Sudden Rough Idle. Please help.

[jdflatten]

2002 4.0 SOHC

112,000 miles on it.

New plugs and wires (15K on them)

New PCV Valve (5K ago)

Driving to the river this afternoon, CEL starts blinking (it was already on steady, 02 sensor)
I was stopped at a stop sign, gave it the gas and noticed a sort of chugging feeling, stopped put it in park and listened. I could hear a definite miss, and it was overall just running rough, I could feel it from the seat as well, shaking.

Drove home, shut it off. Heres the kicker, Start it back up, runs fine for 20 seconds, no rough sound, no shaking, runs perfect. At 20 seconds, rpms go from 1000 to 600 and runs rough again, cel blinks again.

I went to town and got some MAF cleaner, cleaned it, that wasn't it.

Any help would be greatly appreciated as I've already dumped about 300 bucks on shocks and springs in the pig in the last week. I really don't need another repair bill.

Thanks,

Josh

 

[Bob Ayers]

When you changed the plugs, did you use Bosch? Your symptoms sound like the classic misfire from Bosch plugs.

 

[Bruce]

Run a scan on it or get it scanned it will probly point you in the right direction since the CEL is flashing.

 

[jdflatten]

Nope, I bought the bosch plugs, and before I went to install them, I did some reading on this forum and RPS and thankfully took them back and got the right ones. They've been in for almost a year now and the truck has run FLAWLESSLY since I bought it at 22,000 miles. ...........until about 2:30 this afternoon.

Just got back from Oriely's. Borrowed their code reader and here's what she read. 4 different problems.

1. cylinder # 4 misfire detected.

2. Exhaust gas recirc. flow insufficient.

3. EGR EVP Sensor High voltage

4. Intake Air Temp Circuit High input.


Any help?

 

[jdflatten]

I'm assuming I need to replace the EGR EVP sensor. Is this one unit or 2??

Would this cause the misfire and insufficient Exhaust gas recirculation?? What could be causing the High Input reading for the Intake air temp circuit??

Thanks in advance.

 

[Yellowsplash]

Well....since nobody has replied yet, I'll get you started in the right direction...

1. Cylinder #4 misfire detected - I would start by replacing plugs and gapping them to spec, then wires, etc...
2. Exhaust Gas Recirculating Flow Insufficient - Usually a code thrown when the DPFE sensor goes which is probably the...
3. EGR EVP Sensor High Voltage - I would suspect the DPFE sensor. Its the little guy near the intake and egr valve that measures the amount of exhaust flowing through the EGR valve. Should have 2 vacuum lines and an electrical connector running to it. They might call it the EGR Valve Position Sensor, EGR Pressure Feedback Sensor, or possibly the EGR Valve Solenoid at the parts store.
4. Air Intake Temp Circuit High Input - If you have a 6 wire MAF sensor, the Intake Air Temp (AIT) sensor is built into it. If you only have a 4 wire sensor, you have a separate sensor located in the intake pipe just downstream of the MAF before the throttle body.

 

[jdflatten]

Thanks Yellowsplash, I appreciate your help.

Here's what I found....

Couldn't sleep last night, and I kept going over posts I read yesterday and just brainstorming. The first thing that came to my mind when it started missing was that a plug wire came loose, so I checked all of them and they were on tight. Then I got to remembering a post I read where the guy suggested to turn the shop lights out and pop the hood, look for a short in the wire. Sooooo....I went outside, popped the hood, started her up..... Plug wire was zapping the egr tube right under the DPFE. I guess it just vibrated a hole through it. I electric taped it up really good ( for now) and started her back up. Ran perfectly. Engine light still on, but not flashing. Today I went into car quest and bought a DPFE sensor, installed it, reset the computer, and check engine light went off, and is still off. The combination of Dirty MAF, Bad DPFE, and Bad plug wire had me stumped yesterday, now CEL light is off and I am one happy dude.

Thanks

 

[parson2008]

maybe bad head gasket leaking into a cylinder

 

[KELLY88]

Pretty sure he just said he got the problem fixed.

 

[03Shadowbob]

How coincidental. My 02 Ranger 4.0 started doing this this morning at a red light. She was running fine, pulled to a stop and the idle was going crazy from 1200rpm down to about 400rpm and idling terribly. CEL was coming on then going off consistently. Got it home, let it sit for about 4 hours then when I started it up to take it to the shop it idled fine. Reversed out of driveway, put it in drive and the rpms went up to about 2k without my foot on the gas. It was cruising at 35mph without my foot on the gas.
I took it to the mechanic and he will call me tomorrow to tell me what his diag test reads. Hopefully it reads something similar and not something more major.
I really don't want to have a major repair bill since I just got new rims and tires (that's where I was going this morning and they are still sitting in the garage dangit).