Half of engine not firing

[DY]

Have a compression test and leak down test done!

Thanks for the suggestion. Just curious, why would you suggest that?

Because I still feel that it is something to do with the closed loop circuit. as when it is running in open loop, there is no idling issue at all.

and wouldn't a blown gasket or a burnt valve cause symptoms in both OL and CL?

edit:

after more thought.

-Rich Misfire (negative LTFT, also shown by plug condition)
-localized to one bank (can't be fuel regulator, vacuum leak, MAF, TPS), possibly injectors
-not o2 sensor (both just changed), possible harness or ECM.
-is definitely caused by closed loop operation.

[Rob]

What's the mielage on this engine? Both banks are running rich but bank two is running very rich. IF you can view current/live data on a scanner that would tell you a lot more than just the freeze frame, but sometimes we're limited.

If mileage is high there could be an accumulation of carbon in the cylinder that could cause this. A compression check could tell you this: if compression is very high it could be an indication of carbon buid-up. A good engine flush/cleaning with a product called Forte internal engine cleaner could work well.

[DY]

What's the mielage on this engine? Both banks are running rich but bank two is running very rich. IF you can view current/live data on a scanner that would tell you a lot more than just the freeze frame, but sometimes we're limited.

If mileage is high there could be an accumulation of carbon in the cylinder that could cause this. A compression check could tell you this: if compression is very high it could be an indication of carbon buid-up. A good engine flush/cleaning with a product called Forte internal engine cleaner could work well.

Hi Rob. Thanks for the reply. I thought everyone was outta ideas on this one. I only have a cheap OBDII reader so I can't get that. Is I/M readiness anything like live data?

The mileage is 150,000km.

I pulled the plugs out last Friday and had the look. Both banks now look like exactly the same. They both look like the passenger bank from the previous picture. Which I believe is still lean.

I've also been adding seafoam on every fill up. The shake is alot better than before but is still there.

[NP6000]

Looking at the plugs won't tell you if there is a large carbon accumulation in the head and on the top of the piston.

You could try an italian tune-up to clear out the carbon if you can't do a compression check. may want to run shell v power 91 octane before you try the italian tune-up method.

http://en.wikipedia.org/wiki/Italian_tuneup

my car gets the italian tune up every day, so im pretty sure the top end is clean !

[DY]

Looking at the plugs won't tell you if there is a large carbon accumulation in the head and on the top of the piston.

You could try an italian tune-up to clear out the carbon if you can't do a compression check. may want to run shell v power 91 octane before you try the italian tune-up method.

http://en.wikipedia.org/wiki/Italian_tuneup

my car gets the italian tune up every day, so im pretty sure the top end is clean !

I have to redline this thing just to get it onto the highway! its a heavy beast and the engine has to work to get moving.

I pointed out the plugs because atleast both sides look identical now. that is one issue solved but doesn't really help with the random misfire whatsoever.

the freezeframe still says that bank2 is running richer alot richer than bank1.

[Greg manton]

did you replace the plugs when o2 sensor replaced those things were incredibly fouled and are cheap try that first then continue. i know they were new before o2 sensor but platenum plugs are very seceptable to deposit fouling. may just be screwed becaus of o2

[DY]

did you replace the plugs when o2 sensor replaced those things were incredibly fouled and are cheap try that first then continue. i know they were new before o2 sensor but platenum plugs are very seceptable to deposit fouling. may just be screwed becaus of o2

no i did not. these are the old plugs from before.

The plugs cleaned up nicely by themselves though. if they fouled plugs now looked like the lean ones on the passenger bank, would they be okay?

I cleared the code this morning just to see if it would come back..

yepp....its back.

everything is looking okay except for bank 2 LONGTFT

its still sitting around -10% when the other side is at around -5% all the time.

