Hey guys, I recently got a 96GT. I've had an 88GT for the past decade and had plenty of stuff done to it so I know a thing or two. I don't know a whole lot about the 4.6 though. I have an engine light on, codes are P0171 and P0430. I did some looking and found that the vacuum line to the FPR was broken so I replaced that. Figured I may as well change the plugs since I just got it last thursday, so as I was taking them out I noticed that all but two had a lot of oil on top of them when I removed the plug wire. The number 4 plug had a ton of coolant sitting on top of it, but the guy i got it from did say his heater core hose burst and he replaced it, and it is right above that plug so I'm hoping that's all it was. Anyway, what's the deal with the oil all over the others? Valve cover leak or intake leak? I'm hoping the vacuum line was why I had the P0171 code, haven't reset it and driven it around to find out yet, it needs a clutch which I am gonna do this weekend. Any ideas on the P0430 code? The previous owner said it was an O2 sensor, he replaced one but it was the wrong one. He didn't seem like the type that could diagnose anything so I figured I would ask you 4.6 pros for some advise. Motor seems strong, but drivability is crap due to the clutch so I won't know more until I replace it. Oh, and I was gonna go with a spec stage 2+. Anyone think of any clutch I should go with instead?
first 4.6 for me, odd problem
- Thread starter slick86gt
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wmburns
SN Certified Technician
The spark plugs holes on the SOHC 4.6 point straight up. They are bad about collecting ANYTHING and EVERYTHING that falls on top of the motor. That includes water, oil, coolant, and grit.
That is why it is so important to clean out the spark plugs wells before removing the plugs. Otherwise, it will go straight into the combustion chamber and a "smoker" is the usual result. And yes, #4 and #8 are a PIA to clean. I usually take an old pick up tube from a spay bottle and tape it to an air nozzle. The small stiffer tube can get all the way to the bottom of the spark plug holes.
If the plugs have not be torqued correctly (or left in for a long while), a small amount of blow by may migrate past the threads. Recommend anti-seize on the top threads and torque to 11 foot pounds. Some models of 4.6's may eject the spark plugs if incorrectly torqued.
A valve cover leak is another possible source of oil in the spark plug wells. A visual inspection should be able to determine if the valve covers are leaking.
P0171 is pinpoint test H41 fuel control. (My 2000 reference does not have a P0430 DTC). Likely the broken vac line is the cause. Reset and drive. Post the results.
Do you have a lot of upgrades planned? If not, I don't think a 96's motor can really over power the stock clutch. Save your $$. Save your left foot.
That is why it is so important to clean out the spark plugs wells before removing the plugs. Otherwise, it will go straight into the combustion chamber and a "smoker" is the usual result. And yes, #4 and #8 are a PIA to clean. I usually take an old pick up tube from a spay bottle and tape it to an air nozzle. The small stiffer tube can get all the way to the bottom of the spark plug holes.
If the plugs have not be torqued correctly (or left in for a long while), a small amount of blow by may migrate past the threads. Recommend anti-seize on the top threads and torque to 11 foot pounds. Some models of 4.6's may eject the spark plugs if incorrectly torqued.
A valve cover leak is another possible source of oil in the spark plug wells. A visual inspection should be able to determine if the valve covers are leaking.
P0171 is pinpoint test H41 fuel control. (My 2000 reference does not have a P0430 DTC). Likely the broken vac line is the cause. Reset and drive. Post the results.
Do you have a lot of upgrades planned? If not, I don't think a 96's motor can really over power the stock clutch. Save your $$. Save your left foot.
fast97gt
Active Member
If you plan on doin any mods to around 300hp a king cobra would do just fine, even a ram hd. However if you use it for a dd I would go back to stock, only because of the peddle pressure will suck in traffic, also I do recommend changing the clutch quadrent at the clutch peddle. The stock plastic piece sucks and will break with anything heavier than stock on the clutch, and don't forget the firewall adjuster or the adjustible cable or both when replacing the quadrent.
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twogts4us
15 Year Member
I agree 100% - Spec clutches seem to be hit or miss quality. The KC will be OEM quality and pretty cheap last time I bought one. If you really felt the need to step up higher, invest in a Centerforce Dual Friction.
thanks guys, hopefully this weekend I will have my clutch in so I can drive it and see if the vacuum line fixed that code. I plan on mhs heads, cams, full exhaust and intake and tb. Would like a blower but that is down the road a ways. I just decided to order the king cobra kit from upr, only $250 and i get the clucth kit, throwout bearing, pilot bearing, clutch cable, quadrant and firewall adjuster. Figured it was a hell of a deal and when I do all the mods down the road I can replace the clutch as needed and no big deal. The way those spark plugs sit down in a hole is retarded as hell, I did blow them out before I removed the plugs, thats how I found all the damn coolant blowing all over the place when I stuck my air nozzle in there. The heater core hose that guy replaced is way too long so he just looped it over and it's kinked so I have to remove it and cut it or replace with the correct one. I imagine I'll have to drain the damn coolant so as to not get more crap down in the spark plug area......
