I'm just getting tired of my 03' M45. I have replaced alot of parts, hoping to fix this problem. Sometimes, I get good power when I press on the gas, and other times, no matter how hard I press on the gas, it's like the engine is not just reciprocating.



History/what I have done to fix the problem
1. Rebuilt this engine before, but didn't replaced the timing chains, since at that time, they were in decent shape, and was like just 100,000miles.
2. Replaced valve covers because of the ignition coils were always fouling.
3. Replaced camshaft sensor to fix the stalling issue I always had when driving, or in traffic
4. Replaced crankshaft sensor with a brand new one, to fix a hard starting problem.
5. I have covered ose to another 100,000mikes with the car already.
6. The mass airflow sensor has been replaced
7. Replaced the catalytic converter like two times now.
8. Replaced all ignition coils more than three times now, without any improvement.
9. The only code that keeps popping up is the P0335 crankshaft sensor. This has been replaced with a new one, but still got same problem.
I have also checked for good ground and power on the crankshaft harness.
10. I have also replaced the fuel pump, and fuel filter more than three times too.


Current problems:
1. Loss of power, anytime I press on the gas. But when I removed my leg from the pedal, I get a smooth ride.
2. There's a kind of noise that comes from the passenger side cylinder head, as though the chain needs to be replaced, when you start the engine on a cold start. Kind like a slack chain or so.
3. When I also press on the gas for more power, I hear that rattling noise especially on that passenger side bank like a slack timing chain. So each time I press on the gas and hear that noise, I release my leg from the gas, and just lightly press the throttle as I drive.
4. The engine bucks, and there's this smell of raw fuel, or so, that is somehow pepperish to the eyes.
5. The engine consumes more fuel now than ever before.
6. Each time I'm sitting in traffic, or at a traffic stop, as I'm idling with the engine in DRIVE, the engine begins to "dance", kinda like a zigzag pattern (the RPM does not fluctuate though), just the engine. You'd see yourself like dancing to and forth. Replaced all the coils here, it rectified for a day, then later when I went on a test drive,it started dancing again.


Questions:
1. Can a slacked passenger side timing chain, and/or a misaligned timing chain cause the engine to be idling back and forth, and cause the loss of power I'm experiencing when I press the throttle peddel?

2. Can a partially clogged catalytic converter on the exhaust manifold at the drive side cause all these problems?

Some months ago while driving, I realized there was a rattling and hissing noise coming from underneath the passenger side catalytic converter.
When I opened tht exhaust to check, I discovered the catalyst had blocked the exit on that exhaust. Had to free everything there, before that noise stopped.

Could it be that the exhaust manifold catalytic converter is blocked, and that's why I'm getting a loss of power, and the rattling kind of noise at the passenger side each time I step hard on the gas?

3. I'm thinking of deleting the catalytic converters on this engine, and just run a straight pipe.
We don't much have a stricter emissions laws here in Lagos, and I won't mind removing the catalytic converters, and use a straight pipes.

4. Would removing or deleting catalytic converters affect engine performance, or it's just needed necessarily for fuel economy purposes and emissions. The way I understand it is that catalytic converters are there for emissions and not for PERFORMANCE.

5. So if I delete the catalytic converters, and use spacers in place of the O2S to full the computer into thinking the downstream sensors are working well in conjunction with the straight pipe, would I be good to go?!



Thanks for your replies, and reading through this long thread.
I'm just getting tired of this car; but I just love the power it produces.

Wow, that sounds like quite the problem. I've shared this thread with a few folks to see if they can provide some guidance but hope you get to the bottom of this!

Dxta wrote: ↑

Thu Jun 17, 2021 6:18 am

2. Can a partially clogged catalytic converter on the exhaust manifold at the drive side cause all these problems?

Could it be that the exhaust manifold catalytic converter is blocked, and that's why I'm getting a loss of power, and the rattling kind of noise at the passenger side each time I step hard on the gas?

Your symptoms sound very much like an engine that can't exhale. I wouldn't let that cat go very long if it's rattling, N/I engines are all Miller-cycle and if the cat melts, the exhaust valves will inhale the debris. That's 100% fatal, bye-bye engine.

VStar650CL wrote: ↑

Thu Jun 17, 2021 11:08 am

Dxta wrote: ↑

Thu Jun 17, 2021 6:18 am

2. Can a partially clogged catalytic converter on the exhaust manifold at the drive side cause all these problems?

Could it be that the exhaust manifold catalytic converter is blocked, and that's why I'm getting a loss of power, and the rattling kind of noise at the passenger side each time I step hard on the gas?

