Hey guys,
I am new to the StangNet forums and I am helping a buddy work on his 1990 Mustang Foxbody 5.0. He purchased the car a couple of months ago and we have been working on this issue occasionally in the evenings.
Heres the problem: The car starts and drives fine, with no idling issues. When you get on it, it runs up the RPMs and then falls flat on its face around roughly 3500 RPMs. It feels like the car is just starting to get up and go and then boom, nothing. It almost seems like the ECU is retarding ignition like its hitting a rev limiter.
I have searched far and wide on the internet for a solution to this, including the thread on here talking about the 94 Stang with a similar problem (Thread "Still won't rev over 3500 RPMs" that resulted in a faulty distributor)
Here is what was listed on the sale when the vehicle was purchased:
302 bored over 306.
Forged pistons and crank.
Edelbrock intake setup with 70mm throttle body with spacer new throttle response.
Msd coil pack.
SVO heads roller rockers and rods.
Water pump Bracket kit
spark plugs.
Cold air intake
electric fan powered by a switch
stage 1 clutch
e303 cam
aluminum driveshaft
gauges in hood water temp boost and oil press and tach
grant gt steering wheel
24-pound injectors
rear seats removed - front racing seats
8.8 rear with 4.10s lower
upper tubular control arms
tubular k member and control arms
Solid motor mounts
new front bumper and fenders
new headlights tinted no fogs
has dumper with 10 series mufflers
Catless H-Pipe
No AC or Heat
new oil change and new gear Fluid
1inch springs in back and Viking coil overs in the front
5 lug convert Jegs 28 spline axles and brakes
sn95 front spindles with new hubs drilled rotor and new pads and calipers
3.5-inch cowl hood
rear cobra bumper
I know most of the above items have nothing to do with the issue but there's the full list at the time of purchase
So far, we have done the following as we were working through the thought process:
Electrical
Checked TPS at idle - ~0.94v
Current idle RPM - around 800
Fuel -
Replaced in-line fuel filter
Replaced in-tank fuel pump with 255 GPH pump and pickup foot, line, etc.
Checked fuel pressure at the rail - around 40 PSI
Ignition
Spark Plugs do not seem to be fouled
Replaced MSD distributor (Hoping issue was bad PIP sensor as was the issue in the thread mentioned prior)
Checked base timing with spout connector out - 14*
Went to check for vacuum leaks but all vacuum ports on the car are plugged/capped and the vacuum tree removed
We have not touched:
ECU
Ignition Coil
Injectors (Currently 24lb)
I am hoping this is something obvious that we are missing (very possible - we are glorified DIY at home mechanics with not a little but not a ton of knowledge)
Any help or ideas with this would be greatly appreciated!
Thank you
I am new to the StangNet forums and I am helping a buddy work on his 1990 Mustang Foxbody 5.0. He purchased the car a couple of months ago and we have been working on this issue occasionally in the evenings.
Heres the problem: The car starts and drives fine, with no idling issues. When you get on it, it runs up the RPMs and then falls flat on its face around roughly 3500 RPMs. It feels like the car is just starting to get up and go and then boom, nothing. It almost seems like the ECU is retarding ignition like its hitting a rev limiter.
I have searched far and wide on the internet for a solution to this, including the thread on here talking about the 94 Stang with a similar problem (Thread "Still won't rev over 3500 RPMs" that resulted in a faulty distributor)
Here is what was listed on the sale when the vehicle was purchased:
302 bored over 306.
Forged pistons and crank.
Edelbrock intake setup with 70mm throttle body with spacer new throttle response.
Msd coil pack.
SVO heads roller rockers and rods.
Water pump Bracket kit
spark plugs.
Cold air intake
electric fan powered by a switch
stage 1 clutch
e303 cam
aluminum driveshaft
gauges in hood water temp boost and oil press and tach
grant gt steering wheel
24-pound injectors
rear seats removed - front racing seats
8.8 rear with 4.10s lower
upper tubular control arms
tubular k member and control arms
Solid motor mounts
new front bumper and fenders
new headlights tinted no fogs
has dumper with 10 series mufflers
Catless H-Pipe
No AC or Heat
new oil change and new gear Fluid
1inch springs in back and Viking coil overs in the front
5 lug convert Jegs 28 spline axles and brakes
sn95 front spindles with new hubs drilled rotor and new pads and calipers
3.5-inch cowl hood
rear cobra bumper
I know most of the above items have nothing to do with the issue but there's the full list at the time of purchase
So far, we have done the following as we were working through the thought process:
Electrical
Checked TPS at idle - ~0.94v
Current idle RPM - around 800
Fuel -
Replaced in-line fuel filter
Replaced in-tank fuel pump with 255 GPH pump and pickup foot, line, etc.
Checked fuel pressure at the rail - around 40 PSI
Ignition
Spark Plugs do not seem to be fouled
Replaced MSD distributor (Hoping issue was bad PIP sensor as was the issue in the thread mentioned prior)
Checked base timing with spout connector out - 14*
Went to check for vacuum leaks but all vacuum ports on the car are plugged/capped and the vacuum tree removed
We have not touched:
ECU
Ignition Coil
Injectors (Currently 24lb)
I am hoping this is something obvious that we are missing (very possible - we are glorified DIY at home mechanics with not a little but not a ton of knowledge)
Any help or ideas with this would be greatly appreciated!
Thank you