Misfire. Not coil related, help (1 Viewer)

[TRDdrew]

Ok guys I’m having an issue I’ve spent the last two days researching and reading different posts. Recently bought a 02 lx470. I’m having a misfire issue. The truck has codes for misfires on cylinders 2 4 6 & 8 also a random cylinder misfire code, so all cylinders on the passenger side. CEL blinks while at idle but goes solid once moving. first thing I did was replace all the plugs because I just wanted to make sure they where fresh. Second I swap all the passenger coils to the driver side and vice versa. The codes came back which tells me that the coils are fine. Also on a side note while I’m driving it the check engine light will turn off and the truck seems to run very good while just cruising around. But when I come back down to an idle the truck will start running rough again, it is very sluggish on take off as well but then clears up

This seem almost like a fuel pressure issue, has anyone ever come across This issue? The LX in question

 

[FxFormat]

After coils/plugs next step would be to test injectors/fuel delivery, but if the entire bank is affected it could be skipped timing but you said it corrects itself sometimes so...how many miles on the truck, and have you done compression test on it?

 

[JunkCrzr89]

Normally with an entire bank misinforming, the culprits are either Timing is off or head gasket. What are your engine temps? Sounds like this may be intermittent tho. The flashing CEL = stop before you blow it up.

 

[TRDdrew]

Normally with an entire bank misinforming, the culprits are either Timing is off or head gasket. What are your engine temps? Sounds like this may be intermittent tho. The flashing CEL = stop before you blow it up.

Engine temps are normal truck seems to run fine when just driving around. Does have 274k on it I’ll be checking the condition of the timing belt

 

[TRDdrew]

After coils/plugs next step would be to test injectors/fuel delivery, but if the entire bank is affected it could be skipped timing but you said it corrects itself sometimes so...how many miles on the truck, and have you done compression test on it?

Idk if corrects itself is the right term I have a fairly adavance scanner that I can read misfire counts on and it only misfires at idle the second it comes off idle the misfire count drops to 0 on all cylinders, 274 on the clock.

 

[ramangain]

Check the knock sensor

 

[gregnash]

Just went through something similar. Get a can of brake cleaner or carb cleaner and spray at the base of the injectors to see if you have an idle up. I chased mine for a month and was a combination of bad injector grommets at the intake and the manifold gasket being toast on that side.

 

[BullElk]

Check the knock sensor

Ah haaa. My LC has very similar symptoms with knock sensor code. Just haven’t decided to pay for the rather extensive labor.

 

[gregnash]

Engine temps are normal truck seems to run fine when just driving around. Does have 274k on it I’ll be checking the condition of the timing belt

Idk if corrects itself is the right term I have a fairly adavance scanner that I can read misfire counts on and it only misfires at idle the second it comes off idle the misfire count drops to 0 on all cylinders, 274 on the clock.

Yup look for my thread from a little over a month ago about chasing a P0171 code

 

[TRDdrew]

Well today I noticed the PCV valve hose was even hooked up, the line was bad so I replace it. And then moved on to testing for vacuum leaks with carb cleaner. I sprayed all around the injectors, I take manifold and all vacuum lines. No change in idle at all. So I’m gonna bring my bore scope home and try and look at the knock sensor wiring and we will go from there

 

[TRDdrew]

also looked at the condition of TB and it appear to be in pretty bad shape

these where the plugs i pulled out and replaced

 

[driller1]

I would look at #3 injector

 

[driller1]

I would look at #3 injector

#5

 

[TRDdrew]

#5

I did spray everything down with carb cleaner, including the injectors, looking for a surge in idle and didn't find anything yet. but its the other side of the engine that is giving the misfire codes

 

[driller1]

Just looking at the plugs, #5 looks to me like it is running leaner than the rest. I would replace that injector or at least have it tested for spray pattern and volume.

 

[PDPerry]

Did you diagnose the issue?
No codes, but I've been chasing-down a rough idle/stumble issue for about a year now...

 

[ramangain]

Cracked vacuum hoses tends to be the flavor of the month fix.

 

[TRDdrew]

Cracked vacuum hoses tends to be the flavor of the month fix.

ya ive been looking at those as well, im going to smoke test it. Im about to tackle the Timing Belt and wanter pump on it check everything for TDC and go from there

 

[TRDdrew]

Did you diagnose the issue?
No codes, but I've been chasing-down a rough idle/stumble issue for about a year now...

Well it looks like @JunkCrzr89 is the winner. I pulled it apart this weekend and started to tackle the TB and WP. Rotated to TDC and sure enough the passenger side of the engine was about 2 teeth off. Proceeded to finish the job, just have to put the thermostat housing back on and button everything up and we will be hopefully firing up tonight