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Discussion Starter #1
Problem:
Hey forum I have finally reached my whits end with my Mustang and decided to seek out help on the forums. I just recently finished my contract with the Marines and am back home. Unfortunately my car sat in the driveway for 4 years and I have been going through hell to fix it up. My current problem is the following: while driving in and around town I can feel a misfire and engine hesitation. If I floor the gas pedal the engine roars but chokes with a misfire once around 3000rpm. While slowing down for stop lights I also experience a huge drop in rpms once the car is put into neutral sometimes dipping below 500rpm. Driving on the interstate is a frustrating experience as well. Sometimes I will feel the engine hesitation and the rpms begin to drop very very slowly causing the car to slow from going 70 mph. I have tried to take my foot off the gas and press down again but nothing as if the engine just gave up. The engine just slowly starts to go down and shuts off eventually when I am on the side of the road pressing the brake. When attempting to turn the car back on it will not start for about 5-10 minutes. The engine cranks but seems to not have the life to start. In the past 6 months I have been working on it I have put an estimated $2,500- $3,000 to get it running and on the street(2-3 times what I owe the credit union on it).

Things that I have done outside normal maintenance:
I purchased a new fuel pump and replaced it.
Alternator was taken to a shop and rebuilt.
All spark plugs were changed.
Fuel filter changed.
All 4 o2 sensors replaced.
Catalytic converter was clogged so I replaced the mid pipe with a BBK x-pipe without the cat converter.
I do have the MIL Eliminators for the cat back o2 sensors.
Clutch burned out so I replaced it with a new one at the same time as the pipes.
MAF sensor replaced.
Fuel injectors have been cleaned.
TPS sensor replaced.
EGR vacuum regulator/solenoid replaced.
Fuel filter changed again.
All 8 COP have been changed out.

Everything above has been done over the span of 6 months and is close to the correct order. I love my Mustang and unless I have some serious problem that costs thousands to fix I am going to continue to work on her and get her running back like she used to. I have like 3 more payments and I'm done. That has been helping me stay motivated. The following OBDii codes are what it shot today after my problems on the interstate.

P0156- 02 Sensor Circuit Malfunction (Bank 2 Sensor 2)
P0172- System Too Rich (Bank 1)
P0175- System Too Rich (Bank 2)
P0301- Cylinder #1 Misfire Detected
P0305- Cylinder #5 Misfire Detected

My DTC self test thing in the car shoots the following code. dtc5284

Any suggestions would be greatly appreciated guys. I know its long but thanks for reading it. I also bought a PCV valve today and am going to change it once I am done here. Thanks again.
 

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IMO, the critical symptom are the misfire/rich codes. The other issues should be secondary until the critical DTC codes are resolved.

I don't normally handicap threads with such pointed suggestions. But based on the large number of items already replaced, my vote is a fuel sensor issue. Maybe even a leaky or disconnected intake vacuum reference to fuel pressure sensor. Without the vacuum reference, the fuel pressure is too high. A rich condition is the result.

The misfire and excess fuel is killing performance.

Of couse I could be wrong and the rich DTC is from the misfire. Based upon the large amount parts already replaced, this tends to rule out the easy stuff.

The things I can think of that cylinder 1 and 5 have in common are the same crank throw. Also the first cylinder in the firing order. Which #1 misfires are sometimes rooted in a cam sensor problem.

An unstable CKP sensor can also cause misfires. However, these tend to be more random. Any underdrive pulleys? Any other mods affecting the crank damper?

To rule out a base engine problem, perform a compression test.

Allow me to make a suggestion. Spend your money on an ODB2 scanner that can monitor operational data. This will allow you test more and change parts less. I hazard to guess that an ODB2 scanner could have already been purchased for the cost of parts already spent.


>>
For lean and rich DTCs:

Fuel system
  • Excessive fuel pressure.
  • Leaking/contaminated fuel injectors.
  • Leaking fuel pressure regulator.
  • Low fuel pressure or running out of fuel.
Vapor recovery system.