Your symptoms sound very much like an engine that can't exhale. I wouldn't let that cat go very long if it's rattling, N/I engines are all Miller-cycle and if the cat melts, the exhaust valves will inhale the debris. That's 100% fatal, bye-bye engine.

If that's the case, I might just remove the exhaust catalyst, to inspect it.

Would there be any problems performance wise if I delete all the catalytic converters, and out a straight pipe and oxygen sensor spacers in place?

Dxta wrote: ↑

Thu Jun 17, 2021 1:58 pm

Would there be any problems performance wise if I delete all the catalytic converters, and out a straight pipe and oxygen sensor spacers in place?

No, as long as you can keep it from throwing codes then you shouldn't have issues. Healthy cats don't actually generate much backpressure compared other points downstream, so the engine should run fine without them.

VStar650CL wrote: ↑

Thu Jun 17, 2021 2:18 pm

Dxta wrote: ↑

Thu Jun 17, 2021 1:58 pm

Would there be any problems performance wise if I delete all the catalytic converters, and out a straight pipe and oxygen sensor spacers in place?

No, as long as you can keep it from throwing codes then you shouldn't have issues. Healthy cats don't actually generate much backpressure compared other points downstream, so the engine should run fine without them.

Thanks for the response.
I think I need to totally remove the entire exhaust system, and take a look. It could also be that from years of piled up degraded catalyst could also have clogged the muffler too.

Dxta wrote: ↑

Thu Jun 17, 2021 4:16 pm

I think I need to totally remove the entire exhaust system, and take a look. It could also be that from years of piled up degraded catalyst could also have clogged the muffler too.

Mufflers and pipes are pretty hard to clog, but it certainly wouldn't hurt to shake it out and dump whatever might be in there for inspection.

VStar650CL wrote: ↑

Thu Jun 17, 2021 5:18 pm

Dxta wrote: ↑

Thu Jun 17, 2021 4:16 pm

I think I need to totally remove the entire exhaust system, and take a look. It could also be that from years of piled up degraded catalyst could also have clogged the muffler too.

Mufflers and pipes are pretty hard to clog, but it certainly wouldn't hurt to shake it out and dump whatever might be in there for inspection.

Thanks for taking the time to respond. I'm trying to remove the exhaust system today to inspect the muffler.
Here's what i noticed when I drove the car this morning.

1. Started the engine, allowed to warm up, while it was idling.
2. When I gave it has idling, the RPM got to 6/7rpm, without a problem. Does this not appear to you that the engine is exhaling properly?
3. But when I was driving on the freeway, immediately I have it has, I was hearing the engine bugging down and it's like shooting, the more I gas it gas. Can we say this might be an overstretched timing chain issue or misaligned one cos of the p0335 code?

Thanks once again.

So today, I removed the exhaust system, just from the Y-section, to the tailpipe. When I shook it, it was like making some rattling noises in it. I was able to remove awhole lot of fragmented pieces of the catalytic converters, and powdered stuffs.

When I started the engine without the exhaust, I noticed that the driver side exhaust manifold outlet was breathing out properly, while the passenger side was not commensurate with the breathing (flow of the driver side). It was gradually when the engine started getting to operating temperature, that suddenly, the passenger side breathing equalised like the driver side. So from this, it could mean that the passenger side exhaust manifold is partially clogged, and only tends to breath well, when the temperature of the engine gets to operating temperature.

I'm planning on removing the exhaust manifolds tomorrow, to inspect.

Dxta wrote: ↑

Fri Jun 18, 2021 11:39 am

When I started the engine without the exhaust, I noticed that the driver side exhaust manifold outlet was breathing out properly, while the passenger side was not commensurate with the breathing (flow of the driver side). It was gradually when the engine started getting to operating temperature, that suddenly, the passenger side breathing equalised like the driver side. So from this, it could mean that the passenger side exhaust manifold is partially clogged, and only tends to breath well, when the temperature of the engine gets to operating temperature.

Keep in mind that your long term A/F-alpha (LTFT) will be all screwed up on the side that can't breathe. Some of that "up to temperature" behavior may have been the ECM realizing it could breathe again once it reached closed-loop operation, then unscrewing some of the bad adjustments it had to make.

VStar650CL wrote: ↑

Fri Jun 18, 2021 2:07 pm

Dxta wrote: ↑

Fri Jun 18, 2021 11:39 am

When I started the engine without the exhaust, I noticed that the driver side exhaust manifold outlet was breathing out properly, while the passenger side was not commensurate with the breathing (flow of the driver side). It was gradually when the engine started getting to operating temperature, that suddenly, the passenger side breathing equalised like the driver side. So from this, it could mean that the passenger side exhaust manifold is partially clogged, and only tends to breath well, when the temperature of the engine gets to operating temperature.

