Code P0301! Please tell me I don't need head work!

[Hardwareman]

I just had the code ran at an auto shop because they had a "Grand Opening" special where they scan for free.

I ended up with a P0301 code! Cylinder #1 Misfire Detected!

I was starting to lean towards an EGR Valve because it's really noticeable at idle when cold. It's there when warm also but not nearly as bad. I've read around on the internet and it seems as if everyone that's encountered this code in a Ranger has had to have the cylinder head redone because of valve problems. Is anyone familiar with this or should I remove both intake and exhaust plugs and wires to have a look see? Thanks a bunch!




Allen

 

[Hardwareman]

Ok well I just went out and checked #1 cylinder for spark and sure enough there was no spark on the intake # cylinder! I fixed that but the problem continues.

I swapped out the coil pack for one I had in my toolbox and threw the old one out. I've now verified all 8 plugs are firing and the plugs are good as well. It will idle good for 20-30 seconds or so and then will drop in rpm's and sound like it's starting to miss again. I don't know what else it could be. Disconnecting the IAC has no effect on idle AT All!

I guess tomorrow I'll try to swap out the computer if I can locate one for under $100 bucks. I'll also look into the egr valve.......actually I think I'll go out right now and check voltage to the egr solenoid since I can't remeber if I checked that one or not. DPFE sensor was changed out with a new one last week.

Either way, at least I know the misfire in cylinder #1 is gone........at least for now. Any ideas anyone? PLEEEEEASE!!!!




Allen

 

[Doofy]

Code PO303...Cyl #3 misfire on my '98 3.0L Ranger. Problem was the brand new E3 sparkplugs. Should have read all the posts on TRS that mostly stated "Run the plugs that the manufacturer puts in". Threw away the E3's and went back with Motorcraft! Purrs like a new truck.

 

[Joelzme]

Try pulling off that EGR and cleaning it up. You will need a 1 1/4" wrench I think. It was a bitch to get off. Also when you do pull it off check the resistance on the EGR position sensor.

Have you hooked up a vacuum to it to verify that it is opening/closing correctly and not losing vacuum? Also, hook up your hand vacuum pump to the EGR valve and slowly apply a vacuum. If the EGR valve is functioning then the engine should begin to run poorly and stumble. If you apply full vacuum and notice no RPM change or can’t pull a vacuum at all, then check for a faulty diaphragm in the valve or a restriction of the EGR tube, exhaust or intake manifold EGR ports.

Hope you get it fixed, glad to hear it's not a misfire!
Joel

 

[Hardwareman]

Thanks guys, well it was a misfire which is odd because I never thought I'd have a problem like that. I don't know what caused it because I checked that coil pack before and it was good according to the manual. Maybe it was an intermittent problem. Either way, that seems to be done for now.

As far as the plugs, I'm running "AutoLite Platinums". I've always run them because of the high cost of the MotorCraft ones and I have 8 plugs! Could this all of a sudden be the cause of the problem?

I'm going to check the EGR with a vaccum pump today and see if that's working right as well, although it could be sticking you know? I'll post up the results later.




Allen

 

[Joelzme]

Also one other thing. When you pull the vacuum, it should hold steady and not leak down. If it does, you have a problem with the internal gasket of the valve and it will need to be replaced. When you let the vacuum go you should hear it pop back closed. I have heard suggestions that when you replace the valve that you also replace the position sensor on top of it.

I did all this on my 91 2.3L and was able to rule out the EGR. You can do most of this with aquarium line sucking on it, if you don't have a vac pump.

Gook luck and keep us updated.

 

[Hardwareman]

Ok running out of options here guys. EGR checked out ok. I actually pulled the entire tube off of the header and checked the entire assembly. The EGR stays sealed air tight unless vaccum is applied to it. I've already replaced the DPFE as well, so I think I'm ruling out the EGR system as of now.

It does'nt really misfire but it only idles well for about 20-30 seconds before the idle drops way down to the point where it sounds like it's missing because it's so low you know?

I'm wondering if my coil packs are going bad. When they go bad do they just go out completely or do they weaken and/or have intermittent problems over time? They passed the test according to my Haynes but since I had a misfire in #1 cylinder yesterday I'm wondering if they're the problem. I swapped them to test them, but I only had one and just swapped the front first to see if there was a change and then did the same with the rear.

Tomorrow I'm going to remove my cluster to replace about 3-4 bulbs on the left side that have been burned out for a while. My temp gauge has also not worked in some time so I'll have a look at that as well. I checked the wiring from the temp sensor in the block all the way to the PCM and it was good so it's either the gauge itself or something in the PCM. Man, I'm starting to think I need a PCM. I'll try to locate one on Monday and try that. I've basically done everything else and if it was a mechanical problem the idle would be bad all the time and not drop the way it does all of a sudden. Stupid sensor controlled engines.............gotta love'em!



Allen

 

[Joelzme]

Man, I feel your pain. I have an alldata subscription and it says that my 1991 2.3L engine (I think same as yours) should idle at 575-725 RPM I was having the *exact* same problem and the MAF made it better, but did not make it go back to the way it was idling.

To be sure, as of now you have no codes showing, right? When I finally brought my truck in to Ford for a diagnostic they said I had no voltage on my MAF and O2 sensor. You have changed your O2 sensor, right?

I am just as fustrated. I got mine finally running again and my starter crapped out today. Pulled it and bringing it in to test it tomorrow, but it looks like the brushes are totally worn down on one side.

 

[Hardwareman]

Actually no, I have'nt changed out my 02 sensors (I have 2) in a while. I've only had to change them about 3 times the entire life of the truck and I've always gotten a code for it.

They never made the Ranger run like this though even when they did throw a code. You may be right though, you never know. It's just that they cost about $40.00 a piece I think.............at least the last time I bought them anyway. Let me look on AutoZone's website first.

The reason why I want to try a new PCM is because this one's been going for almost 500,000 miles now (this is my third motor), and another guy I talked to told me he had a wierd misfire/idle that only went away after he swapped out his PCM.

I really appreciate the help Joel.




Allen