Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Tue 13 Mar 2018 09:07
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - dangthe

Hello, I drive a 2006 Mitsubishi Colt CZ3 and lately noticed that the car eats up significantly more gas than before. Cant give you exact numbers but it's really noticeable. I also noticed that when idling the car sits at about 900 rpm while previously it was at 750. So I want to start diagnostics on what could be wrong, but dont know where to start. Any suggestions?

Reply | Report as offensive | Link
Tue 13 Mar 2018 09:14
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - dangthe

Another curious thing I forgot to mention is that when I go downhill in idle it now shows how much gas it uses but previously it always said 0. Dont know if this means anything, but I noticed it

Reply | Report as offensive | Link
Thu 15 Mar 2018 17:27
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - Manatee

Another curious thing I forgot to mention is that when I go downhill in idle it now shows how much gas it uses but previously it always said 0. Dont know if this means anything, but I noticed it

So it's not shutting the fuel off on the overrun. Sticking throttle cable or problem with the throttle position sensor? I don't know these cars, so could be a daft suggestion.

Reply | Report as offensive | Link
Tue 13 Mar 2018 09:43
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - hardway

Scan it,

concentrate on the lambda figures and the sort term and long term fuel trims.

Reply | Report as offensive | Link
Tue 13 Mar 2018 10:38
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - dangthe

What do you mean exactly by 'scan it' ? Attach it to a computer?

Reply | Report as offensive | Link
Tue 13 Mar 2018 11:06
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - dieselnut

Does it have an engine temperature guage & if so is it reading normal.

Does the heater work well within a few miles of starting from cold.

Reply | Report as offensive | Link
Tue 13 Mar 2018 11:55
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - elekie&a/c doctor
That was my first thought. Check engine coolant level.
Reply | Report as offensive | Link
Tue 13 Mar 2018 12:22
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - dangthe

Just checked, the coolant level is at max. Also, air warms normally after several minutes.

Reply | Report as offensive | Link
Tue 13 Mar 2018 12:58
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - elekie&a/c doctor
Could be a fault with the engine coolant temp sensor,sending incorrect info to the engine control system. A diagnostic test should be able to read the engine temperature to see if it is accurate.
Reply | Report as offensive | Link
Tue 13 Mar 2018 14:07
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - hardway

Well yes,

or a dedicated scanner.

Reply | Report as offensive | Link
Tue 13 Mar 2018 14:29
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - dangthe

I just called the dealership and scheduled a diagnostic on Monday, they said according to the car age and mileage, it could be a spark plug issue. So we will see how it goes.

I have another question while we are at it, up until now I have been using Mitsubishi Diamond Protection engine oil, and wanted to switch to something else just to see if there is any difference. My car has a rough idle since forever, someone says that it's because of the 3 cylinder engine, but I just want to see what else is out there. Was thinking about Castrol GTX Magnatec, some people claim that they feel a difference in engine operation with that oil. Has anyone tested a different oil apart from the original one and noticed better results?

Edited by dangthe on 13/03/2018 at 14:36

Reply | Report as offensive | Link
Tue 13 Mar 2018 17:23
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - skidpan

I have another question while we are at it, up until now I have been using Mitsubishi Diamond Protection engine oil, and wanted to switch to something else just to see if there is any difference. My car has a rough idle since forever, someone says that it's because of the 3 cylinder engine, but I just want to see what else is out there. Was thinking about Castrol GTX Magnatec, some people claim that they feel a difference in engine operation with that oil. Has anyone tested a different oil apart from the original one and noticed better results?

Use any oil providing it neets the Mitsubishi specs, they will be in the handbook/service book.

All 3 cylinder engines have a slightly uneven idle.

Castrol will not make a car better.

Reply | Report as offensive | Link
Thu 15 Mar 2018 17:13
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - TheUrbis

If this is a CZ3 as the OP mentioned then it won't be 3 cylinder.

It'll be a 1.5 4 cylinder, turbo or NA / 1.5 diesel

Reply | Report as offensive | Link
Thu 15 Mar 2018 18:10
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - skidpan

If this is a CZ3 as the OP mentioned then it won't be 3 cylinder.

It'll be a 1.5 4 cylinder, turbo or NA / 1.5 diesel

The OP said its a 3 cylinder engine and not us

"My car has a rough idle since forever, someone says that it's because of the 3 cylinder engine,"

Reply | Report as offensive | Link
Fri 16 Mar 2018 12:36
Mitsubishi Colt 3-door - Low mpg all the sudden and higher idle - Gibbo_Wirral

When was it last serviced?

Reply | Report as offensive | Link