car engine problem

[WWJD]

if any of you have any thoughts what I can check before taking my car in...
my car is sputtering BADLY. it was pretty humid the on Sunday and driving around town, first I noticed taking off was kinda jerking. so I pulled over and stepped on the gas a few times. it would hesitate, sputter, then go. shortly after, I tried again and it lost half it's power, and it was WONKING like it only had 2 or 3 cylinders firing. I pulled off and checked the wires to the plugs - because I'm mechanically challenged and that's all I know to do - one seemed a little loose but tightening it made no difference.

I had checked the oil the day before: full, clean, happy, and it has previously been running fine as far as I know. I drive it hard, usually to 6500/7000 redline whenever I can, so maybe I wore it out.

is there anything obvious I can check before taking it to the dealer where I'll get to pay them a grand to bend me over?

Maybe a mouse called into an intake? replace the plugs? bad gas? ideas?

sorry, ima car engine idiot. I got the car used with 91k miles on it - 1990 Mazda Miata - but the engine was rebuilt by the dealer who happens to produce race Miatas. Otherwise, it's been a great car

 

[omslaw]

Looks like you hit on some things that I would check...


Bad Fuel? Clogged Fuel Filter? Plugs?

 

[Projekt]

Could be a lot of things. Do you have maintenance records? If so look through them for routine and major services completed. (to me it sounds like your fuel pump could be failing)

A thorough visual inspection of ignition components should be a first. Check for spark, it should be Blue or brilliant white, if dim or yellow, you could have a bad coil.
Are the ignition cables (spark plug wires) in good shape ie, no burned out electrodes at either end? Replace if bad since these will deteriorate when they get hot reaching operating temperature.
Does that car have a distributor? If so check the rotor and cap, maybe they are both really crusty, could be grounding instead of pushing to the plugs.

Has the fuel filter been replaced since you've owned it or at all? If not this could be a cause.
How about the air filter, clean or clogged?
Fuel pressure regulator may be on the fritz.
Air meter could be dirty.
Throttle position sensor could be going out.

Best bet is to buy the chiltons/haynes manual for it and do some reading.

 

[Projekt]

By the way I had a very similar problem when my distributor cap/interior got wet with condensation and steam after a car wash. Could be that the humidity condensed inside the distributor and is causing those symptoms.

 

[proud dad]

Looks like you hit on some things that I would check...


Bad Fuel?  Clogged Fuel Filter?  Plugs?

what he said.

and could be fuel pump going out.have to check fuel rail pressure[need gauge for that]then again it's fuel injection,could be sensor related.better hope it's not a mass air flow[what ever Mazda calls theirs]they are extremely $$$.can't say for sure without seeing it.

 

[Mr Bogus]

my guess would be ignition as well... Need to know what kind of car, year and motor you have however.. (most new cars do not have distributer caps anymore so that will not be an issue)

Secondary ignition insulation is most sensitive to humidity and is pretty easy to check btw...

Get a bottle of windex (non alcohol please is the key)

Fire up the motor and start spraying wires from the sparkplug up..

It does help to have someone in the car with it in gear if it is an auto. Engine load helps load the wires..

If you do this in a dark garage you will be treated to a neat light show but please keep your fingers out of harms way..

 

[Sloto200]

like above... it sounds like bad gas or clogged fuel filter to me...

 

[WWJD]

yeah project, the humidity thing is a very good point. I've had that happen in the past on older cars, and wondered if maybe that is all it is. being a 1990, I suspect it has the good old distributor thang going on. I'll see about pulling some wires and maybe the dist cap, but that's it for me. im not tool-equipt to do anything more

I forgot to mention, it had little back fires going on, on the down rev when testing it. Engine has always ran fine [for the 12k that I put on it] and it FEELS like one of those small fix things. It's nice today, I'll check it out after work.

thanks for all this great advice, guys! you're the best

 

[Mr Bogus]

fuel system issues usually affect all cylinders (unless it is a shorted injector) and you will notice limited rpms (noses over) or the motor completely dies on off idle or hard acceleration.

If you feel a distinct miss, it is usually spark related. If the miss only occurs after the engine has warmed up well, it "could" be an injector but is pretty rare.

