[crazymjb]

Hey all, taking advantage of work bringing me down south for a year (we normally live in the northeast) and bought a very very yellow 2005 GT convertible with 120K on the clock for $6500

The car is very clean, and unmolested. The only thing added was a newer head unit. I wanted a fun, mildly more family friendly weekend car for when we move back to replace the Harley I don't really ride anymore.

It runs and drives really well as far as I can tell, being a somewhat novice standard driver. I've never owned a manual car, but have driven them. I did manage to drive this back to my place 100 miles from where I bought it, including a couple hill starts, without stalling. I've ridden a bike for 10 years, so I get the concept of a clutch and shifting.

As to the issues:
1. The temperature gauge is pegged well past the "hot" indication at all times. The thermostat opens and the radiator heats up, but I'd like a reliable engine temperature indication.
2. The oil pressure gauge isn't moving. It has oil pressure... or if it doesn't, it's been driving really well for a car with zero oil pressure. I trust the woman I bought it from isn't lying and has said it hasn't worked the past 10-20K miles.
3. There is a ticking sound that I haven't decided if is coming from the exhaust or the engine (sounds like a manifold leak, and is just as audible with the hood closed, but I haven't narrowed it down)
4. I have a CEL for a cam position sensor and it idles a little rough. That said, off idle the engine runs very smoothly. I was reading there is a TSB for an alternator diode and it likely is not a CPS. Since there is a TSB, will a dealership look at it for free for me? Should I try replacing the CPS before the alternator?
5. It has these hideous mustang decals on the lower sills. It's hard to tell if these are clear-coated over or just decals. I hope to god they are just decals, and I'd like to remove them.

 

[crjackson]

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[145566]

Hey all, taking advantage of work bringing me down south for a year (we normally live in the northeast) and bought a very very yellow 2005 GT convertible with 120K on the clock for $6500

The car is very clean, and unmolested. The only thing added was a newer head unit. I wanted a fun, mildly more family friendly weekend car for when we move back to replace the Harley I don't really ride anymore.

It runs and drives really well as far as I can tell, being a somewhat novice standard driver. I've never owned a manual car, but have driven them. I did manage to drive this back to my place 100 miles from where I bought it, including a couple hill starts, without stalling. I've ridden a bike for 10 years, so I get the concept of a clutch and shifting.

As to the issues:
1. The temperature gauge is pegged well past the "hot" indication at all times. The thermostat opens and the radiator heats up, but I'd like a reliable engine temperature indication.
2. The oil pressure gauge isn't moving. It has oil pressure... or if it doesn't, it's been driving really well for a car with zero oil pressure. I trust the woman I bought it from isn't lying and has said it hasn't worked the past 10-20K miles.
3. There is a ticking sound that I haven't decided if is coming from the exhaust or the engine (sounds like a manifold leak, and is just as audible with the hood closed, but I haven't narrowed it down)
4. I have a CEL for a cam position sensor and it idles a little rough. That said, off idle the engine runs very smoothly. I was reading there is a TSB for an alternator diode and it likely is not a CPS. Since there is a TSB, will a dealership look at it for free for me? Should I try replacing the CPS before the alternator?
5. It has these hideous mustang decals on the lower sills. It's hard to tell if these are clear-coated over or just decals. I hope to god they are just decals, and I'd like to remove them.

The dealer won’t look at the TSB for free.

 

[crazymjb]

The dealer won’t look at the TSB for free.

Oh well... So where should I start with this cam position sensor issue? Try a new one and if doesn't fix it, return it? Or should I go straight to the alternator... Seems to be original.

 

[SVT Rider]

Congrats. Hopefully the 2005 being a first year model doesn't give you buyers remorse, but it is still a decent Mustang. Most of the TSBs and issues were remidied by the 2007/2008 year models, so keep that in mind. There are quite a few TSBs for the 2005 to checkup on as problems arise for you as you learn the car.

As a first check before you drive it any more, get a actual oil pressure meter hooked up to the oil filter adapter (fairly easy to install in the port for the dummy temp sender that goes to the cluster gauge) and monitor cold and hot oil pressure. Should be ~65-70psi cold and then settle in at 28-30psi hot. If it goes below 25psi, you have a problem and do not drive it that way if so.

1. Unless there is a bad air pocket in the coolant, most like the stepper motors in the guage cluster are bad. Known issue and can be sent in to be fixed. People have posted good results with sending in the Guage Cluster to some places on ebay to get the stepper motors replaced. Also, the temperature is a derived value from the cylinder sensor in the passenger side inner-rear engine valley. So unless the stepper motors are bad, the value will be actually an offset value of the cylinder head temperature (not the actual coolant temperature).

