Misfire all Cylinders

[camino70]

On cold starts I am getting multiple codes, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308.
Sometimes all of them, sometimes a large group of them. If I start and let idle, it will eventually stumble and throw the code, the stumble will remain until fault is cleared and restarted.
If I start and begin driving, no stumble is felt, but eventually the code will be thrown.

Prior to this issue, I had the transmission rebuilt. I've since replaced plugs, MAF and PCV, all overdue.

I could use some help with troubleshooting steps.

 

[TheGrrrrr]

You may find more info on Tundra forums where the sample size is higher, but I keep a cheat sheet on my phone with basic mechanical references. This is what I had for misfire. I'm sure I found it online somewhere and copied it into my notes:

Most common causes of cylinder misfire are as follows:

• Bad, worn or damaged ignition coils, fuel injectors, spark plugs or wires
• A fuel injector is clogged, dirty or malfunctioning
• Air leak or low fuel pressure
• Weak fuel pump, clogged fuel filter or leaky fuel pressure regulator
• Leaky EGR valve
• Faulty oxygen sensor
• Stuck open PCV valve
• Poor compression
• Air leakage in the intake manifold
• Defective ECU
• Mechanical issues of the cylinder

 

[TeCKis300]

That's a great list @TheGrrrrr .

To the OP - get an OBD-II scanner. Let her idle and watch the short term and long term fuel trims. As it effects all cylinders and based on your symptoms that it seems to run fine for a duration, I suspect it's an air or fueling problem rather than an ignition problem. After a big job like this, I tend to think it's an assembly issue where there's an leak post MAF in the air intake system.

 

[Cruisin911]

Having the code on all 8 cylinders says to me that you need to be looking at all common solutions. Did you buy an aftermarket MAF? Only use OEM DENSO. Replace pcv lately? Fuel pressure?

 

[TheGrrrrr]

One thought is that the PCV may have been overtorqued during install, which is insanely easy to do. If it cracked, it would fail to an open state at all times.

 

[camino70]

I have an obdii, I’ll check the fuel trims.
Once the error popped up it reminded me that I was overdue, so I did plugs(edit: not denso, auto lite app5325), pcv(denso), maf(toshiba, as from factory) and crank sensor (denso).

I’ll have to see what I have to test fuel pressure.

 

[camino70]

I have fuel trims set up in torque plus app, but not sure what I’m looking for.
short term stays near/at 0 at idle, up to 5? Driving slow

long term stays at -13 ish at idle

I don’t see a fuel filter and don’t think the 200 has one in US.

I did the Hewitt secondary bypass a year or two ago, that had a block off plate, could that be related?

 

[TeCKis300]

I have fuel trims set up in torque plus app, but not sure what I’m looking for.
short term stays near/at 0 at idle, up to 5? Driving slow

long term stays at -13 ish at idle

I don’t see a fuel filter and don’t think the 200 has one in US.

I did the Hewitt secondary bypass a year or two ago, that had a block off plate, could that be related?

Let it idle until it stumbles as you were describing. Fuel trims should stay nominally around 0 to +/- 15. If the trims continue to change progressively until it stumbles or pegs out at some high value, that would suggest something is up with metering air or fuel.

You can also try running without the MAF plugged in. Yes, it'll throw a bunch of CELs but does it change the stumbling behavior after idling for awhile?

 

[omar rva]

@camino70 the rest of the group here seems way more with it than I've been on diagnosing faults like these.

The only different perspective I would have to offer is to ask if this vehicle is garage parked or if it lives outdoors or in a detached building. You may have rodent/squirrel damage to a harness.

OA

 

[camino70]

@omar rva - That thought has certainly crossed my mind. I have been on the hunt for damaged wires or other signs of friends visiting the cruiser.

Yesterday, I let it idle for several minutes before heading out. CEL didn't light up until 2 minutes into the drive. No large changes in fuel trims, no noticeable difference in driving/engine feel.
This morning, the cell phone took longer to boot up then expected, so I shut the truck down 20 or so seconds into startup to wait for the phone (older android that still works with my cheap dongle). Second start up, Short term stuck near zero, -.1 both sides. Long term stuck at -3.9, but about 30-40 seconds in what looked/felt like the same exact moment, stumble, CEL and Long term jumped to -4.7 and stayed there, stumbling.

I left it running, cleared the codes, but the misfire was still present and the Long term stayed at -4.7.

Shut it down, cleared the codes, started back up with NO misfire, Longer term at -4.7 again.

 

[Cruisin911]

Were you having this issue prior to swapping your MAF? Can you swap with a known good one? The way those trims are happening with what I would expect to be throttle position changes, I'm still leaning that direction.

 

[CharlieS]

Probably not super helpful but I was having similar issues with fuel trims on a different vehicle, and I went through troubleshooting the MAF, O2 sensors, and it ended up being a vacuum leak (oil cap o-ring) of all things. The O2 sensors were the original concern, but it was a red herring. Since the ECU is in open loop mode while the heat cycle is on, the problem doesn't manifest until it kicks over into closed loop mode and tries to compensate for the conditions reported by he various sensors. It reminded me of the importance of systematic troubleshooting. I guess that's the only real advice I can offer - break the problem down systematically and troubleshoot everything in a logical sequence. Question/test all of your assumptions.

(EDIT: updated my open/closed loop language, since I got it backwards).

