my car feels very weak too It doesnt have power like it used to?


thanx






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1992 camaro z28 350 AT under 67k miles
engine rebuilt at 56k miles

 

The first thing i would do is check your fuel pressure. If your regulator goes bad, it might not be bleeding off at 42psi or whatever its supposed to be at. That would definetely cause poor fuel economy. Does your car have a hard time sustaining an idle? Are you getting a check engine light? Also, black smoke out of your tailpipe is a tell-tale sign of a rich fuel mixture.

 

yes, at idle very low rpm under 500rpm
feels like its going to die but it doesnt though
no check engine lights
black smoke, I need to check it out
I think it does though < I need to recheck again to make sure

when I accerate it feels like car has power after hitting 2k rpm,
car wouldn't pull hard
feels very weak and car shifts to next gear very fast

my car used to run very fast until my engine broke
replaced with rebuilt engine my car felt weak
not only that I paid 5k for rebuilt engine (in 1996)engine installed

 

The symptom of it idling poorly, and pulling fine after 2000 rpm sounds like fuel pressure is a good bet. Since the motor wont need as much fuel at idle as it will in higher rpms. In order to check it, you will need a fuel pressure guage to mount on the shrader valve on the fuel rail. First, check with the car running at idle. pressure should be about 38-42psi. A second check to do is to prime the fuel pump, (turn the key to the "on" position and back off a couple of times) and then with the car off, watch the guage and see if it loses pressure. The fuel rail should continue to have pressure for quite a while after the car is off. And if it is losing pressure, then its possible your fuel pressure regulator is leaking. (though with this test it could also be leaky injectors, or fuel pump check valve.) The last part of this second method is to do it again, but this time pinch off the fuel return line (the rubber part, NOT the metal part ) If your guage holds pressure this time, it definetely a leaking fuel pressure regulator. Sorry that was huge. Let me know how it goes.

 

The engine was REPLACED or REBUILT?

 

replaced with rebuilt engine

 

And the car has run like crap since you got it back?

 

Best bet at this point is to go through a normal TPI tune up / check procedure, and you'll have ALOT better idea of what's going on ( or not going on as the case may be ).


Check the FAQ's here or do a search for details on procedures :

- If you can't remember the last time you replaced the spark plug wires, replace 'em

- Spark Plugs - I prefer plain old AC plugs, but that's me.

- Oil and oil filter if due

- Check air filter(s) replace as needed

- Check distributor cap and rotor, any sign of wear or corrosion, replace with a good quality set

- Check TPS ( throttle position sensor ) voltage. Adjust as needed.

- Check initial timing. Adjust as needed. NOTE : you need to recheck the TPS if you have the adjust the timing.

- I would also reset / clean the IAC valve as well.


- Check fuel pressure. Make sure pressure holds.


- Replace the fuel filter.

- If it's been since '96, I'd go ahead and replace the O2 sensor and the PCV valves as well.


You'd be surprised how many problems turn out to be worn, or low-quality tune up items, or just settings not in spec.


This will give you a much better baseline to actually troubleshoot what's going on...if the problem doesn't "magically" disappear after this work.

 

I have a guage mounted on my fuel rail. Is it normal for the pressure to rise past idle's 42ish psi when i hit the gas? I can't remember off hand but I'm sure it's hitting high 40's easily.

 

Absolutely. Fuel pressure regulators are designed to raise the fuel pressure based on the engines need for more fuel. As the throttle plate opens, the rpms go up, and the manifold vacuum goes down causing the fuel pressure regulator to allow more fuel pressure.

 

yes

 

thanx for info

 

I personally would check the big 3.

Timing
Fuel Pressure
TPS

If its not that, this is a shot in the dark, but maybe he put a engine in your car like a TBI engine, which has poor flowing heads, and considering your ECM is not calibrated to work even remotely close to those junk heads.

I had the same problem, except reverse. I had a L98 engine and a stock prom TBI setup. I ran a 15.98 with my mods. Put a TPI setup in, been extremely happy with the performance ever since.

Just showing you what bad tuning can do.

 

It has Tpi head ,does tbi bottom fits on tpi head
I hope he didn't install tbi shortblock
I had tbi 92 rs automatic
it was very slow
no comparioson to 92 z28

 

Is their serial number on the engine to see
if its tpi short block or not
thanx

 

Yes, but where your power is, is in the heads and cam. There is not much difference in the TBI and TPI shortblocks. (350 vs 350 obviously.)

Unless he put in a 305 or something really stupid.

 

here is picture of engine bay


http://www.hpphoto.com/servlet/LinkP...191b2ed5&size=

http://www.hpphoto.com/servlet/LinkP...3fe72866&size=


http://www.hpphoto.com/servlet/LinkP...12e3d652&size=

http://www.hpphoto.com/servlet/LinkP...2bf442d4&size=