Loss of power have tried everything!!

[TheBabbige]

OK I own a 95 MTX SHO that runs great just has a loss of power. It start's,runs,and drives great it just don't have the power like it used to have.
I have replaced EVERYTHING on this car without going into the motor itself and still cant figure out what it is. It's fine till i try to get it to redline then at around 6000 RPM's it just loses all power and wont pull anymore what could it possibly be? thanks for any help.
PS: i have searched and searched to no avail on the answer.

 

[Ishodu]

What do the plugs and wires look like? Any oil in the plug wells?

 

[AREA 91]

I would also check your cats in the Y pipe.
They may be clogged.
This will cause a loss in power on the top end of the rev range.

 

[rubydist]

the first thing to do is always to pull the codes. what are the codes?

at this point there are so many possibilities that all you are doing is wasting money.

 

[TheBabbige]

Have pulled the codes the only code I have is for the front o2 sensor there is only 1 cat on the car it was like that when I got it the plugs are new and no oil in the wells since the gasket change car used to run fine till I had to change the camshaft and crankshaft sensor since those have been changed I seem to have lost all power at high rpms it acts like a flooded carburetor lol I have check all vacuum hoses they are all connected to my knowledge (that I can see anyway) so I'm really kinda at a loss I love this car I just hate to put moree money into it and the problem persist I hope this helps and clears things up a bit. PS: I had timing checked a little while back its perfectly in time.

 

[msteiny]

Have you checked the fuel pressure at the rail? Could be a fuel pump on its way out. This has happened to me, runs great till you get on it then she falls on her face. I never got a code for this issue, runs great now. Right up to 7K.

 

[rubydist]

also, the lack of cats will not affect the o2 sensor reading, so if you have a recurring o2 code you need to replace the sensor or find why it doesn't read right. that can affect power if the car is really running lean.

 

[msteiny]

Speaking of lean, Have you checked the clamps on your intake couplers or the couplers themselves? Might have a leak there.

 

[TheBabbige]

Haven't checked the fuel pressure yet it seemed ok of course that don't mean anything I'll try and have that checked what exactly is it supposed to be at? As far as the intake clamps I have removed it several times and they seem really tight so I don't belive its a air leak I'll double check though but I will def check the fuel rail for correct pressure I'm pretty sure it still has the original fuel pump so that could be going on the frits but it ran fine till those sensors went out seems kinda odd to just go bad now though. As for the o2 sensor it went bad because of an exhaust leak that has since been fixed so as far as I know it just shorted out

 

[Off Road SHO]

Minimum 35 psi at idle and 40-42 when you take the vacuum away from the fuel pressure regulator. Removing that vacuum hose from the regulator simulates what the engine does at high rpms, that is, much less vacuum.

Put a fuel pressure gauge on the Schrader valve near the throttle body. Start up the car and see if you have 35 psi. If yes, pull the little rubber hose off of the fuel pressure regulator at the other end of the intake and put your thumb over the exposed vacuum hose end. The needle should jump up to 40-42 psi. If it doesn't you could have any one or multiples of the following:

Bad fuel pressure regulator.

Bad fuel pump.

Clogged or restricted return fuel line.

If you test the fuel pressure and find it low and don't understand how to check the above 3 possibilities, let us know and one of us will detail each out. Good luck.

Tom

 

[SHOtimer]

So, the car started having problems after you took it apart and changed the camshaft and crankshaft sensor...?

That would indicate that something either wasn't installed properly (was the crankshaft sensor gaped properly?), or an error in reassembly.

Why were you replacing the cam and crank sensors?

Doug

 

[rubydist]

since you likely took the timing belt off to replace the crank sensor, from your symptoms there is a very good chance you have at least one of the cams mis-timed. It is not a trivial exercise to get it timed properly, and I've seen SHO engines with just one cam off 2 teeth that were way down on power and would not pass emissions. You should pull the covers to verify timing.

 

[TheBabbige]

I had to replace both sensors cause they failed on me the timing belt cover was removed when i baught the car so i didnt have to take the belt off to get to anything just put them on both sensors were baught brand new so i assume they were within spec the timing belt was replaced when it broke on me before and it was put back in time i had it checked at my mechaninc and they said it was perfectly in time so im pretty possitive its not that ill get the fuel pressure checked and then go from there thats all i can think of

 

[SHOtimer]

I was not referring to the crank shaft sensor itself being in spec. The crank shaft sensor has to be properly gaped against the timing belt gear upon installation for it to work properly.

If you just installed it and didn't gap it properly against the shudder then it may cause the problems you are having.

Sounds like it is a rather rough car...

Do you have all four bolts holding the DIS module onto the intake, and the ground strap properly attached from the fire wall to the intake?

Doug

 

[TheBabbige]

Ahh ok i didn't know that i just put it on and bolted it up will have to check into that sorry for the confusion but yes the ground strap is attached and all the bolts to the DIS module are on it the clips that hold the plugs on are broke though if that would cause any problems im not sure but as far as the DIS module it is on and there. It is a good car the motor is strong and solid no doubt its just having technical difficulties at the moment.

 

[rubydist]

since the timing covers are off, it would be trivial to check the timing to either verify it is correct, or confirm it is not. That is worth 5 minutes of your time.

 

[TheBabbige]

I have had the timing checked and checked it myself the marks are lined up perfectly where they are supposed to be so i can assume that it is in time i have narrowed it down to either being the fuel pump,or the crank sensor not being gaped right because everything else seems to be in working order ill check them and keep everyone posted.

 

[msteiny]

When you check the crank sensor don't forget to check the timing mark down there as well.

 

[SHOtimer]

When you check the crank sensor don't forget to check the timing mark down there as well.

Don't worry, he has checked everything else and can assume the only culprits are the sensor not gaped properly or the fuel pump. :corn:

Doug

 

[Mr Anonymous]

Don't worry, he has checked everything else and can assume the only culprits are the sensor not gaped properly or the fuel pump. :corn:

Doug

The crank sensor gap has nothing to do with the proper function of the sensor. The gap is entirely to keep the shutters on the timing sprocket from impacting and damaging/destroying the crank sensor.

Engine issues such as loss of power with no corresponding codes is almost always primary ignition; coil, plugs, wires.