I'm a 4.6 newbie and one thing I learned recently is that you may get a P1000 DCT during and/or after you Clear the DCT's. It's my understanding this code can be produced anytime the PCM is accessed.
I don't know what type of unit you're using to read the codes, but my SCT will not clear the P1000 code.
No worries though as the PCM will clear this on it's own after a number of OBD cycles are completed.
Regards,
-D
I don't know what type of unit you're using to read the codes, but my SCT will not clear the P1000 code.
No worries though as the PCM will clear this on it's own after a number of OBD cycles are completed.
Regards,
-D
Pearl02
Member
That damn P0430 code must be going around. My car set off a "ses" light tonight. Thats the code I pulled with my scan tool. This is what the code means: Catalyst System Efficiency Below Threshold (Bank 2). I either have an exhaust leak, bad cat or bad O2 sensor.
I bought my MRT catted h-pipe about 4 months ago. I'm hoping I don't really have a bad cat. I will start to figure out what wrong tomorrow. I will keep you guys informed. Pearl02.
I bought my MRT catted h-pipe about 4 months ago. I'm hoping I don't really have a bad cat. I will start to figure out what wrong tomorrow. I will keep you guys informed. Pearl02.
Pearl02
Member
Ok, I ran a few test yesterday. I hooked up my scan tool and did some live data logging. The 02 sensor in question is on bank2(drivers side) downstream of the cat. That sensor seems to be a little slow but not to bad compared to the one on bank1. I was gonna flip flop them out and reset the code but the guide tabs on the sensor wire offset differently(thanks Ford). The only way to make them fit is to break off the tabs which I didn't want to do. Other than that the wire harness appears to be the same from side to side. Anyone else flip floped the rear 02 sensors? I can pick up a new Bosch 02 sensor for around 43 bucks locally. Also, check other engine function like ECT,Maf,fuel pressure, IAT, STFC and LTFC, EGR function. These all seem to be in order. Car runs fine and has good power. The car does idle rough. Thanks. Pearl02.
Pearl02
Member
I just swapped it out since I had one lying around. Code went away. There should be test values for the sensors. I think a Haynes or Chiltons have a test for them.
Pearl02
Member
Thanks man. I should have things figured out on Friday. I haven't been able to work on it since last week due to my work schedule. I'll keep you posted. Pearl02.
I'd almost guarantee you have bad O2's. If you really want to check them first rather then replace them you can.
You have to wait for the sensor to heat up before you can check it (600 F) so allow the engine to reach operating temp before doing the check. Using pins or paper clips probe the SIG + and GND - pins on the sensor. During engine warm up its in open loop mode so the voltage should be steady but after it reaches operating temp the voltage should fluctuate between 0.1 and 0.9 volts. Keep in mind this is for pre-cat sensors as the post-cat sensors do not fluctuate but instead produce either a steady high volt signal (Rich) or a steady low volt signal (excess oxygen but not lean).
I consider the pre-cat o2's part of my normal maintenance and try to replace them every 20-30k miles or so. I also recommend staying away from parts store O2 sensors and getting them from the stealership. Anything having to do with the electrical system and the ECU and its interfaces I get from Ford. Just had horrible experiences with just about everything electrical from parts stores.
You have to wait for the sensor to heat up before you can check it (600 F) so allow the engine to reach operating temp before doing the check. Using pins or paper clips probe the SIG + and GND - pins on the sensor. During engine warm up its in open loop mode so the voltage should be steady but after it reaches operating temp the voltage should fluctuate between 0.1 and 0.9 volts. Keep in mind this is for pre-cat sensors as the post-cat sensors do not fluctuate but instead produce either a steady high volt signal (Rich) or a steady low volt signal (excess oxygen but not lean).
I consider the pre-cat o2's part of my normal maintenance and try to replace them every 20-30k miles or so. I also recommend staying away from parts store O2 sensors and getting them from the stealership. Anything having to do with the electrical system and the ECU and its interfaces I get from Ford. Just had horrible experiences with just about everything electrical from parts stores.
wmburns
SN Certified Technician
An option is to use an ODB2 scanner to monitor the signal return from the O2 sensors. No cutting, hacking, probing required.
Not to be a contrarian, but the O2 test being proposed is at best a minimum functionality test. It does not tell if the sensors are accurate. Nor does it tell if the sensors are reacting too slowly.
If the O2 sensors were bad enough to show up on the test proposed, the PCM would have thrown a DTC long before hand.
Here is my take on O2 sensors. Next to the crankshaft/cam shaft sensor, the O2 is very near the top in terms of importance. The way the O2 sensor is incorporated in the PCM’s adaptive fuel strategy means a bad O2 sensor can over ride the valid inputs of almost every other sensor.
