No Power Out Of The Hole

BigE85 · Mar 13, 2017

Hey guys don't know if anyone has post this before so forgive me. But I could not find a clear answer. The problem I have on my 94 gt is when I lay into it from a dead stop it's lacks power bad. But if I just drive it nice and slow it runs great. Idles great no misfire or back fire. I did a full tune up oil,plugs,wires,fuel filter new distributor not reman new put a new tfi module.New Cold air intake cleaned all sensors iac and mas. I did check for codes I was pulling a 172 and 176 which I'm getting ready to change o2 sensors so Im at total lost. Timing is set at between 12 to 14 I do have 93 octane in it. Best way to explain it is from a dead stop to go it's like a surge of no power then is fine it's a stock motor except for the cold intake and flow master exhaust.

General karthief · Mar 13, 2017

How many miles, stick or auto?

BigE85 · Mar 13, 2017

122k 5 speed manual

General karthief · Mar 13, 2017

Fuel pressure?

BigE85 · Mar 13, 2017

Right at 32psi at idle and holds there never drops below that.

BigE85 · Mar 13, 2017

Right at 32psi at idle and holds there never drops below that.

General karthief · Mar 14, 2017

What gear ratio, rear tire size.

BigE85 · Mar 14, 2017

Everything is stock not sure what gears it has what ever a stock 94 gt has but tires are the stock 245/45/R17

General karthief · Mar 14, 2017

This question is relative to certain factors,
Your door tag should have a axle ratio code and the weight of the car, start with that and do a compression test on the engine, this info will give you a starting point.
If your engine is in good shape and no clutch problems I would look at a gear change, at least a 3:55 gear with stock tires will make it responsive starting out.
Show a pick of your engine compartment.
Keep in mind if you are comparing your car to newer versions like a 2010 and up your ride is gonna feel like a dump truck.

Noobz347 · Mar 14, 2017

BigE85 said:
I was pulling a 172 and 176 which I'm getting ready to change o2 sensors

I would spend some time locating the vacuum leak before tossing brand new sensors in there. They will still read lean.

FoxMustangLvr · Mar 14, 2017

I thought fuel pressure was supposed to be about 39 psi? Is it different for a 94'? I don't think gears are your problem, however, they are a nice upgrade. Dumping the clutch from a dig, even with stock gears, is still a lot of fun and there should be no problem with acceleration. Search for a vacuum leak, fix the O2 sensors, recheck codes and take it for a drive. Do you have cats? When they start clogging up you start to lose power too.

BigE85 · Mar 14, 2017

Thanks guys. I will definitely look at this when I got the car I replaced a bunch of vaccum lines. I'll double check them I agree I don't think I have a clutch or gear problem. It feels more like a fuel problem alot of hesitation if going to lay into it bogs down but if I drive it normal it's fine shifts fine. It seems like a fuel or timing but not sure. But I can be in 4th gear and the car pulls good. No hesitation. If I put a fuel gauge on it and I'm reading 32 psi when I rev the car what should the fuel pressure go up to cause.

BigE85 · Mar 14, 2017

Sorry I forgot I have no cats on this car. Its been like that since 94 it was a one owner car and has been stock all its life. Except the exuast but the pervious owner never had any problems like this. The only other thing was when I put the fuel pressure gauge on it the fuel pressure never drop below 32 psi. but when Rev up fuel pressure went up to like 39psi and drop fast but not below 32 psi. Is this a fuel pump issue or is it a mas sensor not reading right due to the cold intake messing with the air and fuel.

Noobz347 · Mar 14, 2017

Your codes indicate that both banks are lean. That's a pretty good indication that you're getting unmetered air from somewhere.

If your car has been running in this condition for some time, it's also a pretty good bet that the additional heat has taken it's toll on the tired O2 sensors. Try finding the leak before you replace them. It could be any number of gaskets and seals or hoses.

If you have an adjustable fuel pressure regulator, consider swapping it out for an OEM piece. If you have the original OEM piece, consider replacing it.

Don't neglect the possibility that the fuel pump may also be at fault. If it's original, it likely time for a replacement. There are very few situations that require an adjustable unit. You do not appear to have those conditions and in some cases, adjustable regulators just provide another avenue of error. A mechanical fuel pressure gauge while you drive would help rule out fuel issues. The smell of gas in the vacuum line going to fuel regulator is a sign of a failing regulator.

FoxMustangLvr · Mar 14, 2017

@jrichker
Should fuel be 39psi for a 1994?

jrichker · Mar 14, 2017

FoxMustangLvr said:
@jrichker
Should fuel be 39psi for a 1994?

Yes

Check fuel pressure:
The local auto parts store may rent or loan a fuel pressure test gauge if you don't have one.
Disconnect the vacuum line from the fuel pressure regulator. Check it for evidence of fuel present in the line by removing it and blowing air through it. If you find fuel, the fuel pressure regulator has failed. Reinstall the line; leave the fuel pressure regulator end of the vacuum line disconnected. Then cap or plug the open end of the vacuum line and stow it out of the way.
Connect the fuel pressure test gauge to the Schrader port located just behind the alternator.
Turn the ignition switch on & start the engine. Observe the pressure: you should see 37-41 PSI at idle.
Turn the ignition off; reconnect the vacuum line to the fuel pressure regulator. Then disconnect the fuel pressure test gauge. Watch out for squirting gas when you do this.

BigE85 · Mar 14, 2017

Ok thanks. i will look over this tonight I did check the regulator for fuel none was presence. Will double check for leaks and go from there. Fuel pump is the original to my knowledge so will be looking at that. Did check fuel pressure and was holding at 32psi

BigE85 · Mar 16, 2017

Hey guys wanted to give you a update. Change some more vaccum lines just to be on the safe side. Change the intake manifold gaskets and the fuel pressure regulator. Put new o2 sensor and recheck timing. Started it up took it for drive same thing so I took the cold air intake off and put the stock back on. And it was a total diffrent car. Guess the stock maf can't read that much air so I'll have to upgrade but thanks for your guys help.

General karthief · Mar 17, 2017

I never thought that, what cai you got? Pics?

Dart68 · Mar 17, 2017

BigE85 said:
Hey guys wanted to give you a update. Change some more vaccum lines just to be on the safe side. Change the intake manifold gaskets and the fuel pressure regulator. Put new o2 sensor and recheck timing. Started it up took it for drive same thing so I took the cold air intake off and put the stock back on. And it was a total diffrent car. Guess the stock maf can't read that much air so I'll have to upgrade but thanks for your guys help.

It might not be that the MAF can't read that much air but that the air it's trying to read doesn't flow correctly into the MAF. That the air flow is disturbed. I've read that this is a problem with some aftermarket cold air ducts.

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