor with carb-cleaner followed by electrical contact cleaner
I’ve pulled the wires off each injector and coil one by one but every single one produced the same result, the engine would idle even rougher.
In one final play of desperation, I played with the timing and A/F mixture through my programmer all to no avail.
One more problem I’m having is with the ABS system. A year ago, it started intermittently turning on and off until a few months back it turned off completely and never came back. I should point out that the main problem started happening before the whole ABS problem and the ABS has been off even when the other problem went into remission a few times.
Any input will be greatly appreciated.
08-19-2009, 11:08 PM
#2
Join Date: Aug 2009
Location: MI
Posts: 25
Does the car have to be moving in order to have the vibration, or can you reproduce the vibration with the car stationary?
Sorry, I just reread and saw that it happens sometimes while idling. I had a similar sounding problem years ago with my 1990 Cougar XR7 and it ended up being where the drive shaft went into the rear differential bolts had came loose. I don't recall it ever affecting anything at idle. Good luck, because that was my only suggestion.
Sorry, I just reread and saw that it happens sometimes while idling. I had a similar sounding problem years ago with my 1990 Cougar XR7 and it ended up being where the drive shaft went into the rear differential bolts had came loose. I don't recall it ever affecting anything at idle. Good luck, because that was my only suggestion.
Last edited by Redwings; 08-19-2009 at 11:13 PM.
08-19-2009, 11:10 PM
#3
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Thread Starter
Join Date: Jul 2003
Location: United States
Posts: 50
At this time, the vibration happens 90% of the time when the car is moving and about 75% of the time when its stationary. So this would lead me to dismiss any connection with the ABS problem...
08-19-2009, 11:16 PM
#5
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Join Date: Mar 2009
Location: CA
Posts: 1,291
Before I suggest anything, I must say that this is very difficult to diagnose without the car being in front of me; plus, you're describing it as intermittent.
Moving on, my initial feeling was an engine vibration that would occur the same at a specific load and rpm. However, this would NOT be intermittent. It may change in severity, but always be there. If the vibration where to get bad enough- it could through an engine code- usually the knock sensor will report a misfire (P030# code).
This vibration could be caused by the aftermarket pulleys, or a faulty injector. Interestingly though, a bad injector could cause the symptoms you described, but you also stated that they have all been replaced- correct?
Additionally, it could be a driveline vibration. Recently, I had a truck with a bad u-joint that made the vehicle accelerate horribly, and run poorly.
BTW, since you replaced the fuel pump with an aftermarket one, are you sure that the proper pressure is reaching the fuel rails?
Easy things to check are the crank and cam sensors- back probe them if necessary.
For the ABS issue- verify that none of the wheel speed sensors are disconnected or bad.
Moving on, my initial feeling was an engine vibration that would occur the same at a specific load and rpm. However, this would NOT be intermittent. It may change in severity, but always be there. If the vibration where to get bad enough- it could through an engine code- usually the knock sensor will report a misfire (P030# code).
This vibration could be caused by the aftermarket pulleys, or a faulty injector. Interestingly though, a bad injector could cause the symptoms you described, but you also stated that they have all been replaced- correct?
Additionally, it could be a driveline vibration. Recently, I had a truck with a bad u-joint that made the vehicle accelerate horribly, and run poorly.
BTW, since you replaced the fuel pump with an aftermarket one, are you sure that the proper pressure is reaching the fuel rails?
Easy things to check are the crank and cam sensors- back probe them if necessary.
For the ABS issue- verify that none of the wheel speed sensors are disconnected or bad.
Last edited by socalwrench; 08-19-2009 at 11:18 PM.
08-20-2009, 12:27 AM
#6
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Join Date: Jul 2003
Location: United States
Posts: 50
As far as compression, I contacted my mechanic friend and he's going to be bringing me the tool/gauge to check it.
Responding to socalwrench, I forgot to emphesize that the best way to describe this vibration is what the car feels like when it's misfiring. The only reason I didn't say that is that the car has never in its life thrown a code for that. Also, the car worked for 3 years with the Walbro 255 pump so thinking this could be causing the vibration, I installed the new Ford one but the symptoms didn't change one bit which leads me to believe that fuel pressure most likely doesn't have anything to do with it.
