Car wants to go but feel bogged down at low end

Cape Cod GN

Member
Joined
May 21, 2014
Hi all I've been dealing with this issue since I got the car back in 2013. I feel the engine spooling, power building, rpm's going up but the car feels like its not grabbing and rocketing forward as it should. This happens at a stop, rolling start and at low speeds. At highway speeds the car feels strong.

Tranny fluid has always smelled fine and regular Tranny service as well as I installed one of Dave's 3021 Torque converters because it "felt loose". I thought that it might of been the torque converter.

The car has: Meth Injection, Turbonetics T-44 w/ the Turbo "tee", 42lb lucas inj, Turbo Tweak 5.7 chip, MAF translator w/LT1 MAF, Turbo Tweak T255LP hot wire fuel pump, and an adjustable fuel pressure gauge on rail.

Car scan master readings at idle are:
MAF: 8
LV8: 42
Volts: 14.1
Int: 128
BLM: 122
Ait Temp: 83.3
RPM: 950
TPS: 0.46
IAC: 71
O2CC: cycling numbers(16,60,102,132,160,194,235) Didn't notice that before.
MV: 483
Ret: 0.0
Fuel Pressure 42lb with vac line off

Could it be could it be the Tranny or settings on the chip for WOT? Any input is appreciated!
 

Dhos1

Self-tuning wanna-be
Joined
Apr 14, 2012
i would have said torque converter sizing until i see that it was looked up there.
 

Pronto

You can't knock them up with spit.
Joined
Dec 9, 2002
Does the waste gate swing freely? How well does the puck seal to the turbo? How old is the turbo? Have you inspected it to make sure the blades are not messed up?
 

Cape Cod GN

Member
Joined
May 21, 2014
Does the waste gate swing freely? How well does the puck seal to the turbo?. How old is the turbo? Have you inspected it to make sure the blades are not messed up?
Hi pronto, yes all is good With The turbo. I get good psi build up and 20lbs of boost. Boost gauge reads peak and drop in psi. Turbo and wastegate were new and only have about 3000 miles on them.
 

Benched

Member
Joined
May 25, 2001
I am thinking you are running lean at low rpms, and not getting enough fuel until you get to a certain rpm or air flow. Check for unmetered air leaks after the MAF. Loose couplings in the air intake or worn out seals/bushings in the throttle body.
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Joined
Feb 18, 2007
Check the PAC controller to make sure the alky settings are on default and the blue knob is on default. PL file would help.
 

Jerryl

Tall Chinese Guy
Joined
Dec 14, 2004
Here is what I think may be going on.

There are 2 problems, which are related.

Unable to get higher than 20 psi. New parts don't mean good parts. Need to test and make sure everything works as intended. It's also rich, which prevents the cat lot from building boost. (Read further)

Boggs; This is because the boost is low and the car is rich. The 5.7 chip will max the MAF reading of 255 gr/sec value around 15 psi. TT programs IDC in the chip based on years of experience for 26 psi manifold pressure (example). The WOT fueling takes effect around the 225 gr/sec mark, to prevent fueling issues as a result of MAF dropout. So fuel is being delivered for 26 psi but the car is set to 20 which now makes it very rich, and bogs. At higher RPMs is less of an issue because the increased RPM uses the extra fuel. It's still rich, but likely not so rich it bogs.

Now, because it's rich it also struggles to build boost. That is the correlation.
 
Last edited:

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
Hi all I've been dealing with this issue since I got the car back in 2013. I feel the engine spooling, power building, rpm's going up but the car feels like its not grabbing and rocketing forward as it should. This happens at a stop, rolling start and at low speeds. At highway speeds the car feels strong.

Tranny fluid has always smelled fine and regular Tranny service as well as I installed one of Dave's 3021 Torque converters because it "felt loose". I thought that it might of been the torque converter.

The car has: Meth Injection, Turbonetics T-44 w/ the Turbo "tee", 42lb lucas inj, Turbo Tweak 5.7 chip, MAF translator w/LT1 MAF, Turbo Tweak T255LP hot wire fuel pump, and an adjustable fuel pressure gauge on rail.

Car scan master readings at idle are:
MAF: 8
LV8: 42
Volts: 14.1
Int: 128
BLM: 122
Ait Temp: 83.3
RPM: 950
TPS: 0.46
IAC: 71
O2CC: cycling numbers(16,60,102,132,160,194,235) Didn't notice that before.
MV: 483
Ret: 0.0
Fuel Pressure 42lb with vac line off

Could it be could it be the Tranny or settings on the chip for WOT? Any input is appreciated!
This isn't telling much of anything as it's at 950rpm.you need to verify fuel pressure rises 1to1 with boost.then what fuel is being run and what boost level are you actuall running(if its lower than what the chip is cut for then it will be rich),need a mv reading in 3rd gear,then check for header leaks,wastegate puck not sealing.
 
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