Mechanics

HESITATION ON ACCELERATION

2004 Mazda 6

Engine Mechanical problem
2004 Mazda 6 6 cyl Automatic 48k miles

Hello,
I have a stock 2004 Mazda 6 sport wagon (48k) that is missing/ hesitating in certain situations. It started about three weeks ago and I noticed it only when cruising in 5th gear and giving it just a little bit of extra gas in order to get up a hill or to merge. It seems to do it in other gears now and usually at or below 2k rpm.
When I put the car in it’s semi-manual mode, I usually like to shift between 3-4k and the problem is not evident there, but when in automatic, the car will be in 5th, travelling 40 or even slower, and at or below 2k rpm- it is then when I apply a moderate amount of gas that the stuttering and often bucking will take place. I’d never noticed before the problem started but that seems a bit low MPH and RPM to stay in 5th? Anyway...
I have tried a few things like running 44k and Seafoam through the tank which did not help. I then did an oil change, air filter change, MAF sensor cleaning ( I was later told a ‘no-no’) that seemed to at least change the “feel” of the problem but it was still there. I partly attributed the change in feel to the fact that I disconnected the battery and thus the computer was relearning...
I then changed my plugs (not wires). While the manifold was off I put an inline PCV valve in to accommodate a faulty one. I looked at the EGR stem and wanted to cut it but stopped short and instead just cleaned it.
I reassembled and took it out on the road and was happy to find my problems were gone. I was feeling pretty proud of myself for about 2-3 hours of driving time when ‘BOOM’! Back with a vengeance was the stuttering and hesitation and now some missing at idle thrown in now and again. I have not scanned for codes and haven’t had any CEL (unless the bulb is out). The dealer wants $100 for a scan and I went to a local garage and they said, “No CEL? No codes. Don’t bother with a scan.”

I’m hoping I might get some ideas about where to look next... Throttle body?

Thank you
Avatar
Cozmotone
December 1, 2008.



Ok first off cleaning the mass air flow meter with mass air flow cleaner is just fine and does a great job when it is dirty so if you didn't use mass air flow cleaner then try it with that. Now as for a scan I would call around to the local parts stores and see which one will do a free scan as many do and just make sure there are no codes. Sense there is not light there shouldn't be but make sure. If you have not codes then get some throttle body cleaner and clean the throttle body just so you know it is clean. Now how about the fuel filter have you replaced it in the last year to two? If you have a digital multi meter check the resistance on your plug wires. If all this checks ok then we will check the TPS ok. Let me know how this goes and we will go from there.

Racefan966
Dec 1, 2008.