As O2 sensors age, their response times slows. A slow reacting O2 sensor causes delays as the PCM tries to adjust the short term fuel trim in response to changing conditions. Best case this results in less than optimum fuel mileage. Worse case can slew the AF ratio.
IMO, if you are having drivability concerns and the O2 sensors have more than 100k miles, consider changing them.
Again, IMO, the Bosch O2 sensors are as good as (if not better) than the Ford OEM’s.
Not to be a contrarian, but the O2 test being proposed is at best a minimum functionality test. It does not tell if the sensors are accurate. Nor does it tell if the sensors are reacting too slowly.
If the O2 sensors were bad enough to show up on the test proposed, the PCM would have thrown a DTC long before hand.
Here is my take on O2 sensors. Next to the crankshaft/cam shaft sensor, the O2 is very near the top in terms of importance. The way the O2 sensor is incorporated in the PCM’s adaptive fuel strategy means a bad O2 sensor can over ride the valid inputs of almost every other sensor.
As O2 sensors age, their response times slows. A slow reacting O2 sensor causes delays as the PCM tries to adjust the short term fuel trim in response to changing conditions. Best case this results in less than optimum fuel mileage. Worse case can slew the AF ratio.
IMO, if you are having drivability concerns and the O2 sensors have more than 100k miles, consider changing them.
Again, IMO, the Bosch O2 sensors are as good as (if not better) than the Ford OEM’s.
patman0911
Founding Member
Man, that's an expensive O2 habit. They should be perfectly functional for a lot longer than 20-30K. Maybe as early as 75K if you're paranoid about your O2 sensors getting slow and love doing stuff preemptively but I'm cheap, um, frugal so I wait until there's some outward sign that their getting old and dying, like mileage starts dropping or the computer starts flagging them.
Yep, Bosch is good stuff. Bosch pretty much is electronic fuel injection as we know it today. They've been doing O2 sensors since the 70's and are OEM for a lot of automakers.
Might be expensive habit but these motors run forever with preventative maintenance and I like keeping my girl at 110%. Every opinion differs on what to replace and when, I just feel I've found the balance in maintaining my car in top shape.
Again in my first line I think my tone when I said "If you really want to check them first rather then replace them you can," says it all. I don't think anyone should really be probing O2 sensors as I consider them part of normal maintenance and replace them without thinking about it.
Also, he stated that he does indeed have a few codes and was trying to isolate which sensor was bad instead of replacing both pre-cat o2's. If there's no codes being thrown why bother with any o2 sensor check? I can't really think of a reason to go probing sensors unless its throwin a code. IMO the pre-cat sensors are so important that if I even suspect either one is not working properly I replace them both just to be sure.
lol if you ask me a mustang can never have too many new parts on it.
Again in my first line I think my tone when I said "If you really want to check them first rather then replace them you can," says it all. I don't think anyone should really be probing O2 sensors as I consider them part of normal maintenance and replace them without thinking about it.
Also, he stated that he does indeed have a few codes and was trying to isolate which sensor was bad instead of replacing both pre-cat o2's. If there's no codes being thrown why bother with any o2 sensor check? I can't really think of a reason to go probing sensors unless its throwin a code. IMO the pre-cat sensors are so important that if I even suspect either one is not working properly I replace them both just to be sure.
lol if you ask me a mustang can never have too many new parts on it.
patman0911
Founding Member
Let me know the next time you get ready to throw out a set of O2 sensors with 20~30K on them - I'll buy them from you 
Pearl02: I think flipping the downstream O2 sensors and seeing if the code follows the sensor or stays on the same side is a good idea. That'll tell you if it's a cat/exhaust issue or just a bad sensor.
How many miles are on the car and when did the car go into service? If it's less than 8 years and 80K then the cats are covered by a federally mandated warranty and Ford has to replace them.
Pearl02: I think flipping the downstream O2 sensors and seeing if the code follows the sensor or stays on the same side is a good idea. That'll tell you if it's a cat/exhaust issue or just a bad sensor.
How many miles are on the car and when did the car go into service? If it's less than 8 years and 80K then the cats are covered by a federally mandated warranty and Ford has to replace them.
Pearl02
Member
Let me know the next time you get ready to throw out a set of O2 sensors with 20~30K on them - I'll buy them from you
Pearl02: I think flipping the downstream O2 sensors and seeing if the code follows the sensor or stays on the same side is a good idea. That'll tell you if it's a cat/exhaust issue or just a bad sensor.
How many miles are on the car and when did the car go into service? If it's less than 8 years and 80K then the cats are covered by a federally mandated warranty and Ford has to replace them.
Well, I have a MRT catted H-pipe on the car now so no more coverage for the stock cats. I've had the MRT on for 5 months. I was going to just flip the senosr but the guide tabs on the sensor wire harness offset differently. The only way to do is to break tabs. Other than that I believe the wire layout is the same. Any suggestions? Pearl02.
patman0911
Founding Member
I don't think there's any harm in breaking off the tabs. Apparently, aftermarket sensors come without them anyway so they can be used at any position.
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