Hesitation and stalling at idle, won't start on a few rare occasions.
I have a 2004 Mazda3 with about 305,000 miles on it. I know that the car is due for replacement soon, but given that I donít know whatís going on with my job because of the lockdown, Iíd like to avoid buying one right now.
Over the past few months, I noticed that it was idling rough/hesitating. Shortly after that, it started stalling at idle or when stopping at red lights, but would always start right back up, although sometimes I had to hold down the gas pedal to get it to start. This doesnít happen until the car has been driven a few minutes and the engine is warmed up. Now that the weather is warmer, Iíve noticed the stalling issue at idle is much more constant with the AC running. Iím able to keep the car running if I increase the throttle a little bit. When the engine is under load (while driving), it seems to run fine.
About a month ago, I went to start it and it almost didnít start. It took a few tries and a lot of cranking to get it started. It had never done that before, and hadnít done it since, so I didnít worry about it.
However, last Friday, I went to start it and it wouldnít start. It felt like it wanted to, but just kept cranking. At times, I think I even heard some minor sputtering from the exhaust like a minor backfire, but I canít be sure. I was getting spark, and also noticed fuel spraying from the injector holes when I was checking spark. I donít know if the amount of fuel was correct, but it was getting fuel. I tried spraying brake cleaner into the throttle body and it still wouldnít start. I tried to start it several times that day, and it never started.
The next day, I sprayed some more brake cleaner into the throttle body, and after a few minutes of trying, I was able to get it to start up. Ever since then, it starts up fine every time now without having to spray anything into the throttle.
Iíve already cleaned the throttle body, reset the KAM, and did a relearn. It made no difference. I checked the values for the MAF, MAP, fuel trims and O2 sensors. All looked good to me, but Iím not a professional mechanic by any means, so maybe Iím missing something.
I feel like I can rule out a timing, compression, or clogged exhaust issue because those wouldnít have fixed themselves after a day. I know I had spark when it wasnít starting, so I feel like it has to be an issue with the fuel delivery. Could the throttle itself be going bad? How can I test that? Any suggestions are appreciated.