Hesitating

[dchiarot]

My MX-3 is doing strange things.<p>It hesitates on acceleration around 2000 RPM.
When ever I bring it in to MAZDA it works fine.<p>What I did notice is that if I remove the oil filler cap during idle the engine almost dies. Is this normal? Any ideas as to what is wrong?

[pelado]

The oil filler cap thing is normal.<p>Any other symptoms?

[dchiarot]

I just recently changed the cap, rotor, plugs and cables and the problem still exists.<p>I just changed the oil and it was worse for about 200km. It is now back to random hesitation.<p>When idling it some times randomly misfires also. Again not all the time.

[eunosads]

check the intake hose from your air box to the throttle body.. they often have a hairline crack that only opens up when it heats up and gets moved around with the engine etc.. <p>usually the problem that you describe is caused by that, or fuel delivery issues.. <p>I had *similar-ish* symptoms when my fuel tank was full of rust flakes and they would sometimes cover up the intake points in the fuel tank.. I don't this is the same though.. <p>@ds

[dchiarot]

The problem does not seem to change depending on how much fuel is in the tank so I think it is not the same problem either.<p>I wish it was warmer around here to be able to do some more work on the car. My next simple try is to change the fuel filter. It is still original with 120000km.<p>I tried on other cars to remove the oil filler cap and the engine idle barely changes. Are you guys out there sure that it is normal for the car to almost die when the Oil Filler Cap is removed. The car even spudders when the dip stick is out.

[eunosads]

if I have my oil filler cap off when I try to start the car it won't start.. and I am not about to take ot off whilst the engine is going.. have you taken the cap of other mx-3s with the same engine as yours? I bet the same thing happens.. <p>whilst you are changing the filter, check the intake hose.. that's the most likely culprit..

[dchiarot]

Thanks for checking that out mor me.<p>I seem to think it is probably the inlet hose too. I will check it out tonight. It is a liitle warmer today.

[eunosads]

let us know how you go mate!

[aaronthehic]

go around to all the connectors and dis- and reconnect them just to make shur it is'nt an bad connection anywhere<p>with the car at idle take a propane torch , turn the gas on (do not light it ) and wave it around the intake in varios spots after the air filter .
if the idle goes up that is where your leak is.<p>use at your own risk! and do it outside

[dchiarot]

I checked out the inlet hose and it is OK.<p>I did more research on the page and figured out how to do diagnostics. I got two codes.
I got code 2 and code 4. My plan is to reset the diagnostics to make sure that these faults come up again. Then I will follow the online manual for trouble shooting. These codes refer to cam shaft position sensors.<p>Does anyone know what NE signal, SGC signal and SGT signal stand for?

[T Biller]

Hey, I have a similar thing with mine but at about 3000 rpm, I thought it was just the torque dip at the VRIS change you can see on the torque curve, but sometimes it doesn't do it. It's most likely to be best when the car his hot and the weather cold, but not always. Some days it has SO much more power there must be at least 20 horse in it from best to worst, especialy in the mid range but noticable all the way through, when at it's best I barely notice a lag at 3000-3500. This might be totaly different, but it did occur to me that a VRIS valve might not be opening consistently. could it be the same thing on yours but a different valve? PS gotta love run on sentences!

[T Biller]

Oh. one more thing, you can find leaks with a bottle of WD-40, much safer than Propane!

[T Biller]

And yet another thing, mine stalls if you take the cap off while running, but I think this is because it has a positive crankcase venting system, so that your whole crankcase become part of the vacuum system, this reduces windage in the crankcase, but if you take the cap off it's like having a HUGE vacuum leak.

[dchiarot]

I think it might be the vacuum chamber that is leaking. What is the best way to test it?<p>Remove both hoses that are accessible and pressurize the chamber to see if it will hold?<p>Is there a way to bypass the chambers and still have the VRIS working? I tried a straight hose bypass connection and that didn't work.