Shorted injectors usually overheat the ECU and kill the car completely (GM is famous for this with their V6's)

If you are pulling wires, make sure you can twist the boot before pulling (they tend to weld to the plug and you can kill one in pretty short order just yanking it off) Dielectric silicon is a good thing to have as well. A small dab inside the boot prior to reinstall can save you a failed wire next time they are taken off..

The older SHO Taurus uses a $50 a piece plug wire (yep $300 a set)so some care is a nice thing

 

[bigjohn141]

Check the ignition like everyone said. When was the last tune up? Sounds like you may have condinsation in the cap or a bad plug. Try pulling the plugs one by one and seeing if there is any build up or oil that may have cause the plug to go bad. Another trick is to wait till dark or if you have a garage shut the door and turn out the lights and look at your engine, if you see any lightning jumping around the motor then it is time for some new wires.

 

[Big Wall]

Could be a clogged up catalytic converter also. It sounds a lot like what my '95 VW Jetta did when it needed the cat conv replaced. It went from a little hesitation to only letting me go about 10-15 mph in about 2 days. It really felt like there was something clogging up the exhaust.

 

[Mr Bogus]

Could be a clogged up catalytic converter also. It sounds a lot like what my '95 VW Jetta did when it needed the cat conv replaced. It went from a little hesitation to only letting me go about 10-15 mph in about 2 days. It really felt like there was something clogging up the exhaust.

Thats pretty easy to hear out the tail pipe and is a normally a gradual failure.

Just stand out back and have someone stand on the gas pedal... you should hear a clear sound of a motor and not just a bunch of whooshing air...

sometimes the honeycomb style will drop a layer and it will turn sideways in the cat and create a blockage but you can hear that under the car.

<div class="iF-Passage"><div class="QUOTEHEAD">Quote:[/Quote]<div class="QUOTE clearfix"><span class="quoteBegin"> </span>
Check the ignition like everyone said. When was the last tune up? Sounds like you may have condinsation in the cap or a bad plug. Try pulling the plugs one by one and seeing if there is any build up or oil that may have cause the plug to go bad. Another trick is to wait till dark or if you have a garage shut the door and turn out the lights and look at your engine, if you see any lightning jumping around the motor then it is time for some new wires.[/quote]

You will see a halo around most wires even when new, that is why we use the window cleaner.. (soapy water will work) Reach down to a known "good" wire in the dark with the engine running, you will see the halo start for your hand... creepy but cool

25 years owning a garage and you do a lot of silly things,, I used carb clean once to check wires...oooops

 

[GSXTacy]

Could be a clogged up catalytic converter also.  It sounds a lot like what my '95 VW Jetta did when it needed the cat conv replaced.  It went from a little hesitation to only letting me go about 10-15 mph in about 2 days.  It really felt like there was something clogging up the exhaust.

+100 Spoiled busas just went out on her FAST. The engine with jumping around like it dropped two of the six cylinders. There was almost no warning, just driving along and then it died.

 

[Vic_E55_2001]

Spray WD40 all around your ignition wires. It will push the moisture out.

 

[johnstein]

try this ! go out at night with a spray bottle on mist , start the engine and pop the hood , if you see sparks jumpin out of the wires or cap , you have already located the problem , if not start misting down one side of the engine at a time close to the block working your way back toward the cap , if you start seeing sparks you found your problem if not move on to the cap , with this method you should be able to track down the culprit . it sounds like ignition to me ?

 

[06BUSA]

A bad O2 sensor can do that. O2 sensor can be the root cause of plugging a cat converter. All the excess fuel buring in the converter, cokes it up. Check the plugs to see if one bank was running rich.

 

[Projekt]

So did you have a chance to take a look?
Any updates?

Wimp out and drop it with the Mechanic?

 

[Mr Bogus]

A bad O2 sensor can do that. O2 sensor can be the root cause of plugging a cat converter. All the excess fuel buring in the converter, cokes it up. Check the plugs to see if one bank was running rich.

the cat actually melts down..

An 02 sensor can cause this but exhaust leaks (between engine and cat) can do this as well. It allows excess oxygen into the exhaust and the cat works "too" well. Bad wires are also a big problem (excess fuel in cat)

plugged cats tend to affect all cylinders anyway and not 1 or 2 as in a miss

 

[proud dad]

see if a LS2 will fit.that'll pirk it up

 

[Projekt]

see if a LS2 will fit.that'll pirk it up

Like he said.

We already know that SBF 302/5.0 fit.