2zzge rough idle and stalling

[Lith]

Calc load 21%
short fuel trim no1 -20.3%
ignition advance 19 deg
Afm 2.58
injector pulse width 1.8 ms
Iac ratio 32-43%

Daily driver

Calc load 13%
short fuel trim no1 -1.6 to 0.0 (fluctuates)
ignition advance 16.5 deg
Afm 0 (goes to 2.58 off idle)
injector pulse width 1.7 ms
Iac ratio 25ish%

Main points I find interesting (no idea whether it is worth paying attention to or not but still)

- Injector pulse width is pretty similar between the two cars, despite the race car claiming it is implementing a -20% fuel trim (which if it works the way I assume would suggest the original calculated IPW might be between 2.1-2.2ms). Makes it seem like either the engine is running way less VE than the fuel map it has setup for expects, or way more fuel is being moved by the fuel system than expected... ignoring any O2 sensor related issue) the first is more likely

- Calculated load is 21% in the race car and 13% in the daily... not sure whether this is linked to the IAC (if it is idle control) being substantially higher in the race car or not, and if so why it is working harder to maintain an idle.

- Ignition timing on the race car is a reasonable bit higher at idle despite being under "more load". Typically the main ignition settings before any trimming has happened would dictate less timing as load increases at a particular rpm range. Some ECUs will bump (or retard) ignition timing to try and stabilise idle.

So, on looking at that - some questions to assist further pondering -

Is IAC the idle control valve? Is there any chance the ECU has had any kind of "remap" at any point? (don't really think this is the case, but just asking questions )

You have said that this issue is is something that developed - like as soon as you installed the cam controller? How does VVT on these things work? Is it on/off or varying degrees? One thing that occurs to me that if the VVT is at a different angle to what the ECU thinks it is then strange shit like this could go down. Strictly speaking if the cam is at an angle it isn't meant to be at low engine speed (whether tuned for it or not) then the engine could easily run like crap anyway.

[captain crescent]

Calc load 21%
short fuel trim no1 -20.3%
ignition advance 19 deg
Afm 2.58
injector pulse width 1.8 ms
Iac ratio 32-43%

Daily driver

Calc load 13%
short fuel trim no1 -1.6 to 0.0 (fluctuates)
ignition advance 16.5 deg
Afm 0 (goes to 2.58 off idle)
injector pulse width 1.7 ms
Iac ratio 25ish%

Main points I find interesting (no idea whether it is worth paying attention to or not but still)

- Injector pulse width is pretty similar between the two cars, despite the race car claiming it is implementing a -20% fuel trim (which if it works the way I assume would suggest the original calculated IPW might be between 2.1-2.2ms). Makes it seem like either the engine is running way less VE than the fuel map it has setup for expects, or way more fuel is being moved by the fuel system than expected... ignoring any O2 sensor related issue) the first is more likely

- Calculated load is 21% in the race car and 13% in the daily... not sure whether this is linked to the IAC (if it is idle control) being substantially higher in the race car or not, and if so why it is working harder to maintain an idle.

- Ignition timing on the race car is a reasonable bit higher at idle despite being under "more load". Typically the main ignition settings before any trimming has happened would dictate less timing as load increases at a particular rpm range. Some ECUs will bump (or retard) ignition timing to try and stabilise idle.

So, on looking at that - some questions to assist further pondering -

Is IAC the idle control valve? Is there any chance the ECU has had any kind of "remap" at any point? (don't really think this is the case, but just asking questions )

You have said that this issue is is something that developed - like as soon as you installed the cam controller? How does VVT on these things work? Is it on/off or varying degrees? One thing that occurs to me that if the VVT is at a different angle to what the ECU thinks it is then strange shit like this could go down. Strictly speaking if the cam is at an angle it isn't meant to be at low engine speed (whether tuned for it or not) then the engine could easily run like crap anyway.

I dont beleive it has had a remap.

