Bad miss, mechanic doesn't know...

[Brandon96]

Ok, upon start up my explorer will sometimes just sound like it's choking out and won't idle properly, it has neever idled properly in it's life actually, but after a few revs and about 30 seconds of warm up it idles, at least to the best of its ability.

Also, while under really light throttle or when I let off the pedal, the engine starts clunking, it's not a knock, it's quite noticable as the entire truck jukes when the clunking occurs. But it's never a daily thing, it occasionally decides to do this when it feels like it, sometimes worse than others.

Plugs and wires are no more than 5k miles old and seemed to get rid of the problem for a while but it came back. Mechanic says possibly a cylinder was burned too hot at one point in it's life and was fried (no clue what that could mean) possibly piston rings bad? Bad compression? no clue... I've cleaned the throttle body, MAF, TPS and IAC (I beleive that's what it's called, I'm drawing a blank) The truck has a new air filter, plugs and wires as well as a new coil pack. I'm just curious as to what you all think it could be before I dump money into this to figure out what this is. Seafoamed about 5 months, 4k, ago and did help the problem it seemed like for a week or so but it could just be me. (The truck was never seafoamed before that point) I'm going today to get another can to see if theres a better point to seafoam it, (I used 1/3 in the gas tank, 1/3 in the booster vaccuum, and 1/3 in the oil). Oil is about 5k old, Pennzoil 5w-30, could that have something to do with it? This is making me angry, any help is greatly appreciated.

 

[MazdaGreg]

Sounds like i'd start with the MAF. I had a 93 that had a really bad surge / jerking problem light throttle, and it was the MAF. Cleaning didnt help. it too was VERY intermittent.

good luck,

 

[Brandon96]

Sounds like i'd start with the MAF. I had a 93 that had a really bad surge / jerking problem light throttle, and it was the MAF. Cleaning didnt help. it too was VERY intermittent.

good luck,

Theres is a perfect time interval between each clunk, would the MAF do that or would it be spiratic? The MAF looked really good when I cleaned it.

also, CEL for the DPFE is back on, anything to do with it?

 

[joshuaj0214]

Is it a SOHC? I would have your mechanic check the intake gaskets if it is.

 

[Brandon96]

Is it a SOHC? I would have your mechanic check the intake gaskets if it is.

Sorry forgot to state that, it's an OHV.

 

[dmc80]

I also have an ohv. Has the dpfe and related tubes been changed? and in my case, cleaning the iac and maf didnt work, had to replace them.

 

[924dr4x4]

maybe a vacuum leak somewhere...i wonder if its any kind of problem with the throttle positioning sensor??my neon did that..also did you check fuel pressure??maybe change the fuel filter and check the tps and go from there see if it helps??and do a compression test on the engine

 

[marragtop]

Probably a dumb question, but were the codes pulled? There may be a code stored even if the CEL is out. Also, how about a new fuel filter and have you checked the fuel pressure?

 

[Brandon96]

I also have an ohv. Has the dpfe and related tubes been changed? and in my case, cleaning the iac and maf didnt work, had to replace them.

I will try checking/cleaning the DPFE tubes tonight. But, in relation to the EGR, where is that located on the OHV engine?

maybe a vacuum leak somewhere...i wonder if its any kind of problem with the throttle positioning sensor??my neon did that..also did you check fuel pressure??maybe change the fuel filter and check the tps and go from there see if it helps??and do a compression test on the engine

TPS is crystal clean and smack on at .96V @ idle. Could the fuel filter do that? it's like narrowed down to one cylinder F'ing up, just gotta figure out which one.

Probably a dumb question, but were the codes pulled? There may be a code stored even if the CEL is out. Also, how about a new fuel filter and have you checked the fuel pressure?

CEL is on, and remains on. It's just the DPFE code. I posted a while back asking what could be causing that, only to find out it was the small tube that plugs into the EGR was rotted/broke, I fixed it and it ran fine, until now... although the current code has not been pulled. I need to find someone with a code tool to do so, i'm not paying $50 to get a code pulled for me.. F the mechanics around here..


I have NOT checked the fuel pressure, how would I go about doing that? I do have access to some mechanics tools, or should I get that done by a pro?

