Throttle Response seems slow...

Cleaning the MAF should help, how old are your O2 sensors?

2 of the 3 O2 sensors are new...I don't recall if I replaced the 3rd one, but when I bought my Spyder 2 years ago, it had the PPE headers with the single O2 sensor in the header collector...always had a CEL code, so I pulled the crappy spliced wiring out, and had 2 bungs welded into the headers at the correct spot.  Bought a new O2 sensor (and another one for the downstream sensor) and correctly wired them up.  CEL light is off and it runs smooth as butter...fuel trims seem to agree.  I wouldn't expect the O2 sensors to be the culprit, but maybe so.

I'll go clean the MAF, and see if that helps.  My 196,000 mile engine is a little low on the compression checks, but it's in spec...not sure how much that would effect throttle response anyway. 

Just seems that when I tap the peddle, it should respond instantly...not a bit later with a slow(er than expected) rev up.  I drove a different MR2 with the 2ZZ conversion and that thing was instantaneous on the response.  Very fast response and sharp increase in revs.  Which is the whole reason I started even looking at mine.  LOL.

Well I think I figured it out...mostly.  I went to clean the MAF and noticed that the CAI (Weapon R) wasn't connected to the throttle body very well.  This isn't the first time this has happened, unfortunately...I don't why it slips off so easily, but when I crank down on the band straps it doesn't seem like it's going anywhere.  But a couple months later or so it'll be off again. 

Either way, cleaned the MAF and re-attached the CAI and the throttle response is much better.  It's still slower than the 2ZZ I drove, though...just not "snappy".  I'm guessing it's just from being a tired engine.

I would invest in a new clamp if its coming loose.  

The 2zz if done right is quiet responsive like a motorcycle because of the short stroke. 

How about doing the MAF Mod..  only Slightly Modified..  You do not have the Opportunity to change Injectors..  but you can raise the Fuel Pressure..

Purchase a few of these..

https://www.carparts.com/details/Toyota/MR2_Spyder/Replacement/Fuel_Pressure_Regulator/2000/Base/4_Cyl_1-dot-8L/REPT318101.html?showfitment=true

and I can raise the pressure to about 50 PSI..  then if you put a Stock air box in, and do the MODS to it.. you should see an improved T-Response

Cap

Haha a cheaper way to do the MAF mod? I removed mine because the 2ZZ injectors I got from MWR were causing a misfire and super high LTFT on one bank (typical MWR, "flow tested" my ass). 

..

1) Pull the MAF back out of the air stream (original mod) a little bit. This tricks the ECU into thinking the engine is starved for air, so it increases air intake.

Pulling the MAF back causes the ECU to calculate a LOWER air charge ingested into the engine.. so it will give less fuel, and earlier ignition spark

2) Use these regulators to increase the fuel pressure to 50 PSI, so the engine doesn't run too lean from the added air.

Raising the fuel pressure has the same effect as increasing the injector size.. more fuel per injector pulse..  the ECU calculated the amount of fuel wrong because of the MAF Displacement.. I can fix it with higher pressure or bigger injectors.

3) Fiddle with the amount of MAF air starvation created by moving the MAF, by simply tweaking the depth of the MAF sensor until the P-codes go away. After the codes go away, use a diagnostic tool to dial in the correct/desired trims.

When I was doing my Inital testing, I NEVER got any codes!.. My set up was a Custom Intake 'Block' that had a hole in it that was too large.. about 2 7/8 I think..  then I machined 'Shutters' that narrowed down the Air Stream to increase the Velocity of the Air passing by the MAF..  I Started out with the green injectors, and got the system ballanced by watching the Air Fuel Ratio on my Wideband, and looking at the Fuel Trims as they were building..  

I was able to get this 'Block Intake' to perform like stock on the stock injectors..  I also could check the Ignition advance on my SSI4 from Innovate..  I had it hooked up to read ignition advance..  a feature they no longer offer..  

By adjusting the Vane Opening on the Block Intake, Taking Ignition, TPS,Air Ratios, RPM Loggings I saw a trend where the More Air 'Logged' into the engine by the MAF, the Less Ignition advance was provided.. So I started to Open the Vanes and get more Ignition..   then the Fuel Trims had to start going Positave to compensate for the Less Perceved Air..  AND as the trims get out past +10, the Partial Throttle Quick Acceleration ( usually called Throttle Enrichment ) was not as good, and the ARF's would thin out during Throttle Movement, causing a stumble.. 

This is when I thought of using larger injectors..  I tossed in yellows and kept testing, and opening the MAF Vanes..  I ended up Driving for a few thousand miled with the system ballanced, using the Block Intake, yellow injectors..  with the Throttle responce feeling GREAT, and the WOT ARF's Improved from the 11's they were at, up to the high 12's..  that is where I stopped.. 

