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PLEASE HELP ME EMERGENCY Pt Gt Problem STUMPED! HELP!

14K views 34 replies 16 participants last post by  chuzz 
#1 ·
HI I am at a loss here. Please take your time and read everything I write here, so you will know excactly where I am at.

I want you to know I really Appreciate any help or suggestions and please don't take offense but
PLEASE READ THE ENTIRE POST before suggesting any theorys.

I have a 2003 GT Car always ran good with no problems before.
Then a week ago one day while driving I had problems with the car losing power and my engine light started blinking..It was stumbling and almost seemed like it wanted to die and when I stopped it started shaken and chockin then the engine light came on. Got home and parked it Next day started it and did the same thing but this time my engine light was blinking so I hooked it up to a DBR II scan tool and got P0172 fuel trim System Rich Bank 1 and "P0302 Cylinder 2 Misfire Detected"
A friend suggested I change the Plugs, Wire, Coil Pack in that order..

So I had on planning to put my stage 1 that I bought a few months back.
So I figured if I am going to change the plugs and wires then I will just install all of the parts while I am there.

So this is what I did.

Changed PCM to Stage 1
Changed Injectors
Changed upper/Lower intake to the plastic ones from a 06 GT
Changed Coil pack from a 03 (used and working)
Changed spark plugs (NGK) gapped at .38
Changed Plug wires to MSD 8mm
Changed MAP sensor

(recently just changed the Fuel pump)

When I was done...she fired up the first crank with no problems. Then I drove it home from my buddys shop which is about half a mile from my house. I didn't have a problem at all with the car. She was running beautiful!

Next day I took her out drove for a good 45 minutes with no problems and then I came to a stop sign and it started shaken and felt like it was going to die. I started going again and it ran fine until I stopped again. It felt like the same problem I had before I changed everything.
Today I used my remote car starter and had no problems at all the car idled fine; let it run for about 10 mins before I left. So I left and got about half a block and she started acting up again..turned around went home and parked it. Went and did some errands with my other Pt; got home and started the GT again but this time it was shaken/dyin right away.

the engine light hasn't come on and isn't blinking like it did before. Checked to see if there were any error codes that came up; but there isn't any.
No smoke, No backfiring, No Engine light on or blinking, No Codes, just shakes and feels like it's going to die; just like it was doing the first time, before I changed everything.

Yesterday I talked to my mechanic friend (sort of) He told me it is the fuel pump. So I got him to put a new one in it and again it ran fine. Then this morning I went out and took it for a drive and it started doing the same thing again! I noticed though it runs alright until I punch it/floor it or give it lots of gas at once then it starts doing the same stuff all over again. I am at a loss????? It is driving me nuts and I hate taking my car to a shop to get it fixed. Anyone have any ideas? It's going to snow the next couple of days, so I really want to fix this soon and I can't really afford to take it in..

Thanks
 
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#2 ·
What reason was given for fuel pump failure? Was fuel pressure measured while the car was running poorly? If foreign material like water is in the tank, it can cause the new pump to have problems also.
The new PCM may need to be initialized and run the adaptive numerator before it can report engine misfire, etc. A car shouldn't be driven with a flashing 'ck eng' light as severe cat damage can occur. If the cat element has broken up, it can cause intermittent loss of power. It takes a long time to set a cat fault code.
Did the old #2 spark plug show any fouling problems? How do the new plug tips look after it runs poorly?
 
#3 ·
With no codes to give you a clue, it starts to become a guessing game unless you can hook up equipment to monitor various sensor outputs or line voltage inputs to the sensors when the problem occurs while you are driving. A couple of good guesses include an intermittant crank position sensor or a bad TPS. Both can become intermittant, but provide enough of a signal so that the diagnostics can detect a hard failure and set a code. You should still get the random misfire code eventually. As much as you have spent, throwing in a CPS or a CKP sensor would not add much to the overall costs so far. Usually a TPS problem will show up at one particular speed, so I would hold off on that one. Prior to replacing anything, cleaning all connections to the sensors with contact cleaner is a good approach as well as checking for loose grounds.
 
#4 ·
He DID get codes, indicating a bad O2 sensor and a cylinder misfire. I would have changed the O2 sensor first, instead of shotgunning it.

Does it ever act up within the first 1-2 minutes of a cold start? If not, that's another clue that it's the O2 sensor, as it's not used on cold starts until it heats up, which takes just about 2 minutes.
 
