91 ciera hesitation/stalling rough idle

[Ian Szgatti]

time for a fuel pump and a fuel filter. Also check the vac line to the trans, and the FPR for good measure.... but anyways, fuel pump im going to say.

[Rayzor32]

How do i check the vac line to the trans? Fuel filter is brand new, and its not a fuel pressure problem my mechanic said. I'm gonna try replacing the IAC, TPS, and coolant sensor and report back..

[CA Cutlass Supreme]

Do you have a multi-meter? They are cheap.

The most glaring thing i see is an OPEN circuit in the O2 sensor (either the sensor is open or the open is in the wiring somewhere). I would really check the wiring to all three circuits w/ the meter on the resistance setting and the suspect wiring isolated (disconnected at both ends @ component)..only do a resistance check with power OFF, could damage the meter. meters are cheap @ any hardware store. Even if the wiring is good, any exposed wire or insulation cut away could be rubbing against something and shorting or grounding. So, you might want to pull the wire out of the conduit and check EVERY inch for visual signs of melting, exposed copper wire, burn marks, scrapes, frayed wire and wire that may be completely severed.

zeroinfinity was spot on with my shorting problem.

Pardon my ignorance if you know how to use a meter. If not, the meter should come with instructions on how to use it or possibly your service manual in electrical troubleshooting.

resistance tests are always done on a DEAD circuit. You don't want power going through when testing for resistance.

[Rayzor32]

I have a small multi meter, the car caught on fire once before from the injector o rings before, but nothing was really damaged other than the wires coming off the injectors which i replaced. But this problem was going on before then, ill check the O2 sensor wire. Are you talking about just checking the o2 sensor wire? I mean cos there is only one not three. can you be more specific on how i check it, thanks. its sposed to warm up next week so ill hit the junkyard and work on the car and report back. i drive the car everyday, and i mean its not that big a deal, but the stalling when its cold and the hesitation are just annoying.

[CA Cutlass Supreme]

Originally Posted by Rayzor32

Are you talking about just checking the o2 sensor wire? I mean cos there is only one not three. can you be more specific on how i check it, thanks. but the stalling when its cold and the hesitation are just annoying.

For the wire itself. disconnect it at the sensor AND at the other end. All you want to be testing is the wire itself from end to end w/ the meter. Set your meter to resistance setting and that the leads are properly attached to your meter (some meters require you to change how it's setup to test for resistance physically). put one lead to the start of the wire and the other lead to the end of the wire. A high resistance or infinite resistance reading would indicate an open wire or a wire that has been cut off or near cutoff/pinched/overheated. What you want to see is near ZERO resistance, showing that current can flow continuously through the wire and there are no breaks in it or shorts. Next have one lead connected to the wire and the other to ground. If you show any continuity, it is shorting to ground and should be repaired (heat shrink over fixed connection) or replaced with a new wire of the SAME guage. Next, i would do both tests while wiggling the wire. If it shows nervousness or hunting, you got a problem with that wire(make sure you have a good lead connection to wire as you wiggle it around) I would NEXT (VERY IMPORTANT!!) visually check each inch of the wire for any signs of overheating, fraying, exposed wire, pinched wire, melting....if it is one wire, find the right guage replacement wire that matches it and replace w/ new. Important that the guage of wire is the same.

Since you have 3 trouble codes. The codes don't necessarily indicate a problem with the component itself, but rather the problem lies somewhere in the circuit (i.e. wiring) of the related component. So don't just test the component, check the wiring also. Because if the wiring is still bad, you might have wasted a new part when you turn on the switch.

I know this is dumb, but how tight are your battery connections?

BTW: When i meant check ALL three circuits, I meant checking each trouble code that your computer came up with. Not the (3) wires you meant for the 3100 engine like i have. So check off each code as you check them.

My car had 11 trouble codes showing! My problem was the short was fooling the computer that ALL these circuits were bad, which they were not. A short can confuse your electronic brain, that is why it is important to do a visual and testing of the wire itself. Replacing a part with new doesn't always solve the problem.

For now, i would follow zeroinfinity's instructions and test/inspect/repair stuff as he says. Just do it methodically and you'll get to the source.

[Rayzor32]

Alright thanks fur explaining that, i get what your saying now. I'll do that next week its sposed to warm up right now its in the teens out i wish i had a heated garage! (or a garage u could fit a car in period ). Grr i hate winter!!! though i just got sum used snow tires and this baby PLOWS through the snow now. a wire very well could be shorted, my battery connections are good. and i never buy new parts ne way i have 4 junkyards down the street frum me, and small sensors and stuff are "free"

[Rayzor32]

I found a maf sensor that looked brand new so i bought it and threw that on, along with a TPS. I got two tps's from the boneyard, the one I pulled off my car has like oval holes for the screw and a metal ring, so I guess its MOVEABLE?? I found two kinds in the junkyard, one moveable one and one fixed one. Whats the difference???? I threw the fixed one on right now. Test drove the car around the block, didnt have any hesitation but still stalled when cold, ill see how it drives tommorow when i go to work though. I also picked up a coolant sensor.

[Rayzor32]

Im gonna put the coolant sensor on today, the car STILL stalls and has hesitation problems, like youll push the gas and itll be fine then once your within this "zone" on the pedal the car just falls on its face and stays that way till you press it more. anyway can ANYONE answer my question about the two different TPSs???