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Can the camshaft on a 2zz be replaced in the car?

3096 Views 124 Replies 13 Participants Last post by  ozone
I'm having some issues with my 2zz swapped MR2. The valves are making a lot of noise. I have removed the valve cover and inspected the camshaft and measured the clearances. There is a little bit of excessive wear on the #3 and #4 intake lobes of the camshaft. Honestly, it doesn't seem like enough to make that kind of noise, but it's definitely coming from the valve train. So what I'm asking is:
1. Could you help me diagnose the problem?
2. If I have to replace the camshaft, rocker arms or something up there, can the cams be removed without removing the engine? The front cover is pretty close to the side of the car.

To get the specifics on the problem you can watch this video: AG 036 MR2 Spyder valve train problem (Help!)

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Oh, and on a related note, I bought a 2020 Hyundai Veloster N. As it turns out, the head gasket on my wife's car was leaking so we needed some reliable transportation. I hope it is reliable. Anyway, there were two cars in the running for me to purchase. They were a 2020 BMW 230i with the track handling package and the 2020 Veloster N. During my inspection of the cars, I pulled the oil cap off while the engine was running and they both pumped out boatloads of air pulses, just like my 2zz. Feel free to comment on why this would be? Still seems like there shouldn't be that much pressure in the valve cover if blowby is minimal.
Ok, I just checked all of the timing marks and regrettably, they all seem to align. I was really hoping this was the answer. I'll try to post pics.
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Got any more suggestions?
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Ha! I'm curious how many turns did it take to get the color links back into position. Good job.

I don't even recall what the original reporting issue is on this car. Was it an issue with lift?

1. now that you have the valve cover off, check the lift bolts. You should be able to back them out and inspect them. But be careful and don't push it if they put up resistance or they might break. [if they are old sylte lift bolts, replace them with new style].

2. check the oil pressure - the fsm has a diagnostic procedure for reading the oil pressure with a gauge on the lift oil pressure sensor location.

3. did I mention previously there is an o-ring between the valve cover and the head for the oil squirters? If it goes bad oil will leak and you lose oil pressure. check it or just replace it as routine maintenance.
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The lift bolts are brand new, installed by MWR when I bought the engine. The o-ring is brand new as well. In fact, I measured it and put it on Spyderchat so others wouldn't have to pay the ridiculous $8.00 cost. They can just find one with those dimensions.

The problems with the car are:
1. Running rich (smells like fuel, fuel trims are negative, LTFT=-16, STFT=-2. Latest, but they will get worse.)
2. Idles poorly. It varies from idling fine to stumbling, to idling too high to surging up and down.
3. When it's cold sometimes it hesitates (bogs down).
4. Popping from the exhaust (this usually happens after it's been sitting for a while, like when I've been working on it). This usually goes away.
5. Poor fuel economy. ( Maybe 250-270 on a tank. I think with my driving it should be around 280-300. It was 300-320 with the 1zz when it ran well.)
6. Dipstick popping out. (It's not the tightest fit. It's possible it's just vibrating out)
7. Valve cover leaks despite being new and torqued to spec. (I hate oil leaks and when I put the engine in, there were NO leaks).

When it's warm and running hard like accelerating onto the highway, it feels good.
I should note the engine started doing some of this probably within two weeks of install. And again, you can see the entire install process on my YouTube channel "antimatter garage." The videos are long, so watch on higher speed.

Oh and it only took one time around to get them to line up, but because I was cranking little by little with the wrench, it felt like an eternity. Also I blame you guys for not reminding me that the car has to be in neutral to turn the engine over. It was embarrassingly long before I figured out how it could be so hard when the spark plugs were removed. LOL.
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Funny you should ask. I was just thinking I might have a leaky fuel injector. It's the only thing I haven't changed since the install. They are yellow.
If I was in your situation without any clues I would start data logging using an ODB2 compatible logger. There are phone apps that can do this now.
Drive the car and the logger will record all the data particularly the events when they happen. On review you can freeze the data where the car is giving you trouble and go over all the data so you can make correlations of what is happening with a cause and effect approach. Sometimes it's a bad sensor or bad connector causing faulty intermittent events.
You can also take it to competent mechanic for diagnosis for a fee and they can identify the problem using better methods and experience to isolate the issue. It would be money well spent.
Good mechanic? What's that?
Actually I came here so I could avoid the "good mechanics."

Obviously, I'm being sarcastic here, but I did just take it to a Toyota specialist. They were the ones that told me it was excessive blowby based on the strong pulses coming from the oil cap. At least they didn't charge me.
Actually I came here so I could avoid the "good mechanics."

