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1999 Ford Ranger - P0304 code
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Flingarrows
Novice
Jan 22, 2012, 6:37 PM
Post #1 of 8
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1999 Ford Ranger - P0304 code
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Hi,
I have a 99 ranger with a 4.0 auto, 2wd 95k miles. Last week started bucking under load. Check engine light came on. It felt like a plug wire was disconnected. If I back off of the accelerator, it was better.
I got code read at autozone. p1405/dpfe, and p0304/mis-fire #4 cyl. Found cracked hose @ dpfe, replaced.
Yesterday I changed coil and wires, reset computer - same bucking. Today, took off upper intake, replaced # 4 injector. Now rough idle but intermittent smooth then rough under load. Kind of like surging with power for 2 or 3 seconds, then rough, then back again. Check engine light back on.
I pulled #4 plug wire to make sure same cylinder, and that I didnt disturb a wire on another cylinder - same. It has a rich smell from the exhaust as well.
I will get code read tomorrow to confirm it is still a p0304 (or something else), any other ideas?
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Discretesignals
Ultimate Carjunky
/ Moderator
Jan 22, 2012, 7:30 PM
Post #2 of 8
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Re: 1999 Ford Ranger - P0304 code
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This may seem like a dumb question, but are you sure you have the correct cylinder? Number 4 on a 4.0L is the first cylinder at the front of the engine on the driver's side.
Did you try swapping number 4 spark plug with another cylinder to see if the misfire moves?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Flingarrows
Novice
Jan 24, 2012, 5:20 AM
Post #3 of 8
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Re: 1999 Ford Ranger - P0304 code
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Thanks for the reply Discrete. I had to look it up, but I am on the front drivers cylinder. I will try changing the plug this afternoon, but it appears yesterdays maintenance has set me back even further.
I have 3 codes now:
P0174-fuel trim bank 2 condition
P0304-cylinder mis-fire - cylinder 4
P0171-fuel trim bank 1 condition
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Flingarrows
Novice
Jan 24, 2012, 5:23 AM
Post #4 of 8
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Re: 1999 Ford Ranger - P0304 code
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This is the #4 plug before a changed coil and injector
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Discretesignals
Ultimate Carjunky
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Jan 24, 2012, 5:53 AM
Post #5 of 8
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Re: 1999 Ford Ranger - P0304 code
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There are a couple of pattern problems on those that will cause you to have lean codes. One is dirty MAF sensor elements. The other is a vacuum leak from the upper intake plenum chamber seals.
Need to look at freeze frame data to see when the lean codes set. You can also look at long and short term fuel trim to determine if you have possible vacuum leak.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Flingarrows
Novice
Jan 24, 2012, 11:14 AM
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Re: 1999 Ford Ranger - P0304 code
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Not to ask too stupid of a question: I am not familiar with what it will take to get that info. Is there a primitive way to track down a leak, such as propane around the base of the manifold? The surfaces were clean and in good shape when I put the manifold back on, and i torqued to spec. Are they known for warpage?
I'll get some electrical cleaner and clean the maf sensor
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Discretesignals
Ultimate Carjunky
/ Moderator
Jan 24, 2012, 12:07 PM
Post #7 of 8
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Re: 1999 Ford Ranger - P0304 code
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You could try propane, but if the leak is small, you may not pick up. Another thing is that it's best to check for vacuum leaks when the engine is cold. When the engine is cold the computer will increase the idle speed making it difficult. You can't unplug the IAC like you can on a GM because the engine will stall.
It's important to look at freeze frame to determine what engine factors were involved when it set the lean codes.
A really good way of finding vacuum leaks is using an EVAP leak tester.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Flingarrows
Novice
Jan 24, 2012, 7:18 PM
Post #8 of 8
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Re: 1999 Ford Ranger - P0304 code
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I fixed the P0304... Spark plug. It would fire the plug tester, but I guess it was not putting out a good spark. I feel like an arse for discounting that early on... It is idling smooth, and under load too.
I think my vacuum leak may be at the egr. There is a bolt on the bottom towards the firewall side, that is missing. I didnt see it when I took it apart to get the manifold off. I read the horror stories about the o-ring on the intake side, and didn't want to disturb it. Heck, the o-ring could be leaking too, I had to rotate the tube to get the manifold off. I'll track that down easy enough, I hope.
Thanks Discretesignals for steering me in the right directions, I really appreciate it
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