#5 ·
Thanks for the imput guys! Started it up this morning; it did it for a couple of minutes right at the start,,,. Let it get warm....
held the gas to bout 1500-1800 rpm then took off for a ride to the mechanic shop. Before I made it to the shop it was acting up again but soon as I got to the mechanics shop (about 10 mins away)..lt stopped acting up. Tried to explain to him the deal but it wasn't doing it now. I know it's not a cold/hot issue because it happens in the colod and when it's hot here. Anyway We hooked up a live data stream and took it out again and drove the piss out of it for about 15 mins and nothing! Everything read normal and no codes thrown. So no point on leaving it there so he could guess too. Bringing it home and going to wait until it does it again and then I am driving it straight to the shop again. I am getting the feeling it's a wiring issue somewhere and I am sures the heck not going to pay $113.00/hr for them to check all the wireing because that could take a whole day until they pin point it.. I'll do it myself in the snow if I have to. :(
 
#6 ·
Data recorders are great for intermittent problems like this. Do they have a data recording tool that they would let you borrow overnight or a day or so?
We would let customers take our Co-pilot for as long as it took to capture data needed to help diagnose a running problem.
It will prevent wasted time and frustration trying to look for a problem that isn't even there at the time and putting on parts that don't resolve the issue. The Co-pilot will hold 3 separate 90 second recordings of any selected engine sensor/Input/Output group that one wants to observe.
It can save both time and money and remove guessing and speculation.
I imagine that your new problems may be the same as your old problems. Diagnose for fuel system rich and #2 cylinder misfire.
 
#7 ·
In your first post, all the events you described were with the engine warm, the way you explained it. In your last post, you said it happens "right at the start", also. And just to be sure, what I was asking is, does it happen immediately upon a cold engine start (regardless of outdoor temperature), or does it take at least a minute or two after the engine starts?

Sounds like there's too much fuel going in. And that can trip the O2 sensor code that you saw, as well as a misfire code. It can also quickly destroy the catcon, as stated. So now you need to find why there is excess fuel. Possibilities include a stuck lifter, a burned valve, a stuck injector, a bad fuel pressure regulator.
 
#8 ·
In your first post, all the events you described were with the engine warm, the way you explained it. In your last post, you said it happens "right at the start", also. And just to be sure, what I was asking is, does it happen immediately upon a cold engine start (regardless of outdoor temperature), or does it take at least a minute or two after the engine starts?

Sounds like there's too much fuel going in. And that can trip the O2 sensor code that you saw, as well as a misfire code. It can also quickly destroy the catcon, as stated. So now you need to find why there is excess fuel. Possibilities include a stuck lifter, a burned valve, a stuck injector, a bad fuel pressure regulator.
What I said was "it did it for a couple of minutes right at the start" I guess what I meant was.... it did it this morning right away as soon as I started it. Here's the thing.....it is intermittent. It doesn't matter if the car is warmned up or not or if it's cold or if it's hot out. Most of the time it starts without any problems... then out of no where when I start it....it acts up and the same goes when I am driving it...out of no where it happens. Although it does seem to happen more often when I step on it. Yes I believe it is a fuel issue definately; but a wiring issue causing it. Like mabey one of the sensors that cotribute to the fuel getting there or the right A/F mixture? It feels liike it is starving for fuel, it doesn't seem like it's getting too much. Let's put aside the Codes that came up with my old pcm for a minute as I am not getting any codes at all with the NEW installed parts. There was nothing out of the ordinary with the live data stream we ran for 15 mins today while driving it. The car just would not do it when we had it hooked up.
PS you keep saying o2 censor code? What code is that? The only codes I got are the ones mentioned in the first post and I didn't get any o2 sensor code that I am aware of?
Thanks Bob


Data recorders are great for intermittent problems like this. Do they have a data recording tool that they would let you borrow overnight or a day or so?
We would let customers take our Co-pilot for as long as it took to capture data needed to help diagnose a running problem.
It will prevent wasted time and frustration trying to look for a problem that isn't even there at the time and putting on parts that don't resolve the issue. The Co-pilot will hold 3 separate 90 second recordings of any selected engine sensor/Input/Output group that one wants to observe.
It can save both time and money and remove guessing and speculation.
I imagine that your new problems may be the same as your old problems. Diagnose for fuel system rich and #2 cylinder misfire
.
They told me to leave it with them and they would drive it untill it happens but I figured I might as well just take it and when it happens I would drive it there and we could hook up the data streamer. I did'nt even ask to see if I could take it, but that would be the cats behind.... as yes it is INTERMITTENT and feels like the same problem as it did before I changed everything. The only difference is---No engine light and No Codes. I have driven lt long enough that it should be throwing a code, you would think.?

Thanks!
 