2. See my 2nd paragraph above. Assume there isn't oil pressure and go from there. Could be as simple as another stepper motor issue on the gauge cluster.

3. Depends on what the ticking sound is. Keep in mind the fuel injectors are very loud on the Mustang and can be mistaken for a ticking. Might be exhaust leak...might be cam sprockets flapping around due to low oil pressure. Get the oil pressure figured out and then come back to the ticking.

4. Post the code for the CEL regarding the Cam Position Sensor issue. We need something to start from.

5. Can't help much there. Decals might be vinyl and peel off with some heat and some effort, but if not good luck.

 

[crazymjb]

I'll see if I can grab that code for you guys this weekend. Not sure if my BT OBDII scanner will work with my iphone.

This is seperate from the injector tick, but its definitely very rhytmic, doesn't sound like something rattling.

Should a live OBDII feed give me oil pressure if it's the cluster that's FUBAR? The needle doesn't move AT ALL from resting position. Likewise the temp gauge is pegged with or without power applied. Is there a diagnostic mode to get the gauges to sweep? Also, can I read the voltage on the sending unit?

For $6500 bucks for a very clean car that has made it to 120K miles, I won't complain if it needs a little TLC. My 5 year old wrangler that was at the end of the run of the JKs has a bunch of problems, my wife's 2019 Rebel has had zero issues. Cars are cars.

 

[crazymjb]

Just checked -- Codes are as follows
P0340 and P0344

 

[SVT Rider]

Should a live OBDII feed give me oil pressure if it's the cluster that's FUBAR? The needle doesn't move AT ALL from resting position. Likewise the temp gauge is pegged with or without power applied. Is there a diagnostic mode to get the gauges to sweep? Also, can I read the voltage on the sending unit?

Again, the only sensor in the engine is the dummy one plugged into the oil adapter. It is basically an On/Off (~5psi) dummy sensor. The cluster oil pressure gauge should never go above middle and has only two positions: Middle (>5psi oil pressue), and Low (Oh crap what is wrong!?? and too late to do anything about it; likely engine internals are scored or needing repair).

That said, low oil pressure is what kills these modular engines; so at the very least do yourself a favor, check the oil pressure with an actual analog gauge plugged into the oil sender port the factory sensor uses.

Just checked -- Codes are as follows
P0340 and P0344

Very good. OK, so those are isolated to Bank 1 (Passenger side cam shaft).

P0340 - Camshaft Position Sensor A Circuit (Bank 1 or single sensor)
Description: The test fails when the powertrain control module (PCM) can no longer detect the signal
from the camshaft position (CMP) sensor on bank 1.
Possible Causes:
CMP circuit open
CMP circuit short to GND
CMP circuit short to voltage
SIG RTN open (VR sensor)
CMP GND open (Hall-effect sensor) CMP circuit short to CMP2 circuit (if equipped)
CMP incorrectly installed (Hall-effect sensor)
Damaged CMP sensor shielding
Damaged CMP sen

P0344 - Camshaft Position Sensor A Circuit Intermittent (Bank 1 or single sensor)
Description: The test fails when the powertrain control module (PCM) detects an intermittent signal
from the camshaft position (CMP) sensor.
Possible Causes:
Intermittent open circuit
Intermittent short circuit
Damaged sensor shielding
Damaged sensor

So the cam position sensor is suspect, but before you replace it you could do some diagnostics. The sensor is on the front of the passenger-side engine bank, it is inserted through the front engine cover and easily accessible. Inspect the wires and contacts and note any fraying or corrosion. You can even unbolt it and remove it for inspection of the hall-effect sensor. Could just have a bunch of buildup which needs to be wiped off. The bolt is 89 lb-in to torque back down.

 

[crazymjb]

Awesome thanks. Glad to hear it’s not buried. I’ll grab some contact cleaner along with a few other things tomorrow. The sensor is 20 bucks so I may try swapping it out and seeing if that works.

Any thoughts on DIYing cluster repair vs sending it out?

 

[SVT Rider]

For the Cam Position sensor, I dug into the pinpoint tests this evening. It is not actually a hall-effect sensor but rather a variable reluctance sensor (2-wire design). So the connector and sensor should have two wires. The pinpoint test has a resistance test you can try with a DMM set to Ohms. On the sensor, measure to see if the resistance between the two pins is between 250Ω and 1000Ω. If not, then it is a bad sensor and spend the $20. The P0344 code for intermittent circuit has me concerned it may not be the sensor. So let me know what the value is for the resistance check and we can go from there.

