I lost muh HPs - Help me find them!

Regi

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Sep 3, 2022
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Hi, i got a 1991 mustang all rebuilt and when i installed a roll cage in it the car it is now slow. I think i may of damage a wire e we hen sliding ghe roll cage bar thru the dash. The car runs fine but it iis just slow. What could I have possibly disconnected to loose so much hp but that the car runs fine in a sense no hesitation no back fire no nothing just missing like 100 hp
 
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Hi, i got a 1991 mustang all rebuilt and when i installed a roll cage in it the car it is now slow. I think i may of damage a wire e we hen sliding ghe roll cage bar thru the dash. The car runs fine but it iis just slow. What could I have possibly disconnected to loose so much hp but that the car runs fine in a sense no hesitation no back fire no nothing just missing like 100 hp

Just in case he's not subscribed to his own thread.
 
@Regi
1. Check for dead bodies or other dead weight in the trunk.
2. Run codes and a cylinder balance test. (Fuel and ignition issues can pull a lot of power or all of it.)
3. Check that the throttle pedal is opening the flap in the TB (or carb) all the way.
4. Go for a timed test run to verify the butt dyno results.
 
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@Regi
1. Check for dead bodies or other dead weight in the trunk.
2. Run codes and a cylinder balance test. (Fuel and ignition issues can pull a lot of power or all of it.)
3. Check that the throttle pedal is opening the flap in the TB (or carb) all the way.
4. Go for a timed test run to verify the butt dyno results.
Great thanks. That’s exactly how it feels like the cage weighing 1000 lbs (its only maybe 150 lbs). I will check the things you said. I had already check the codes but they seem to fit with what was done to the car. K on and E off code 85 the canester was removed. K on and E on code 94 and 44 the air pump removed and code 33 the EGR removed. I bought the car like that 10 years ago and it worked well mind you I never checked the codes until this day.
 
Codes?
You guessing (butt dyno) or ET or dyno numbers change?
Well when I took the stang out for the first time that was exactly my first impression. I got a 347 ci and it use the pull like crazy you could feel it. After the cage installed it now pulls less than stock, no dyno done but the difference is too obvious. The cage is 150 lbs. I installed the cage alone and have to admit that I slidedd the cage bar thru the dash and after realized that wires were going thru there (too anxious to get it done). The fuse box is only a few inches from the bar. I check the best that I could with the cage now blocking the hole and saw nothing damaged. The code: K on and E off code 85 the canester was removed. K on and E on code 94 and 44 the air pump removed and code 33 the EGR removed. I bought the car like that 10 years ago and it worked well, mind you I never pulled the codes up until this day.
 
So did you do the cylinder balance test? What about checking fuel pressure?
Here is the big diagnostic check list you need to do. And do in order.
 
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So did you do the cylinder balance test? What about checking fuel pressure?
Here is the big diagnostic check list you need to do. And do in order.
Ok i will do the check list. The fuel pressure stays at around 50 lbs when idling looking at the fuel line pressure gauge.
 
Ok i will do the check list. The fuel pressure stays at around 50 lbs when idling looking at the fuel line pressure gauge.
The fuel PSI is checked with the vac line disconnected. I am sure that’s in the steps.
If you tested it with the hose off the pressure regulator and the like blocked, that’s way too much pressure.
When the line is hooked up, my needle moves at idle to compensate for the cam.
 
Ok i put it at 45 psi with disconnecting the vacuum line at the fuel regulator. It is now at 40 with the vacuum connected. The engine, i was told makes 450 hp so I thought it need fuel. I am checking the TB plate now. I noticed that it stays at about 3/4 open at full throttle (pedal to the floor). Is 3/4 normal see picture or I need to make sure it opens all the way?? See photo
 

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Ok i put it at 45 psi with disconnecting the vacuum line at the fuel regulator. It is now at 40 with the vacuum connected. The engine, i was told makes 450 hp so I thought it need fuel. I am checking the TB plate now. I noticed that it stays at about 3/4 open at full throttle (pedal to the floor). Is 3/4 normal see picture or I need to make sure it opens all the way?? See photo
For 450 hp, it should have bigger injectors, a matching MAF, and probably a tune with one of an assortment of add on gadgets.
 
Ya it does. All 24 lbs injectors and MAF. My issue only dates a few months now where I only added a rollcage. Before that all good. But in one of the chat someone said to check if the throttle body opened the entire way and now I see that it doesn’t. So i will try to get that TB plate to open completely. Thanks gor the chat. This is a nice place to communicate.
 
Ya it does. All 24 lbs injectors and MAF. My issue only dates a few months now where I only added a rollcage. Before that all good. But in one of the chat someone said to check if the throttle body opened the entire way and now I see that it doesn’t. So i will try to get that TB plate to open completely. Thanks gor the chat. This is a nice place to communicate.
That was one of my first suggestions. I hope it helps.
I am not seeing anyone else big on the wire deal causing a loss in power. :shrug: It seems like a fuse would have popped or magic smoke would have been released from a grounded hot wire.
Just in case, how about pics of where the bars are and the nearest dash wires? Could the cpu in the kick panel be partially unplugged from pulled wires? (Brainstorming with you on this one).

And - was the battery unhooked when the bar was bolted in?
 
I will try to get the TB plate/door to open the all way when pressing the gas pedal the entire way. Trying to read how to do this don’t see any adjustments on the TB or cable so must be at the gas pedal (so removing the seat and all won’t do that today).

Here is some pictures
 

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The gas pedals are known to bend the metal is bent on a U shape. It should be parallel through the bends. If it bends it'll put the peddle closer to the floor.

That probably isn't your loss of driving hp. It'll only affect wide open throttle.

Verify your timing and make sure you don't have any vacuum leaks. Make sure all the pins in all the connectors are tight. I've seen wires slide back in the connector. It looks plugged up but the wires aren't making contact.
 
I will try to get the TB plate/door to open the all way when pressing the gas pedal the entire way. Trying to read how to do this don’t see any adjustments on the TB or cable so must be at the gas pedal (so removing the seat and all won’t do that today).

Here is some pictures
Check the wires and the connector where the passenger kick panel should be.
I agree with @90sickfox about it affecting full power. I assume that’s where people test power. :shrug: If the problem wasworse, it would not have the expected part throttle. Might as well fix it.
 
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