Have a Car Question? Ask a Mechanic Online.
Hi i have a 2004 mk triton v6 3.0lt.It idles to high [1400rpm]for around 15seconds then drop down to 900rpm once warmed up.It does this every time i stop.I have replaced the plugs,fuel pump,fuel filter.Had the injectors done.ecu test,fuel pressure test,fuel treatment,oil change,leads and coil packed tested.Also replaced the idle speed motor.My mechanic says there is no more they can do.Can you please help.Thanks Mark
I HAVE ALSO REMOVED THE THROTTLE BODY AND CLEANED OUT.THERE SEAMS TO BE VERY LITTLE VACUMN ON THE THREE OUTLETS ON TOP OF THE THROTTLE BODY.
YES THE CAR IS IN AUSTRALIA.WE LIVE AROUND SEE LEVEL.IT DOES THIS WEATHER IT IS A HOT OR COLD START/RUNNING.SOMETIMES IT ALSO MISSES ON ACCELERATION.THIS HAPPENS EVERY TIME I PULL THE CAR TO A STOP.
I HAVE EVEB TRIED TO LOWER THE REVS TO AROUND 400RPM BY LEAVING THE CLUTCH IN WHEN I STOP.BUT IT PULLS THE REVS UP BACK UP TO 1300RPM WHEN THE CLUTCH IS DEPRESSED.THEN GOES BACK TO IDLE AROUND 900RPM 15 SECONDS LATER.HOPE THIS HELPS
Sorry for delay. You see, I do some background checks on cars sold outside USA. (I live in US and all my books, data and computer data is more geared to US vehicles we sell or import here) You'd be surprised at the equipment and emissions differences from Country to Country!
At any rate, there's no system or equipment I came across that concerns me. I have some ideas that will help you quite a bit.
First off, your engine shows poor performance. That in itself gives me some immediate direction because of the other symptom. You have a hanging idle as it's called, for one. And - you have what appears to be a misfire as well.
Let's do some quick checks >>
Obvious things that can cause elevated idle and poor performance:
1) A vacuum leak at air intake. This can be anything from an intake manifold gasket cracked at an intake runner, to a vacuum line going to intake, or a leaky power brake booster. Does this problem ONLY happen when your foot is on BRAKE pedal? Try it out. When it acts up release brake. Any change? Try this too: Apply brake in neutral, wait 5 seconds or so and release.. Any change at all?
2) As stated above, a vacuum leak, AKA "unmetered air" can cause high idle, stalling and/or poor performance and misfires. Can cause one, some or all of these symptoms. Can cause other symptoms (not listed here) as well.
3) Similar to above scenario, when the large, rubber/plastic air intake TUBE mounted to the Throttle body - and then connected to MAF (mass air flow) sensor has a CRACK in it - you have vacuum leak type symptoms most often. This is unmetered air. Check this tube and clamps for it as well, at the MAF.
Who tested your fuel pressure as stated in your initial Question? Did they test fuel volume as well? Have you access to a scanner? You may Accept this Answer if you choose. If you do so now, I am definitely here to see this thru. So feel free to post back as needed.
Fuel pressure and volume should be tested. have you scan tool access?
I would have to book it in somewhere to get this done.I have had a scan done last week,no codes came up
Please let me know. I have other checks that would follow. But my detailed Answer above should really do it for you. Just foolow thru it. When you have a hard to solve issue like you do here, it is proper, and pays off, to start with basic tests and work up from there - so long as there are no trouble codes that give us a circuit to inspect first. OK?
No worry... Stay in touch over this!