Induction system:
  • Air leaks after the MAF.
  • Vacuum Leaks.
  • PCV system.
  • Improperly seated engine oil dipstick.
EGR system:
  • Leaking gasket.
  • Stuck EGR valve.
  • Leaking diaphragm or EVR.
  • Base Engine:
    • Oil overfill.
    • Cam timing.
    • Cylinder compression.
    • Exhaust leaks before or near the HO2Ss.
 

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Discussion Starter #3
wmburns. I appreciate the reply and all the information. I will look into changing the CKP sensor. I forgot to mention that we did replace all the vacuum hoses a few weeks ago. I did have a question about "fuel pressure sensor". Could you tell me which sensors would have to do with regulating the fuel pressure? As far as modifications? Nothing else has been done to the car. You also suggested buying an OBD2 that can read measurements. Are there any that you recommend? Thanks again.
 

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Please don't change the CKP sensor unless you are made of $$ (no offense intented).

It actually make more sense to change the CMP sensor. Again, IMO this is premature.

The fuel pressure sensor is located on the fuel rail driver's side. It has an electrical connection and a vacuum line. Start first by INSPECTING the vacuum line for leaks.

Testing the FP sensor is best done by monitoring the Fuel pressure with the ODB2 scanner. The pressure should be around 40 PSI for the Mustang.

IMO, the compression test should be done so that you know what you are dealling with. If the base engine has an issue, you can change every sensor and the problem will remain.

As for recommendations, if you plan on doing any custom tunes, the get the same system as your tuner uses.

I have a cheap AutoXray unit (it was $$ when I bought it). It's a one line display but while limited, I have used it to solve a ton of problems.

I'm sure others will chime in with their reason that one tuner is better than the other. Bottom line is this. An ODB2 is a complex tool that takes time to master regardless of which one you buy.

OBTW, are you sure there isn't any moisture in the spark plug wells? When the COP's were replaced, were the boots replaced as well? What is the condition of the spark plugs (esp #1 and #5).
 

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Another possibility occured to me. Cylinder #1 and #5 also share close proxmity to the intake coolant cross over. What if the intake is leaking coolant into the combustion chamber? This could create a misfire from the coolant comtamination.

Does the motor use coolant? How about the oil use?

Consider performing a coolant system pressure test.
 

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Discussion Starter #6
Thanks again for the advice. I will look into doing these tests as soon as I can and get back to you with my results. The boots on the COP were changed as well. Oil use on the car is good and it does use coolant. I will make sure to double check for any leaks in the coolant system. No offense taken but you are right. I should stop buying parts that I think might make it better and finally get down to the problem. Thanks again. I'll report the progress as I find out.
 

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Discussion Starter #7
wmburns. I bought an Actron CP9575 today. I used it and got the following data.

MIL Status on
ABSLT TPS (%) 19.6
ENG SPEED (RPM) 702-716
CALC LOAD 22.7
MAF (LB/M) 0.61-0.62
COOLANT (degrees F) 208
IAT(degrees F) 129
IGN ADV 17.5-19
ST FTRM1(%) -1.6 - 2.3
LT FTRM1(%) 8.6
ST FTRM2(%) -2.3 - (-1.8)
LT FTRM2(%) 8.6
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11(V) 0.04-0.79
ST FTRM11(%) -1.6-2.3 (spike 4.7)
O2S12(V) 0.11-0.325
O2S21(V) 0.095-0.78
ST FTRM 21(%) -0.8-7.0
O2S22(V) 1.275
OBD2 STAT CA

I do not really know what I am looking at. I was not able to get fuel pressure but my code reader does read it. I think that might have something to do with Fuel system 1 being closed and fuel system 2 being N/A. Although I honestly do not know why. I am hoping you may be able to give me more insight into what the car is trying to tell me. The numbers with dashes in between are simply the average range that I saw the numbers moving. Thanks for any insight you may have.
 

