Multiple misfires after rebuild ** FIXED **

It’s normal for these motors as far as I know. All the videos I watched has the same.

 

What’s odd is that when I first start it, it feels good. It idles where it is supposed to. Then as it runs the idle slowly starts dropping and the misfire counter starts. I am going to go drive it around the block. Hopefully I don’t have to push it back.

 

So I just drove it around the block. While I was driving there were no misfires. Of course it sounds like a tank with no front o2 sensors and open pipes. Could it just be that it needs to be driven? When I slowed down the idle got lower but no codes.

 

When first started and temps have not quite reached proper temp, the ECU is managing the air/fuel ratio via the Map table preprogrammed into the ECU. Once it reaches a certain temp, it should go into Closed Loop and the Air/Fuel O2 sensors are now responsible for air/fuel ratio adjustments.

 

If you’ve got open pipes, you should be able to keep the front o2s in without issue, it might just need some drive time.
I know when I first put in 12hole injectors, it had a bunch of misfires(I assume it was due to the fuel rail being empty and needing to push/purge fuel/air out of the lines)

 

So I took it out for a drive and I have the same issues and then some.

The usual 1-3-5-7 misfire codes.

My speedometer doesn’t work. And I got a new code, a P0330 knock sensor error. I did put 2 new knock sensors in when I was in there.

I am wondering if all my issues are electrical in nature.

 

Been following this thread in hopes you get it fixed. I searched around on some other sites and found someone with the misfire on 1-3-5-7 and they also checked similar items including compression, timing, coil packs, ecm, fuel pressure, plugs, ect. Their issue ended up being the pin on the timing gear on the left side sheared off, letting it rotate about 30 degrees. Maybe something else worth taking a peek at.

 

I am pretty sure the pin is fine. I took the gears off and replaced the seals. I assume I would have seen that. I appreciate the suggestion.

 

With all these new issues that appear to be electrical I am leaning toward getting a new wiring harness from a junk yard. Thoughts?

 

I’m not sure what that’s going to achieve if you did a continuity test from the ECM to coils. Preferably with someone holding it while another wiggles the cable to insure there isn’t a partial breakage.

I can’t remember, but you did ohm out the coil packs in addition to just swapping them, right? You probably want to clean them up with isopropyl alcohol to insure there’s no carbon residue giving you a resistive short to ground.

This is the kind of situation having an LCR meter might be nice to measure the actual inductance of the coil and not just the resistance.

 

I have not really tested the electrical stuff. To my mind, it is either mechanical or electrical. I have verified all the mechanical pieces (timing, spark, fuel pressure, etc.) so that leads me to believe it is electrical. I can buy a junkyard wiring harness for $200. How much money and time will it take for me to test all the electrical stuff? What would it cost to pay someone to do it? It makes more sense to get a new harness.

 

What do you think about grabbing the junkyard ECU that matches the harness? That way you know the pin outs match and also you can exonerate the computer at the same time as you do the harness.

 

Can I just get an ECU that is the same part number and plug it in? I thought the ECU would need to be programmed?

 

Plug and play. Absolutely. Make sure it's the same part number, exactly.

And if buying used, make sure you crack it open to look for water damage.

This is what water damage would look like normally: https://www.tundras.com/threads/time-to-ask-for-help-truck-wont-fire.108227/#post-2791821

I'm still trying to figure out how your ECU would be shorted though ...

 

It would be worth just taking it to a dealer for diagnosis before throwing more time and money at it.

 

If I had known that I would have found another one at the beginning of all this. It is worth the check to see if it is good or not. If it’s not the ECU then I would think the harness.

 

I wonder what they would charge me to diagnose it.

 

If it’s $250 and they pinpoint the problem, would you go back 2 weeks and pay that and just fix the problem? After all you’ve been through, it seems it would be worth it. You can call ahead and ask what a diagnosis would cost to get an estimate.

 

I agree with you 100%. I might give them a call tomorrow. The problem will be getting it there. I’m not sure close to one and I don’t really want to pay to have it towed.

 

That's pretty much where I was from the last page also:

 

Maybe rent a U-haul pull-behind and pull it there yourself? You may even be able to rent a truck to pull it with and still come out way ahead of a tow truck.

 

Its too bad they don’t use parylene conformal coat; that would essentially make the ECU circuit card assembly waterproof. Unfortunately, only the military pays for that luxury.

 

I was sitting in church thinking about the car and I realized that one thing I had to do was replace the alternator connector. The stock one broke off in my hand when I took it off. I had to get a new one and solder it on to the existing wires. There is a very small chance that I soldered the wires incorrectly. It’s possible, but I was pretty sure it was correct.

What do You think would happen if I put the wires backwards? Could it damage the ECU? Would there be any kind of indication that I did it wrong?

 

I've heard of people frying their ECU from installing battery cables in reverse. But I'm not an EE, I'm not sure if reversing things at the alternator, despite its ultimate link to the battery, would do that. "Maybe plausible?"

I'd love to hear others' feedback.

 

I am pretty sure that this is the way the connector plugged into the alternator.

 

I just thought of another possibility to check, which is throttle position sensor. As it slowly fails, it will create an intermittent misfire that appears and disappears and drives the owner insane. If one bank is a little leaner/richer than the other, maybe the TPS fault could manifest on the one side preferentially. On my little civic, it drove me nuts for months before it finally set a code and bailed me out.

 

According to the 2002 EWD, it appears to be correct if that flat side of connector in your hand goes downward in the plug I see on the Alienator/Generator.

 

Usually the rubber grommets are recessed into what should be the plug, maybe it’s not fully seated on the pins when it’s connected

 

I guess it is an easy test, just unplug the alternator and start it up. Of course if the ECU is damaged it won't matter.

 

You could check the voltages at harness connector pins 1(Yel-Grn) & 3(Wh) to GND according to below checks.
Side Note: if you have it unplugged and turn IGN ON/ENG OFF, you should see the battery indicator light lit on Instrument Cluster signifying a Charge Warning.