car starting problem....

[Gibson486]

Car: 07 Mazda 3 auto...47K mi

problem: It shakes violently when I start it up (right after the engine truns). This only happens when I start it up after it has been sitting over night. It almost stalls when I start it up (hence the shaking) and the tach drops all the way down to nearly zero (hence almost stalling).

Do I need a new battery? Is my starter roughed up?

update


Ah man....I am being prepared to be taken to the cleaners.....my cars been there for about 5 hours and they have not found anything yet. They said it did do a brief hiccup when it first started, but it has stopped (as I said it would). They said they are going to try to reprogram stuff....I am hoping that this $99 charge for non warrenty checks covers what they are doing

They said it is not the fuel pressure, it is not the fuel pump....

Then, out of the blue, he goes, "by the way...your front brakes pads...they are almost done...$320 if you want us to do it". I said no, ofcourse.


UPDATE

GRRRRRR.....they found nothing.....they tried to charge me for "additional diagnostic time" and the bill was $300. Fvck no! I told the guy that I signed a paper saying it would only cost $100. HE said fine, but he is not going to work on the car anymore. They were able to reproduce the shaking, but they cannot find the problem, so they cannot use my warrenty. I wonder how much money i will dump until I can find the problem. GRRRRR....

ANOTHER UPDATE:

It's happening again

I brought it to the dealer twice.....cost me $200 b/c they found nothing. When I bring it to the dealer, it never acts up.

Here is a more clear explanation:

scenerio 1: I start car, it starts, it goes for about about 2 seconds, then it hiccups and the engine begins to stall and shake. Sometime it will actually stall, other times it recovers.

Looking at the tach: it revs up to a little over 2K (like it is supposed to), settles for a second then dips back down while the engine hiccups (if it is the engine).

scenrio 2: I start car up, it seems like it barely starts, but the engine fires up. However, about 5 seconds after it turns, teh engine begins to kind of throttle up and down. During this time, you can kind of hear the engine throttle and unthrottle... It goes through oscillation this until I hit the gas. If I do not give it gas, and then I go in reverse, the engine begins to struggle. It shakes a little and you can hear the engine want to stop, but somethign is just barely keeping it going. Once i give it gas, it just revs up (although it shakes a little while I do it).

Looking at the tach: when I start, the tach does not do that initial rush like it usually does (where it jumps to about 2.3K and settles down lower). Instead, it climbs up slowly to about 1.5K-2K. After it turns, it goes to 1.5K-2k, then dips down to 1K or a little below then back to 1.5K-2k. It just keeps oscillating until I give it a little gas, then it goes.

I am hoping I can close teh book on this by this month. I only have about 800 miles left on my warranty

BTW: this only happens when the car sits for a while. Like when I start the car after work or to go to lunch

 

[Horsepower]

Not battery or starter, find a good local mechanic with references. Some items may still be covered under emission warranty.

 

[LTC8K6]

Idle control valve?

 

[Gibson486]

I'd bring it to the dealer....but....

1. It only happens when I start the car after it has been sitting over night. That means that once i drive it to the dealer, I cannot replicate the problem unless I keep it there over night.

2. If it is not covered by warrenty, I am out $90 + cost to fix it.

 

[brblx]

the shop will just have to leave it over night, as well. i've seen cars that took days to diagnose because the tech only got one shot at observing the problem per day. it sucks.

i would also guess IAC is sticking, or maybe a fuel issue- a bad regulator could leave you with just enough fuel to start it, but it may idle poorly until the line is properly pressurized.

 

[kalrith]

If it is the IAC, you can probably just clean it out with some carb cleaner and be set for a while. I've had to do that twice on my '01 Mazda Tribute, and it's lasted for about a year each time. The symptoms are somewhat different from yours (it will intermittently die without holding our foot on the gas), but the cause and solution could be the same.

 

[exdeath]

What happens if you crack the throttle just a little bit after starting and try keep it around 1000 RPM or higher?

Does it idle fine after start up after the shaking goes away? If so it's not the idle valve.

