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This is an interesting one.. I've searched around a bunch and realy would like some opinions.
Some background: I'm a mechanic and I love this car since I found it for $1200 with 70k miles. The interior is trashed, it sat in the sun for about a decade but some little old lady owned it and her son maintained it very well-- it's run synthetic since about 1990. The engine doesn't leak a drop, the trans is dry, and the rear diff is only a little wet at the back. All the syncros feel like new.
It's an '88 and has been pinging at WOT under full boost since I got it 6 months ago. I don't drive it very often and haven't had the time or money to figure out what's up till now.
The pinging is random at WOT, sometimes just one 'ping' per second, sometimes a few pings in a row, sometimes four or five within a second. It fluctuates but is infrequent enough that it isn't blowing my head gaskets yet but I feel like I'm throwing the dice every time I hear it just waiting for a cloud of white smoke to appear in back.
I've never driven a turbocoupe before, so I don't know what to expect.. but 1st gear feels strange, kind of like the engine is falling on itself when it tries to pull real hard. Torque feels a LOT smoother in 2nd and 3rd gear, but that's where I'm hearing the pinging. Do these things pull like freight trains in 1st normally?
I've checked fuel pressure under boost and it's 42 psi all the way to redline.
I found the timing set at 21 degrees, so I dialed it back to 10. That definitely made it better!
I removed the defective stock boost controller and put in an adjustable one, setting it to 13 psi (I'd like it to run at stock levels for diagnosing this and I don't want to push anything yet with the stock fuel pump).
Installed an air/fuel ratio, boost, and oil pressure gauges into the dash.
Replaced TPS, set it to .95 volts, replaced the intercooler plumbing, installed a bosch bypass valve, deoxidized every connector I could put my hands onto.
Took three weeks, but ford just put a new cat/downpipe on as well as wired in a new ignition switch and new switch wiring-- for free! Prior owner didn't have either recall performed. My wiring burned up and left me with no brakes, turn signals, etc. All fixed now.
ECU checks out, only one code: VAM Air Temp sensor out of range. It seems intermittant, and I'm getting mixed information regarding the location of this sensor for a 1988 turbocoupe 5-speed. Some say it's in the VAM itself. Some say it's down in the intake manifold on the drivers side near the brake booster. I've not looked in either location yet. When I DO find it, I can measure it to see what's up. I STFA and found resistance values for what it should be. Can this cause it to ping?
EGR- no idea on it's functionality or cleanliness. Idle fluctuates randomly, but since getting the ignition switch replaced it hasn't done the stutter-stutter-rev pattern that it did prior. Could it be causing pinging at WOT?
IAC- no idea on it's functionality or cleanliness. I pull the plug on it while the engine is running and it dies. It could be causing the odd idle. I have a spare laying around.
ECU Coolant Temp Sensor- no idea on it's functionality. Can test it this weekend. Could it be causing pinging?
Replaced most vacuum lines. Zip tied everything. No boost leaks that I can find.
Today I turned off the premium switch and the pinging went away, though the turbo spools slower and the car is noticeably sluggish. I always use 93 octane, the best I can find. The switch could just be coincidence, as 5 out of 10 times I get into the boost at WOT, it doesn't ping at all. Is it possible that the 10 degree mark isn't 10 anymore, and is closer to 15?
When it pings, the acceleration noticeably decreases, as though the ping sensor is dialing back timing. (This is a good thing)
But I also notice that -sometimes- the A/F gauge drops out of the rich area and does a nose dive into lean during this pinging. I don't know if this is a symptom of the pinging/timing dialed back or the -cause- of the pinging... if it is the cause, that sure is strange since the fuel pressure is good.
It doesn't always do this, sometimes when it's pinging it's all the way over in the rich area and stays there.
So... does the ECU cut out the injectors if it pings bad enough?
The VAM is directly connected to a K&N air filter and it's pretty much just laying in the engine bay, though various wires have it wedged in their pretty tight. I could probably zip tie it down or mock up a bracket to bolt it in place. Are they ultra sensetive to movement?
Things I have scheduled to do this weekend:
replace front rotors, pads, bearings, seals. Got ABS brake rotors from www.brakerotorsrus.com for $50/each, and they look like realy nice pieces with the bearing races already pressed in.
replace rear rotors, pads
install dual 15" electric fans. The stock ones died and I put in a mechanical fan/clutch and while it works alright, it sure does suck every time I take off from a light, sounding like a big truck for a few seconds with the engine straining to spin the fan up until the clutch unlocks.
Replace fuel pump with 170LPH unit. The fuel filter looks new, I might replace it anyways.
Measure VAM voltage output as I move it through the range.
Check PCV functionality
Measure ECT
Toss in some injector cleaner
Plugs and wires were new when I got the car, but I have no idea what the gaps are set to. I don't even know if they're the correct plugs.
Measure barometric pressure sensor output (if there even is one on this car).
If anyone has ever encountered this sort of problem, or has some advice-- I welcome it all!