#9 ·
I would think that a PCM should learn the adaptive numerator and be ready to run monitors and set fault codes after a few miles of driving. Adaptive numerator is learned after an accel/decel event:
http://books.google.com/books?id=-njiYtrSJqsC&pg=PA275&lpg=PA275&dq=learned+adaptive+numerator&source=bl&ots=uVs4WW08Fj&sig=h4TXIrzoA2-DTQp791-1rCMBbVk&hl=en&sa=X&ei=r3mbUKPsBIjf0gHDlIHgBA&sqi=2&ved=0CCsQ6AEwAA#v=onepage&q=learned%20adaptive%20numerator&f=false .
It gives the PCM a baseline to measure crankshaft speed and only then can it then determine cylinder misfire.
Where did this Stage 1 PCM come from? Has programming been tampered with? Are there any EPA-exempt stickers on it? Some 'racing' PCM programs have very limited self-diagnostics.
You may want to swap the old PCM back in until you can diagnose the problem.
The fuel trim is probably try to peg itself lean in order to protect itself from an over-rich mixture. A misfire will make it worse as raw oxygen is being 'sniffed' by the O2 sensors as it passes by the sensor tip.
 
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#32 ·
. . . You may want to swap the old PCM back in until you can diagnose the problem.
The fuel trim is probably try to peg itself lean in order to protect itself from an over-rich mixture. A misfire will make it worse as raw oxygen is being 'sniffed' by the O2 sensors as it passes by the sensor tip.. . . .
I would tend to follow I C suggestion. Too many parts swapping causing too many variables to change in trying to diagnose this problem.

As mentioned the short term fuel trim is a key monitor. If there is a vacuum leak that is causing the air - fuel mixture to become too lean, the oxygen sensor will notice that and report an extremely lean signal to the PCM. The PCM in its internal logic then increases the fuel injector pulse width incrementally to get the oxygen sensor to report a rich air fuel mixture. But an extremely lean mixture will cause the PCM to increase the pulse width on the fuel injection to a high level (fuel trim 20 - 30% positive) which can cause poor running and drivability. So you need to look at the oxygen sensor signal along with the short term fuel trim value. If the oxygen sensor is constantly less than 0.45 volt and never goes above 0.45 volt (always lean) and the short term fuel trim is constantly pegged at positive 20 - 30% (and never drops below 0%) then a vacuum leak is a possibility. Incidentally if there is an intake vacuum leak, as you increase the throttle opening from idle to 1500 - 2500 rpm, the short term fuel trim if pegged at positive 20 - 30% will decrease and move towards a more normal range (less than 10%). That is a definite clue if the situation is caused by an intake manifold leak.

It is also possible that you could have an exhaust leak near the upstream oxygen sensor. More oxygen in the exhaust stream (external leak) fools the oxygen sensor into reporting a lean air - fuel mixture to the PCM. And you get the same scenario as mentioned above; the PCM incrementally increases the pulse width of the fuel injection (richer mixture) to try and get the oxygen sensor to report a rich air-fuel mixture condition.

Monitor the oxygen sensor readings and short term fuel trim at idle and at 1500 - 2500 rpm and report the values.
 
#10 ·
P0172 is an O2 sensor code. Either the sensor is bad, or it's good and reacting to a rich condition. Since it happens right away on a cold start, and the sensor is ignored during that time, it's likely that it's just reporting a rich condition and has not failed.
 
#11 ·
It would be important to test the fuel pressure, especially when it is acting up.
The new fuel pump doesn't guarantee correct pressure. The fuel pressure regulator could be defective or wrong or there could be a problem inside the tank.
 
#12 ·
It would be important to test the fuel pressure, especially when it is acting up.
The new fuel pump doesn't guarantee correct pressure. The fuel pressure regulator could be defective or wrong or there could be a problem inside the tank.
My Dad actually suggested that there may be condensation or water or something in the tank that is causing the problem. I forgot to mention I did put a half a can of seafoam in the tank(only half cause I only had half a tank of gas in it) yesterdays.I took it for a spin around the block hoping to get it to run through the system. Mabey he was right? Because when I started to go to the mechanic shop it was acting up and then just before I got there it went away like I had posted above. Mabey it took that long to get through the whole system and just by coincedent it did it's job just before I got there(hence that's why we coudln't replicate the problem?) Ahhhh whom I kidding ; what do I know lol... Today it is snowing like Christmas
and we are expecting like 15cm+................ but I am going to start it up and see what happens...I'll let you guys know.. I wish you guys could come for a ride when it happens. If it does happen I am going to take a vid of the engine. I did that before when it was really bad but I ended up deleting it
Thanks!
 
#13 ·
How many miles do you have on that PT? I know it sounds like a stupid suggestion, but have you had the catalytic converter checked? That sucker could be stopped up and if that happens you can have all kinds of problems.
 