My charting showed increased Ignition advance at partial Throttle, and I could feel it..  the WOT charting of the Ignition Advance was a Little better..  but not a Lot..  

My Inital Goal was to make a Reversable MOD for my car..  I hate hacking up shit..  So to replicate my 'Block Intake', I started tweeking the MAF mounting of the stock intake..  that is where I ended up Removing the Vanes, and Raising the MAF to achieve the same results..  

The Block Intake ended up going to Vatic's 2ZZ swap that had Terminal Lean Conditions diring Lift.. He tossed the Block Intake on his car, and then started closing down the vanes to get the driveability back..  It worked..  He ended up in California, and was unable to Smog it with that Maf Housing..  ultimatly he ended moving back out of California, and I've not see the Block Intake again, except in my pictures.. 

4) Grin.

Oh yess.. I do..  That 1ZZ engine lived about another 100K miles..  then the Smoke Police were starting to come looking for me..  so I rebuilt a different junk 1zz..  actually took two to get enough pieces to get one good one..  and that motor is in my car now..  

• Light weight Flywheel
• Crower Stage 1 Cams
• MAF Mod

All of the Logging Equipment is still in my car..  it just does not get recorded..  I have about 65K on the new motor..  I no longer do a 175 Mile per day Commute..  so the Spyder gets driven every other week or so..  it shares the drive with my 300 ZX and my 24 Model T truck..

Because Lost Pilot is in CSTR Class he can not change Injectors, but he can raise fuel pressure, and if you crush the Fuel Pressure Spring a little, the pressure can be raised..  then swap it in the Fuel Pump Housing in the tank..  I built a Fixture so I can Crush the FPR and watch it's pressure at the same time, to get it where I want.. 

Cap

Posted by: haloruler64

Haha a cheaper way to do the MAF mod? I removed mine because the 2ZZ injectors I got from MWR were causing a misfire and super high LTFT on one bank (typical MWR, "flow tested" my ass). 

Agreed..  but if you read through the post above..  the Idea of the MAF Mod was to make a Reversible MOD..  when I did the work, the Regulators were only available from Toyota and about $150..

I agree this might NOW be a better way to do the MAF Mod.. as the FPR's are cheeper, and you do not run the risk of Getting Crap and Junk in the Injector or the Port for it..  and trying to get the Injectors to re-seal all the Gasketts..  

Cap 

..

I am grasping to understand how moving the MAF out of the airflow causes the thing to say "I detect too much air" and thus cause the ECU to lower the charge,

It does not..  It detects too little Air, thinking the engine is working less hard then it is, and will dispense too little fuel on the initial calculations..  the fuel trims will snif the exhaust pipe, and detect a lean condition and try and richen it up..

The threaded rings are an option..  not one I wanted to machine..  

The resistor is also an option, but you would never be able to get to MAX air flow, as the MAF sensor is now Biased Down about 10 % or so..  but it might work..  not a direction I chose to go.. A Piggyback ECU can do the MAF offset Voltage in a programmable fashion.. but someone has to tune it.. 

The side effect of the Complete MAF Mod, is increased Performance by causing the Ignition to be earlier..  This raises Combustion Temps causing increased Nox Emissions..  How much?..  can't say..  I can say that my first Tailpipe Idling Test went well after the mod..  and all the rest of them have been OBD2 port Tests..  not expected to have any effect on Cat Longevity..  

[Soap Box On]

I do live in California..  and we have been taken over by burocrats who are finding better ways to interpolate laws to reduce our ability to have fun, and somehow protect our sensitive environment..  but it's ok to have a homeless encampment where you defecate on the streets and toss trash in the rivers . Its a fact I'm still willing to put up with for now..  so I try and still live 'between the Lines' of what is allowed..  Exhaling CO2 is illegal, as it's considered a pollutant..  I still do it to survive.. 

[Soap Box Off]

I like having fun..  and will do so..  

Cap

How do all of you know so much about working on cars??

Posted by: hello

How do all of you know so much about working on cars??

They all did not survive this learning curve..   mine were all autopsied by someone smarter than me, so I could learn..  and the most fun was watching the Post Mortem of others mistakes..  

Seriously..  it's just a lot of small things that makes this all work.. start understanding the little things, and the picture starts to get clearer..  It's not magic.. its just physics  

Cap

Here is the book I got my theory from..  

https://www.amazon.com/Internal-Combustion-Engines-Analysis-Practice/dp/B000XLZP0Q

It deals with mechanical controls, which are simpler to understand for most humans..  ( myself included )..  Modern books, in my opinion, are harder to read.. 

Mine has my dads notes in it as well, when he was going to college..  

Cap