[Greg manton]

this is going to sound crazy but grab a magnifying glass and inspect those plugs what people tend to consider fuel or deposit fouling is usually oxidation of the metal on the plugs. show up as little white spiders. even if not plugs are cheap and it would be good to rule them out. now that you have one problem solved really step back and start diag a new whether you just replaced parts or not, i have many times seen people spend alot of monney chasing a problem they have caused had one guy replace wires coils injectors o2 sensors brought it in to us and we took his bosch plugs out put delcos in and his missfire and cold start issue fixed. HTH let us know how it goes

[Greg manton]

also check exhaust leek before o2 sensor leaking exhaust =skewed o2 sensor readings you did say the last guy replaced the manifold. now im just spitballing

[DY]

also check exhaust leek before o2 sensor leaking exhaust =skewed o2 sensor readings you did say the last guy replaced the manifold. now im just spitballing

no problem. the more ideas the better!

it is common for stock pass. side manifold to fail on these engines because of a design fault. the last guy replaced it with a new manifold (updated design).

the driver side manifold is stock. When I seafoamed the engine (multiple times), i always kept an eye out for white smoke out around the manifold.

never spotted any. I don't know if this is a effective way to do this but the thing is cover in a heatshield and that would be a pain to take off!

this is going to sound crazy but grab a magnifying glass and inspect those plugs what people tend to consider fuel or deposit fouling is usually oxidation of the metal on the plugs. show up as little white spiders. even if not plugs are cheap and it would be good to rule them out. now that you have one problem solved really step back and start diag a new whether you just replaced parts or not, i have many times seen people spend alot of monney chasing a problem they have caused had one guy replace wires coils injectors o2 sensors brought it in to us and we took his bosch plugs out put delcos in and his missfire and cold start issue fixed. HTH let us know how it goes

okay for sure. I guess they aren't that expensive. i'll give it a shot.

Thanks again.

[DY]

Okay, finally got time to change the plugs out. some weird observations.

one plug on the driver side is wet as in soaking wet with gas. I didn't let the engine warm up however, just drove it into the garage to work on it. might be the choke but its alot of choke...

other plugs were fine. looked exactly like the passenger side plugs. changed them anyways.

didn't fix the problem.

I wanted to test for a leaking exhaust manifold again so I seafoamed the crap outta the engine. alot alot of smoke came out again (even though this is the 3rd time i've done this).

I saw smoke seeping from the driver side manifold. it looks like its coming from the exhaust gasket, i'll have to take the heatshield off and get a look.

I'll check for cracked manifold first. how would i check for broken studs? if not that then the gasket is gonzo.

really hoping its only the gasket.


As for correlation to the symptoms, im not sure how they add up.

how will a leaky manifold affect o2 reading?

[NP6000]

Exhaust leaks upstream of the 02 sensor typically cause lean 02 readings. IIRC this is opposite what your scan tool is showing - so I would wait until someone else with bench experience can confirm my above statement before you take it as gospel.

[v.1]

I'm new to your site. I don't ride any more but had many bikes from the time I was 10 until my 20's so I guess it's in my blood. Anyway, I hate to try to revive a zombie post but I came across this in a Google search. I tried to PM DY, but haven't gotten a response. I'd LOVE to find out his resolution to this problem... I have a 98 Pathfinder with the same issue. And I've tried everything. If anyone wants to chime in and help or knows DY and can poke him with a stick for me I'd be greatly appreciative.

[vrus]

I'm new to your site. I don't ride any more but had many bikes from the time I was 10 until my 20's so I guess it's in my blood. Anyway, I hate to try to revive a zombie post but I came across this in a Google search. I tried to PM DY, but haven't gotten a response. I'd LOVE to find out his resolution to this problem... I have a 98 Pathfinder with the same issue. And I've tried everything. If anyone wants to chime in and help or knows DY and can poke him with a stick for me I'd be greatly appreciative.

Not an April Fool's joke.

He sold it , bought a Subaru

[v.1]

Hahahahahaha.... ahhhhh..... hahahaha. Ok, well, first, thank you very much for the info. I guess there's only one thing left to do.

[Freestyle72]

Thanks for the help. I'm not sure to be honest. This is my first time working on a car. I only came to that conclusion because ALL the plugs on the passenger bank looked out-of-the-box brand new and the other side looked rich. it runs smoothly revving all the way to redline though. so its probably not the issue.
I don't know what I'm doing. that's the problem. I've been just googling random misfire and checking stuff by other peoples suggestions.

The plug wires are brand new. I didn't check the resistance through them. I followed the firing diagram online and it seems to be correct.

I also tried finding out which cylinder is not firing by unplugging one ignition wire at a time.

each time i unplugged a pass. side plug, the engine would slow down. each time i unplugged a driver side plug, the engine wouldn't slow down.

