Misfire/lean issues on Ford 4.2- thoughts?

S

Stationwagonguy

Forum Member
OK, this all happened during a rain storm last wednesday. I was driving home in our van, and I hydroplaned it through easily a foot of water. It never stalled, never died, but it began to misfire immediately. I drove it home, let it sit overnight, and tried to drive it the next day, and the CEL started flashing under acceleration. Waited a few more days, still the same deal. So I finally took it to an autozone, and used the scanner there. #4 is misfiring, #1 and #2 are running lean.

Although I knew it wasn't going to help, I changed the plugs because they had about 80,000 miles on them, and it still runs no differently. I checked all the plug wires to see if they were on, and I pulled them individually to check if they got water in them. Nothing. I couldn't see inside the coil, and that may be my next route. However, I'm being screamed at to change the plug wires (which are also not the source of the issue), but because it's not really my car and he's paying... whatever.


I don't know, does anyone else have any thoughts as to what could be going on here? I understand a misfire- but how the hell did it start running lean? It's a 4.2, coil pack, in an E-150.

Any help is much appreciated.
 
The lean issude may be caused my clogged EGR ports in the lower intake. they can cause a miss. We had a whole bunch of them come in at a shop I used to work at, 97-02 f-150s were the worst. 4.2L is a 4.2L tho.....


if the coil/plug/wire swapping doesnt help..
 
Sean said:
Got a scanner ? Check the DPFE voltages.
Click to expand...

What are DPFE voltages? :shrug: I don't personally have a scanner, I have to borrow one again.

And doesn't the EGR port clogging cause it to run rich, not lean? I'm confused.

Someone else said maybe the O2 sensors could have gone bad, but I don't see how that would have happened just from water.

Anyone else?
 
it will be in the scan tool display. Get the voltage and make sure they move when you give it a big throttle snap. If not that could be the culprit.
 
Sean said:
it will be in the scan tool display. Get the voltage and make sure they move when you give it a big throttle snap. If not that could be the culprit.
Click to expand...

Out of curiosity, what is it exactly?


Someone mentioned #3 and #4 are on the same part of the coil, so I tested #3- and it has spark. So does that neccessarily rule out the coil or no?

I want to buy a coil, but i hate to spend $80 if this isn't the problem. I've already spent $60 on stuff that wasn't the issue.
 
DPFE is Differential Pressure Feedback EGR

the voltage is how the sensor tells the PCM the EGR flow



where are you located?

I might have a test coil you can try to see if it helps
 
dave89iroc said:
DPFE is Differential Pressure Feedback EGR

the voltage is how the sensor tells the PCM the EGR flow



where are you located?

I might have a test coil you can try to see if it helps
Click to expand...


I'm in Troy.

I actually went and bought a coil today. I'm rather pissed though, I drove down to 9 and I-75 to pay for it, to backtrack up Stevenson to 14 mile so I could get it at their parts warehouse and not wait a day. It was supposed to be left outside so I could grab it quickly since they'd be closed before I got there.... and there was nothing outside. So I wasted like $15 in gas today for nothing. Argh. I need this van fixed, the 300 kills me in fuel. And sitting in traffic with the heater blowing and windows down is no fun.
 
Alright, well, I picked up the coil and got it installed today. I knew I was on to something as I pulled off the old one and saw the mounting ear was cracked off the side I couldn't actually see. Got it all the way off, and right near the #4 plug, there were several hairline cracks. THrew the new one on, put it together, no more misfire! Yay!

I don't know about the lean however, I need to go back to someone with a scanner to find out again.

Thanks for all the help everyone! I really do appreciate it! :)
 
#1 and #2 being lean could be the lower -or- upper intake gasket leak.Very common on the 3.8/4.2's.Let the vehicle idle and spray brake cleaner around the gaskets and if the idle goes up.....its leaking.
 
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