alright this is my major issue.. the gas mileage is very much a part of the problem. but my idle and acceleration is very bad

when i start the engine in the morning or after it cools it runs horrible. idle is very lopey(unstable) if i put it in gear the engine almost stalls at about 500rpm but raises to 650-750 after acouple seconds.
When i rev the engine to 3k rpms it sound real good but at 2k or lower its not soo good.

if i put it into gear and try to take off it hesitates for a second then accelerates but its pretty rough.. it does the same thing in park.

once warmed up the hesitation is almost gone but the engine is still not smooth and the idle is lopey... mileage is about 13mpg.

vacuum is 13 in park, 10 in drive with no leaks anywhere


if anyone knows of a sensor that i've not replaced that may be the problem or something i've over looked please let me know



i've replaced

Timing Chain
Manifold gaskets
Spark Plugs
Plug Wires
Ignition Rotor
Distributor Cap
PCV Valve
Water Pump
Alternator
Battery
MAF sensor
Fuel Filter
Rebuilt Transmission
Wheel Bearings
Vacuum lines
USED Rear end(good)
USED FWD Injectors
USED 92 Camaro Coil
USED TPS
USED Ignition Module
USED Fuel Pressure Regulator

 

What about the idle air control valve? It could be carboned up. Is your check engine light on? If so what codes are you getting? Is the timing right? What about fuel pressure?
Just throwing some ideas out there. Some more info will help tho.


Seth

 

the fuel pressure has been check out and its right on...

timing was done and is correct..

iac was cleaned somewhat but not replaced neither was the paper gasket

 

Was the check engine light on?

 

no check engine light.. but when i replaced my TPS sensor i wasnt able to work the damn voltage meter right and had to fool around with it till i got the check engine light to turn off

 

go to wally world and get a $18.00 GE Digital multimeter.

hook up to the tps with the car in the ON position, not running. read the voltage. it should be .55 for v6 cars. fiddle with it until there, leave it snug, but not tight (the bolts). at WOT it should be like.... 4.5v? or something like that. i think mine is at 4.3-4.4v. anyways, fiddle with the idle and WOT voltages and you will see a HUGE improvement. after you get both voltages around where u want them... tighten the bolts, re do your readings to make sure you didn't move the tps out of sync. if good, start up the car and take it for a test drive!

 

Also, check for vacuum leaks again. Whether you spray something on the engine, or use the old "put your hand over the intake pipe" trick, verify that there are no vacuum leaks.

10 and 13 are horrible vacuum numbers.

Smack your MAF around some while it is running. It is not uncommon to have a new or remanufactured unit to be bad right out of the box.

Are you sure your timing chain was installed correctly? I am asking because of the low vacuum numbers. I am still leaning towards vacuum leak...

 

If you can't find any vaccum leaks then you can have what I had done. I went to a shop and they hooked a smoke machine up to my motor. Any intake gaset or leaking vaccum hose had smoke comming out of it. I still had a few areas to work on that I thought that I fixed. Also what do your injector o-rings look like. Mine were bad and causing a big leak.

 

those are the vaccum reading from before the timing chain...

all the gaskets/o-rings on the top of the engine have been changed out and vaccum lines replaced many times.

this is why im so desperate to fix this issue.. i've tried almost everything...

if it wasnt for smog checks and other bullshit here in cali i would just drop my v8 in and get better mileage

 

There seem to be a few that plug in to the upper intake from below at the back that always come off. Those are the ones that I suspect.

What is your vacuum reading now? If you take the pipe off at your air filter can and hold your hand over it, does the rpm start to die or does the engine speed up and smooth out when you partially block the hole?

What is your fuel pressure doing while the engine is stumbling? Steady? High or low?