As for DIY repair of the cluster, I am an electrical engineer and familiar with soldering components. This task is not something I would like to do. If memory serves me, the stepper motors are a surface mount style and getting them setup just right and oriented is a bit of an undertaking. I have been dreading the day mine crap out as I know I will want to take a stab at DIY repair. However, I would recommend finding a reputable repair service on ebay that is tooled for the job and knows what they are doing (telling future self this as well...skip the DIY 😄). I recall a forum post on one of these forums advertising their services to the Mustang crowd. You might look around on the forums to see what others have done and who they chose.

 

[crazymjb]

Yeah I’ve seen a few advertised in the $100 neighborhood. Probably worth it. I’ve done some soldering but I’m far from a pro.

Ill have to grab a new multimeter tomorrow. My electrical stuff is back home and didn’t come with me for this temp move.

There does seem to be a known issue with a bad alternator causing this issue, so hopefully I can find an auto parts place that can test it (as well as the diodes) in the car. First order of business will still be verifying the oil pressure gauge issue is in fact a gauge issue.

 

[SVT Rider]

Sounds like you are on the right track. I'll monitor the thread if you need help.

The bad alternator is exactly what I have in mind here with the intermittent CMP sensor code. A bad alternator is one of the hardest things to diagnose on these 4.6L modular engines. A bad alternator masquerades as various gremlins and people throw tons of money at other components before trying the alternator.

Best thing I have done in this department is to upgrade to the 2010 Mustang's Denso Alternator when mine started throwing codes on a track day. The 2010 alternator is built like a champ and saves a lot of worry while I am at the track beating the snot out of this amazing car.

By the way, have you checked the engine bay cowl rubber grommets (two of them) for debris? Big known issue with this generation of Mustang is the cowl filling up with water and then frying the Smart Junction Box computer in the passenger floor area. Very easy to check both grommets as well as the inner cowling for debris and will save you a lot of grief, gremlins, and wet carpets.

 

[crazymjb]

I’ll take a look tomorrow. It was a bit less researched than my usual purchases as I don’t have a ton of free time at the moment to tire-kick.

Off-hand do you know if any of the auto parts chains have what is required to check the alternator in the lot? I might give the ford dealer a shout just for shits and giggles, but trying to keep this project budget friendly. I’m hoping it takes no more than 300 bucks to get everything working.

A couple other questions I thought of
1. Any good guidelines on lubricating the convertible mechanism
2. Is there a go to “budget” suspension setup that is still comfortable for daily driving? It could use shocks anyway. I’d love to lower it slightly. It is mainly going to be a cruiser, not a track car... at least for now.

 

[SVT Rider]

Autozone, O'reilly's, Baxter Auto - Most of the mainline auto parts stores have alternator and battery test equipment. How good of a tester, well that is store specific. If you happen to have an Interstate Battery nearby, they have awesome testers that they will plug in and check the battery and alternator and does a thorough job. All those places should be free of charge.

In my experience, the dealership will want some money for doing anything...even a alternator/battery test.

1. Nope. Mine is a hard top and never had a convertible to maintain.
2. That a tough call to advise you and point you to. Lots of suspension options for this car. Some cheap options may not be ideal. Honestly, the stock GT suspension is good (many will do track days with it). You likely would want some shocks if the current ones are tired. My recommendation there: go with Koni Yellows (my current strut/shock combo), or Monotube Bilsteins. Last I checked they are on the spendier side, but will give you a good ride, last a good long time, and give you room to grow if you want to do more with the car (thinking springs etc).

 

[Bullitt95]

Hey all, taking advantage of work bringing me down south for a year (we normally live in the northeast) and bought a very very yellow 2005 GT convertible with 120K on the clock for $6500

The car is very clean, and unmolested. The only thing added was a newer head unit. I wanted a fun, mildly more family friendly weekend car for when we move back to replace the Harley I don't really ride anymore.

It runs and drives really well as far as I can tell, being a somewhat novice standard driver. I've never owned a manual car, but have driven them. I did manage to drive this back to my place 100 miles from where I bought it, including a couple hill starts, without stalling. I've ridden a bike for 10 years, so I get the concept of a clutch and shifting.