 

[924dr4x4]

go over to auto zone they do the scans for free,i took mine there and it was the tps...there is a pressure guage they sell to check the pressure..i think its in the back of the motor where u check it at..kinda looks like a tire valve

 

[Brandon96]

Got the code read, turned out to be the same DPFE code... I ripped the whole thing out of the vroom vroom bay and cleaned the sensor itself and both tubes. I must admit a shload of black chunks came pouring out of them, so I hope I did something good...

I also Seafoamed her one last time through the vaccuum line in the throttle body. I reset the code so we'll see how it turns out. It still had a rough start up though even after the seafoam cleared out. I checked for any and all vaccuum leaks, turned up empty... I'm still baffled

 

[Brandon96]

OK, problem is back, and I've got more information.

Threw a P0304 yesturday - Misfire on Cylinder #4

I turned my truck on and the same problem, extremely rough idle. While accelerating out of my neighborhood and between 1700 and 2500 rpm there was horrible surging of power, I've never ever felt something so bad. Upon letting off the gas, the thing would start banging again, but worse. A mile up the road I was just cruising at around 37-39mph with the thing surging like a *****, I began to stare at the rpm guage flucuating between 1700 and 2100 rpm. Then the CEL threw, I was on the gas, crusing, no banging when it threw.

What.. the.. heck?

Autozone says spark plug not gapped right, I checked it at .052, is that not correct?

I compression tested cylinder 4 and it's slightly over 150psi, I didn't have much time, but i beleive thats about where its supposed to be?

 

[marragtop]

Switch the #4 wire with another one, clear the codes, and see if the code moves to a different cylinder. The 'banging' you referred to... could that be unburned gas popping in the exhaust system?

 

[Brandon96]

Switch the #4 wire with another one, clear the codes, and see if the code moves to a different cylinder. The 'banging' you referred to... could that be unburned gas popping in the exhaust system?

Wires are practically brand new. They've been changed twice since this nonsense started

 

[ThePhoenix]

fuel fliter?

 

[Brandon96]

fuel fliter?

Can I remove that without the special tool that is needed? Is there a writeup somewheress?

 

[surf]

Could it be a bad coil pack?

 

[Brandon96]

Could it be a bad coil pack?

the pack has also been replaced, sorry, I'm going to update a list of everything done so far.

Problem: Rough Idle / banging under deceleration and light throttle (assuming from cylinder 4)

Codes thrown: DPFE failure / sensor failure - cleaned the DPFE tubes, hasn't returned. Also, Misfire on Cylinder 4

Things Done / checked:
- Seafoamed, from the vaccuum line in the front of the engine, forgot what it is called, right near the throttle body
- Spark plugs new
- Wires are new
- Coil pack is new
- Throttle body, DPFE, PCV, IAC, TPS and the MAF sensor have all been cleaned NOT with carb cleaner, but with sensor safe cleaner and all appear to be in good working order, MAF functions perfect..
- Compression is right around 150psi
- spark plugs are gapped correctly
- Oil / oil filter was replaced with synthetic 5w-30 (it just needed it..)

I've kinda narrowed it down to just cylinder 4, somethins going on in there and I want to know what. :shifty_ey

 

[Runnin'OnEmpty]

........ Also, Misfire on Cylinder 4
.......I've kinda narrowed it down to just cylinder 4, somethins going on in there and I want to know what. :shifty_ey

I think it's a faulty injector/wiring plug-in/wiring on cylinder #4.
Most likely the injector's sticking upon startup, then sticking
intermittantly and causing the surging......

If you have a mechanic's stethescope, you can listen to the #4
injector and hear if it clicks differently than the others.....

 

[Brandon96]

I think it's a faulty injector/wiring plug-in/wiring on cylinder #4.
Most likely the injector's sticking upon startup, then sticking
intermittantly and causing the surging......

If you have a mechanic's stethescope, you can listen to the #4
injector and hear if it clicks differently than the others.....

Cleaned the Injectors, seems so far to be a problem solver on the misfire / engine banging. Thank you Runnin'!



Now, on to the Surging, which is still going on, could that definentally be fuel filter? I looked up under there and it appears the OEM filter is still there.. 131,000 miles.. Oopss?