chasing misfires.... thinking egr valve??

[dunner]

2003 4.6 explorer limited.
-replaced intake manifold, vehicle ran fine. had a misfire on #2. i chalked it up to maybe some coolant getting in during the changeover. I replaced #2 plug. everything ran fine.
- sat for about 3 days. Monday morning, fire it up, heading outta town and lose all power withing the first mile. CEL comes on, barely has enough power to pull itself. I turn around and head back home, CEL light flashing, low oil pressure warning comes on, although all gauges indicate otherwise.
- pull it into the shop, will barely idle. misfire on multiple cylinders, first 100 revs. changeover all plugs. no misfires, but now coil e and g come up on scanner. move coils around to eliminate coil problem, clear codes. -start up, no codes, but engine idles horribly still and EGR valve is making a "vibrating" noise. pull vacuum line on egr valve, vibrating noise goes away, vehicle still sounds like garbage and wont idle well. throttle up, no power at all, engine wants to almost die when it returns to idle.

I'm confused. This vehicle ran awesome after the intake manifold change, but when i started it up a few days later, it was horrible. Will the EGR valve have that drastic of an effect on the engine if its stuck open? I cant figure out what the issue is....

 

[dunner]

changed EGR valve. no change in behaviour. does anyone have an idea where i should start looking next?

 

[Tech By Trade]

Coil.

 

[Flatplane]

R.T.F.B.
Read The Ford Book
Diagnostics start with understanding the way the system/s work correctly. Diagnostic by Forum/Committee is for people that don't spend the time to learn.

Rant Over

Do the due diligence to submit test results of things you have really tested

 

[dunner]

So, the misfires are all gone. All that i have now is absolutely NO power. sitting at idle, it idles a little rough, if i throttle the truck up, it bogs out and produces no power. when it returns to idle it almost wants to die. Here is what i have done.

** NO CODES or CEL***
- tripled checked all vaccuum lines
- new plugs
- replaced egr valve, vibrating noise eliminated.
- tested compression- 150 psi-ish across the board, tested when engine is cold as i cant keep it running long enough to get it to temp.
- tested fuel rail pressure, by use of the schrade valve. 60 psi, wether i turn the ignition or fire up the vehicle
- resistance tested every COP. all came back good according to the clymer/haynes manual
- cleaned throttle body, MAF sensor and IAC valve
- I thought that i may have had a plugged CAT but i think the air flow coming from the exhaust is quite strong still and dont think that is the problem, as the vehicle started bogging almost instantly.

- Going through other peoples problems, ive seen that the ECT sensor can cause an engine to run rich if its not functioning properly so I'm going to replace the ECT sensor today and hope for a positive result ....
- My next step is to check each injector. I'm a little unsure how to fully do this so im reading up on it, and trying to figure this out.
- I have noticed a fuel smell coming from the exhaust so am thinking it may be an overfuelling issue?

I really enjoy working on vehicles and getting to understand them better but i need this girl on the road....

 

[lincolnshibuya]

use a scanner (or ForScan) to check your fuel trims (LTFT and STFT), you'll know if you're running lean or rich on which side of the bank.
i haven't tried mode 6 on ForScan but it will also help you which of the cylinders are underperforming (misfire) and doesn't trigger a code.

 

[Roy Martinez]

Try pulling out the upstream 02 sensors and see if the power improves, you could have one cat plugged. I have experienced this myself. After going crazy for a week, it came to me. I told my tech to "uncork it" meaning unbolting the head pipes, it fired right up. These cats were so plugged it wouldnt even start. Turns out it was a recall. I told my customer to take it in for that. She got it done for free. Shee had offered me the car for $200 I turned her down because I knew it wasnt that bad. Thank goodness she listened

.

 

[shadowless127]

This might be a long shot, but I remember when I used to work at a used car dealer, we'd get tons of Fords in from the early-mid 2000's and a lot of them had similar symptoms that were caused by a bad/corrupt PCM. Hell, I had a similar issue with my 2001 Ex in December/January, wound up needing to have the computer reflashed.

 

[dunner]

thanks guys, had to order a cht sensor, so im gonna give it a shot anyhow. next is the CAT s ill keep posted!

