North American Turbocoupe Organization



Pinging @ Premium, 10 BTDC. Strange... (Long, but please read)
Keman Offline
Member
#1
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
Eric "Keman" Uratchko
1990 Mustang 5.8 GR-40
1988 Thunderbird Turbocoupe 5sp
2005 Audi S4 Avant MT6
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sicsiksix Offline
Member
#2
I'm by no means an expert by any standard, but did you set the timing with the SPOUT unplugged? I know with the plug in you will be in the high 20's for timing. Also have you checked your cam timing? what about the cap and rotor (although I'm pretty sure this would cause a misfire if bad no pinging, always good to check/replace them).
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grey88smokin Offline
Posting Freak
#3
First get the basic tune up first. Motorcraft plugs,cap,rotor,PCV and uatolight 764's.
Timing is a big factor and a couple of degrees will make a huge difference. Make sure spout is out.
If your going lean at WOT and full boost....its gonna ping because its not getting the fuel it needs for combustion. Maby its a bad O2 ? If that doesn't do it I would run the fuel system diagnostics. Could be the fuel pump or FPR are taking a dump and begging to be upgraded.
Just go with the walboro 255HP pump and never wory about it again.
84 SVO 1C
08 MKZ
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Pete D Offline
Administrator
#4
Timing needs to be set w/ the spout out as mentioned and should be 10* for now. It should then advance about 1-20* whenyou plug the spout back in. The spout is a dark square plug hanging down in the wiring harness to the Dist.

Since you had the cat changed, we can rule that out. Sounds like a fuel pressure problem as pressure should go up 1 psi for each psi of boost. If yours is staying constant, even at full boost then your running very lean under boost and it would ping.
It could be the pump or the regulator. Go through the fuel system diagnostics to determine what. http://www.turbotbird.com/techinfo/Fuel_...ostics.htm
If it's the pump, get back to us as there are better choices than a stock pump at less $$.

Quote: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.

Supports what I said above about a fuel pressure problem.

There are 2 air temp sensores in the 87-88. One is the VAT (vane air temp) located inside the VAM. The other is the ACT (air charge temp) located on the backside of the lower intake. It's the lower one of the two back there that point toward the fire wall. the upper one is the knock sensor - make sure it's plugged in for now. For more info see: http://www.turbotbird.com/FAQpage/engine.jpg

The EGR can cause light load pinging if stuck open. In this case it probably not the issue. It would be a good idea to clean it and check it's functioning. Does yours have a little black/green check valve in the vacuum line close to the valve on the upper intake?. That is a sign that the EGR recall was performed. If not you may want to get that done. http://www.turbotbird.com/FAQpage/FAQpag...20Cleaning: http://www.turbotbird.com/FAQpage/FAQpag...all%20Info:

IAC is an air bypass around the throttle plate that the EEC uses to maintain idle. It can also function as a dashpot during decel and to kick idle up slightley when the AC is on or during heavy alternator loads. They sometimes get carbonded up inside and get sticky. Remove it and spray out w/ carb or brake cleaner.

The ECU will cut timing if the KS sensor tells it there is knock (detonation) the KS has to be plugged in to function.

It would be a good idea to fab a bracket for the VAM. It could be somewhat vibration sensitive and you don't want it wearing the insulation off wires.

Thanks for the tip on where to buy brake rotors. Most places want a whole lot more than that.

The turbo PCV are somewhat unique. Remove it, hold it straight up and down. big end down. Try to blow through the small end. If it passes ANY air at all it's bad. Replace with ONLY THE FORD PART. Ford P/N: E5ZZ-6A666-A (this is the correct p/n, 5/13/02) The Motorcraft box will also have EV-127-A on it

Tuneup
We reccommend the stock Motorcraft replacement wires, Motorcraft: WR-4011-C
These things are real tempermental about wires, stick with the tried and true.
We also recommend Autolite copper 764s or Motorcraft AWSF32-C or NKG # 2238 plugs. Gap them between 0.030 and 0.032"

Use a good grade of cap and rotor

You would need an osicillascope (sp) to measure baro output. It generates frequency, not voltage as an output. If you didn't get a code for it, it's probably OK


Don't worry about the 02 sensor until you get the fuel issue resolved and a good tuneup. Those are the basics (tuneup) and the known problems (fuel pressure)
Pete Dunham


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Joe F Offline
Posting Freak
#5
Quote: I've checked fuel pressure under boost and it's 42 psi all the way to redline.

