Idle Problem

Plucka · 05-11-2009, 04:38 AM

Hi All,
I'm having an issue with my 2001 Jimny (M13A EFI Engine) not being able to maintain a stable idle when coming to a stop.

I recently had the issue of the EFI going crazy when trying to travel at speeds over 80, which i have solved by replacing the crank and cam sensor, however it has also alway had this idle problem since i got it.

It only seems to happen when i'm coming to a stop or if i'm returning to a normal idle after the engine has had some revs which makes me think its occuring when the engine goes from its fast idle to the slow idle. Also if the aircon is on or not it will also still occur.

The idle will sit at about 1K rpm for a few seconds after coming to a stop, and then will drop back to 700 rpm (or 900 if the aircon is on), but then after a few seconds it will drop right down like it is about to stall (about 200 rpm) and then will come back up (it will also jump back up if i pump the gas).

My initial thoughts were that i might have a vacumn leak somewhere, however i've been unable to find one, although i have limited knowledge on EFI systems and to me it is hard to hear the hiss of a vacumn leak over the sound of the engine revs.

I'm just about to give up and take it to a mechanic, however any info that anyone may have on this problem, or if you've had a similar issue would be appreciated.

cheers,
Luke

hotrodsami · 05-12-2009, 01:07 PM

you can buy a vacuum tester that will help with finding a possable leak.

ranger88den · 05-13-2009, 07:23 AM

This is Jerry's website from the Track/Kick forum. He has a lot of troubleshooting info., maybe you can find something useful there. Good luck

Jerrys main sidekick page

squid · 05-14-2009, 05:59 AM

we don't have jiminy in the united states but maybe this will help. you can use carb spray to find vacuum leaks. Spray around gaskets and if leaking you will get a monentary idle fluctuation. secondly did you try cleaning the throttle body and idle control valve?

Plucka · 05-18-2009, 05:01 AM

I went out and bought some throttle body cleaner today to clean up the throttle body and IAC, but i read on the can that it shouldn't be used on plastics or sensors?

Does anyone know if it is safe to spray this to clean the IAC or do i need to pull it out and clean by hand?

squid · 05-19-2009, 03:56 PM

it is safe to clean the iac with the spray throttle body cleaner. I use an old tooth brush and spray to clean the throttle plate and bore. I insert the the spray can tube into the iac port and spray until the engine stalls, I let soak for a moment than restart and repeat process a couple of times.

Plucka · 05-25-2009, 05:13 AM

So today i've cleaned the throttle body and IAC with the throttle body cleaner ... i pulled the whole thing out and cleaned it throughly.

5 mins down the road the funny idle dropping down to 200 rpm occurs at my first set of lights and then continues for the rest of the stops during the test drive.

I couldn't have cleaned these parts any better, it was super clean and i noticed my throttle response was much better.

The airfilter is new and everything else around this area looked clean ... is there anything else that could be causing this issue?

I've also noticed in the last week my fuel use has risen and now i only get about 300 km per tank instead of around 450 which i was used to. Though this could be due to the excessive reving i've now had to give the engine at every set of lights to prevent the revs from dropping down so low when i stop.

Cheers,
Luke

ranger88den · 05-26-2009, 06:27 AM

EGR system maintenance? O2 sensor testing? TPS testing, adjustment? Coolant sensor testing?

ripoil · 06-02-2009, 02:02 AM

I just solved this same problem with my '94 Sammy with TBI. Try disconnecting the vacuum line to the fuel pressure regulator and see if gas comes out of the fitting on the regulator. On my Sammy it was on the front of the throttle body and had a fuel line connected to one end and a vacuum line on the other with 2 screws attaching it to the throttle body. If gas come out then the diapram is ruptured and it needs to be replaced. I got one for $25 from a salvage yard and it completely solved the problem. I found the solution by pinching off the vacuum line first and noticing the idle smooth out.

Hope that helps. Chasing these problems can be frustrating.