Multiple misfires after rebuild ** FIXED **

Hey guys, I pulled my engine to freshen up the gaskets and seals and to fix an oil leak. Did timing and replaced the oil pump. Put on long tube headers as well.

I got it all back together and just fired it up. I am getting multiple misfire codes:

P1320 - igniter circuit #5
P0305 - cylinder 5 misfire
P0301 - cylinder 1 misfire
P0300 - random misfire
P0307 - cylinder 7 misfire

so far I have verified spark and checked compression. All are over 190. The plugs are fairly new so I don’t they could be dirty. I also swapped the coil packs with other known good ones I have, didn’t make a difference.

I extended the o2 sensors myself, if I messed up the black wires (since there are 2) could that be causing the issue? I have upgraded 12 hole injectors so I doubt they are the issue.

It all worked fine before I did the rebuild. Any suggestions would be greatly appreciated before I just start throwing money at parts.

SOLUTION: The timing was off between the cams and the scissor gears were not engaged. Totally all my fault.

 

Check timing belt on odd # cylinders. Seems your misfires are all on that bank. Maybe a tooth off?

 

I agree, timing is the first place I went also. At least one of the cams has a penchant for kicking forward when reinstalling the belt. Are you 100% positive you nailed it?

I'd re-check harness connections, just in case anything plastics cracked and now aren't seating right, for example, at the coil packs. I'd check the MAF harness, the the crank position harness to make sure it was properly secured and isn't getting (or hasn't gotten) nicked by a pulley or belt. I'd consider cleaning the MAF w/MAF cleaner.

But first things first, how is it running? If running rough, does that change if you fully erase all codes, forcing the ECM to re-learn everything?

Does anything change if you unplug the rear post-cat O2? The rear and the pre-cat O2 at same time?

 

Thanks for the replies. I won’t be able to check it until Monday evening, but I will check the timing first. I’m pretty sure I did it right, I have done timing belts before.

I did clear the codes and it is still running rough. Rough idle around 500 rpm. Not smooth.

 

Is there a data logger for our trucks that shows misfires? I wouldn’t mind investing in one.

 

Following up, is there an easy way to check the timing without pulling everything off? Can I just remove the cam covers?

 

3 or 4 bolts on the upper plastic cover iirc. Just got to line the crank up with the timing mark to check it.

 

Assuming the timing is correct, what should I check next? I have a couple hours tonight and I don’t want to waste my time. What do you think?

 

See earlier reply. https://www.tundras.com/threads/multiple-misfires-after-rebuild.110071/#post-2841093

 

thanks. I am going to do those things, but I just wondered if anyone knows of this issue and the solution. I searched the board and most issues were caused by bad gas, but that’s not my issue.

 

I checked the timing and it appears to be spot on.

 

Yup, that looks on-point to me.

Given the symptoms, while it probably sucked to check, it's way better to rule that one out.

 

I’ll be swapping all the plugs on drivers side bank and then trying it again this evening. I reset the ECU and an hoping to have a scanner that shows live misfire data.

 

I'd go ahead and swap the plugs and coil packs left bank to right bank/vice-versa, if that's not already in the works. Just as a sanity check.

The "igniter circuit" code on cylinder 5 and random misfire codes are the reason I'm saying this. If this was just a case where all odd or all even cylidners were doing something weird, I'd have other thoughts. But, same way you confirmed the timing as a sanity check, knowing that would cause this, time to explore the electrical side.

I don't expect you to pull your ECM and crack it open to check for water damage. But swapping the coil packs and plugs (and confirming plug condition in the process), this will help you to isolate whether the problem moves with the coil packs. If so, you've got your culprit(s), though multiple packs going back would be outlandish, it may just be the 1st pack in the series causing issues downstream.

If I remember right, the fire order is 1-4-6-7 and 2-3-5-8, but I'd need to look it up. So I'd caution against getting hung up with 1357/2468. I'd also consider checking the crank position sensor, you can use a multimeter, and it's an easy check. Sometimes just cleaning and reinstalling will do it.

If you swap the coils and plugs over and it persists on same cylinders, honestly, time for another sanity check beyond just checking wires and cables. If it was me, I'd the pull ECU and look for water damage on the board. Then I'd want to see live data to see what my MAF is measuring for input, and live data from all four O2 sensors while running, just to see what's coming back.

 

What gap should the plugs be at?

 

.031 according to 2002 Owners Manual....



1st Gen Tundra Brochures & Owner's Manual

 

Well, I took the cam sensor out and cleaned it, put it all back. Swapped all the coils and plugs from one side of the engine to the other and fired it up. I am now getting:

P1300 - igniter circuit 1
P1310 - igniter circuit 3
P1320 - igniter circuit 5
P1330 - igniter circuit 7

and all the misfire codes for the same cylinders.

so where do I go now? Is there something that controls that bank of injectors? It is definitely following that side of the motor.

 

Not cam position sensor. crank position sensor.

 

Taking this from another post, but note that it's for my '06. I would expect generally similar for your 02 for these two. Cam position sensor wasn't unique to VVTi in 05-06

 

So you are thinking that the crank sensor might be causing half the cylinders to fail?

 

Oh, to your point, no, but figured it couldn't hurt to check and it's one of the things I'd have tested, along with the MAF, and checking O2 output.

I could see a vacuum issue or lack of fuel pressure causing the combo. But weird on the igniter circuit new failures.

 

And at this point, I'd definitely pull the ECM and crack it open and check for damage.

 

How extensive was this “rebuild”? Did you replace head gaskets? Valve guides/seals? iIntake manifold gaskets? Did you use all OEM, or aftermarket gaskets and seals? Are all the harnesses plugged in properly?One head isn’t performing properly. I would retrace what occurred during the rebuild and rule out something there. Computer is a possibility. But why now?

 

Great questions, I redid all the oil pan gaskets, replaced the head gaskets, cam seals, oil pump, front and rear main seals, all valve cover gaskets, replaced the valve seals, replaced intake manifold gaskets, did the timing belt and water pump, and put long tube headers on.

I used a fe-pro gasket set. It came with MLS head gaskets. I have used them in the past without issue.

I am going to reseat the ecu connections tomorrow and check some electrical stuff. Thanks for all the suggestions.

 

From peanut gallery….I keep seeing “long tube headers” since first post and for whatever reason, maybe from previous discussions, proper location of sensors in bung holes or something to that affect ?

 

I did extend the o2 sensor on the drivers side myself. It possible I switched the 2 black wires because it was hard to tell which went where after I cut the wires. We have an actual jba o2 extender coming and will swap it out just in case.

 

I’m wondering where all the ground points on the engine are for the ignition system. I’m wondering if I forgot to hook a ground up or something.

 

At this point I am considering buying a new ecu and wiring harness. If there is a broken wire in the harness I will never find it. I have to get my truck working.

I am going to get a coil pack spark tester today and make sure that the coil packs aren’t firing.

 

The below pic is from your "Part Identification" thread. Pretty sure those Brown wires(noted in red) are the Ignition Coil gnds. The 02 EWD pic shown below showing Cylinder 1-3 pin 4 BR(brown) wires going to gnd point EC which is possibly the gnd wires shown in the engine block pitch you posted. Also, the remainder cylinders not showing in EWD pic cyl 4-7, all go to EC gnd point. If you have a VOM(volt ohm meter), check pin 4(BR-brown) wires to gnd for continuity.

 

Thank you so much. I will check the grounds tonight.