Extremely violent shaking is caused by missing cylinders caused by missing spark or fuel starvation, and being that it's only at start up I also suspect fuel pressure regulator.

Try leaving the key on longer before you attempt to start it, and see if you can hear the fuel pump running louder or longer than normal. It would also be easy to borrow a fuel pressure test gauge from a place like Autozone and leave it sitting overnight and see if it holds pressure.

Edit: Oops, that car uses a Duratec engine with a returnless fuel system so it wouldn't have a conventional style fuel pressure regulator. Still my first step would be check to make sure fuel pressure and hold time with key off is within spec.

 

[Gibson486]

yes, it idles fine after start up and shaking goes away.

SHould I try giving it some gas (just a light touch on the pedal) when starting it tomorrow?

edit:

Here is more detail by step.

1. I start car
2. Car fires up as usual for about 1 second
3. After that 1 second and engine starts to idle, it begins to shake for about a second and tach drops alot while engine light goes on.
4. Second later, all is good, engine light goes away and all is smooth.

 

[exdeath]

Just enough to see if you can *hold* it open to stabilize idle between 1000-1500 RPM, don't rev it before you have oil pressure or anything. It won't have any effect if it's a fuel problem, it would shake just as bad or worse until the problem passes in the usual amount of time.

The engine light coming on is helpful, you should have someone check for any codes in the computer. I suspect something like "FRPS output low".

The reason I think fuel is because other common sources like vacuum leak, ignition, idle control valve, or coolant temp sensor that can cause rough start and idle stick around in the long term and last several minutes/miles or show up randomly at other times like accelerating. Running violently rough on first start for an instant then no further problems only seconds later indicates a fuel system not holding pressure when the key is off.

The fuel system (especially returnless) is also one of the few systems in an engine that is susceptible to response time (pump inertia, pressurization time, etc) that can cause issues briefly just the one time and then go away as it "catches up".

 

[LTC8K6]

I think you can unplug the IAC valve and see if there is a change in idle behavior. If there is, it was probably working. If there isn't, it may be stuck in one position.

 

[Gibson486]

Originally posted by: exdeath
Just enough to see if you can *hold* it open to stabilize idle between 1000-1500 RPM, don't rev it before you have oil pressure or anything. It won't have any effect if it's a fuel problem, it would shake just as bad or worse until the problem passes in the usual amount of time.

The engine light coming on is helpful, you should have someone check for any codes in the computer. I suspect something like "FRPS output low".

The reason I think fuel is because other common sources like vacuum leak, ignition, idle control valve, or coolant temp sensor that can cause rough start and idle stick around in the long term and last several minutes/miles or show up randomly at other times like accelerating. Running violently rough on first start for an instant then no further problems only seconds later indicates a fuel system not holding pressure when the key is off.

The fuel system (especially returnless) is also one of the few systems in an engine that is susceptible to response time (pump inertia, pressurization time, etc) that can cause issues briefly just the one time and then go away as it "catches up".

I gave it some gas when it was about to sputter....it started to shake, but it stopped as soon as I applied a little gas. I guess I will bring it to the dealer when my gf comes back from vacaction so she can drop me off at work.

 

[Jugernot]

Don't Mazdas have a 4year 50k warranty?

 

[Gibson486]

Originally posted by: Jugernot
Don't Mazdas have a 4year 50k warranty?

3 year, 60K.....but if you bring it in and the problem is not covered by warrenty, you pay around $90

 

[LTC8K6]

Emissions parts are usually covered for a long time. Don't know if the IAC valve is considered an emission part though.

 

[Gibson486]

this may cost me a pretty penny....I finally found a dealer that would take it. They just go "well, powertrain only covers so much and your bumper to bumper is up, so do not bank on your warrenty covering this. We will let you know tomorrow". I always thought that bumper to bumper was non engine stuff

 

[Gibson486]

Ah man....I am being prepared to be taken to the cleaners.....my cars been there for about 5 hours and they have not found anything yet. They said it did do a brief hiccup when it first started, but it has stopped (as I said it would). They said they are going to try to reprogram stuff....I am hoping that this $99 charge for non warrenty checks covers what they are doing

They said it is not the fuel pressure, it is not the fuel pump....

