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Discussion Starter · #1 ·
I installed a set of 2JZ cams the other week and the idle was a fairly rough after that. All the valve clearances were within spec when I did the install, but some of the valve clearances were at the limit.


I then re-shimmed the valves using the shims off of my spare head and got the clearances closer than what they were before and now it runs even rougher.


Any suggestions? Should I get new shims from the dealer and get all the clearances to minimum spec? I don't understand why the engine would run like this when the clearances were ok to begin with.
 

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Your Neighborhood Pikey
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Define rough please. Do you mean that it has a bumpy idle, is it making a lot of noise? What do you mean exactly? If it's making a lot of noise, then clearances are your problem. If it's a bumpy idle, then fueling and timing is your problem.

For example...

I have HKS 272's. If I reset my ecu and start it for the first time, it will not even run the 272's. I have to take out -35% fuel and open my throttle slightly just to get it to idle. As it's warming up, I slowly and methodcially take out fuel in -2% increments until I get back to zero fueling. The cams idle so crazy on the motor that I have to assist the ecu in learning the idle of the car. If I don't, it will never idle on it's own properly. Once I've done this, the car idles on it's own no problems, and the only real lope comes when it's cold. When the motor is hot now, it barely lopes at all.

IF your A/F's are too low at idle, below 14.2 or so, the ecu will NOT trim the fuel tables for idle. I would check that first and let me know. If that's the case, then you need to take out fuel at idle to get the ecu to fuel 14.8-15.2, where it wants to be. Then slowly take out small increments of fuel, letting the ECU compensate each time. Eventually you'll have a nice stock idle back.

Another thing... My 272's have a pretty aggressive ramp-up. Even with proper valve clearances, the valvetrain is just plain noisy and there's nothing I can do about it. Kind of like a cammed LS2, it makes a lot of noise.

- Chris
 

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Discussion Starter · #6 · (Edited)
thanks for the informative post. What I mean by rough is that it idles like a cammed V8, very bumpy. When I rev it moderately high (about 4000 rpm), the engine dies. Also, the idle speed is about 450 rpm.


I have no means of adjusting or measuring the A/F ratio, this is all on the stock ECU. No aftermarket electronics.


I made sure that the cam timing is dead on, so that isn't the issue. I haven't driven the car because I don't have a radiator yet.

I'll get a video of it later today.
 

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Discussion Starter · #7 ·
Pete_Howard said:
did you get the timing pulleys to line up correctly? it was a little hard on my engine to do. you need to be balls on.

Hey Pete, when you installed your 2JZ cams were you able to maintain the stock idle and driveability??
 

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Yeah, you can't even tell there are 2J stock cams in the car. It idles flawlessly. You only feel it in the top end. It really pulls hard to redline, compared to the 1J cams.

Later
 

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Your Neighborhood Pikey
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You should hear my car idle when it's cold. It's REALLY lumpy.... I'll shoot a video for you, it's pretty nasty sounding!

- Chris
 

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I know you aren’t supposed to on stock ecu but can you not wind the throttle stop screw in a bit to open the throttle a little more and up the idle?

I think you are going to need some sort of fuel control though. Can you adjust idle AFR’s with a SAFC?
 

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going broke fast
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i installed the 272 crower cams from the gb in my car.i turned the idle screw up just a bit.when its cold it sounds like its ready to stall.when its warm it idle's at like 750rpm and smooth almost like its stock.i probably wouldn't have to touch the idle screw,if it wasn't running so rich.
 

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Discussion Starter · #12 ·
hey thanks for the help guys, I adjusted the idle screw and it idles a lot better. I have a slight miss through. I just put in NGK 6097s gapped at .028. Any suggestions?
 
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