Bucking at low rpm boost..S5 TII
09-23-10, 04:12 PM
#1
Bucking at low rpm boost..S5 TII
S5 TII pretty much all stock
Regrounded
New spark plugs
Runs fine 3000 rpm+ with boost or without, no hesitation. Part throttle and full trottle, no problem.
5-9 psi...Idling fine, starting ok.
Problem is when i hit boost (about 5psi) in lower rpm (2000-2500). Then it starts bucking and does not want to go.
Any ideas?
Regrounded
New spark plugs
Runs fine 3000 rpm+ with boost or without, no hesitation. Part throttle and full trottle, no problem.
5-9 psi...Idling fine, starting ok.
Problem is when i hit boost (about 5psi) in lower rpm (2000-2500). Then it starts bucking and does not want to go.
Any ideas?
09-26-10, 09:10 PM
#3
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it sounds like Fuel cut,but I am new to Turbo engines Higgi,so take that advice with a grain of salt(just a guess).
My engine setup is pretty Finicky too.It will buck,etc if I have the TPS ON the TB.I take it off but still have it connected to the wiring it Drives Excellent.
so,that means try a different Tps if you can.
My engine setup is pretty Finicky too.It will buck,etc if I have the TPS ON the TB.I take it off but still have it connected to the wiring it Drives Excellent.
so,that means try a different Tps if you can.
09-27-10, 12:32 AM
#5
it sounds like Fuel cut,but I am new to Turbo engines Higgi,so take that advice with a grain of salt(just a guess).
My engine setup is pretty Finicky too.It will buck,etc if I have the TPS ON the TB.I take it off but still have it connected to the wiring it Drives Excellent.
so,that means try a different Tps if you can.
My engine setup is pretty Finicky too.It will buck,etc if I have the TPS ON the TB.I take it off but still have it connected to the wiring it Drives Excellent.
so,that means try a different Tps if you can.
This is more gradient.
I will try another TPS, another ECU, AFM and see if anything will helps...
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10-06-10, 09:34 AM
#8
There have been cases of this problem in which other posters have had and their problem was caused by the fuel pump resistor relay. To test this possible cause just disconnect the plug (should have 6 wires) to this relay and jumper the Blue/Red wires to the Blue/Green wires and take the car for a spin.
10-06-10, 11:07 AM
#9
There have been cases of this problem in which other posters have had and their problem was caused by the fuel pump resistor relay. To test this possible cause just disconnect the plug (should have 6 wires) to this relay and jumper the Blue/Red wires to the Blue/Green wires and take the car for a spin.
Replaced fuel pump resistor relay (under airbox), no change.
As Bamato mentioned, my last resort is injectors itself. Car runs great when secondaries are on, there is no hesitation but u can feel that it really comes alive once it will turn the secondaries on.
I guess i ran out of basic swaps and i will have to get dirty (injectors swapping etc..)
10-09-10, 04:53 AM
#12
Replacing fuel pump resistor relay did not helped, relay works, but signal to relay was somewhere lagging. Above 3000 rpm , relay was switching from 9 to 12V as it should.
But in low rpm's and in boost, it was not.
Bypassing resistor and keeping it at 12V permanently solved problem with bucking.
But in low rpm's and in boost, it was not.
Bypassing resistor and keeping it at 12V permanently solved problem with bucking.
10-09-10, 09:37 AM
#13
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Replacing fuel pump resistor relay did not helped, relay works, but signal to relay was somewhere lagging. Above 3000 rpm , relay was switching from 9 to 12V as it should.
But in low rpm's and in boost, it was not.
Bypassing resistor and keeping it at 12V permanently solved problem with bucking.
But in low rpm's and in boost, it was not.
Bypassing resistor and keeping it at 12V permanently solved problem with bucking.
10-09-10, 09:47 AM
#14
Full Member
my car has been doin the same thing. and ive done just about everything you have minus the ecu swap... but would like to know more about this "resistor" method??
10-09-10, 04:36 PM
#19
Disconnect the plug to the relay and jumper the Blue/Red wires to the Blue wires. This is just to see if there is an improvement and not necessarily to be an end all repair. You can situate the plug from the relay properly such that the upper right terminal is terminal A and below that is terminal B. Top center is terminal C and below that is D. Upper left is terminal E and below that F. With no key necessary check the resistance between A and B (0 ohms), C and D (68-92 ohms) and E and F (.64 ohms).
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