As to the issues:
1. The temperature gauge is pegged well past the "hot" indication at all times. The thermostat opens and the radiator heats up, but I'd like a reliable engine temperature indication.
2. The oil pressure gauge isn't moving. It has oil pressure... or if it doesn't, it's been driving really well for a car with zero oil pressure. I trust the woman I bought it from isn't lying and has said it hasn't worked the past 10-20K miles.
3. There is a ticking sound that I haven't decided if is coming from the exhaust or the engine (sounds like a manifold leak, and is just as audible with the hood closed, but I haven't narrowed it down)
4. I have a CEL for a cam position sensor and it idles a little rough. That said, off idle the engine runs very smoothly. I was reading there is a TSB for an alternator diode and it likely is not a CPS. Since there is a TSB, will a dealership look at it for free for me? Should I try replacing the CPS before the alternator?
5. It has these hideous mustang decals on the lower sills. It's hard to tell if these are clear-coated over or just decals. I hope to god they are just decals, and I'd like to remove them.

Problems 1 & 2 are almost certainly due to broken gauge stepper motors. I'd recommend replacing all of them with the newer generation x27 units that you can buy from eBay. I did it myself last year and the task isn't as daunting as people might think.

Problem 3. Have the car raised on a lift with the engine running. That'll make it easier to pinpoint the ticking sound.

Problem 4. The cam position sensor itself is rarely at fault. Which cylinder bank is the problem?
Use a digital multimeter to perform an AC ripple test (there are YouTube videos describing the procedure) to determine if you have a faulty alternator diode. If that's ruled out, I suggest you replace the VCT solenoid on the affected side.

 

[crazymjb]

I grounded the oil pressure connector out directly to the battery. At first I got about an 8th of an inch of movement, I disconnected it from the ground, then it went back to zero, and then it stopped working completely, as it had been. I’m still going to swing by harbor freight and grab a pressure tester for piece of mind. I’ll probably order some of those stepper motors and try my hand at doing the repair myself.

 

[crazymjb]

Just tested the oil pressure and it’s right around 70-75 at a cold start... let it run for 5 mins and it settled at 70. Also tested the sending unit with a multimeter and it works fine. Going to assume it’s the stepper motor.

going to run back out there and see if this ****** harbor freight multimeter shows any AC voltage off the alternator.

 

[crazymjb]

With the oil pressure sending unit disconnected, I now get a low oil pressure message. So I think it’s the stepper.

As to the CPS. I am seeing .25VAC at the alternator wire when disconnected from the battery. Also it may be in my head, but the idle seems to smooth out with it disconnected. Also, the alternator whines when connected.

 

[SVT Rider]

Just tested the oil pressure and it’s right around 70-75 at a cold start... let it run for 5 mins and it settled at 70. Also tested the sending unit with a multimeter and it works fine. Going to assume it’s the stepper motor.

Yep, sounding like the stepper motors are out. Might consider also changing the fuel gauge stepper motor if you do take on this task.

Now that you got the cold reading, I still highly recommend monitoring the oil pressure at hot temp (~220F cylinder head temp, or until the radiator fan turns on a few times (~30-45mins of idle depending on outdoor temperature)). Once the oil gets to temp you will see the pressure go down. It is the pressure at high temp that is of concern. When I monitored mine it was ~15-18psi and would climb to only around 40psi at 2000RPM hot; did a full timing and tensioner overhaul and found the timing chain tensioner seals had blown out and were bypassing oil (common problem). Only was seen at hot temperature on the oil pressure.

Problems 1 & 2 are almost certainly due to broken gauge stepper motors. I'd recommend replacing all of them with the newer generation x27 units that you can buy from eBay. I did it myself last year and the task isn't as daunting as people might think.

I was not aware of a part number for the stepper motors. Maybe Bullitt95 can provide some more details for a DIY job like this?

With the oil pressure sending unit disconnected, I now get a low oil pressure message. So I think it’s the stepper.

As to the CPS. I am seeing .25VAC at the alternator wire when disconnected from the battery. Also it may be in my head, but the idle seems to smooth out with it disconnected. Also, the alternator whines when connected.

Quite agree. Sounds like bad stepper motors. Did you happen to get the resistance measurement across the two pins on the passenger side Cam position sensor? This would be measured with the wire connector disconnected.

Ideally, you would probe the alternator's positive terminal and then a ground on the engine or chassis for the ripple check. A ripple of >100mV on the DMM AC setting would indicate bad diode rectifiers. That however, is only one piece that could go bad on the alternator, but a good check since you have a DMM.

 

[crazymjb]

With the Ohmmeter set to 2K I’m showing .390-.410 with the engine running across the driver side CPS.

Alternator is fluctuating between .227 and .230 with multimeter set to 2VAC. When I disconnected the alternator control wire from the harness it shows .310. This is taken directly off the wire that goes from the alternator to the battery. I can easily get to the terminal on the back of the alternator with the intake on.