Keep in mind that your long term A/F-alpha (LTFT) will be all screwed up on the side that can't breathe. Some of that "up to temperature" behavior may have been the ECM realizing it could breathe again once it reached closed-loop operation, then unscrewing some of the bad adjustments it had to make.

I think you're right with the LTFT here. Checking on my scan tool on the live data, I can see that it's only the STFT that's in the -2.3% or so, while the LTFT remains at zero without switching.

Dxta wrote: ↑

Fri Jun 18, 2021 11:39 am

So today, I removed the exhaust system, just from the Y-section, to the tailpipe. When I shook it, it was like making some rattling noises in it. I was able to remove awhole lot of fragmented pieces of the catalytic converters, and powdered stuffs.

When I started the engine without the exhaust, I noticed that the driver side exhaust manifold outlet was breathing out properly, while the passenger side was not commensurate with the breathing (flow of the driver side). It was gradually when the engine started getting to operating temperature, that suddenly, the passenger side breathing equalised like the driver side. So from this, it could mean that the passenger side exhaust manifold is partially clogged, and only tends to breath well, when the temperature of the engine gets to operating temperature.

I'm planning on removing the exhaust manifolds tomorrow, to inspect.

One thought I had on this is that you have a compression issue when the engine is cold and it takes the engine getting up to temperature for everything to seal right and have some flow going like it should. If you do have a borderline seal issue then I could imagine it being a problem under hard accel with suddenly losing compression on one or more cylinders and becoming that loss of power you mention. I know you said you already rebuilt the engine, but to me that just makes it even more likely on what I am thinking here. Piston tolerances are set to within a couple of thousandths of an inch, so if the slightest bit of measuring was off or if the proper care was not taken then something could easily be wrong inside the engine. You also said you have replaced the cats before a couple of times, and yet now when you take the exhaust off you already see fragmented pieces of the news ones? Seems strange unless the engine is blowing out a lot of unburned fuel due to some sort of issue. That is known to cause quick Cat death.

EniGmA1987 wrote: ↑

Mon Jun 21, 2021 7:48 am

Dxta wrote: ↑

Fri Jun 18, 2021 11:39 am

So today, I removed the exhaust system, just from the Y-section, to the tailpipe. When I shook it, it was like making some rattling noises in it. I was able to remove awhole lot of fragmented pieces of the catalytic converters, and powdered stuffs.

When I started the engine without the exhaust, I noticed that the driver side exhaust manifold outlet was breathing out properly, while the passenger side was not commensurate with the breathing (flow of the driver side). It was gradually when the engine started getting to operating temperature, that suddenly, the passenger side breathing equalised like the driver side. So from this, it could mean that the passenger side exhaust manifold is partially clogged, and only tends to breath well, when the temperature of the engine gets to operating temperature.

I'm planning on removing the exhaust manifolds tomorrow, to inspect.

One thought I had on this is that you have a compression issue when the engine is cold and it takes the engine getting up to temperature for everything to seal right and have some flow going like it should. If you do have a borderline seal issue then I could imagine it being a problem under hard accel with suddenly losing compression on one or more cylinders and becoming that loss of power you mention. I know you said you already rebuilt the engine, but to me that just makes it even more likely on what I am thinking here. Piston tolerances are set to within a couple of thousandths of an inch, so if the slightest bit of measuring was off or if the proper care was not taken then something could easily be wrong inside the engine. You also said you have replaced the cats before a couple of times, and yet now when you take the exhaust off you already see fragmented pieces of the news ones? Seems strange unless the engine is blowing out a lot of unburned fuel due to some sort of issue. That is known to cause quick Cat death.

Im just getting tired already, but won't give up. I'm trying to take a look at the timing chains here. Appears the passenger side may ha e timing chain issues, or slack. When I start the engine when cold, you hear rattling sounds from the passenger side, before it stops, and sometimes when I press hard on the gas when I need more power, ascending a hill, or so, you get to hear that rattle also. Why do you think this could be?

Some good comments/directions in here already, but I think you should be able to pop off the valve covers with the engine at top dead center and check the position of the cams just to verify base valve timing.
The rattle could either be a lazy tensioner, or bad tensioner/guide/super worn chain slapping around in there. Or it could be piston slap

I can't remember if the crank angle sensor gap is adjustable on these cars, but if it is (or there's any play available), you should inspect it. Also look for any shmoo on the sensor or the wheel that could cause funky readings.