Obviously, I'm being sarcastic here, but I did just take it to a Toyota specialist. They were the ones that told me it was excessive blowby based on the strong pulses coming from the oil cap. At least they didn't charge me.
I would take it to another one for a second opinion. Just make sure not to tell them about what the other one determined.
Let them know your compression and leak down findings and let them independently diagnose. Checking data and reaching a diagnosis is real salt of the earth work that a lot lazy mechanics like to avoid so they can do water pump and other things that make economical use of their time.
The brown injectors flow slightly more than the yellow. If you have the yellow injectors then you have the lowest flowing injectors.

Pulsations in the crankcase are a red herring. Anyone who thinks that pistons, rods, and crankshaft can rotate at 1000rpm and not produce any air movement comes from a different universe where the laws of physics are different than ours. The design of the crankcase and rotating assembly will affect how much pulsation is felt from engine to engine.

Things that can cause negative fuel trim:

Intake duct configuration and sizing leading to incorrect MAF reading.
Faulty MAF
High fuel pressure from faulty fuel pressure regulator (this is unusual)
Incorrectly sized or faulty injectors
Faulty or incorrectly positioned O2 sensor.
Misfires do not cause a rich reading. Misfires cause a lean reading because of the excess uncombusted oxygen, because the O2 sensor detects oxygen, not fuel.

Do you have one of those exhaust manifolds where the O2 sensor is positioned on just one exhaust runner? Or do you have the O2 sensor positioned after the merge of all four cylinders? If you have the former, swap injectors on that cylinder.
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If I'm running rich, how will higher flowing injectors help? What vehicle are the brown ones from?

I do expect pulsations in the valve cover as a normal situation, but these are very strong pulsations that after experiencing with 3 vehicles, I'm assuming is actually normal.

-The intake duct is the MWR intake that came with the engine. The air filter is dirty, but these symptoms have been around since it was new.
-The MAF is new and didn't change the way the engine ran from the previous one, although I don't believe the new one is from Toyota, so that could be an issue.
-The fuel pump and fuel pressure regulator are new. Regulator is from Toyota. Not sure about the pump.
-The injectors are new (with install) and are the yellow ones, as stated. Could be bad. I can try to check them.
-I made (with crappy welds) the exhaust system. See the discussion above. The O2 sensors are both on the aftermarket cat, one before, one after. The location of the upstream O2 sensor is no farther from the exhaust ports than a stock Celica and it is after the collector. I think they are not Toyota parts.
-Not sure I understand where the misfire comment came from. But I would have thought is was the other way around. Excess fuel or air causes a misfire. The misfire being the result of the incorrect combustion. In fact, I thought misfire=incorrect combustion. Is that wrong? Is it only electrical?
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You're fine with the yellow injectors.

My prime suspect in your situation is the intake. As an experiment, after warming up, remove the air filter and idle without it for a minute or two. Check fuel trim. Is it different? Does it go up? Or down?

What happens when you race the engine up to 2500 rpm ahd hold it for a minute at tidle (this wil l not harm your engine, it is a routine test performed on all kinds of engines) ? Are fuel trims more negative? Or less negative? You can try this both with filter on and filter off.

Ideally take a data log that shows fuel trim at varying load and engine speed. The variables to log would be LTFT, STFT, absolute load %, rpm. These are all available in any scantool app, like torque pro for example. The log should be taken after the learned values have reached equilibrim which could mean after an hour or two of driving if you are starting fresh.

While you're at it check the TPS value it should be about 10% with the pedal in the idle position and about 90% with the pedal to the floor.
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Could be a bad MAF if it isn't Toyota/Denso.
Ok, I will do all of this tomorrow. I can tell you the TPS is also new. The old one tested "out of spec" according to the manual, so I bought a new one and it too tested out of spec. So, just to be certain, I put the new on one. It shows 11% at idle.

My scan tool is old. It's called Auterra. I got it because it has a horsepower measuring tool. It's pretty cool. Not sure if it logs though. Let me look through the menus.

I don't recall if the MAF is Toyota or not, but I can tell you that the previous one was pretty new and I bought another new one, which is on the car now and they both perform the same.

I have some snap shots of live data I took while idling for about 10 minutes. Let me see if I can upload them.
Here they are. What I notice is it looks like the O2 sensor after the cat isn't flat-ish. It seems to vary almost one for one with the one before the cat. But I don't have a code for the cat and even if that O2 sensor was bad, I was under the impression it is really only there to monitor the health of the cat. Either way, this was just idle. Toyota calls for a trip test with a series of driving and idling to properly test that sensor.

Also, these scans seem to be out of order. I'll tell you in the next post what they are. I need to see how they come in.
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Ok, so the last one is the first test, after a reset. You can see that the fuel trims are 0%.

The first one is the second test while it was warming up and the values are already at -16.4% and -2.4%.

The second one is the third test I did after shutting off the engine and restarting the test.

And the third one is while the engine was idling for a while, like 10 minutes. Look at the bottom O2 sensor data.

Can you just summarize briefly in words what you found with filter on, filter off, idle rpm, 2500rpm. I am not following your charts
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