This could be a part of your problem. Fuel pressure should be 39psi with the vacuum line removed from the regulator and should increase 1psi for every psi of boost pressure with the line on. So with 10psi boost, fuel pressure should be 49psi, and so on.

Good articles on fuel pump and fuel system diagnosis in the FAQ's.

Also, the VAM air temp sensor is in the VAM itself; the one on the side of the lower intake is the ACT (air charge temperature) sensor and AFAIK is only present on 87's & 88's.

HTH.

EDIT: Dang, Pete, you beat me! [Image: biggrin.gif]

------------------
Joe F.
JR's Aerie - Our 3 TC's

[This message has been edited by JoeCool (edited 08-11-2005).]
JR's Place - My '87 Turbocoupe
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TCKen Offline
Member
#6
42 pounds of fuel pressure is inadequate! Base should be 39 pounds at idle with the fuel regulator's vacuum hose disconnected, with 1 pound of fuel pressure added for each pound of boost (15 pounds of boost = (pause) 54 pounds of fuel pressure (sorry for the pause - had to find a calculator to add 39 + 15 [Image: redface.gif]). Possibly needs a new fuel pump/regulator - look at the Fuel System Diagnostics in the Tech Articles section.

Damn - Pete and Joe beat me to the mouse!

------------------
88TC, Black/Raven, Gillis valve, K&N cone on VAM, MSD ignition box, coil, and plug wires, Hurst Mustang T5 shifter, 2 1/2" cat-back duals, trunk battery with disconnect, CHE rear control arms.

[This message has been edited by TCKen (edited 08-11-2005).]
88TC, Black/Raven, FMIC, 130 amp alternator, MSD ignition, 40Bob manifold with 3" downpipe and Magnaflow 2 1/2" duals, trunk battery with disconnect, CHE rear control arms, Koni Sport shocks, MM front coil-overs and caster/camber plates.
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Jeff K Offline
Administrator
#7
You have a fuel pressure problem if FP stays at 42 psi under boost. Press should be 39 psi + boost. i.e., if base fuel press is 39 psi, and boost is 15 psi, FP should be 54 psi. Does fuel pressure drop under high vacuum conditions, like idle and decel? If it doesnt, is the FPR vac line connected and not leaking?

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 23 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 04 Taurus Duratec (wifes car) // 91 Topaz (daughters first car)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Keman Offline
Member
#8
Thanks a lot for the swift response.

Quote:Originally posted by Pete D:
Timing needs to be set w/ the spout out as mentioned and should be 10* for now. It should then advance about 1-20* whenyou plug the spout back in. The spout is a dark square plug hanging down in the wiring harness to the Dist.

The spout was definitely pulled when I set the timing, and I did remember to put it back on. It sure is strange that it was set to 21 degrees BTDC. I'm going to have to re-check it to see what I put it to. Do the timing marks ever spin on the balancers?

Quote:Since you had the cat changed, we can rule that out. Sounds like a fuel pressure problem as pressure should go up 1 psi for each psi of boost. If yours is staying constant, even at full boost then your running very lean under boost and it would ping.

Whoops. I missed that part. I guess I should be seeing up to 50# of fuel. Looks like the fuel pump isn't matching the demand of the flow when the regulator tries to dial up the pressure. I've got an adjustable regulator laying around, it's an Accel unit. It was cheap- should I put it on? The regulator on it right now is a brand new one from the parts store, but isn't adjustable.

Quote:It could be the pump or the regulator. Go through the fuel system diagnostics to determine what. http://www.turbotbird.com/techinfo/Fuel_...ostics.htm
If it's the pump, get back to us as there are better choices than a stock pump at less $$.