The problem occurs when the rev drops below 1000 rpm. when I first start it, it is fine but when the choke comes off, it gets worst. The very worst is when its stopped in gear.

The idle speed is about 700-750 which i believe is correct. How would i check ignition timing? Also I had to replace the knock sensor because throwing a KS code.

I believe it uses a IAC. I'll check tomorrow. dirty injectors are also possible. How could I possibly have three injectors on the same bank dirty at the same time, when the other side is clean?

Here is a picture of the plugs btw: left is passenger bank, right is driver bank. the two others on each side look the same. I still can't wrap my head around how one side is so rich and one side is so clean. I know its a definite telltale to the problem as well but i don't know what it is.




I've been thinking about that. I don't have the tool to check fuel pressure. is there a simple test for this?

NM...

[v.1]

Not an April Fool's joke.

He sold it , bought a Subaru

Not the best news... but what can you expect on April 1st. So, now that I've regained my resolve - and worked through my suicidal thoughts - I'm wondering if any of you guys feel like picking up where DY left off????

[Freestyle72]

Not the best news... but what can you expect on April 1st. So, now that I've regained my resolve - and worked through my suicidal thoughts - I'm wondering if any of you guys feel like picking up where DY left off????

I had similar problems on my jetta had to change the coils... But I noticed he said the engine had plug wires instead, so I don't know. Have you checked all your grounds?

[v.1]

I had similar problems on my jetta had to change the coils... But I noticed he said the engine had plug wires instead, so I don't know. Have you checked all your grounds?

I have not. But I just realized that I should probably give everyone an idea of what I have done so far and what issues I'm seeing.

I had an ex-Toyota mechanic do a tuneup on the truck. Changed timing belt, water pump, thermostat, plugs, wires, cap, rotor and accessory belts. Truck ran fine after. Then, like DY, I got a cylinder 4 misfire code and a knock sensor error. Car ran a little rough but after clearing the error code I drove the car for months before getting the error again. I went back to the same mechanic and had him replace the 3 injectors under the intake manifold (cylinders 2, 4, 6) and the plenum gasket. Things went downhill from there. I now get a 'random cylinder misfire' code (no longer specific to cylinder 4. White smoke and raw gas comes out the tailpipe. And again, like DY, the sparkplug in cylinder 4 is soaked in gas. I then replaced (again) plugs, wires, cap, rotor. Same issue.

What I've found since then is that the gas making it out the exhaust pipe has also leaked down the cylinder walls and is in my oilpan. I've pulled the Mass Airflow sensor and started the truck and it runs smooth (something a friend in NY suggested to truly test whether it's causing issues.)

Another local mekanik said that I need to replace the 3 new injectors... I kindly declined as I've never heard of injectors being DOA. I have a replacement MAS that I plan to drop in this weekend. And I'll now add checking the grounds as you suggest.

Keep 'em coming!

[RockerGuy]

I have not. But I just realized that I should probably give everyone an idea of what I have done so far and what issues I'm seeing.

I had an ex-Toyota mechanic do a tuneup on the truck. Changed timing belt, water pump, thermostat, plugs, wires, cap, rotor and accessory belts. Truck ran fine after. Then, like DY, I got a cylinder 4 misfire code and a knock sensor error. Car ran a little rough but after clearing the error code I drove the car for months before getting the error again. I went back to the same mechanic and had him replace the 3 injectors under the intake manifold (cylinders 2, 4, 6) and the plenum gasket. Things went downhill from there. I now get a 'random cylinder misfire' code (no longer specific to cylinder 4. White smoke and raw gas comes out the tailpipe. And again, like DY, the sparkplug in cylinder 4 is soaked in gas. I then replaced (again) plugs, wires, cap, rotor. Same issue.

What I've found since then is that the gas making it out the exhaust pipe has also leaked down the cylinder walls and is in my oilpan. I've pulled the Mass Airflow sensor and started the truck and it runs smooth (something a friend in NY suggested to truly test whether it's causing issues.)

Another local mekanik said that I need to replace the 3 new injectors... I kindly declined as I've never heard of injectors being DOA. I have a replacement MAS that I plan to drop in this weekend. And I'll now add checking the grounds as you suggest.

Keep 'em coming!

Have u checked the vacuum hoses going to PCV valves?
Coil tests?