02 mustang misfire

mesho

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Apr 8, 2019
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I've been having this problem ever since I bought this mustang I changed few stuff, but I still have it. Hopefully you guys can help. I have a mustang 2002 3.8L coupe and it has the weirdest misfires at times. In the morning when the engine is cold It starts perfectly and It has no problems what so ever, but during traffic and when the engine is warm if i'm driving lower than 20mph the car seems to misfire and shakes a little and when I hit the gas pedal it feels like i'm doing nothing it doesn't take any gas like for few secs then after that it runs. When I get out of the traffic and I go back to the normal speed which is 55mph the car no longer have misfire nor any type of shaking. The 2nd misfire that I get is when I go to the grocery store and turn off the car for about 5-15 mins. When I get back to the car and turn it on it shakes and it seems to have a misfire going on the rpm keeps going under 1 and its not stable at all, but when I push the gas pedal for few secs or mins it depends the car goes back normal with no misfire at all also I smell a very odd smell its like a type of gas, but not gas I don't know how to explain it. That's pretty much it I've been having this problem for about good 2-3 years. The thing is sometimes this car runs normal for like a solid 3-4 months then it goes back into misfiring. Keep In mind that sometimes It doesn't take any gas and it just shuts down I have to wait for the engine to cool off it won't start at all.
UPDATE-- I looked under the hood today because the car was acting up again.The antifreeze coolant somehow came out to some part of the engine and a little on the battery so there's that.
I check the codes this morning here's what I got : p0316 - p0456 - p0174 -p0304.
- The things that I've checked/ changed is :
1.fuel injectors
2.Spark plugs / wireset / coil.
3.Air filter/ IAC.
4.Camshaft/Crankshaft position sensor.

Any help is appreciated thank you in advance!
 
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wmburns

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Aug 14, 2009
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In the morning when the engine is cold It starts perfectly and It has no problems what so ever, but during traffic and when the engine is warm if i'm driving lower than 20mph the car seems to misfire and shakes a little and when I hit the gas pedal it feels like i'm doing nothing it doesn't take any gas like for few secs then after that it runs.
IF this were my car I would be attempting to rule in/out:
  • Weak ignition system. It seems to me that your problem happens during increased load which is more difficult to ignite.
  • An intake vacuum leak
  • An exhaust leak
  • Excessive EGR flow.
The next thing I would to is to test the engine vacuum. Low engine vacuum could play a factor in a motor's ability to take gas. What's a possible cause of low engine vacuum? How about poor base engine health? To that end, perform a compression test with leak down test on the cylinders with low compression.

Do you know the long term fuel trims (LTFT) when this problem happens? What about MAF? EGR flow? Fuel pressure? Do you have an ODB2 scanner? If you did it might make short work of this problem. Here's information on an affordable Windows based unit.

ForScan ODB2 scanner w ELM327 USB

Do yourself a favor and make sure that your alternator is in tip top shape. A bad alternator diode can "cause" excessive AC ripple. This in turn can cause symptoms of a bad cam sensor.

Howto perform charging system voltage drop test
 
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mesho

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Apr 8, 2019
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IF this were my car I would be attempting to rule in/out:
  • Weak ignition system. It seems to me that your problem happens during increased load which is more difficult to ignite.
  • An intake vacuum leak
  • An exhaust leak
  • Excessive EGR flow.
The next thing I would to is to test the engine vacuum. Low engine vacuum could play a factor in a motor's ability to take gas. What's a possible cause of low engine vacuum? How about poor base engine health? To that end, perform a compression test with leak down test on the cylinders with low compression.

Do you know the long term fuel trims (LTFT) when this problem happens? What about MAF? EGR flow? Fuel pressure? Do you have an ODB2 scanner? If you did it might make short work of this problem. Here's information on an affordable Windows based unit.

ForScan ODB2 scanner w ELM327 USB

Do yourself a favor and make sure that your alternator is in tip top shape. A bad alternator diode can "cause" excessive AC ripple. This in turn can cause symptoms of a bad cam sensor.

