DIY - 1.8L 1ZZ-FE TB Connector Chip Swap

[jkuchta]

Hey everyone:

I did this swap this last Sunday...and man what a differeance!

First off I installed the 1ZZ TB stock (no idle screw adjustment or chip swap). Cold idle was high (around 3K) and fluctuated, like everyone has mentioned, though my warm idle was around 850-900rpm, with a pretty bitchin' roughness (think bigger cam). There were definate problems though.

1) CEL: came on intermittantly with P0171 (iirc) lean condition, especially while transitioning from idle to part throttle, though once cleared, this CEL would not come back while driving or coming back to a stop, which makes me want to rule out any sort of air leak.

2) Throttle response was lacking, and pretty disconnected..i.e. while shifting the engine would over-rev 500-1000rpm, and the car seemed to lack any real grunt anywhere in the powerband. I have a scangauge, and could see I was getting full throttle operation.

3) When the car went into DFCO it would feel like I had just released the 'chuts! With the OEM TB DFCO is almost inperceptable, but with the unadjusted 1ZZ TB it was pretty uncomfortable feeling.

4) Heel-toe downshifting was pretty much impossible as well due to lack of fine rev control, and a wierd over-rev/under-rev (the car stalled itself twice) on deceleration.

These symptoms were consistant over more than 3 hours of driving.



On Monday afternoon, I removed the 1ZZ TB and swapped out the chip with the OEM 1NZ chip. I did this without disconnecting the battery, as I wanted to see how big a difference this swap would make, all other things being equal.

BIG DIFFERENCE!

1) High Cold idle lasts about half as long. Also, there is no ocillation. The rpms just go straight to 2500-2700, and then slowly taper back down.

2) The idle is also much more stable (like stock), with no (albeit cool) roughness.



Now I got to work setting the correct idle speed. For some reason, the epoxy over the idle set screw on my 1ZZ TB came off nice and easy, an in one piece. After a few minutes idleing, the engine settled to about 1K rpm, which set off a CEL (I think P0220 iirc(TB stuck open)). I adjusted the screw to the point of killing the engine (which triggered another CEL (P0505...bad idle)). I then screwed the idle set screw back in about half way, which when the engine was turned back on, gave me an idle of about 850 rpm. I then shut the engine back off and adjusted the screw back out about a turn, which (when the engine was turned back on) gave me a nice stable (and smooth) 720-750rpm.

Based on the manual, this is as high as you can go without running the risk of getting a "bad idle" CEL. This idle rpm also makes leaving stoplights a little better in that the engine doesn't bog quite as much.



A note on setting the idle:

Adjustments should be made with the engine and ignition off, as doing the adjustment with the engine running will only cause the ECU to compensate to maintain the idle speed, almost regardless of the idle set screw position (took me 10 min. to figure that out).


Driving impressions:


1) Throttle response is better than stock, and the car pulls like a motha' (well....way more than with the stock TB) above 2200 rpms.

2) Heel-toe downshifting is better than stock (rpms come up a little faster, and with a little more "control" (i.e. a little tap gives a few hundred rpm (great for the 5th-4th shift), and a bigger dab gives about 1000 rpm (great for 4th-3rd, and 3rd-2nd shifts).

Once the idle was set there have been no CELs of any kind, and the car is a riot to drive!

As far as I'm concerned...this is a must-do mod for anyone with the stomach to do the chip swap (drilling out that first rivet is mentally the hard part), though the idle adjustment is pretty much a requirment to make this thing feel right.




A big THANK YOU to T-sport for the diy (and having the nuts to do this in the first place)!




Side note:

I also did the TB coolent bypass. My other mods are as follows : Simota Carbon SRI (the big box), WR header, Thermal axle-back, and nology hotwires, running Shell V-Power and Motul 300V 5W-30.