[Johnson’s GT]

To start this off I will be posting to many, many forums my problem. First off,

Details Of Motor:

Block: 302 bored 30 over
Crank: Stock
Pistons: Stock
Cam: B-303
Heads: Aluminum Gt-40 SVO
Rockers: Stock
Intake Lower: Gt-40
Intake Upper: Gt-40
EGR Spacer: 70mm
Throttle Body: 70mm
Intake Tube: Aftermarket Cold Air
Mass Air Meter Housing: 70mm
Headers: BBK Shorty 3/4
Cats: None
Exhaust Pipe: Off-Road H-Pipe
Mufflers: Flowmaster
End Tips: Dumps
Computer: ’93 A9L Mass Air Computer
Fuel: Stock Fuel Pump
Injectors: Stock 19lb
Fuel Lines and Tank: Stock

Problem(s):

First two problems interchange but first problem is more present:

1) Surging Idle ( 1500 rpms to shut off ):

When cruising at rpms higher then 1500, letting of the gas and pushing the clucth, the car’s idle will drop till it cuts off.

If cruising at the same rpm as above then slowing the car down to where it should it, then 50% of the time, it will stay there or it may surge till it cuts off.

If at idle the car will idle if cold but after a few minutes the car will start to surge till it cuts off.


Parts Tested To Find Problem:

Throttle Postion Sensor: Set to .97 Volts

Parts Tested But Not Sure If Bad:

Stock Mass Air Sensor: 12 Volts to + and - Wire, 12 volts to 3rd wire,
Signal Wire is the problem wire. It is suppose to stay at around the same idle at idle. It changes erratically at idle and when the throttle is pushed. Please give opinion.

Vaccum Lines:

All visible vaccum lines have been checked with cleaner to check for vaccum leaks. Advise if all lines should just be replaced.


Parts Replaced To Fix Problem:

Idle Air Control

2) Hanging Idle:

When starting the vehicle it will hang to around 2000 rpms then drop slowly to 1100 rpms.

As I push the throttle to gain speed then shift, it stays at that rpm for 2 to 3 seconds then drops to around 1100 rpms.

Parts Tested To Find Problem:

Throttle Postion Sensor: Set to .97 Volts

Parts Tested But Not Sure If Bad:

Stock Mass Air Sensor: 12 Volts to + and - Wire, 12 volts to 3rd wire,
Signal Wire is the problem wire. It is suppose to stay at around the same idle at idle. It changes erratically at idle and when the throttle is pushed. Please give opinion.

Vaccum Lines:

All visible vaccum lines have been checked with cleaner to check for vaccum leaks. Advise if all lines should just be replaced.

Parts Replaced To Fix Problem:

Idle Air Control

3) Whining/Whistle Noise:

Vehicle as a whining/whistle noise coming from the engine compartment at idle and cruise. Noise does increase as rpms increase. All gaskets and suppected hoses have been sprayed for leaks.

Parts Tested To Find Problem:

Vaccum Lines/Gaskets

Parts Tested But Not Sure If Bad:

Vaccum Lines:

All visible vaccum lines have been checked with cleaner to check for vaccum leaks. Advise if all lines should just be replaced.

Not the Problem:

Pulleys

My Note:

Please post on the thread. I need help with this problem really bad. This is my daily driver and I have no clue what else to do. I need you to list what you think I should replace, test, or do to find the answer to my problem(s). Thank you so much everyone.

[ALEXLOPEZ62188]

Well I'm pretty sure you did the mass air flow conversion, I would check my harness.
Did you make your own, did you buy the kit, or did switch out the entire engine harness?

[428CJ]

As for the hanging idle, you could try cleaning your throttle body. Mine had that problem from some build up inside the tb.

[Bubba95SN]

SBFTech has test proceedures and how to run tests.

[PhillyGT]

Im having the same issues.When coming to a stop does the idle drop to almost stalling then bounce back up??When you rev it does it hang at around 1500,then slowly drop to normal rpm's??.Mines doing the same.I cleaned my maf, iac,tb,and it did nothing.When you fix it let us know how you did it.Thanks

[428CJ]

Originally Posted by PhillyGT Im having the same issues.When coming to a stop does the idle drop to almost stalling then bounce back up??When you rev it does it hang at around 1500,then slowly drop to normal rpm's??.Mines doing the same.I cleaned my maf, iac,tb,and it did nothing.When you fix it let us know how you did it.Thanks

Have you set your TPS to the correct voltage?

[PhillyGT]

No i havent,what do i need to do it??.

[428CJ]

Originally Posted by PhillyGT No i havent,what do i need to do it??.

Its pretty simple, and here is a good write up on doing it. Setting the Mustang TPS Voltage