The pump I've got laying around came out of a friends mustang. He used it for a few months and it's been kept in a dry place. It either says 170 or 190LHP on the outside, I believe it's a Walbro unit. It was free. I loathe the idea of getting under the car to drop the gas tank though. Those two bolts holding the straps in have 17 years of rust. Tongue

Quote:There are 2 air temp sensores in the 87-88. One is the VAT (vane air temp) located inside the VAM. The other is the ACT (air charge temp) located on the backside of the lower intake. It's the lower one of the two back there that point toward the fire wall. the upper one is the knock sensor - make sure it's plugged in for now. For more info see:

Ah, so it has BOTH sensors. The error code was for the VAT one. I guess I'll try to figure out how to measure it when I measure the voltage of the VAM as it's moved through it's range of motion.

Quote:Does yours have a little black/green check valve in the vacuum line close to the valve on the upper intake?.

I'll have to check to see if the little check valve is on it. I've not pulled codes since I got it back from the dealer, so it might have it on it now and produce the code.

Quote:The ECU will cut timing if the KS sensor tells it there is knock (detonation) the KS has to be plugged in to function.

I've not even checked, I just assumed with the power loss associated with the pinging that it was yanking timing. If it is connected, who knows how much crud is on the connector-- it's not one of the ones I deoxidized. I use DeOxit by CAIG laboratories btw. Incredible stuff- I used it to eliminate voltage drops on the elctrical system of a TR-7 once. If it can do that, it can do anything.

Quote:Thanks for the tip on where to buy brake rotors. Most places want a whole lot more than that.

No prob. Ford wanted like $250 each. The best price I could find locally was $159, special ordered. The best price I could find online was around $65, but shipping was very expensive, about another $30 on top of that for a pair. I don't see CHINA stamped anywhere in the casting, it has the #'s for the minimum thickness stamped into the front, and overall seem to be quality castings- the vanes don't fluctuate in thickness relative to the rotor surface, which is something you see on real cheap brakes all the time.

Quote:The turbo PCV are somewhat unique. Remove it, hold it straight up and down. big end down. Try to blow through the small end. If it passes ANY air at all it's bad. Replace with ONLY THE FORD PART. Ford P/N: E5ZZ-6A666-A (this is the correct p/n, 5/13/02) The Motorcraft box will also have EV-127-A on it

It's funny, because I had a normal metal one laying around that I forgot to stuff in there. Whatever is in it, is still in it. Which is probably a good thing.

Quote:We reccommend the stock Motorcraft replacement wires, Motorcraft: WR-4011-C
These things are real tempermental about wires, stick with the tried and true.
We also recommend Autolite copper 764s or Motorcraft AWSF32-C or NKG # 2238 plugs. Gap them between 0.030 and 0.032"

I'll add that to my list. It might have motorcraft wires on it, if it does I'll leave them alone, otherwise I'll replace them. The plugs are cheap enough that I'll toss those regardless. I'll check the cap and rotor but I think it's probably new.

Do the TFI/PIP setups in these distributers cause problems with timing over time?

I'm honestly not sure what the camshaft timing is at. I'll have to search for the way to check that, is it easy? If the ignition timing was at 21 degrees because the cam jumped a tooth forward, and I dialed back the timing to 10 degrees.. I wonder how it would run.

Quote:You would need an osicillascope (sp) to measure baro output. It generates frequency, not voltage as an output. If you didn't get a code for it, it's probably OK

Yeah, I forgot about that. I'll leave it alone, they don't die often and they are expensive to replace anyways. I've only ever seen one die in my life, it was on an F250 with the 460 in it. It's symptoms were a rich idle and bad gas mileage.

Quote:Don't worry about the 02 sensor until you get the fuel issue resolved and a good tuneup. Those are the basics (tuneup) and the known problems (fuel pressure)

Yeah, the O2 sensor is skipped under WOT anyways, which is where this problem is occuring. The gauge moves pretty fast, so I think the O2 sensor is prolly fine. It's definitely not the stock one, as it's been spliced in with electrical tape holding the wires together. Someone must have put a cheapy in with a different connector and 'made it work' ... seems good enough.

Keman
Springfield, VA
Eric "Keman" Uratchko
1990 Mustang 5.8 GR-40
1988 Thunderbird Turbocoupe 5sp
2005 Audi S4 Avant MT6
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