Hi guys, almost a month now, my sister bought a used car in my country since used cars a wayyyy cheaper than new, anywho, the car was working fine but when I carried it to mechanic we changed spark plugs and usual stuff when buying a used car, till now there has been a slight misfire but recently has gotten worse, the thing is when the ac is off it doesn’t really misfire but when the ac comes on it misfires a lot, Note: this misfire or what ever it is only happens at idle. When it misfire the idle drops by 100 rpm then goes back normal.
2007 Suzuki SX4
around 221000 Kilometers on it
upon replacing spark plugs, it was found that the number 4 coil was broken and it was replaced when the new spark plugs were installed.
Did you scan for codes?
1. Check engine light didn’t came on and 2. I don’t have a code scanner
Clean the MAF sensor and throttle body to start off.
I cleaned the throttle body but not the MAF
Tomorrow, I’ll clean the MAF sensor as it is night but are there any other causes to this issue?
Check the Throttle Position Sensor, fuel injectors and engine mountings.
Fuel injectors good, mechanic did a service cleaning on them. Honestly not sure where the TPS is if it has one and I think the engine mounts are good and it was just the #4 coil that was replaced only since the lower part and the unit was separated.
I think it maybe something with the ignition system because the car was fine when it was bought but when we changed spark plugs the issue started but it kind of slight like misfire once or twice and now it misfires alot especially when the ac is turned on. Like way worse when the ac is on.
Have your mechanic scan the vehicle for any type of code. Even if the check engine light isn't on, your mechanic can still see all data which can tell you if your car is having a problem or not.
Alright, Thank you for all your help, have a great rest of your day/night.
I don’t have a code scanner
you can get it scanned for free at Autzone and other suppliers
upon replacing spark plugs, it was found that the number 4 coil was broken and it was replaced when the new spark plugs were installed.
it's a good idea to replace the plug wires at the same time. (unless it's a coil-on-plug system)
An engine needs fuel to work properly so measure the fuel pressure as well. See our FAQ there's oodles of misfire troubleshooting info.
Make sure you use a designated MAF sensor cleaner and a designated throttle body cleaner. They are two different things.
are they though? I'm not convinced
@mmj - My experience has been that the throttle body cleaner (CRC brand) is very similar to carb cleaner in that it is a combination of mostly solvent and some oil to clean and lubricate the throttle body where the MAF sensor cleaner has no lubricant at all to contaminate the MAF and attract crud making it malfunction. It's like those guys who post every once in a while who can't figure out why their car runs like crap after installing a K&N cold air kit with an oiled filter that renders their MAF sensor useless.
oh did you see a residue from TB cleaner?
You'd think they wouldn't add any lube if they knew people were going to be spraying it all over their intake and sensors.
It's just based on my personal( anecdotal) experience and the fact that CRC and others make different cleaners for MAF and throttle body applications. I think I'll get out my magnifying glass and actually read the labels. Stay tuned!
that's ok I'll just grab it off the safety data sheet
the heaviest ingredients there are the petroleum spirits ,and those will evaporate when the engine gets hot.
Everything else flashes off in seconds at room temp.
CAS 64742-89-8 - Boiling point 90-100C
CAS 64742-49-0 - Boiling point <40C
@mmj - The CRC Throttle Body & Air-Intake Cleaner, #05678 says -
#4 -" Do not spray through air filter or across mass air flow (MAF) sensor."
probably so you don't stir up the grime and deposit it onto the sensors. But better safe than shelling out hundreds for a new one I guess.
Good point.