 

[dunner]

just a quick question. When turning key to engage fuel pump i'm getting 60-65 psi at the schrade valve. When cranking over the fuel is all over the place form 65 psi to 30 then back up to 60 then drop to about 40ish. Like i said, all over the map. Is this normal?

 

[MarX]

Weird I'm dealing with a similar problem. Recently just had to replace my intake manifold, had a coil go bad on a trip and the bolt with the intake went bad, had to rip the coil and and rig in a replacement till I got home and then did the swap. I went on ahead after that swap and replaced any coils that hadn't been replaced as well (all but 2). I had already replaced IACV and fuel filter thanks to input from this site after first buying my car a couple of years ago. I had already done plugs too. Unfortunately my car started a rough idle today and while driving sometimes. I did recently a few weeks back clean the throttle body and MAF too. Worst part is after I replaced the intake, I took the car on a trip 10+ hours each way. So it did more than 20+ to and from, had zero problems. I'm leaning towards fuel injectors now and then maybe fuel pump. My truck is close to 140K currently. Good luck with your fix.

 

[MarX]

I forgot to mention, when I go start testing and checking items that could be the issue/ ruling out I'm going to check the EGR stuff as well. Here is a link on some basic testing stuff from prior models. Might be useful, it's not for our specific years but could be of some help in the process of elimination. http://easyautodiagnostics.com/ford/4.6L-5.4L/how-to-test-the-egr-system-1

 

[toy4x4]

just a quick question. When turning key to engage fuel pump i'm getting 60-65 psi at the schrade valve. When cranking over the fuel is all over the place form 65 psi to 30 then back up to 60 then drop to about 40ish. Like i said, all over the map. Is this normal?

I've never tested but I would think the pressure would fluctuate some as the fuel pressure regulator usually gets input from the engine vacuum.

Also check that your coil boots are dry I got mine wet from coolant leaking from the intake and started having problems... Then I washed the engine off before replacing the intake and real problems started... Afterwards I had lot of random missfire issues sometimes quite bad... ended up replacing all the coils after many failed attempts to swap around and locate the bad coils using a code reader and spare coils. I think my engine washing might have messed up the coils or maybe they were on their way out at 190k miles... But you will definitely have issues if there is any residual moister in the coil boots or plug holes in the head. Hopefully it's not your new intake leaking into these?

 

[dunner]

ok. well i did some thinking. I replaced the cylinder head temp sensor (it was broken) nothing changed. so i pulled my o2 sensor upstream from the CAT. Fired up the truck and did she take off. Was loud as hell and revving at about 6000 rpm. is it normal for it to run that high with that o2 sensor out?

 

[dunner]

SOLVED THE PROBLEM!!!!!

When i bought the truck, the previous owner had obviously cut and "rigged" up the hoses from the intake and valve cover vent. was shoddy to say the least. When i replaced the intake manifold, I redid those lines with the proper venting tubes and hoses. My mistake was when i hooked them back up, i somehow ran the valve cover vent tube to the pvc valve and the throttle body tube to the intake, essentially turning my engine into a pressure cooker. This would likely explain why when i took off my CATS and gutted them, that the inside of the passenger side cat came out as a melted together clump. Add the overfuelling to the mix and i think she got a little hot.

once i gutted my cats (yeah yeah, i know. i had to see if it solved the problem before i bought new ones), the rpms were very high and when i took it for a spin, the vehicle ran fine but i heard a swoosh, like a turbo dump. I opened the hood and oil everywhere. I caused enough pressure to get blowback from my valve cover vent tube all over my engine. Changed over the lines and voila. purrs like a kitten!!!! Thanks everyone for your help!!

 

[dunner]

Try pulling out the upstream 02 sensors and see if the power improves, you could have one cat plugged. I have experienced this myself. After going crazy for a week, it came to me. I told my tech to "uncork it" meaning unbolting the head pipes, it fired right up. These cats were so plugged it wouldnt even start. Turns out it was a recall. I told my customer to take it in for that. She got it done for free. Shee had offered me the car for $200 I turned her down because I knew it wasnt that bad. Thank goodness she listened

.

thanks for the heads up. helped me solve the problem!!

 

[Cozymike225]

Coil.

Could loose egr cause issues with missing and no power