hesitation sometimes kills car....where do i start

[bobbysixkiller]

thinking about replacing maf

have a 70 mm throttle body
k and n af
accutec fuel pressure reg set at 44 psi
alot more aftermarket stuff...

[Turbo2nr]

Mine is maxed out at around 20psi, I need a chip to add in some more fuel when drag racing, I think it just shoots in the dark, and I fine tune with a 7th shooter, and fuel pressure. I just heard of a new chip for stock ECUs, that uses the maf for setting fuel up untill the MAF reads high (like 240+), then going into a closed loop with a wide band 02 located in the down pipe. The "new" WB O2 sensor will be used in place of the IAC sensor, and you can tune into the chip a fuel ratio "target"(like 11.5 A/F), and chip will control the inj to make 11.5 A/F. Still use stock MAF, no need to buy a FAST system. Tunes itself to boost changes/alchohol inj. There is a thread about it @Turbobuick.com, chip/electronics section. Going to sell like hot cakes..

[Keller]

Now back to the original question...

What makes you think it is the MAF? Any scan tool data?

You can run with it unplugged for a test. I wouldn't run gonzo boost, and it will set a code, but it is an interesting test. The car will basically run in a speed density mode and illustrate if the MAF is the culprit. I would unplut after startup and secure the wire safely away from belts, etc.

[Turbo2nr]

When you installed the 3"throttle body, did you set the "set screw" for the IAC to come down to a reasonable level. If you bought a Kenne Bell TB, they come with the set screw way too far away from throttle linkage. Need to get scan info to check TPS, IAC when swapping TB. What are readings for MAF at idle, cruise, and WOT? How about BLM numbers? With a hot air car, you should not need a Huge MAF (I don't know what year TR you have), but if it is bad, well. Just be ready to tune car with some scan tool to set up a larger MAF, if thats the way you go. Research!

[Keller]

When you installed the 3"throttle body

3" would be 76+mm. Regardless, its a LARGE throttle body! ;)

[bobbysixkiller]

thanks for the input guys
the iac is set at 20 and the tps @ .46

a little better description of the problem is when i am starting to accelerate, from a dead stop whether i lighly feather the gas or smash it to the floor there is a pretty big hesitation. sometimes it dies, sputters or even backfires. goes away a little after she warms up, but almost always a huge hesitation.
running an aftermarker turbo, don't really know how big, green ring injectors, not quite sure if the chip is stock, scanmaser works well, but still learning how to tune the car correctly. a friend told me if my injectors are aftermarket and the maf is stock, this could be causing my hesitation. please help

[Turbo2nr]

3" would be 76+mm. Regardless, its a LARGE throttle body! ;)
Ok 70mm throttle bodys are 3"OD, 70mm ID. Either way,
what chip do you have in car? Any markings/numbers. What about Blm numbers?

[Keller]

the iac is set at 20 and the tps @ .46

Sounds reasonable.

The 'green ring' could mean 30 lb/hr or 42.5 lb/hr. It is important to know what you have. Still no idea on what turbo you have or what chip you have. Again, important to know. Cars with stock MAFs and stock computers go into the 10s, so I would not consider those to be restrictions. The 70 mm throttle body is only used where a lot of airflow is anticipated. I've tuned a 11.0 car that used a completely stock throttle body (as well as ECM, and MAF), and I doubt it was a real restriction.

I would test the resistance across pairs of terminals of the coil pack to see if you have a bad pack. In addition, get more familiar with the meaning of the scan tool data. And, find out what parts are on your car. That will be key in tuning it. Not knowing what pieces you have make it hard to solve the puzzle. :nono: