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Putting the age old lift engagement debate to rest  

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marsrock7
(@marsrock7)
Reputable Member

A little while back, before this place existed, a topic on AdChat about the struggle to hit lift on the 1-2 shift with a 2zz\c60 drivetrain devolved into a debate about whether the lift engagement point was at 6000, or 6200 rpm. At the end, it was basically me vs everybody else. I was told repeatedly my ecu did not engage lift at 6000, but rather, my tach was slow, and so was my bluetooth OBD app. Of course I know both the tach and the OBD data are slow, but I had accounted for that by doing a test while holding the car at ~5900rpm in 3rd or 4th, and getting lift immediately when I put my foot down. Having no second ecu, and no way to collect reliable data, I was just dismissed as stubborn, which I most definitely am. 

Now, I have an E-manage, and I also recently acquired a second 2zz ecu... you know... for science. Over the past two days I have taken datalogs of my original ecu (which I suspected engaged lift at 6000rpm), part number ending in 81, and the new ecu, part number ending in 83. Here are the results:

ECU1 (81)

ecu1 1
ecu1 3
ecu1 2

ECU2 (83)

ecu2 1
ecu2 2
ecu2 3

 

I believe the data speaks for itself. 

The first time I drove the car with the 83 ecu, I noticed the difference without even looking at the tach. I know when lift is supposed to hit... and when I got there, I thought "did I not let the car warm up long enough?" Then it hit. Accelerating in second or third (I'm now using a c56) with my usual ecu, lift would hit when the tach hit ~5900rpm. Definitely before the 6k mark. With the 83 ecu, the needle is always past 6k before lift hits, usually around 6100 while under full throttle. 

IMG 20200308 133448

I hope this is ample evidence for the naysayers. There are USDM Celica ecus out there with a 6k lift point. If I had to guess, I would think the 80s, and some (or maybe all) 81s engage at 6k.

I'm in no way bitter about that conversation, I just like to separate the truth from unfounded public opinion, with hard evidence 🙂 If anyone wants to look at the logs, I'm happy to share them. You will need WinXP or an older platform to run the software. I am running XP in Virtualbox to be able to communicate with the e-manage.

 

Edit: The E-manage Ultimate does not have any way to modify the lift engagement point without additional hardware. All pulls were done with zero map modifications. For this experiment, I used the E-manage only for datalogging what the OEM ecu was doing.

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Posted : March 8, 2020 12:29 am
dev
 dev
(@dev)
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Thats a good find. I did find a thread where you made your claim and I was the one that stood by my assertion that its hard to read captured data using ODB2 because its not very fast or even the difference between the slight variation between 6k and 6200 is not easy to eyeball on the tach when you are in the moment. I also said probably on the thread in question and not knowing definitively only what was written anacdotally for years. 

There have been many changes to the ECUs with varying lift points so last night I wanted to do a deeper search on New Celica and confirmed that the very early ECUs do have a 6k lift engagement and not long after that it was changed to 6250. After that subsequent years kept changing but it didn't concern us too much because we cant use those ECUs.   

 Its also possible that the JDM ECU is the same as the early US version in both power, lift and limit, its just that the power figures of that extra 10hp might be based on a different measurement. It would have to be verified.  

 

 

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Posted : March 8, 2020 11:27 am
marsrock7
(@marsrock7)
Reputable Member

As I understand it, many of the JDM ecus have a rev limit as high as 8600rpm. I don't have any firsthand experience with them, that is just what I have read elsewhere. Unfortunately my 2zz came with a JDM auto ECU -_-

Both ecus I tested hit fuel cut at 8300. In a couple places I saw over 8400, but only when the engine was being held on the limiter. 

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Posted : March 8, 2020 12:31 pm
dev
 dev
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Posted by: @marsrock7

As I understand it, many of the JDM ecus have a rev limit as high as 8600rpm. I don't have any firsthand experience with them, that is just what I have read elsewhere. Unfortunately my 2zz came with a JDM auto ECU -_-

Both ecus I tested hit fuel cut at 8300. In a couple places I saw over 8400, but only when the engine was being held on the limiter. 

I think that  83 and 84k rpms difference is probably a variance when the fuel is cut since the engine is still in motion and cant be on the nose every time with clock like precision since the engine is not mechanically limited obviously however the fuel is cut precisely at whatever it is programed for. Probably not noticeable for that low of a difference  unless you have a means of measuring and in the real world most people bounce off the limiter making it hard to know anyway.  Rarely I hit the limiter if im not paying attention but I try to shift around 8100rpms.  The good thing about the stock ECU is its conservative rev limiter to keep it reliable but I imagine if you raise it might actually shorten the life even if you don't come near to  floating the valves.  

 

 

 

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Posted : March 8, 2020 3:42 pm
marsrock7
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On both ECUs fuel was cut right at 8300. I try not hit the limiter either in normal use but pushed it a couple of times for logging purposes. 

After some more driving, the new to me (83) ECU feels much better in the low and midrange. Torque delivery feels smoother. I'm guessing this is due to not only changes to injection cycles, but also VVTI. BTW, I've been using yellow injectors with both ECUs. The only detriment is the 6200 lift engagement instead of 6000... Which is exacerbated by the fact that I have a c56. Now there is a 200rpm larger gap before I get back to lift on the 1-2 shift, and I have to push second that much closer to the limiter to land lift in third.

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Posted : March 8, 2020 4:15 pm
dev
 dev
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Posted by: @marsrock7

On both ECUs fuel was cut right at 8300. I try not hit the limiter either in normal use but pushed it a couple of times for logging purposes. 