I am unsure when the problem has evolved i just drove and maintained it to be honest untill i started getting the stalling issues.
the cams work by degrees i have checked the valve and had it actuated with voltage from a battery. The engine manual has an actuaton test that i have preformed and as it says the engine does stall.

Just a note i have replaced the "lift bolts" in the engine but i THINK these just hold the shafts .http://www.billswebspace.com/EliseLiftBolts.htm

[captain crescent]

Today I have changed the complete throttle body from my daily driver as a complete unit so idle control valve and throttle position sensor fitted.
Once again there has been no change.

[sergei]

Tried swapping ECU?

[captain crescent]

swapped ecus between cars no difference to either car

[Lith]

And once driving it seems fine, it's just idling or coming to a stop that it is a problem?

[captain crescent]

It seems to perform as well as my daily driver .It goes on to lift at correct time and everything just when driving cruising around 100 kms if i start to slow down by taking foot off throttle completely or almost completely that's when I feel the engine has cut out if I put foot back on throttle it will start again with a small backfire from the exhaust . I do quite often put my foot on the clutch as an instinct then letting the clutch back out and open the throttle a little it does start. It does not do it all the time maybe 2 or 3 times in a hour of driving and seems to be more when the engine is warm.

So the concern there is the stalling while backing off.

[captain crescent]

So after a few weeks more of pottering away at it (after missing the event I really wanted to enter ) I decided to recheck the cam chain and timing and decided I would also check the valve lash.

The exhaust valves on no 1 ,2 and 4 all have .127mm or less lash (recommended .35 - .45) no 3 was within spec .
This could explain my issues and corresponds to the spark plugs on 1,2 and 4 being sooty (incomplete burn) and no 3 looking how it should.
New shims are ordered and I will fit them tomorrow.

[disturbedphil]

fingers crossed it sort the problem out bro

[captain crescent]

So i fitted the new valve shims (thanks again 1I1) And...............................................................................................................................................................................................................
it runs just like a toyota sowing machine ! No stubling idle, No chuffing from airbox or exhaust and the fuel trims are sorting themselves out.

[Lith]

Awesome, glad to hear - cheers for updating the thread after solving it

[jaypines]

did you use the SST for the 2ZZ to adjust the lash or cams out?

[captain crescent]

did you use the SST for the 2ZZ to adjust the lash or cams out?

I took the cams out and it was difficult to get the shims in and out as it was so dont know what it would be like with the cams and sst in the way.
it only turned out and 2 hour job in the end plus about half an hour measuring all the old shims . cam was in and out ten mins each way.

[disturbedphil]

AWESOME!!

[jaypines]

did you use the SST for the 2ZZ to adjust the lash or cams out?

I took the cams out and it was difficult to get the shims in and out as it was so dont know what it would be like with the cams and sst in the way.
it only turned out and 2 hour job in the end plus about half an hour measuring all the old shims . cam was in and out ten mins each way.

its good you have it sorted... may i ask whats your final clearance? its been suggested somewhere that setting the intake lash a bit looser than factory saves wiping the cams.

[captain crescent]

did you use the SST for the 2ZZ to adjust the lash or cams out?

I took the cams out and it was difficult to get the shims in and out as it was so dont know what it would be like with the cams and sst in the way.
it only turned out and 2 hour job in the end plus about half an hour measuring all the old shims . cam was in and out ten mins each way.

its good you have it sorted... may i ask whats your final clearance? its been suggested somewhere that setting the intake lash a bit looser than factory saves wiping the cams.

It was the exhausts that had closed up. I didn't actually measure the final clearance but when I did the calculations I went for .400 mm clearance so closer to the looser side ( a rattly tappet is a happy tappet) they will all be within .030mm of that clearance but i must admit that I was a little blasé about it as this engine only needs to last 1 event and a 2nd hand engine will be going in while I rebuild it.

The car is a race car and has don 25+ events and has 130k on the clock and the cams are in perfect condition with no wear and the inlet clearances are on the lower side of the spec so I don't see a huge advantage of the lager clearances .