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A couple of things look "off" to me. The MAF flow is a little low for a motor at idle. This could indicate a vacuum leak.

Monitor the Long term fuel trim (LTFT) bank 1/2 at idle and load (higher RPM). Another sign of a vacuum leak is for LTFT to go from positive value (adding fuel) to lower/zero under load.

Why? Because at an idle the intake is under vacuum. Under load the intake is under less vacuum. Therefore the vacuum leak has more effect at idle than under load. Hence the reason LTFT goes from large positive values to closer to zero under load.

If the motor is using coolant, it seems likely this is the source of the vacuum leak AND the contamination.
 

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Discussion Starter #9
Alright. I've run a few tests on the car today and I have the following results. Since you pointed out MAF, LTFTRM 1/2 I concentrated solely on those 3 things. When I began looking at everything I found the following codes.

P0156 Same as above
P0171 Bank system Lean (Found this one very interesting because the one above was rich when tested.
P0300 Random- Multiple Misfire detected
P0301- Cylinder 1 misfire
P0305- Cylinder 5 misfire

I then turned the car to idle to write down the measurements and got the following data.
MAF 0.79- 0.81
LT FTRM 1 25.0
LT FTRM 2 13.3
Closed

I then placed the engine at about 3000 rpms and wrote down the following changes.

MAF 2.56
LTFTRM1 7-12
LTFTRM2 16.4
Open

I drove the car around for a bit to let it get warmer. I noticed today that the problems seem to progress as the engine warms. When I got back into my driveway I revved the car up to about 4000 to see what the numbers would say and how the car would react. I did this twice and when I let my foot off the pedal the engine dropped rpms rapidly until it shut off. At the "time of death" I wrote down the following data.

LTMTRM1/2 31.3
Open

I decided I would do a 3rd test on idle and 3000 rpms but before I did that I checked the engine light codes. Oddly enough the only codes it was giving me were
P0156
P0171

I then did a 3rd and 4th test back to back on idle and under load(3000).
Idle
LTFTRM1 25
LTFTRM2 13.3
MAF .75-.77(it then began to gradually drop to about .67-.68)
Closed

Load (3000)
LTFTRM1 4.7-7.0
LTFTRM2 16.6-17.2
MAF 3.13-3.48
Open

Idle
LTFTRM1 25
LTFTRM2 11.7
closed

Load(3000)
LTFTRM1 -7-(-5.5)
LTFTRM2 1.6
open

Load(3000)
LTFTRM1 -21
LTFTRM2 -18

I find these to be strange even though I do not know what I am looking at. Upon shutting off the engine I did one more check engine light test.
P0156
P0171
P0305
P0720 Output shaft speed sensor cicuit.

As far as coolant use it is not leaking. I looked everywhere and my coolant tank was still full from when I filled it a month ago. I also attempted to look for a vacuum leak but was unsuccessful. I recently changed the hoses on the car but I looked everywhere to see if I may be able to see a crack anywhere at all and came up blank. One more thing I have noticed is the smell of fuel when the car is running at higher rpms. I hope that helps a bit and I appreciate all the insight and help.
 

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Do you not see the LTFT values doing what I said they would under a vacuum leak?

This is what the home mechanic needs to find vacuum leaks.

Amazon.com: Thexton (THE382) Vacuum Leak Detector: Automotive

However, the trouble shooting book says to attack any "misfire" DTC first. It's a waste of time to look at rich/lean DTC codes when a misfire is occuring. Why? because the misfire itself is dumping fuel into the exhaust and slewing the results.

SO.....you really need to attack the P0300 and the misfire on 1 and 5.

Consider pulling the fuel injectors and send out to an injector cleaning service such as Injectorrx.com. Once cleaned the injectors are as good as new. Cheaper than new.

