My problem is misfires under acceleration. I have flailed about on the forums a few days, and am going to confine myself here for some advice.


What has been done:

As of this moment, it is throwing P1300, P0303, P0304, P0305, and P0308. The 3 and 5 cylinders are a surprise; I have endured a couple of weeks of 4, 6, and 8 misfires, but nothing from the driver side. I was getting misfires on 4, 6, and 8 and an occasional random misfire. I was also getting the P01300, O2 codes, and Gear Ratio 3 codes (all of which disappeared when I put the new sensors in).


Since the misfires were on one side of the engine, I suspected a coil, but I have looked at the diagram and it is coming from both coils (duh). I suspected wires, so I swapped 7 and 8 (the shortest ones) at both the coil and the plugs, with no change (misfire stayed at 8).


I have a code reader and have noticed that resetting the codes (while driving--yes, I am that talented), generally, but not always, IMMEDIATELY makes the misfires go away without changing my pace, on the same road, in the same condition, etc.


Should I let my engine run some more to adjust to the new sensors? I drove about 20 minutes, checking the codes and writing them down. The 3 and 5 cylinder misfires really threw me for a loop... the 4,6, and 8 misfires have been really consistent and I haven't seen anything from the driver side during these troubles.


Can anyone make a suggestion?


Best,


Charlie V

 

I should add it catches a little on the first startup in the morning. This problem was bad when before the HG job.

Also, the first time I drive it each day it always misfires until it warms up. I sometimes hear a knock coming from the engine bay (not pinging, as from bad gas; a knock like someone is kicking something). I always use premium, which is 93 here.

 

Possibly a weak coil?

 

I do have a spare coil. Replacing one is such a PITA but it could be... I'm getting to the point that I wonder if I shouldn't pull the intake, replace the coil, and check all of the head bolts for torque.

 

If the misfires really go away when you clear the codes, it throws a serious doubt on any standard issue in my mind. It's honestly not that I doubt you, it's just crazy. It's hard to imagine it's a failing part when resetting the codes clears up the issue. That said, I'd physically inspect every spark plug, and I'd check the seating of the plug wires both on the plug and the coil if you can reach it. I'd also look hard for any possible vacuum issues.

So it's misfiring really bad, and when you clear the codes it instantly clears up? Every time?

When does it start misfiring again?

Because the problem is changing, my initial thought is you should just drive it for a week and keep a daily diary of codes thrown and symptoms, then post it.

I wouldn't mess with the HG bolts. I have serious doubts that is your issue. If anything, I'm wondering if it's a weird grounding problem. But that diagnosis is based on very little thought or info, so don't take it too seriously yet.

 

I did have a serious vacuum leak. The foremost hose that going n the intake manifold. The one with the little red ring that everyone breaks. I put gasket maker in that as a temporary fix and it did make a difference.

I know the code thing is crazy. But it is consistent. I erase the codes as I drive and it instantly clears up. I mean instantly. Then it may return quickly or take a couple of drives to return. I have really dogged it... Foot to the floor, trying to replicate the misfire right after clearing the codes. It won't misfire. Then a few miles or maybe a day later they return with a vengeance.

Today, when I replaced the oxygen sensors, I didn't make it one block before the ses started flashing. Normally it takes at least 20 minutes before it appears. I erased the codes just before turning it off to replace the sensors.

I know that sounds crazy. Maybe it is. But I've made a point of clearing the codes while driving and it immediately clears up the misfires, just like seating the vacuum hose cleared them up.

The grounding comment is good. Hmm. I know the grinding strap is in place at the back and I connected the ground near the alternator... Maybe I should check those again. Could that be the problem?

I know this sounds crazy but could the battery be the problem? It is new but it has been very cold the last couple of months. I don't recall whether it was always cold when it happened. I once got a new transmission over a battery. I'm so glad that shop went bankrupt.

 

I'm sorry this is on my phone at the moment so it sometimes picks the wrong words. Please translate with that in mind.

 

Could it be that my spark plug wires touch? They are a jumble.

 

I guess plug wires could be an issue. It certainly can't hurt to get them sorted.

But I'd be a bit surprised if it fixed the problem.

I've done a bit of reading in the service manual, but I don't have any great ideas yet.

Has it misfired since the HG job? Was there a period where it ran ok?

 

It started misfiring about a week after the HG job, or roughly a week ago.

It is 16 degrees here but I drove and got more misfires. I sorted the wires very carefully. I need to drive some more but to my complete shock I got po134 po135 po141 po154 p0155 and po161. Of course, it was running terrible. I reset it a few times. The misfire codes disappeared but I can tell it is still misfiring... I may just have to drive it some more.

Sorry, I distracted myself; my shock relates to the fact that those are O2 codes and my O2 sensors are less than a day old. All 4.

In sorting the wires I did notice, in the dark and cold, that the number 2 wire has arced at some point. There was a clear white spot in the boot. I rotated it around and that point would hit just below the valve cover (on the head).