 

[camino70]

Were you having this issue prior to swapping your MAF? Can you swap with a known good one? The way those trims are happening with what I would expect to be throttle position changes, I'm still leaning that direction.

Yes issues were existing prior to MAF swap. I still have the old one, but not exactly what I would call known good.

 

[camino70]

Probably not super helpful but I was having similar issues with fuel trims on a different vehicle, and I went through troubleshooting the MAF, O2 sensors, and it ended up being a vacuum leak (oil cap o-ring) of all things. The O2 sensors were the original concern, but it was a red herring. Since the ECU is in closed loop mode while the heat cycle is on, the problem doesn't manifest until it kicks over into open loop mode and tries to compensate for the conditions reported by he various sensors. It reminded me of the importance of systematic troubleshooting. I guess that's the only real advice I can offer - break the problem down systematically and troubleshoot everything in a logical sequence. Question/test all of your assumptions.

Thanks Charlie, I need to come up with a test plan to make sure I don't miss anything in the matrix.

 

[camino70]

I pulled the MAF while running and it died immediately. This brings me back to my bypass kit, trying to eliminate variables, I unplugged the bypass and replugged in the factory harness for the water temp and MAF. I am going to give this a shot for a bit.

 

[TeCKis300]

@omar rva - That thought has certainly crossed my mind. I have been on the hunt for damaged wires or other signs of friends visiting the cruiser.

Yesterday, I let it idle for several minutes before heading out. CEL didn't light up until 2 minutes into the drive. No large changes in fuel trims, no noticeable difference in driving/engine feel.
This morning, the cell phone took longer to boot up then expected, so I shut the truck down 20 or so seconds into startup to wait for the phone (older android that still works with my cheap dongle). Second start up, Short term stuck near zero, -.1 both sides. Long term stuck at -3.9, but about 30-40 seconds in what looked/felt like the same exact moment, stumble, CEL and Long term jumped to -4.7 and stayed there, stumbling.

I left it running, cleared the codes, but the misfire was still present and the Long term stayed at -4.7.

Shut it down, cleared the codes, started back up with NO misfire, Longer term at -4.7 again.

The ECU operates in two modes. Open loop (no feedback) and closed loop (w/ sensor feedback). Based on your description, the problem is manifesting in closed loop. The ECU is adjusting for something that's not quite right. Either the sensors (less likely) or some issue the sensors are seeing.

So you're armed with info, the car always starts in open loop. It's running well in open loop. When coolant temp and some other minor things reach threshold, it goes into closed loop. Seems that's when you're experiencing issues. -4.7 is not a huge deviation, but then again, idle is finely controlled so may be enough for it to stumble. High on the list of possible issues in my mind are vacuum leak but that usually manifests with positive trims, e.g. air coming in after MAF is not metered, so the ECU has to add extra fuel to pair with the extra air.

But this is a negative fuel trim. Could be a leaky injector but that wouldn't be as expected given it wasn't touched in assembly. An exhaust leak pre-O2 sensor that letting oxygen into the exhaust could cause such a thing. May want to check the exhaust manifold where it attaches to the engine for leaks. Though these types of issues would generally only affect one bank (ECU manages each bank on the engine separately), so check the trims on both banks to see if they match or not?

I pulled the MAF while running and it died immediately. This brings me back to my bypass kit, trying to eliminate variables, I unplugged the bypass and replugged in the factory harness for the water temp and MAF. I am going to give this a shot for a bit.

Pull the MAF before starting the car. This should force the engine to run in open loop continuously.

 

[camino70]

Thanks teckis300
I added open/closed to the screen with trims to keep an eye on it.

 

[TeCKis300]

The ECU operates in two modes. Open loop (no feedback) and closed loop (w/ sensor feedback). Based on your description, the problem is manifesting in closed loop. The ECU is adjusting for something that's not quite right. Either the sensors (less likely) or some issue the sensors are seeing.

So you're armed with info, the car always starts in open loop. It's running well in open loop. When coolant temp and some other minor things reach threshold, it goes into closed loop. Seems that's when you're experiencing issues. -4.7 is not a huge deviation, but then again, idle is finely controlled so may be enough for it to stumble. High on the list of possible issues in my mind are vacuum leak but that usually manifests with positive trims, e.g. air coming in after MAF is not metered, so the ECU has to add extra fuel to pair with the extra air.

But this is a negative fuel trim. Could be a leaky injector but that wouldn't be as expected given it wasn't touched in assembly. An exhaust leak pre-O2 sensor that letting oxygen into the exhaust could cause such a thing. May want to check the exhaust manifold where it attaches to the engine for leaks. Though these types of issues would generally only affect one bank (ECU manages each bank on the engine separately), so check the trims on both banks to see if they match or not?



Pull the MAF before starting the car. This should force the engine to run in open loop continuously.

I've got my logic backwards on the pre-O2 leak. That would cause the O2s to read lean, and the ECU to add extra fuel. Need more coffee!

 

[camino70]

No CEL or pending after bypass removal. It feels better, but I’m afraid that’s my brain playing tricks on me.

I’m not exactly sure how I want to approach tomorrow morning, possibly leave bypass unplugged, but I think that’ll put me in limp mode.

 

[camino70]

I started the truck this morning with the bypass unplugged. The CEL came up quickly, it was Misfire on multiple and both SAIS. The stumble occurred with the CEL.

I shut her down, cleared the codes unplugged the MAF and restarted. It stays in open loop with a message due to temp. No stumble/misfire CEL yet.