Howto perform charging system voltage drop test
Thanks for replying. For the vacuum leak I have it checked out already and fixed the issue, but unfortunately It didn't fix my problem. Also for the exhaust leak one of the exhaust manifold was broken and I ended up buying a new one and installing it, but yet again unfortunately It didn't fix anything at all. For the EGR flow what should I do to make sure it's fine ? once again appreciate the reply!
 

mesho

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Apr 8, 2019
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Update : this what happens every time almost when I go for a stop turn off the car then turn it back on in about 10-15 mins at first it works but after that rpm goes lower than 1 and it feels like it’s starting to die I hit the gas pedal but the car won’t take any gas then it just dies and now I have to wait for the engine to cool off then I can start it again. here's the video : View: https://streamable.com/vrgzy
 
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wmburns

SN Certified Technician
Aug 14, 2009
5,361
417
164
Houston Texas
I stand by my earlier advice regarding the use of an ODB2 scanner. Monitoring just LTFT's can give direction. Otherwise, I gave you a bunch of possible stuff to rule in/out. Or resort to guess and/or more "parts changing".

Regarding EGR flow, the easiest way is to monitor EGR flow as reported by the DPFE sensor. Otherwise the low tech method is to block the EGR port and see IF there's any improvement.

Have you done anything to ensure that it's not something simple like a bad alternator diode? The V6 is highly affected by the cam (CMP) sensor. If not installed exactly as the manual or excessive AC ripple can cause problems.

Does this car have under drive pulleys? The V6 is also bad about cracking crank dampers. This will create an unstable CKP sensor signal.

Also note that one of the DTC calls out a leak in the EVAP system. Sometimes a stuck open vapor management value will crate a vacuum leak like situation.

P0316 - Misfire Occurred in the First 1000 Engine Revolutions
P0316 code will be set in addition to any type B misfire DTC which occurs in the first 1000 revolution test interval, following engine start​
  • Damaged CKP sensor
  • Ignition system
  • Fuel Injectors
  • Running out of fuel
  • Fuel Quality
  • Base Engine
  • Damaged PCM
Freeze Frame Data and the P03XX DTC will also be stored, indicating in which cylinder the misfire occurred.​
 
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mesho

New Member
Apr 8, 2019
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I stand by my earlier advice regarding the use of an ODB2 scanner. Monitoring just LTFT's can give direction. Otherwise, I gave you a bunch of possible stuff to run in/out. Or resort to guess and/or more "parts changing".

Regarding EGR flow, the easiest way is to monitor EGR flow as reported by the DPFE sensor. Otherwise the low tech method is to block the EGR port and see IF there's any improvement.

Have you done anything to ensure that it's not something simple like a bad alternator diode? The V6 is highly affected by the cam (CMP) sensor. If not installed exactly as the manual or excessive AC ripple can cause problems.

Does this car have under drive pulleys? The V6 is also bad about cracking crank dampers. This will create an unstable CKP sensor signal.

Also note that one of the DTC calls out a leak in the EVAP system. Sometimes a stuck open vapor management value will crate a vacuum leak like situation.

P0316 - Misfire Occurred in the First 1000 Engine Revolutions
P0316 code will be set in addition to any type B misfire DTC which occurs in the first 1000 revolution test interval, following engine start​
  • Damaged CKP sensor
  • Ignition system
  • Fuel Injectors
  • Running out of fuel
  • Fuel Quality
  • Base Engine
  • Damaged PCM
Freeze Frame Data and the P03XX DTC will also be stored, indicating in which cylinder the misfire occurred.​
I've tried premium fuel for about 2 weeks and it didn't fix it. Also I've had a few bad fuel injectors that I had them changed and cleaned them at least twice. I never let the tank empty like never, but once it drops a little from the middle gauge the car seems to hesitate a lot. If you can check the video above maybe you will get a better idea. Once again thanks for replying!
 

wmburns

SN Certified Technician
Aug 14, 2009
5,361
417
164
Houston Texas
Trouble shooting today's cars is either:
  • A data driven activity.
  • A trial and error activity.
If this were my car I would be looking a things like:
  • fuel pressure
  • MAF flow
  • RPM's
  • IAC duty percent
  • open closed loop.
Looking for PID's that are out of "normal" ranges.

1996+ Crank with no start check list

Follow the recommendations and test in the check list.

Perform a compression test to measure the motor's base health.