I'm almost positive its not a driveline issue since when the vibration is happening, its happening exactly the same at idle, low speeds, high speeds, low RPMs and high RPMs.
I'm trying to fix this car up so I can sell it to a friend that's already waiting for it so I'm trying to minimize the costs so I'm having my mechanic friend bring me tools. I'll make sure to ask him for a fuel pressure gauge and I'll check the pressure at the rail.
BTW. I have an SCT Flash Tuner which has capability to log the car's data. If I were to capture one of these logs, could I actually read anything from it?
Responding to socalwrench, I forgot to emphesize that the best way to describe this vibration is what the car feels like when it's misfiring. The only reason I didn't say that is that the car has never in its life thrown a code for that. Also, the car worked for 3 years with the Walbro 255 pump so thinking this could be causing the vibration, I installed the new Ford one but the symptoms didn't change one bit which leads me to believe that fuel pressure most likely doesn't have anything to do with it.
I'm almost positive its not a driveline issue since when the vibration is happening, its happening exactly the same at idle, low speeds, high speeds, low RPMs and high RPMs.
I'm trying to fix this car up so I can sell it to a friend that's already waiting for it so I'm trying to minimize the costs so I'm having my mechanic friend bring me tools. I'll make sure to ask him for a fuel pressure gauge and I'll check the pressure at the rail.
BTW. I have an SCT Flash Tuner which has capability to log the car's data. If I were to capture one of these logs, could I actually read anything from it?
08-20-2009, 09:22 PM
#7
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Thread Starter
Join Date: Jul 2003
Location: United States
Posts: 50
OK. I've done a lot of work today. I rented a compression tester but before I got to use it, I noticed some coolant build up on top of the block that wasn't there before. I checked the level and it seems like it was little below the norm. So I found a small leak around the thermostat housing where the upper hose brings in the coolant. So I followed it and found small amounts of coolant in all four right side spark plug holes. Took out the spark plugs, cleaned the coils, replaced all 4 spark plugs and now the car is behaving a lot better. At idle and low RPMs, there is absolutely no vibration. Once you put the gas down, you feel the same vibration but its waaaaay down from what it was before.
I pulled the left side plugs and they seemed brand new (they have less than 10k miles on them) but I'm going to replace them tomorrow anyway.
I pulled the left side plugs and they seemed brand new (they have less than 10k miles on them) but I'm going to replace them tomorrow anyway.
08-20-2009, 11:35 PM
#8
4th Gear Member
Join Date: Mar 2009
Location: CA
Posts: 1,291
So, it is an engine vibration then- caused by the imbalance of power between cylinders.
The coolant near the coils and/or plugs concerns me though. Was the coolant just around the top of the plugs or was it actually inside the cylinder? Could be a blown head gasket.
As far as datalogging goes- I would run a cylinder balance test. I know that the Ford IDS has this feature, but I am not sure about the SCT tuner.
The coolant near the coils and/or plugs concerns me though. Was the coolant just around the top of the plugs or was it actually inside the cylinder? Could be a blown head gasket.
As far as datalogging goes- I would run a cylinder balance test. I know that the Ford IDS has this feature, but I am not sure about the SCT tuner.
08-21-2009, 11:04 AM
#9
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Thread Starter
Join Date: Jul 2003
Location: United States
Posts: 50
So, it is an engine vibration then- caused by the imbalance of power between cylinders.
The coolant near the coils and/or plugs concerns me though. Was the coolant just around the top of the plugs or was it actually inside the cylinder? Could be a blown head gasket.
As far as datalogging goes- I would run a cylinder balance test. I know that the Ford IDS has this feature, but I am not sure about the SCT tuner.
The coolant near the coils and/or plugs concerns me though. Was the coolant just around the top of the plugs or was it actually inside the cylinder? Could be a blown head gasket.
As far as datalogging goes- I would run a cylinder balance test. I know that the Ford IDS has this feature, but I am not sure about the SCT tuner.
08-21-2009, 10:48 PM
#10
4th Gear Member
Join Date: Mar 2009
Location: CA
Posts: 1,291
Sounds like you figured it out. Without pictures, I can't tell how much coolant was seeping into the plug holes- perhaps grounding out the connection between the coil and spark plug?
Are there any black marks on the valve covers? down the tubes?
Are there any black marks on the valve covers? down the tubes?