Keman
Springfield, VA
Some background: I'm a mechanic and I love this car since I found it for $1200 with 70k miles. The interior is trashed, it sat in the sun for about a decade but some little old lady owned it and her son maintained it very well-- it's run synthetic since about 1990. The engine doesn't leak a drop, the trans is dry, and the rear diff is only a little wet at the back. All the syncros feel like new.
It's an '88 and has been pinging at WOT under full boost since I got it 6 months ago. I don't drive it very often and haven't had the time or money to figure out what's up till now.
The pinging is random at WOT, sometimes just one 'ping' per second, sometimes a few pings in a row, sometimes four or five within a second. It fluctuates but is infrequent enough that it isn't blowing my head gaskets yet but I feel like I'm throwing the dice every time I hear it just waiting for a cloud of white smoke to appear in back.
I've never driven a turbocoupe before, so I don't know what to expect.. but 1st gear feels strange, kind of like the engine is falling on itself when it tries to pull real hard. Torque feels a LOT smoother in 2nd and 3rd gear, but that's where I'm hearing the pinging. Do these things pull like freight trains in 1st normally?
I've checked fuel pressure under boost and it's 42 psi all the way to redline.
I found the timing set at 21 degrees, so I dialed it back to 10. That definitely made it better!
I removed the defective stock boost controller and put in an adjustable one, setting it to 13 psi (I'd like it to run at stock levels for diagnosing this and I don't want to push anything yet with the stock fuel pump).
Installed an air/fuel ratio, boost, and oil pressure gauges into the dash.
Replaced TPS, set it to .95 volts, replaced the intercooler plumbing, installed a bosch bypass valve, deoxidized every connector I could put my hands onto.
Took three weeks, but ford just put a new cat/downpipe on as well as wired in a new ignition switch and new switch wiring-- for free! Prior owner didn't have either recall performed. My wiring burned up and left me with no brakes, turn signals, etc. All fixed now.
ECU checks out, only one code: VAM Air Temp sensor out of range. It seems intermittant, and I'm getting mixed information regarding the location of this sensor for a 1988 turbocoupe 5-speed. Some say it's in the VAM itself. Some say it's down in the intake manifold on the drivers side near the brake booster. I've not looked in either location yet. When I DO find it, I can measure it to see what's up. I STFA and found resistance values for what it should be. Can this cause it to ping?
EGR- no idea on it's functionality or cleanliness. Idle fluctuates randomly, but since getting the ignition switch replaced it hasn't done the stutter-stutter-rev pattern that it did prior. Could it be causing pinging at WOT?
IAC- no idea on it's functionality or cleanliness. I pull the plug on it while the engine is running and it dies. It could be causing the odd idle. I have a spare laying around.
ECU Coolant Temp Sensor- no idea on it's functionality. Can test it this weekend. Could it be causing pinging?
Replaced most vacuum lines. Zip tied everything. No boost leaks that I can find.
Today I turned off the premium switch and the pinging went away, though the turbo spools slower and the car is noticeably sluggish. I always use 93 octane, the best I can find. The switch could just be coincidence, as 5 out of 10 times I get into the boost at WOT, it doesn't ping at all. Is it possible that the 10 degree mark isn't 10 anymore, and is closer to 15?
When it pings, the acceleration noticeably decreases, as though the ping sensor is dialing back timing. (This is a good thing)
But I also notice that -sometimes- the A/F gauge drops out of the rich area and does a nose dive into lean during this pinging. I don't know if this is a symptom of the pinging/timing dialed back or the -cause- of the pinging... if it is the cause, that sure is strange since the fuel pressure is good.
It doesn't always do this, sometimes when it's pinging it's all the way over in the rich area and stays there.
So... does the ECU cut out the injectors if it pings bad enough?
The VAM is directly connected to a K&N air filter and it's pretty much just laying in the engine bay, though various wires have it wedged in their pretty tight. I could probably zip tie it down or mock up a bracket to bolt it in place. Are they ultra sensetive to movement?
Things I have scheduled to do this weekend:
replace front rotors, pads, bearings, seals. Got ABS brake rotors from www.brakerotorsrus.com for $50/each, and they look like realy nice pieces with the bearing races already pressed in.
replace rear rotors, pads
install dual 15" electric fans. The stock ones died and I put in a mechanical fan/clutch and while it works alright, it sure does suck every time I take off from a light, sounding like a big truck for a few seconds with the engine straining to spin the fan up until the clutch unlocks.
Replace fuel pump with 170LPH unit. The fuel filter looks new, I might replace it anyways.
Measure VAM voltage output as I move it through the range.
Check PCV functionality
Measure ECT
Toss in some injector cleaner
Plugs and wires were new when I got the car, but I have no idea what the gaps are set to. I don't even know if they're the correct plugs.
Measure barometric pressure sensor output (if there even is one on this car).
If anyone has ever encountered this sort of problem, or has some advice-- I welcome it all!
Keman
Springfield, VA
Eric "Keman" Uratchko
1990 Mustang 5.8 GR-40
1988 Thunderbird Turbocoupe 5sp
2005 Audi S4 Avant MT6
1990 Mustang 5.8 GR-40
1988 Thunderbird Turbocoupe 5sp
2005 Audi S4 Avant MT6