Finally, check your engine grounds. Make sure they aren't corroded or anything. I've had some really weird stuff happen when grounds go bad.

PapaSmurf2k3 wrote: ↑

Mon Jun 21, 2021 3:34 pm

Finally, check your engine grounds. Make sure they aren't corroded or anything. I've had some really weird stuff happen when grounds go bad.

+1. If it's eating cats and timing chains among other unexplained failures, chronic rich-running from ground gremlins is entirely possible. Check the grounds the right way, too (there's only one right way, and it isn't your eyes or an ohmmeter):

keep-your-engine-on-the-ground-not-just ... 28130.html

PapaSmurf2k3 wrote: ↑

Mon Jun 21, 2021 3:34 pm

Some good comments/directions in here already, but I think you should be able to pop off the valve covers with the engine at top dead center and check the position of the cams just to verify base valve timing.
The rattle could either be a lazy tensioner, or bad tensioner/guide/super worn chain slapping around in there. Or it could be piston slap

I can't remember if the crank angle sensor gap is adjustable on these cars, but if it is (or there's any play available), you should inspect it. Also look for any shmoo on the sensor or the wheel that could cause funky readings.

Finally, check your engine grounds. Make sure they aren't corroded or anything. I've had some really weird stuff happen when grounds go bad.

Thanks. I'm in the process of opening the valve covers, timing chain cover today. Anything observed, would communicate over here.
1. Crankshaft is brand new, and that eventually help stopped the hardstart issues I was having.
2. I just wished it wasn't a piston slap. That'd piss me off. But let's see what I get to find during the timing cover removal.
3. I'd also check those grounds today, including the ones on the engine itself, and the body of the car, especially the ones by the side of the coolant reservoir.

Alright! Today, I opened the timing cover, turned the engine, to see if it was properly timed.

When I checked the alignment marks on the camshaft sprockets/gears, they were all out by a tooth, on both banks.

The coloured chain links between the camshaft gears on each bank, was supposed to be 14 links between coloured links. But on checking the cam gears and coloured links on both banks, it was 15 links instead of 14.

I think this has been the reason for the p0335 and the loads of power, and probably, the poor fuel economy and raw fuel smell I usually perceive when I start the engine.

I'm bringing down the engine, to inspect for any hidden issues this week. I want to really get to the root cause of the rattle I hear, when I accelerate after a traffic stop, or when accelerating hard.

The exhaust catalytic converters were pretty much ok. I'm so happy. I have soaked them in water and soap solution overnight, to help with any minor blockages. I'd be getting catalytic converters for the Y exhaust also.

Thanks everyone for your inputs.

PS: can a jumped timing on both banks by a tooth, cause all of the symptoms stated in my initial thread?

Yeah like if the chain jumped a tooth to the crank, I would think everything would be off, and all of your sensors (cams, crank) would hate life.

I have been working on my car throughout last week till now.
Had to finally just take out the engine of the car, through the hood up, without the transmission system. Not difficult though.

I prefer this method than doing the engine and transmission system through the bottom of the car.


Discoveries:
1. The timing chains on both Banks were off by a tooth
2. The right side hydraulic tensioner was broken on its sides (the hooks preventing the chains going sideways); and the left side tensioner guide was also broken on the sides.
3. The brownish stuffs I saw in the oil sump, were from the broken pieces from the guides.
4. Connecting rod bearings, and the crankshaft journal bearings were all scoured (the oil pump screen was partially clogged, and that could have been the reason for the scouring).
5. Some of the valves were stuck in their bores (I think this accounts for the reasons why I was loosing power during take off; raw gasoline smells; jerky feelings on traffic stops; some of the spark plugs were little bit wet).

Jobs done:
1. Replaced all parts, with brand new Nissan parts.
2. The rod bearings and crankshaft journal bearings used were not standard, but a 0.25mm sized ones, which I had to grind to fit the engine block bores.
3. Crankshaft had some unevenness on the loves, which I had to give a machinist to cut to 0.25mm
4. Replaced the piston compression and oil rings.

When I'm done with the car this week hopefully, I'd feedback my observations.



PS: when buying aftermarket parts, especially timing chains, pls don't make the mistake of using the chains as is. Try and place your old chains and the new ones side by side. Look at the two orange camshaft to camshaft links on the old chain, and the red paint mark link for the crankshaft, and compare with the new one. I did a mistake, using the new chains like that, only to discover that the timing was way off when I looked at the camshaft loves on both Banks. Removed the new chains, and discovered that the coloured link for the crankshaft, was a link ahead of the correct mark link on the old chain. This I solved by transferring the old mark to the new chains.
Also note that some chains don't have paint links on them.


Dxta