After some more driving, the new to me (83) ECU feels much better in the low and midrange. Torque delivery feels smoother. I'm guessing this is due to not only changes to injection cycles, but also VVTI. BTW, I've been using yellow injectors with both ECUs. The only detriment is the 6200 lift engagement instead of 6000... Which is exacerbated by the fact that I have a c56. Now there is a 200rpm larger gap before I get back to lift on the 1-2 shift, and I have to push second that much closer to the limiter to land lift in third.

 I have to check my ECU once more. I think it is an 81 version.  Is the 83 the revised one or supposed reissued one that used the brown injectors. This is before the ECUs changed to the two wire knock sensor I presume. 

 

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Posted : March 8, 2020 5:11 pm
marsrock7
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@dev

Yes the 83 is the reissue which is supposed to be used with the brown (330cc) injectors. I have not gotten any kind of CEL with this combo yet. I do not have a set of brown injectors on hand but I do have the Scion 340cc injectors, I may put them in... With either ECU I am seeing duty cycle go as high as 94% when I get over 8k.

Edit: Here is the TSB for the 82>83 ECU switch

 

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Posted : March 8, 2020 6:04 pm
dev
 dev
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Posted by: @marsrock7

@dev

Yes the 83 is the reissue which is supposed to be used with the brown (330cc) injectors. I have not gotten any kind of CEL with this combo yet. I do not have a set of brown injectors on hand but I do have the Scion 340cc injectors, I may put them in... With either ECU I am seeing duty cycle go as high as 94% when I get over 8k.

Edit: Here is the TSB for the 82>83 ECU switch

 

 Thats not good at all. I would not drive the car with the injector duty cycle that high because the margin for error is razor thin especially if you are fooling the ECU somehow to not throw a CEL.  I know you will upgrade the injectors but I still think you need some headroom even if you just want to fool around with it. 

 

 

 

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Posted : March 8, 2020 6:48 pm
marsrock7
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Reputable Member

That 94% duty cycle does coincide with an AFR of 11:1 or lower, so the engine is safe in that regard. Probably gonna put the 340s back in thou either way.

Not fooling the ECU at all currently. The emanage map is all zeroed out so it's just passing info through and collecting data. 

Duty cycle may also be high due to the use of a (presumably) 19 year old fuel pump.... Probably ought to find a way to check fuel pressure while under load.

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Posted : March 8, 2020 6:52 pm
FormInFunction
(@forminfunction)
Eminent Member

Not to thread-jack, but is there any problem with engaging lift at much lower RPMs (like 3500 or 4k) if you are using a standalone ECU to tune it with proper A/F ratios, ignition timing, etc? Just wondering since the topic was related to staying in lift on the upshift. 

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Posted : April 29, 2020 8:14 pm
dev
 dev
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Posted by: @forminfunction

Not to thread-jack, but is there any problem with engaging lift at much lower RPMs (like 3500 or 4k) if you are using a standalone ECU to tune it with proper A/F ratios, ignition timing, etc? Just wondering since the topic was related to staying in lift on the upshift. 

There is if you are naturally aspirated. It was found  that the lowest you could go before you run into power losses is around 5800rpms for the switch over and this is after tuning for it.  With aggressive cams and other modifications it could be lower than that but it depends. 

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Posted : April 29, 2020 9:04 pm
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marsrock7
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Reputable Member

Agreed. When I had a PFC I tinkered with the lift point a bit and I think 5750 was the lowest I got to and didn't feel any power loss. Any lower than that and it's just noise. This was on an internally stock 2zz.

Different internals and/or forced induction could easily change where the engagement point is most useful. 

The supercharged RSX folk have had excellent success dropping VTEC in the 3500-4500 range, on an engine with stock fuel cuts around 8200. 

When my TSX was stock VTEC would come on at 6000, but fuel was cut at 7300. It was nearly pointless. Now with hondata reflash VTEC is at 5000 and fuel cut at 7600. A forum member has developed his own reflash abilities and has also found success; more power and economy than hondata and his flash sets VTEC to 4600 and fuel cut to 7700. The K24A2 is quite a bit different than the 2ZZ... Lift andd VTEC also have some major differences. On the K24, the goal is to smooth the powerband and keep power rising steadily instead of falling off before the cam profile changes. 

Here is hondata's dyno plot of a completely stock TSX before and after their flash:

dynotsx stock vs reflash

 

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Posted : April 30, 2020 2:47 am
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FormInFunction
(@forminfunction)
Eminent Member

Interesting, thanks for the feedback. I figured there had to be a lower limit for sure but tbh I thought it was be closer to the 4.5 -5.5k rpm range. Obviously I've never done any tuning (this is clearly for the best), but I've always wanted to learn more about it if I ever find the time

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Posted : May 2, 2020 11:25 pm
nocoolname
(@nocoolname)
Estimable Member

I've got an 81 and an 82 2zz ECU, haven't plugged the 82 in to even test it yet, but the 81 definitely has the 6k lift engagement and it's been well documented on newcelica back in the day about the lower lift engagement of the early ecus.  For the JDM ECUs, I'm not sure on rev limit, but most if not all are speed limited to around 120mph IIRC.

 

For moving the lift engagement, the only way to do so properly is on a dyno.  Set the lift engagement high, like 7000RPM and tune fuel, ignition and cam timing.  Then do the same with the lift set low like 3500-4000RPM and re-tune the fuel, ignition and cam timing above the lift point.  Overlay the final pulls of each tune and where the power of the low lift tune crosses over the high lift tune, that's your lift engagement.  From there you can combine the maps and do a little final touchups to get the tune finished.  This will result in a lot smoother transition into lift, but more usable power as it'll maximize the area under the curve.

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Posted : May 3, 2020 12:27 pm
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