Low/Rough idle 94 4cy. DOHC

April · Post by **April** » September 27th, 2007, 2:26 am

Hey guys!
I'm having a issue wih my cars idle. I just did spark plugs and a new air filter in hopes to et the idle up to normal level.
But my car idles too low, it almost stalls out and has actually done so on 3 occasions. I'm not sure what it could be but Ive been told 800 different things. And I thought I could get someones opinion who actually owns an mx3. If anyone could help me out with any info, I'd greatly appreciate it.
Thanks!

April

shameem · Post by **shameem** » September 27th, 2007, 4:35 am

First - try reseting your ECU (unhook battery negative and push brake pedal for 20 seconds).

Second try reseting your idle - jump pins TEN -> GND in the diagnostic box and turn the idle screw while the engine is running.

If the idle drops everytime you brake (especially with the headlights on) - then either the alternator is getting too weak to support the electrical load (the brake lights take up a lot of juice) or the ground points need to be cleaned (and possibly more ground wires need to be added).

Vaccum leaks are also an issue causing the idle problems and hesitation/stumbles during acceleration.

You might also want to get new plug wires, cap & rotor depending on when they were replaced last.....

Tunes67 · Post by **Tunes67** » September 27th, 2007, 10:09 am

Also do a compression test on the engine. I have a 94 DOHC and when I first bought it, it had a low & rough idle as well. I was able to adjust it as Shameem mentions above.. but it was only hiding the true issue which was a burnt valve. A compression test will reveal any serious valve sealing issues.

Tunes67

ModMX3 - (Carmaster2005) · September 27th, 2007, 4:37 pm

The majority of posts like yours turns out to be the alternator, or bad/weak grounds. I had the same problem after adding new ground wires cleaning old ones and installing a higher output alt. 90 amp, all idle and lighting issues where solved. This seems to be a desigin flaw with the mx. other things to look for are leaks between MAF sensor and throttle body or all along the intake hose. vacuume leaks in general. Also recommend the things allready mentioned. Good Luck.

April · Post by **April** » September 27th, 2007, 8:23 pm

ok I will try all the things you all mentioned. hope fully something works! ll
thanks alot guys!

bawolvesfan · Post by **bawolvesfan** » October 9th, 2007, 3:35 pm

i had the same problem and after replacing almost the entire fuel system i found it was a fuel pressure regulator, theyre bout a hundred bucks new, or i just got one for 4 at a pull it yourself junkyard

Tropical Emerald 1993 · October 9th, 2007, 4:12 pm

also check for holes in exhaust.