O/T Mazda 3 engine hesitation with A/C on

[bstark]

I recently bought an 06 plate Mazda 3 Sport as a daily driver (having had company cars for years). It's in very tidy condition and mostly drives like a new car but the engine often feels like its missing slightly with the aircon on. Doesn't seem to matter if its a light throttle or hard acceleration.

 

Other symptons are a slightly rough idle that occasionally hunts up to 700-750rpm where it is smooth before dropping again to 600-650rpm where it jiggles the car (aircon on or off, but worse with on).

 

Only other sympton is that the car sometimes starts instantly (like most modern cars) and sometimes takes 3-4 seconds of churning...

 

Any ideas? It's due a service in 2,000 miles but if I can do something before that without incurring a main dealer that would be great.

 

 

Bob Stark

Supersprinter

[elie boone]

My guess is that the engine is a bit small to take it all, airco abs....

[6speedmanual]

Sounds to me as if you have one or two underlying issues which may not be connected with the aircon at all.

 

The missing under load could be an ignition misfire caused by overdue plugs or failing HT leads.

 

The erratic idle and intermittent poor starting could be some type of idle air control valve problem. Either sticking or not deating properly. They can get clogged with carbon and oil residue from closed engine breather system. It may be possible to pull in pieces and clean it and associated passages. Another possibility is a air leak on the inlet side - check all the joints arond the throttle body and pipes and hoses particlarly downstream of the airflow meter.

 

Airflow meter itsself may be wonky but put this low on the list as it plays little or no part in the initial firing of an engine from switched off.

 

HTH

 

Peter

 

BRAWNGP green SUPERLIGHT

FCITW 2009 😬

[bstark]

Thanks Peter - I'll start there

 

Elie - engine is a 2 litre and a friend has a similar one without any problems.

 

Bob Stark

Supersprinter

[bstark]

Not HT leads as it doesn't have any - looks like an individual coil pack for each cylinder.

 

Played with all the connectors anyway, just pulling them then reconnecting and it suddenly drives like a different car. Much more willing, smoother and faster spinning. The missing has virtually gone, as has the rough idle .

 

I'll have another look tomorrow and give the contacts a proper clean - would WD40 be ok for this or am I better off getting a specific electrical connector cleaner?

 

Bob Stark

Supersprinter

[elie boone]

Oeps Bob i tought it was a 1.4ltr.

I would first use a specific cleaner and afterwards WD40 or the like.