#14 ·
It just turned over yesterday to 114,000km. I am going to do a resistance test on the wires going to the fuel pump..because it is so intermittent I got a strange feeling the wire has a break in it or fray that is causing the problem....going to wait until next week cause the weather is supposed to be in the + range I think like +3 lol at least it might be a little warmer when I crawl under the car arrrrg! (I don't have a garage that's what makes it so hard for me) I don't have any friends with a garage either and I don't want to drive it to U-wrench (they rent indoor space to work on cars..basiccaly a garage with lifts and tools ect...) It's quite anways from my house and I don't want to take the chance when the weather is so crappy right now.

PS no suggestions or thoughts are stupid at this point.

Thanks!
 
#15 ·
That wouldn't trip a misfire code on just one cylinder. I'd work backwards from cylinder 2. And test compression all around.

A friend just had an issue like this, turned out to be a burned exhaust valve. He found it through a compression test.
 
#17 ·
I'd buckle down and find a really good mechanic with more than 10 years of experience that you can trust, google and find some mom and pop shops and look at their reviews. at this point shotgunning it isnt working. I have seen on Scanner Danner's youtube page how a bad ECM ground can cause this, so it wouldnt hurt to check and maybe clean up where it's grounded

and you did change the PCM, so I would start DEFINITELY look there
 
#18 ·
Sounds similar to an intermittent problem I had with my old Stratus with a 2.4L. It started to buck and choke, and then would smooth out. In my case, it was broken insulation on the wires right at the cam position sensor connector. I taped them up to insulate them, and the problem never appeared again. It may not be the cam position snesor in your case, but look at areas where the wires enter connectors and bend; or where some of the plastic protective sleeving may have rotted and broken away.
 
#19 ·
The one weak link I see in everything done is a used coil.
What are the chances of 2 coils being faulty (my original and a used one that came out of a working running motor at time of salvaging it)

I'd buckle down and find a really good mechanic with more than 10 years of experience that you can trust, google and find some mom and pop shops and look at their reviews. at this point shotgunning it isnt working. I have seen on Scanner Danner's youtube page how a bad ECM ground can cause this, so it wouldnt hurt to check and maybe clean up where it's grounded

and you did change the PCM, so I would start DEFINITELY look there
Yes I changed the ECM but this problem started with the old one in it...(everything.... harness,ground ect.. was double checked when we installed the Stage 1 ECM) I'd love to find a good mechanic but it is not going to help unless the car does it when I see him.....that's why the last place I took it could'nt help me...arrrrrg

Sounds similar to an intermittent problem I had with my old Stratus with a 2.4L. It started to buck and choke, and then would smooth out. In my case, it was broken insulation on the wires right at the cam position sensor connector. I taped them up to insulate them, and the problem never appeared again. It may not be the cam position snesor in your case, but look at areas where the wires enter connectors and bend; or where some of the plastic protective sleeving may have rotted and broken away.
Yeah I thought about that but the symptoms don't sound like the CPS and it is not bringing up any codes to suggest it is. Soon as it gets a little warmer I am going to check all the connections (wires) that I can see or get to...

Thanks Guys!!
 
#20 ·
Please keep us posted on anything you find. Alot of this info can really come in handy in the future.

Best of luck.

Doug
 
#21 ·
If you believe the coil is good then I would also go back to stock copper plugs and gapped to the spec on the sticker on your car. I had put double platnium in my 07 and on a trip from Atlanta to NY I fouled out two spark plug at the South Carolina and North Carolina boarder at 2a.m....... The dealer that installed the correct plugs said that platnium plugs do not fire as hot as the copper plugs do which caused the misfire. I would do a Seafoam treatment. If you do not know how to do it just go to you tube and watch some of the videos.
 
#22 ·
If the PCM has chosen the #2 cylinder failure code more than once. I would look very closely at the #2 cylinder.
General fuel or spark fault codes will pick and choose between the 4 cylinders at random.
 
#24 ·
New Allpar user Mel Stephenson writes:

"I had similar problem w/05 non turbo touring, I put in new Mopar crankshaft positioning sensor and finally it is running fine. Make sure you get Mopar or you might have to do it again. You have to take out air cleaner, then remove battery, then remove bracket with 5 bolts, then take starter loose with two bolts.....then slide starter to your left...and finally you can get at and remove and replace the sensor....still not easy....cost for part is about $50."
 
#26 ·
Copper plugs offer a much better burn. Copper conducts electricity and heat better than other metals. Platinum spark plugs may outlast the plug wires. The recommended change interval for copper is 30K miles (50KM) and platium is 100K miles (160KM).
Platinums can cause driveability issues in some cars. Iridium is probably overkill. Always use the spark plug type recommended on your underhood label or in your owners manual for best results.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2583605

http://www.carsdirect.com/car-repair/copper-spark-plugs-vs-iridium-and-platinum-understand-for-top-performance
 
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