Random Putter / Power Loss ('93 GT Vert)

[celicagtvert]

I have a 1993 Celica GT Convertible Automatic that randomly putters for a few seconds until you gas it more. Happens when it's standing still and when driving, feels like it wants to stall but never has. It's not predictable at all and is completely random. I can also hear the RPMs rising though the speakers, I wonder if this is related or a seperate issue? So far it has new plugs, wires, oil change.

What do you think could be causing this random puttering/power loss till the gas is applied more?

Thanks!

[93celicaconv]

Regarding noise coming through your speakers, do your have an original OEM head unit, or do you now use an aftermarket head?

What kind of maintenance is this car getting? Have you kept up with the normal service manual maintenance items (plugs, wires, distributor cap & rotor, etc.)? How many miles are on it?

Does the check engine light come on at any time?

[celicagtvert]

Just bought the car from an adult who pretty much took care of it religously but now he's stumped as to what it can be. Since I bought it I only did the wires, plugs and oil change. The head unit is OEM and no check engine lights.

I'll ask if and when the distributor cap and rotor were replaced.

[93celicaconv]

Checking with the original owner would be a good idea.

If you know how to check engine compression, it might be wise to do that, and let us know what values you get.

On an OEM head unit, you really shouldn't be getting ignition interference, so that part is interesting. Do you have the System 10 in there? If so, good system, except some of the speakers in the doors and rear of the convertible tend to have their foam suspension break apart - so they may need to be resuspended.

Anyway, back to the original problem, it sounds like your ignition system is generating interference that is being picked up by your speakers, possibly through the wiring. That should not happen. You could have a coil that is starting to go bad. Or your spark plug wires could be starting to go bad.

When you start getting the rough engine and the speaker sound, what is your tachometer doing? It is showing engine RPM like normal, or is it jumping around erratically when the engine is stumbling? If your tachometer does act erratically, you may have an igniter starting to go out.

[celicagtvert]

Oh yeah I forgot to add that very important detail, when I get this random putter the RPM's bounce up a little. The last owner is my neighbor and said he changed the plugs about a month ago.


And I can always hear the engine accelerating though the speakers.

[93celicaconv]

Well, if your tachometer isn't acting bouncing around between 8k and zero, but just barely moves a litlte, then I don't think the igniter is the problem (unless it is just starting to go bad).

When it sits in your driveway, engine idling, does it run rough then? And describe rough. Does it sound like one cylinder is continuously misfiring? Or does it just wander a little bit in terms of engine speed (say wanders between 700 to 800 RPM), but otherwise sounds smooth?

[MR2Jedi]

I would be looking at the ignition system/ timing and /or a vacuum leak.
Resistor type plugs can illiminate the sound your sound system is picking up.

[celicagtvert]

The distributor and rotor & cap were replaced, funny thing is when I initially went to pick the car up after the work, it wouldn't start so they had to order a new distributor. It works now but does the random putter at idle and when driving but the RPM's don't bounce up too high. Car is 100% stock.

How would I go about checking for vacuum leaks and do you think it's not a misfire since there is no CEL?

[MR2Jedi]

If you're getting a CEL, the 1st step would be to see what it's for.Then go from there.


I would do a visual check for cracks/splits in vacuum lines.

You can use propane or starter fluid to check for leaks. Spary on lines with engine running,if idle increases, you've found a leak.

[celicagtvert]

No Check Engine Light.

Do you know of any common leak areas?

[MR2Jedi]

Ooops. Sorry. Misread that.
Check all vacuum lines starting at the intake manifold. Have you checked the timing?