Pull the CKP sensor and inspect the sensor for damage. Do the same thing with the CMP (cam) sensor. Clean the electrical connector with contact cleaner and re-grease with silcone di-electric grease.

What about the crank damper? Is it out of round?

Do the timing chains make noise? How many miles? Excessive slack in the chains can degrade the cam sensor.

Consider getting an oil filter cutter and inspect the oil filter for metal and plastic debris. If the timing chain guides have worn down, then debris will be in the oil.

Looking for anything that could degrade the quality of the CKP signal.

I can't do this for you. At some level you have to take an educated guess and start some where.

Good luck.
 

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Discussion Starter #11
wmburns,
I just wanted to give you an update on what is currently going on. I pulled out both the CMP and checked it with my voltmeter. Everything registered correctly with the CMP. I was not able to figure out how to take off the CKP without taking the entire AC Compressor out due to slack issues. Although I did test it with the voltmeter while I rotated the engine as the Haynes Manuel tells me and that also checked out fine. Strangely, I found that the CKP sensor was not tightened all the way down. For a second I doubted myself and thought I might have screwed it the wrong way but I realized that whoever was the last person to touch it did not screw it in completely. The car has been running ok cold but as it warms it worsens. I rarely if ever get a cylinder misfire. It perplexes me because it will jump randomly between 1 and 5 then the code turns off. I've been reading a bit on different forums and I have a hypothesis I would like to share with you. Could the Coolant Temperature Sensor be the culprit? I have been reading that this would cause the problems that I am facing.
 

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Discussion Starter #12
One more thing! I read on one of the forums on here is that the IAC causes huge problems because it was a faulty piece. Apparently this is the source of about 75% of the misfires in the forums I have read. I swapped out my IAC but made a mistake. The mistake I made was not resetting the computer after the swap. I read that you have to do this too. It did not occur to me so I went back to autozone and got my money back. Stupid mistake I know. What do you think about these new revelations I have had?
 

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An IAC causing random misfires? In 75% of cases? House feathers! BS!

Just for a moment, could you tell me how a bad IAC would do this?

The loose CKP sensor is far more likely to be the source of your problems.

It's well known that anything that degrades the quality of the CKP sensor output could be the cause of random/specific misfires. Examples normally include things like:

Incorrectly torqued crank bolts.
Cheap under drive pulleys
Out of round crank dampers (or dried up rubber isolators)

I'm afraid that based upon the large number of parts already replaced, there is no quick easy fix for you.

Thinking about your problem. Don't ignore the timing chain angle. I could show you pictures of what can happen as the timing chain tensioners wear down. I have a new motor in my 2000 for that very reason. What you could be seeing are the early warning signs.
 

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Discussion Starter #14
Haha! You are right. Not random misfires but from what I did read it does cause the fuel and air mixture to mess up which does cause the hesitation I am having with mine. I too am starting to realize that there is no easy fix for these problems. Although this is a drain on the pocket and not having a Mustang that runs at 100% does suck. This has been an enormous learning experience and I have learned how to do a whole battery of things on my own without a mechanic. I must say that even though the problem persists I still am happy I have learned so much by being a do-it-yourself-er. Back to the issue at hand I had some extra money left over, $20.00 on my autozone card, and 10% military discount so I decided to try my theories out to see. The car has run better than it has this entire time. Upon inspecting my IAC I did find that it was cracked in several places on that little bar thing in the middle. Although this was not source of the problem the car did improve. My code reader is not reading cylinder misfires anymore, strangely enough, but it does still read a vacuum problem because as my dad was driving it I monitored the data the OBD2 was giving me. My next endeavor will be to open my oil filter and search for the metallic parts as you suggested. One of my bosses has a Saleen Mustang, fourth generation with a Paxton supercharger, that thing is a beast. I bring this up because he told me there is a guy here in Central Florida that is the go to guy for mustangs. He does dyno tuning and is the expert on mustangs in this area. I have been thinking of taking it to him to see where my problem is. I have a theory that my vacuum leak is coming from my intake manifold. Thank you for all the help, by the way. You have and continue to educate me on my car and the way things run. If I am ever in Houston drinks are on me. I have some Marines out there so I may be around in the next few years. What are your thoughts on this new information? I have heard that the intake manifolds are another part that was not made that well and can cause problems.
 

