Loss of acceleration

[EagerBeaver]

1994 Chevy Lumina APV 3.1L V6 158+k miles

Ok, had start problems initially...figured it was starter too late and towed to my favorite mech.

After replacing the starter van had an issue when trying to accel to speed limit of on ramp/thruway got up to about 50mph and lost everything?!?! Took it back to my fav mech and he checked fuel filter, PSI, good spark, and checked the fuel module. It ended up being the fuel module he said was not recieving a pulse.

$500 bucks later, still seem to have the same accel prob. Was on way to work changing lanes and began to accel over 55 to pass. I had the accel to the floor and engine didn't do a thing! Speedometer fell like a rock and all I could do was sit and watch (in the meantime PO the guy who decided to follow my lead--guess he figured I did it on purpose!!).

Anyway, after letting the van slow down, I let off the accel and slowly increased speed in hopes of it coming back. It thankfully did. However, it seems that my problem still lingers within the machine and I cannot figure out what it could be? Would like to not have to spend another $500 to determine what this problem is, but I think I may have to.

Any suggestions...Yes, I'd like to buy a new vehicle, but already did that so the wife and kids have a safe reliable vehicle...I'd rather keep this another year for back and forth to work...hopefully??

[maxwedge]

First of all I would drop it back in the lap of the $500 guy. This sounds like low fuel pressure or a cat going bad, there are standard checks for either condition that based on your driving experience or a road test any good tech could find the problem.

[NeonKnight]

sounds like a fuel problem, maybe even the ECM. have it put on a scan tool by your mechanic and have him check it out.

[Beaver420]

Some similar things were happening with my 3.1 when the cat was clog. There was a minimal difference from 0-30 when at low rpms. But above 4000 rmps at higher speeds the engine would just bog down and die and then come back screaming but the car wouldnt move anywhere.....

[richtazz]

does it only do it when you attempt to accelerate from about 40-55mph in overdrive? If so, you may have a Torque Converter Control (TCC) solenoid that is not unlocking the converter to allow the engine to gain rpm. Symptoms would be similar to trying to accelerate a stick shift car in too high a gear.

[jeffcoslacker]

Originally Posted by richtazz

does it only do it when you attempt to accelerate from about 40-55mph in overdrive? If so, you may have a Torque Converter Control (TCC) solenoid that is not unlocking the converter to allow the engine to gain rpm. Symptoms would be similar to trying to accelerate a stick shift car in too high a gear.

Yeah, in the shop we used to call that "trailer hitching", because it describes the sensation perfectly. Feels like you are suddenly pulling a huge weight and the motor can't overcome, won't build any speed. TCC will do that, cat can do it too, but usually will give other symptoms, black exhaust smoke, engine overheating, sometimes hissing exhaust sound, and generally if you stay in the throttle, it'll just continue to loose speed until it stalls.

A quick vacuum reading test under acceleration can diagnose the cat being blocked, the reading will drop steadily under constant throttle input. (normally it will drop to zero when the throttle opens, then recover and hold once the RPM steadies.)

[EagerBeaver]

Update:

Ok, as I said, I have had the starter replaced, the fuel module...and $500 out of my pocket.

It was suggested I take it for a transmission check. Took it there, the guy said it tested fine (was a free test thank goodness). However, he noticed while driving it that it was losing power. He suggested a place and they checked it out with $90 initial fee. They checked it, found the ignition switch faulty and replaced it as well as took care of some wiring issues he found. Another $250 gone with the $500, so am out the value of the car at least...

They said they can't repeat the issue I had before, but now when you go heavy on the accel...stomp on it, the car bogs almost into a stall but doesn't die. The wife and I have had it and aren't putting another dime into it and will drive it til it completely dies...don't care if I have to walk home from whereever I am...

I've asked about the CAT and most everyone has said no. The pressure is fine, the injectors are fine, plugs and wires are good...????

Am lost and out $750...this bites...