Toyota MR2 Message Board - View Single Post - Other 2ZZ-GE Engine Swap Info

blown59 · 01-26-2007, 05:21 PM

Brief summery...

I had a hesitation issue with cam-changeover shortly after the swap. I had thought it was a fuel issue, but wasnt sure. Problem seemed to self correct as the seasons changed and temp dropped. On cooler days, changeover was great, no problems. Warmer (humid) weather and it was back...????

These results were on a Dynojet.

Mods:
-CAI
-Brad Bedell header
-My custom 2-1 collector B-Pipe
-Factory Cat with CherryBomb "turbo style" muffler
-B-pipe Collector merges to a 2.5" into the cat and 2" from cat exit back

All are SAE: 1.00 corrected, Max HP @ 7400, Max TQ @ 6800

Pull 1 - 158.64 HP 6:19pm
116.07 ft/lb
63.55 deg.
46% Humidity

Pull 2 - 158.29 HP 6:22pm
114.31 ft/lb
63.42 deg.
46% Humidity

Pull 3 - 161.35 HP 6:44pm
117.13 ft/lb
64.72 deg.
46% Humidity

I had originally thought the factory pump may have been limiting the fuel. Not the case... I'm running FAT!!! In all of the runs I was rich, down about 9 something.

The difference on the last run was the motor cooled a bit and we ran a fan for the radiator. It appears the fan also helped with the rich condition. The cooler air may have helped the air/fuel because on the last run I saw a low of about 10.5.

Im thinking if I can get my air/fuel into the 13.5-14.5 area I should be putting down about 169-173 HP. Time to fix some A/F ratios.

Im not sure if its the 4age's fuel pump combined with the 2ZZ's pressure regulator making for the wrong combo of parts. Should try the other pump. Or if its the cold air intake that the computer is over compensating for. It seems as if it hesitates more on hot days and not at all on the cooler days.

Im thinking this could also be due in part to a faulty O2 sensor. The one that came with 2ZZ's downpipe was slightly damaged, though I still used it. It could be that the O2 isnt properly reading the signal.

**It is my understanding that the O2 only monitors in closed loop. I also understand that when under W.O.T. the system goes into open loop, at which time the computer just dumps fuel. ...so this may not be my issue. I have considered using an Apex'i VAFC-II piggy-back to help lean it out. Some ppl say that the piggy-back will be over ridden by the factory ECU. I understand this as true, when in the closed loop. But, when under open throttle, your in open loop... At this time the piggy-back will kick in and run your engine at the parameters which you have set. Now some of this is just my theory, but really would like to try and correctly resolve the issue before going piggy-back.

Links to pics can also be found in my signature.

01-26-2007, 05:21 PM	#4 (permalink)
blown59 MR2ZZ-GE w/ 6spd Join Date: Apr 2006 Posts: 90 Thanks: 0 Thanked 14 Times in 7 Posts iTrader Rating: (1/100% )	Mk1 2ZZ-GE Dynojet Results Brief summery... I had a hesitation issue with cam-changeover shortly after the swap. I had thought it was a fuel issue, but wasnt sure. Problem seemed to self correct as the seasons changed and temp dropped. On cooler days, changeover was great, no problems. Warmer (humid) weather and it was back...???? These results were on a Dynojet. Mods: -CAI -Brad Bedell header -My custom 2-1 collector B-Pipe -Factory Cat with CherryBomb "turbo style" muffler -B-pipe Collector merges to a 2.5" into the cat and 2" from cat exit back All are SAE: 1.00 corrected, Max HP @ 7400, Max TQ @ 6800 Pull 1 - 158.64 HP 6:19pm 116.07 ft/lb 63.55 deg. 46% Humidity Pull 2 - 158.29 HP 6:22pm 114.31 ft/lb 63.42 deg. 46% Humidity Pull 3 - 161.35 HP 6:44pm 117.13 ft/lb 64.72 deg. 46% Humidity I had originally thought the factory pump may have been limiting the fuel. Not the case... I'm running FAT!!! In all of the runs I was rich, down about 9 something. The difference on the last run was the motor cooled a bit and we ran a fan for the radiator. It appears the fan also helped with the rich condition. The cooler air may have helped the air/fuel because on the last run I saw a low of about 10.5. Im thinking if I can get my air/fuel into the 13.5-14.5 area I should be putting down about 169-173 HP. Time to fix some A/F ratios. Im not sure if its the 4age's fuel pump combined with the 2ZZ's pressure regulator making for the wrong combo of parts. Should try the other pump. Or if its the cold air intake that the computer is over compensating for. It seems as if it hesitates more on hot days and not at all on the cooler days. Im thinking this could also be due in part to a faulty O2 sensor. The one that came with 2ZZ's downpipe was slightly damaged, though I still used it. It could be that the O2 isnt properly reading the signal. **It is my understanding that the O2 only monitors in closed loop. I also understand that when under W.O.T. the system goes into open loop, at which time the computer just dumps fuel. ...so this may not be my issue. I have considered using an Apex'i VAFC-II piggy-back to help lean it out. Some ppl say that the piggy-back will be over ridden by the factory ECU. I understand this as true, when in the closed loop. But, when under open throttle, your in open loop... At this time the piggy-back will kick in and run your engine at the parameters which you have set. Now some of this is just my theory, but really would like to try and correctly resolve the issue before going piggy-back. Links to pics can also be found in my signature.