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Discussion Starter #15
Also, please let me know if I was right about the problems the IAC can cause. I am still learning but what I wrote is my general understanding of what problems can cause.
 

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Genltemen, I hate to jump in on this thread with someone as smart as Mr. Burns but I have a couple of questions;
1) Are your back or downstream o2 senors turned off or just "tricked with the MIL eliminators?
2) Is it possible that the wiring to each one is crossed?
3) Do you still have your old MAF sensor that you could put back on and see if the problem changes?
4) After installing the old MAF, could you please disconnect the negative off of the battery and pull your headlight switch ON, let the car sit overnight and then turn headlights OFF and connect battery negative, start the car without touching the gas pedal and let it run for 15 mins without touching the gas. Then give it a drive and see if anything changed. Good Luck!
 

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Thanks for the offer of drinks.

Consider for a moment the IF it improves after replacing the IAC, don't you recall what else was done? (hint...tighten the CKP sensor).

So which repair made the difference????

Regarding the vacuum leak. Here's the thing about vacuum leaks, there are tons of places for them to happen. Most guys only find the super obvious ones because:

A- they don't believe they have one so they don't really "look".
B- they don't have to tools to find a difficult vacuum leak anyway.
C- They don't believe that that tiny little crack in such and such line would actually cause so many problems.
D- They don't want to think about the work involved with fixing a possible intake vacuum leak.

So regarding your theory about the IAC. On the black vented IAC, the purpose of the black vent is to provide air to start the motor. Once the motor is running and creating a vacuum, the black vent is designed to close.

Vacuum leaks can be a real PIA to find. That's where a professional smoke test or a propane based leak detector comes into play.

Note, I don't like spraying carb/choke cleaner on an intake to find vacuum leaks. The cleaner could damage the gaskets and thus trading one problem for another.

What a lot of ppl don't understand is why the Black vent IAC can't be cleaned. It's because of the internal springs and such needed to close off the vent.

So.... if the IAC doesn't close and allows unmetered air to enter, then it very well will affect the motor.

Will it cause misfires? Is it the cause of your misfire? I don't think so.

WHY?

Because any root cause such as excessive EGR flow, upper vacuum leak, MAF problem (ect) would affect ALL cylinders.

Since your symptom is limited to cylinders #1 and #5, doesn't it make sense to focus on the things that could affect only #1 and #5?

IMO, this rules out an O2 sensor problem for the same reason.
 

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Just my 2 cents, You said your car sat for four years in your driveway, was there any signs of mice being in your car or under your hood, they will chew on wire's, your problem may be a short in wiring somewhere, missfire on 1 and 5, new cops, how about checking the wiring for these. Take a good look behind the right kick panel where the computer is, also take a good look behind center console and glove box. I have found in 20 years of fixing cars and planes, when you are chasing a problem this long it's usually wiring. Hope this helps and good luck.
 

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Discussion Starter #20
Thank you gentleman for all the suggestions. I did look at all the suggestions but I must say that I believe Mr. Burns is spot on. I did disconnect the battery from the car just to see what happened but same problem. I am taking it to a mechanic for that smoke test tomorrow so I will be able to find the vacuum leak. I will keep you guys posted. No signs of mice making a home in my vehicle. The only thing that has lived there are wasps. They have created their former homes in my car. I have already cleared out all the nests and there does not appear to be a short in electricity anywhere. Once again thank you for the suggestions and explain the IAC to me. I will keep you guys updated.
 
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