I have a valve tick/tap - How to fix?

Bijan said:
What are you idling at? Specifically...

Is it ROUGH?
Click to expand...

700 in park and 600 in drive, the RPM's are not the issue. It literally jostles my seat it idles so rough though. It's almost rhythmic now. When I let off the brake to let it creep forward in drive, it shakes and jolts because the miss is so bad.
 
gamefreakgc said:
700 in park and 600 in drive, the RPM's are not the issue. It literally jostles my seat it idles so rough though. It's almost rhythmic now. When I let off the brake to let it creep forward in drive, it shakes and jolts because the miss is so bad.
Click to expand...



Cams with more overlap and duration will not maintain a smooth idle. You trade one for the other. A cam with 280 degrees advertised duration will start to lope and may require an increase idle to keep it happy.


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96RedRunner said:
That lope comes with the cams, with that much lift/overlap gona be hard to drive on the street.
You might be in the area with cams you chose of losing vacuum also.
Click to expand...



I forgot to mention the lower vacuum thanks. The 396 in the Chevelle with a 292 degree cam only has around 5" of vacuum at 900rpm with around 23 degrees of advance at idle and 35 degrees total. Increased overlap and duration usually require more timing.

The 396 lopes nice enough it usually has someone opening the back door at the drive ups to see what they hear in their headset.


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19963.4lsr5 said:
Cams with more overlap and duration will not maintain a smooth idle. You trade one for the other. A cam with 280 degrees advertised duration will start to lope and may require an increase idle to keep it happy.


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Click to expand...

96RedRunner said:
That lope comes with the cams, with that much lift/overlap gona be hard to drive on the street.
You might be in the area with cams you chose of losing vacuum also.
Click to expand...

It didn't stumble like this the first 2 months I had it installed. It only started after the valve tap, which turned into a valve knock. The cams did change the idle a little but not much.
 
If the tick got better but it's running worse make sure you didn't get the valves too tight. Not enough clearance will be quiet but make the engine run like shit. And burn valves. Also try swapping the fuel pressure regulator. Look at the air filter and see if it smells a bit like fuel. Thats one sign of a bad regulator but it could still be bad without that happening. If I remember right u gotta pull the intake to get at it, it's like back center of the motor. I've seen those go bad and cause nasty injectorish tapping. When it's real bad it almost sounds like rod knock on cold starts.
 
well shit....

700 sounds perfect for being in park, but like you said it's not the RPM..which DOES sound like a cam, but you say it didn't do it before...so.... yea... what [MENTION=84389]wshiverick[/MENTION] said ^^
 
Bijan said:
My trusted mechanic relayed to me that the Evap VSV is making the noise on mine. Thoughts?
Click to expand...

The Evap canister does make a ticking, and even a "mooing" sound (pretty hilarious) but it's fairly quiet.

My engine grenaded on Tuesday, I think I broke a valve or cracked a piston.
 
gamefreakgc said:
The Evap canister does make a ticking, and even a "mooing" sound (pretty hilarious) but it's fairly quiet.

My engine grenaded on Tuesday, I think I broke a valve or cracked a piston.
Click to expand...

So sorry to hear this, Jarod! I was going to offer Marvel Mystery Oil (MMO) -- I had a very very similar sound when I first started my JDM engine and after running a good amount of MMO w/ Mobil 1 it cleared up. For the next oil change I tried JUST Mobil 1 and that sound came back so I put more MMO in it. For the following oil change I did just Mobil 1 and it hasn't come back since -- I've driven >10,000K miles w/o MMO. Cylinder compression is 197-205 on all. I think it was a sticky/stuck valve, spring, tappet.. something. MMO is awesome.

Are you thinking of rebuilding this engine or getting a JDM one? I can speak to the JDM experience -- what to look out for, etc.
 
96RedRunner said:
Sorry to hear that! You going to tear it down to see what the damage is? Salvage cams ?
Click to expand...

I will. I have a ton of parts I need to take off my current engine, cams (which should be fine) crankshaft pulley, injectors, headers, etc. that I hope are all still in good shape. After it's done I'm going to pull the heads and see what went wrong.

Funny thing is, for as hard as I push this engine it failed just after a cold start going 15 MPH down the street next to my house.
 
Hopefully you didn't lean out a cylinder and melt something. With only 1 O2 sensor that can easily happen and you can't watch knock retard live to know something is wrong. Only way to catch that condition IMO is watching the Long Term Fuel Trim on a regular occasion so you know what's normal.


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19963.4lsr5 said:
Hopefully you didn't lean out a cylinder and melt something. With only 1 O2 sensor that can easily happen and you can't watch knock retard live to know something is wrong. Only way to catch that condition IMO is watching the Long Term Fuel Trim on a regular occasion so you know what's normal.


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Click to expand...

I don't think so, but you never know. I've been running the current injectors for about a year now. I have a wideband AFR gauge and it's always been in spec and LT fuel trims have been staying at or very close to 0 the whole time. I'll know when the engine is out and taken apart.
 
gamefreakgc said:
Funny thing is, failed just after a cold start going 15 MPH down the street next to my house.
Click to expand...

Perfect place for it to go! well maybe in driveway been perfect.
Going to be interesting, with you thinking bent valve, piston cracked I wonder if a spring colapsed, cause and effect. Part of spring and gap issue prior?
 
My 04 4Runner has ran great for years no problems at all. That being said Friday I was driving and heard a knock I was only going around 30mph when it happened then it started knocking continuously so I turned my car off and got it towed. The shop is saying the motor is blew. But it still runs fine sounds just like yours.
 
This is for 3RD Gen ('96-'02) T4R's.

Maybe the mods can move this to the 4G section?


Eddie




Figgs said:
My 04 4Runner has ran great for years no problems at all. That being said Friday I was driving and heard a knock I was only going around 30mph when it happened then it started knocking continuously so I turned my car off and got it towed. The shop is saying the motor is blew. But it still runs fine sounds just like yours.
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