[illadef]

I've had a 2zz swap for awhile now and started having problems with a very high idle. My idle, after already being warmed up, would do a slow raise from 1000RPM to 2500RPM and back down, and repeat. I took it to a local shop for repair. The found that there was a intake leak, in which the MAF was loose and air seeping in. Another thing they did during this repair was lower the idle itself on the throttle body. While the idle has been steady since getting it back, the car exhibited a new problem. Anytime driving over 4000 RPM there is a sudden boost is power. Then when bringing the idle back down it's very erratic, jumping from 1500k to 2500 until it eventually dies. Does anyone have any insight as to why the car would run normal at lower RPMs, then jump in power after hitting 4000 rpms with the idle all of sudden becoming erratic? I've been able to repeat this continously with the steps below:

1. Initially starting the car everything seems ok. Temperature of the car doesn't seem to matter (i.e. cold start or warmed up). While the car is warming up, VVTi switching on can be felt consistently at 4500 RPMs.
2. Easy daily type driving shows no problems. I'll drive with steady acceleration, with the RPM's never going above 4K. The idle is stable, and remains at ~1200 RPMs. However, it is EXACTLY at ~1200 RPMs. When I first got my cams in, the RPMs would have a constant/slight fluctuation?
3. After the car has completely warmed up is when the issue seems to occur. If I bring the car's RPM's above 4K RPM's, the VVTi doesn't seem to turn on. I've tested this at both 50% or at 100% on the gas pedal, separately.
4. If I keep the RPM's in 4000 range for several seconds eventually there seems to be a be a boost in power, with the car lunging forward for a second (it feels like the VVTi all of sudden turns on?) @ 4000 RPMs. I've been able to repeat this using either 50% or 100% on the gas pedal. During a test drive with my co-worker he initially thought the 'lunge' was me hitting 100% the gas pedal to try to make the issue happen, but at the time at had kept it at a constant 30%. After the 'lunge', it feels as if the car has a 5% increase in power through the entire range of RPM's.
5. During this time when I let go of the gas, RPM's are now slightly erratic, and the engine is louder and more throaty (the way the car was when I first got my cams installed). The car has 5%-10% more power as well, and is much more responsive to the gas pedal. On occasion (at least once a day) the idle becomes unstable, jumping around from 500 RPM to 1500 RPM until it eventual dies unless I level it out using the gas pedal. Once I level it out the car runs normal again.
6. As soon as I restart the car idle is back to normal, but back to the original power, and without the obvious feeling of the VVTi turning on at 4500 RPMs.
7. I'm able to repeat this issue with step #3.
   

 

[ThangCu35]

How old are your spark plugs?

 

[T-bone]

000000000

 

[illadef]

How old are your spark plugs?

I've changed the spark plugs and it had no effect. :-(

 

[Rasheed]

I am not sure but I have never heard of reaching LIFT at 4500 RPM!! They usually set it at 5500 RPM with a PFC and supporting mods unless you have a DD performance intake manifold!!

Rasheed

 

[illadef]

so you are saying you are getting lift at 4500? not sure you can feel variable vale timing. do you have a PFC? if you set lift higher does the problem then not occur until you hit lift?

seems like you have a lift problem. the cam lift bolts that move you to the higher lobes might be the problem.

it's not the vvti. i've had a performance shop take a look at this. the pfc is tuned so that the vvti is engaged at 4500RPM and they put it back on the dyno to confirm. this 'boost' in power is at 4000RPM exactly. also, you'll only feel this 'boost' once. once it happens the first time it doesn't occur again until the car shuts off and has to be restarted. the shop is suspecting its a faulty tps sensor, but they're unsure if it'll solve this problem entirely until it's been installed. they're suspecting this issue is a result of the previous shop tampering with the throttle body in the attempt to smoothen out the idle.

 

[Cap Weir]

The FIRST thing that should have been Mentioned in the Post was the MODS...

PFC!!!..

You are on your OWN..

Depends Upon how and Who tuned it..

When a PFC it Tuned, it is posable to set it up a BUNCH of different ways.. and as such, it will not ( Or My Not ) behave Properly when things are Changed.. Like Adding Cams, or the Temp Correction Might be Wrong..

WAY to many things to guess at..

Take it to have it Re-Tuned...

Cap

 

[T-bone]

000000000

 

[ThangCu35]

The 2zz does have VVTi map like the 1zz, but with an extra lift option, but to my knowledge you can't turn on or off VVTi. It does sound it needs a retune like what Cap says. I would try to datalog the AFR/timing when it lurches

 

[silversprint]

When they fixed the intake leak did you redo the idle learn procedure with the PFC? PFC controls idle

Why is the lift point set so low?

I am not sure the shop you are using is completely familiar with the PFC?

It sound like the tune in the PFC needs to be checked then the idle reset. May need a retune.

 

[Sherwin]

First of all, engaging LIFT at 4k is way to early...
Indeed get a retune by someone who knows what he is doing. It might that the lift does 't stop working, because of the higher cam profile it wont run smooth on idle.

You have a 2ZZ-GE engine, it's provided with VVTL-i; variable valve timing & lift intelligence.

First check what you've got so that it is also clear to you!!

 

[Kevin Beane]

That's too low for lift. Given that and the fact that you have a PFC, the problems are most likely because of tuning.

 

[grumpy]

09iujn

 

[2zzmr2]

Maybe one of the sensors are malfunctioning?
Idle control sensor..

If you still have the stock ecu for the 2zz try replacing the PFC to see if the engine runs better?
Not sure if not having the correct gap on the spark plugs would cause this problem.

 

[jellis]

I've had this problem before.
It was bubble in the coolant jacket.
And just to verify... the high idle only started after you got up in the rpm's right? then would continue for some time then slowly come down and then begin to surge?


Drain the coolant refill. Make sure you purge the heater core properly and it should solve the problem.

its also noted on the celica forums that the low speed cam makes more power than the high cam at 4500rpm. the best settings have been noted at 6100 engage, 5800 from drop.
I've spent a lot of time playing with different lift engagement points and it takes a lot longer to build power with a low lift engagement. keeping it within 500 rpm of factory defaults

 

[T-bone]

000000000

 

[jellis]

No signature pictures allowed on this site.

The forum should have a public notice.

 

[MikeV]

Do you own a stock ECU? First and easiest step in troubleshooting is to put the stock ECU in for a week and see what it says/does. My guess is you'll be throwing cam position sensor codes (e.g. P1346 and/or P1349). But that's just a SWAG.

But... yeah... you have a PFC. The engine is pretty much going to do what the PFC tells it to do. "When I got my cams installed" -- you're running stage 2 or 3 cams? You need a professional tune.

 

[T-bone]

000000000

 

[jellis]

Do you own a stock ECU? First and easiest step in troubleshooting is to put the stock ECU in for a week and see what it says/does.

The limiting factor there is the cams and the injectors if they have either.
The car can run stock ECU on stage 2 cams but it will want to break up and idle like shit.

I'd say start narrowing down the possibilities.
Make sure the throttle body set screw matches the idle settings on the PFC.
Then make sure your fuel cut is set 4-600 rpm higher than idle.
Make sure you have a good water temp map, maf map, and corrections set for what you need

speak to the admin - it has been suggested.

Sig pics make a form look cluttered and generally less readable. Did you not notice the lack of pics and how nice it is to read?

yes and no.
There should be a newb section on every forum splash page with the rules and shit.