hey, all!

my girl's car has been having some morning sickness. it's hesitating to accelerate at low rpms <2000. I drove it one morning and it seems to buck and surge at low throttle. once i give her higher throttle, the power comes back.
Changed: spark plugs, wires, distributor cap and rotor, fuel filter, cleaned maf, air filter is new, new o2 sensors (front).
Strange thing though: disconnected the map sensor, and the problem is gone! ok, so i went and bought a new one, seemed to fix it, but came back the next day. Got a different one again - same thing. However, if i disconnect it, the problem is instantly gone!
I'm running out of ideas. Fuel pressure seems to be fine.
Could it be the tps? dirty egr? but it idles fine.

thank you, all!

 

Vehicle specifics? Is this a '99 Olds Bravada?

Disconnecting the MAP sensor doesn't mean that it is the problem, it just means that the problem disappears when the PCM goes to a default program such as it does when it doesn't have all of its sensor inputs.

Have you cleaned your MAF sensor or EGR valve? When was the last time a tune up consisting of plugs, wires, cap, & rotor was done?

The TPS sensor can be tested rather easily with a multimeter. Should register ~0.5V at closed throttle and ~4.5V at wide open throttle. The transition from closed to wide open throttle should be a smooth increase in voltage out of the sensor. Test with the key on, engine off.

 

Yes, it is a 99 olds bravada.
Changed spark plugs, wires, cap and rotor a couple of months ago.
Maf has been cleaned, but not the EGR. Wouldn't the truck idle rough if it was sticking/dirty? her idle is fine.
I was thinking TPS also, but why would it not act up when the map is disconnected? maybe the wires to the map are bad? I'll need to run some tests.
Thank you!

 

ok, so i do believe it is the tps. she's been having some intermittent rpm "jerks" at steady throttle, like the torque converter was locking and unlocking.
do we have to adjust the tps or it's a "plug-and-play" sensor? does anyone know the size of the torx bit i need to use?
thank you, all!

 

hey, all! i shot a video today of the problem. here's the link: http://yfrog.com/j4video0013iz

at first, the map is disconnected and i rev the engine to show how smooth it is. once it's connected, however, the engine starts to shake violently. any help is greatly appreciated! i've swapped a new tps in it, btw.

 

Mine did the same thing, distibuter gear was worn

 

hmm. that's def. one thing i haven't checked. the whole distributor assembly has to come out, correct? what is map sensor's relation to the distributor, by the way? thank you!

p.s. should i get a new gear or the whole thing?