SteelerNation82

Hi MF,

Sorry for long post, but here are all the specifics and details outlining my problems.

Specs: '00 V6/Auto, 100k miles, stock
What's been done: EGR Press. Sensor, EGR Valve(no change), Air filter, Plugs/Wires, Fuel Filter, Ignition Coil, Battery Terminals

It already had CEL for P0401 & P0402 and exhibited the conditions outlined below.

Looking for a bit of guidance or suggestions here with my problem. Symptoms:
-Car is hard to start when cold, for example after sitting overnight and I go start it up, it has to crank over for a few seconds until it comes to life. On the flipside, when warm or after I've been driving it and park it, go start it up and fires right up.

-Exhibits rough idle, sounds like it's misfiring very subtle. If I rev it either in P/N the engine shakes quite a bit between 1500-2500RPM or so then seems to smooth out when revved higher.
-Today I noticed after I let it warm up a bit that there is a faint tapping/fluttering sound which can only be heard in very low RPM's when I modulate the throttle plate.

-While driving, the entire car shudders within that same RPM range no matter what gear. Hwy cruise 55-70 mph steady throttle the entire interior shakes. If I increase speed to 75+ it's much smoother. If I let off the gas while cruising speeds it doesn't seem to exhibit the vibrations. Remember the flutter mentioned above? It seems that I can replicate it and hear it faintly when cruising on the hwy under very light load coming from the pass. footwell.

I've started checking for vac leaks but everything seems to be hooked up and sealed. Will check over again over the weekend.

Again sorry for the long winded post, but figure I'd get all out at once and be as specific as possible. Thanks to anyone taking time to read and reply with suggestions.

Derf00

Have you changed the fuel filter?

Also P0401 and P0402 while related to the EGR valve can also have something to do with the DPFE sensor on your car. Is that the EGR Press. Sensor you mention?

Follow the EGR valve vacuum line until you get to a plastic sensor with a wire harness and another vac line going to it, that's the DPFE sensor. If you've replaced it already and the EGR valve, it could be your EVAP system.

In the front passenger side wheelwell (behind the splash assembly) there is a pump system there. I recall having the one my 00 V6 replaced around 70K because it was failing. It's classified as a smog pump and is electric.

SteelerNation82

Hey Derf,

Fuel filter was replaced, and yes that EGR sensor mentioned aka DPFE was replaced with the updated Motorcraft plastic version. The hoses and lines checked out ok.

Thanks for the tip regarding the smog pump, I'll have to check that out this weekend.

SteelerNation82

Edit, if you were referring to this sensor, no I have not replaced it.


I replaced this one -EGR Pressure Feedback Sensor aka DPFE , the original was aluminum and have been told very common failure to throw those codes.

corker

Sounds like you have a couple of different problems. You will have to investigate the hard cold starting a little further. However, the missing and engine vibration you are feeling may be attributed to a bad harmonic balancer. I had a similar issue with my son's 2000 mustang 3.8L v6. I was chasing a miss on the engine and I couldn't find any cause - no codes (although you have EGR codes) and all components in good shape. It turned out the rubber insulator on the harmonic balancer was dry-rotted and allowed the pulley section to rotate a small amount. The weight on the balancer was no longer in the correct position to balance the crankshaft and the vibration developed. I put a new balancer on and the engine smoothed right out. You can take a look at the balancer, but it was almost impossible to see where it was bad. A new balancer (dealer only) cost ~$325 - you can try one from the junkyard, but it won't be long before you will have to replace that one.
I'd post a few pictures, but the site doesn't show the means to post.
Corky

Chromeshadow

100K miles on the 3.8 is not much, I put 190K on mine and it still ran perfectly.
My electric smog pump failed, it did not affect the engine-just got an error code. It did not affect starting when cold. (not to say this is not causing your cold start prob)
Most of the time if you have a miss-you will not feel it over 50 mph. If your engine pulls strong but vibrates -I'd look at Corkers suggestion. Vibration at a repeatable engine rpm sounds like something out of balance. Have you checked the serpentine belt for cracks? Any bent pulleys?

SteelerNation82

Belt looks fine, although at this point I may replace it for good measure since I've done an otherwise complete tune up. I purchased this car about a month ago cheap and knowing it needed some work. The previous (original owner) had the car sit for some time, always disconnected the battery. I had the car out yesterday on the highway and noticed it seems to run a bit smoother, doesn't seem to shudder/vibrate as much. Maybe it just needs to be driven.

Of course, the cold start issue still needs to be looked at. Going to test the battery (it's aftermarket but no idea when it was replaced), check for vacuum leaks further and go from there. My E36 M3 I previously owned used to have a similar issue on cold startup, turned out to be a leaking intake manifold gasket(vac leak).

I might gamble and also change the transmission fluid/filter this fall. Never been done from what p/o told me.

Derf00

Yeah the DPFE is the one in the second picture. I'm not familiar with the one in the first picture.

I hadn't thought about the Harmonic Balancer, yes, they can be problematic and will make the car feel like its missing (yet throw no codes).

If you do look at that definitely pay attention to which version you have. In 2000 they had two different ones available. Internally balance and externally balance. Depends on the build date.

Here's a link to a pic to tell them apart: Essentially, the one that has a thick/thin part on the balancer is externally balanced. The one where the diameter is all the same is internally balanced.

http://www.rpmoutlet.com/images/asp820117stock.jpg

https://www.v6mustang.com/attachment...al-jpg.145263/

SteelerNation82

I definitely have the externally balanced but haven't had the chance to really inspect it up close yet. I need to get the car jacked up or on ramps to really see, maybe next week I will get to that.

SteelerNation82

Update:

The cold starting issue appears to be gone. Only things I have done were:

-Pulled the plugs and rechecked gap (.054) they were all clean(Motorcraft DP replacements, less than 1k miles). #5 had a black spot on the insulator tip due to me crossing the #5&6 wires when I originally replaced the plugs and starting the car up then shutting down immediately. Not sure if I should replace that one? I swapped that plug w/ the #4 just in case if I decide to change it out to make it easier.

-I've run a full tank of 93, then dropped in some techron fuel system treatment and added that to a half tank of 87. It's still in there currently.

I replaced the entire length of fuel vapor hose that runs off the upper intake manifold down into the purge? valve in the pass fender as it was a deteriorating mess. All the other hoses in there and the ones going to the smog pump looked fine.

This past weekend I got under the car and checked out the harmonic balancer and the inspected the rubber seal seen behind it and it looked good, no signs of cracks or separation. I picked up a new gates belt which I installed. When I removed the old belt I checked out all the pulleys and ran the engine breifly w/o the belt and that shudder/vibration is still present. Put new belt on and took it out for a drive, still acts the same. I'm convinced it's a miss because you can hear it in the exhaust at idle and off idle. If I rev it up slightly in P or N the exhaust will pop a little bit on rev down.

I have a Cen Tech OBD II scanner that reads live data which I'm still playing with but there are no codes present and it doesn't show any cylinder misfires when I run the test for it with the KOEO. Car also passed NJ inspection 2 weeks ago in the current running condition.