Then, out of the blue, he goes, "by the way...your front brakes pads...they are almost done...$320 if you want us to do it". I said no, ofcourse.

 

[Gibson486]

GRRRRRR.....they found nothing.....they tried to charge me for "additional diagnostic time" and the bill was $300. Fvck no! I told the guy that I signed a paper saying it would only cost $100. HE said fine, but he is not going to work on the car anymore. They were able to reproduce the shaking, but they cannot find the problem, so they cannot use my warrenty. I wonder how much money i will dump until I can find the problem. GRRRRR....

 

[Gibson486]

It's happening again

I brought it to the dealer twice.....cost me $200 b/c they found nothing. When I bring it to the dealer, it never acts up.

Here is a more clear explanation:

scenerio 1: I start car, it starts, it goes for about about 2 seconds, then it hiccups and the engine begins to stall and shake. Sometime it will actually stall, other times it recovers.

Looking at the tach: it revs up to a little over 2K (like it is supposed to), settles for a second then dips back down while the engine hiccups (if it is the engine).

scenrio 2: I start car up, it seems like it barely starts, but the engine fires up. However, about 5 seconds after it turns, teh engine begins to kind of throttle up and down. During this time, you can kind of hear the engine throttle and unthrottle... It goes through oscillation this until I hit the gas. If I do not give it gas, and then I go in reverse, the engine begins to struggle. It shakes a little and you can hear the engine want to stop, but somethign is just barely keeping it going. Once i give it gas, it just revs up (although it shakes a little while I do it).

Looking at the tach: when I start, the tach does not do that initial rush like it usually does (where it jumps to about 2.3K and settles down lower). Instead, it climbs up slowly to about 1.5K-2K. After it turns, it goes to 1.5K-2k, then dips down to 1K or a little below then back to 1.5K-2k. It just keeps oscillating until I give it a little gas, then it goes.

I am hoping I can close teh book on this by this month. I only have about 800 miles left on my warranty

 

[blipblop]

If you car is under warranty, they still charge you money to look at it?

I had to bring my car in a couple of times because of squeaking and rattle issues, but I was never charged anything.

Which dealer do you go to in the MA area?

Maybe check MAF? See if it needs a cleaning or something?

 

[kornphlake]

I'm not nearly as qualified as the mechanic who has seen your car in person, but I'd guess a temperature sensor, idle control valve, possibly the throttle position sensor, EGR valve, some vacuum leak in a strange place, MAP sensor, MAF sensor, crank position sensor, knock sensor or fuel filter. Diagnosing problems like this is incredibly difficult, it takes a good, honest mechanic to keep searching until the real problem is found. Most mechanics will throw an hour at it looking for the obvious then give up since its an intermittent problem, customer service isn't often a mechanic's strong point.

 

[Vette73]

Have you done anything after market to it? Like K&N filter (or one like that)?
Also have you sprayed out the throttle body with soem carb cleaner yet?

 

[Gibson486]

If you car is under warranty, they still charge you money to look at it?

I had to bring my car in a couple of times because of squeaking and rattle issues, but I was never charged anything.

Which dealer do you go to in the MA area?

Maybe check MAF? See if it needs a cleaning or something?

yes....it's all the dealers. Reason they did not charge you anything was because they found something.

 

[Gibson486]

Have you done anything after market to it? Like K&N filter (or one like that)?
Also have you sprayed out the throttle body with soem carb cleaner yet?

nope....how to you spray the throttle body?

 

[Vette73]

That is the throttle body. It has a hose(usually black plastic) running to it from your airbox/filter. Move the butterfly in the valve open and spray soem cleaner in there.
Do this while the car is not running. You can also spray some down the vacuum hose attached to your PCV valve.

 

[Vette73]

here is the mazda 3 motor. the Throttle Body is on the right of the picture.

or to the left of the blue hose here on this mazda