98 Liberty high idle

Tezwah · Post by **Tezwah** » Sun Nov 07, 2010 6:55 pm

Hi all, my liberty wagon was suffering a hesitation/ surge problem. I reset the ECU to see if that would fix the problem but instead the problem still exists and now the car idles all over the place! it has been sitting on around 1500rpm but runs as low as 800rpm. I unplugged the air flow meter to see what impact that would have and the idle did drop to around 700rpm. I also noticed a check engine light come on every now and then so I ran the check engine readout and using the ECU errors codes I have been able to see that the o2 sensor and the AFM must be faulty. At this stage I havent reset the ECU to see if the air flow meter will show up in the diags again but I'm just wondering if the idle variation could be caused by those parts or is there a chance that there mighe be something else causing it that didnt show up in the readout?

AlpineRaven · Post by **AlpineRaven** » Sun Nov 07, 2010 7:12 pm

Happened to me once and it was AFM related, i swapped over to another one and the problem was solved.. I think I had stalling problems which was AFM related. O2 will keep the engine running okay.
Cheers
AP

RSR 555 · Post by **RSR 555** » Sun Nov 07, 2010 10:34 pm

Yeah.. I'm going AP and say it's your AFM.. make sure you're not using an aftermarket airfilter that is over oiled

Tezwah · Post by **Tezwah** » Mon Nov 08, 2010 6:43 am

I will swap out the AFM and see if that helps. Cheers

steptoe · Post by **steptoe** » Mon Nov 08, 2010 8:16 am

idle speed control circuit itself ? These must have them surely, its an air bypass of the throttle plate - stuck or corroded terminals or just stuffed or broken wire bad earth ?

Tezwah · Post by **Tezwah** » Mon Nov 08, 2010 12:19 pm

Mmm well i changed the AFM and the high idle still exists.. The plot thickens..

Tezwah · Post by **Tezwah** » Mon Nov 08, 2010 5:26 pm

Since todays reset the CEL came on for a while. I just connected the black ECU leads together and it flashed error 32.. I dont think that the o2 sensor would cause high idle but would it cause acceleration hesitation?

steptoe · Post by **steptoe** » Mon Nov 08, 2010 5:47 pm

block off the air supply to or from the idle speed control if you can, if it is stuck open it will allow air to bypass the throttle plate causing higher idle.

Tezwah · Post by **Tezwah** » Mon Nov 08, 2010 8:59 pm

I will give that a shot, I am a bit curious as to why resetting the ecu would cause the idle control to stay open. It's quite an annoying problem. Would the ecu readout give better information to someone who a obdII cable and ecu managing software? I'm thinking about just paying someone to look into the ecu management.. Dam modern cars and their sensors!!

steptoe · Post by **steptoe** » Mon Nov 08, 2010 9:13 pm

The EA82T mpfi's use a bypass circuit mounted above the thermostat and control filtered air from the intake boot after the AFM flapper to then enterthe intake manifold underneath the throttle plate. I have bypassed it entirely as in blocked it off - gives no grief as I am now LPG and have no AC to load up against the idle speed. When I did go back to petrol for a ...um...diagnostic period.. it was an absolute bitch to start as it had no old fashioned choke and no fast cold idle speed so my right foot had to help warm it up once it got started. Do the same to your EJ and likely to be same.

If for experiment sake the EJ has hoses you can interfere with or intercept - I hope, you could make up your own fast idle circuit out of rubber hose with a garden irrigation tap as the control. Close it off and you should get a normal idle at op temp. At cold or with AC on just a smidge open to let some air in. Introduced air needs to be tapped off after AFM to avoid messing with mixture control

steptoe · Post by **steptoe** » Mon Nov 08, 2010 9:14 pm

Hey it may be a chance to try subies $17 intake manifold spray foam cleaner see if it gets in ISC bits and cleans up!

Tezwah · Post by **Tezwah** » Tue Nov 09, 2010 5:27 pm

Following the instructions of two mechanics i have now replaced both the AFM and the o2 sensor to try and fix the hesitation issue. Doing this has not changed the cars problems what so ever. I am now left with the hesitation problem and the high idle problem..

RSR 555 · Post by **RSR 555** » Tue Nov 09, 2010 5:57 pm

I'd say 2 things are happening.. 1. you have an air leak somewhere on the manifold and 2. clear your codes.. NOT by disconnecting the battery but doing it by the book.

Tezwah · Post by **Tezwah** » Tue Nov 09, 2010 7:01 pm

I just tried to clear the codes by turning the car off and plugging in the black connectors and the green connectors, then leaving it sit for a minute then running the car above 11km for 1 minute or so and then keeping it above 2000rpm. That yielded a costant '32' code. Since unplugging all the connectors i am now getting a solid CEL..

The high idle only came about when i reset the ECU using the negative terminal method. Since then i have not been able to fix the original hesitation problem and instead managed to gain a high idle to boot! :P

RSR 555 · Post by **RSR 555** » Tue Nov 09, 2010 8:14 pm

Ok..

32 is still the O2 sensor so maybe that new one is not correct for the car

High revs I believe is from an air leak.. check all your hoses to the inlet manifold and air intack pipe (the one from the airflow to throttle body) it can also be from a sticky IAC valve so you can remove the controller and check the shaft turns freely.

Tezwah · Post by **Tezwah** » Tue Nov 09, 2010 8:30 pm

Yeah i dunno its all a bit too weird for me :P Even if the things you have mentioned arent functioning properly i cant understand how an ECU reset would make the problem happen. As i said before it had a nice and low idle albeit lumpy prior to the first ECU reset i performed upon purchasing it. I also belive the LPG kit is doing something stupid as well.. Too many little things going wrong i dont know which ones to address first haha

steptoe · Post by **steptoe** » Tue Nov 09, 2010 8:47 pm

now you tell us LPG ! Or did I miss that? What sort of LPG ? smog with a mixer ring inserted in the intake or vapour injection? Some applications of some cars get a modification at the idle speed control circuit .

Only occur with petrol or without?

Some cars also get an ECM light trigger with gas conversions and either ignore the light, smash the bulb has been done too or disable the power to the ECM light on LPG

Why did it happen at all ? Coincidence is a common thing with cars

Tezwah · Post by **Tezwah** » Wed Nov 10, 2010 6:20 am

I know nothing about gas but the inlet is a 'Gas research' branded gas system. Prior to ECU reset the car did not idle on gas, it would stall. Havent tried Gas since reset because it blew the airbox open with a very loud bang last time i drove it on gas. I guess what I'm trying to do is figure out where i should take it to get fixed.. On gas it blows the air box off, on petrol it has a high idle and still hesitates.. I'm a bit lost

Venom · Post by **Venom** » Wed Nov 10, 2010 6:55 am

Take off the idle air control valve and give it a clean. Its a good idea to get a replacement gasket from Subaru before you start.

steptoe · Post by **steptoe** » Wed Nov 10, 2010 7:30 am

Find GRA in Adelaide and ask them who they recommend to look at their system in your car in your area.. Google their stuff to see if you can identify just what is on your car. Some gas guys understand and swear by GRA - others go the other way so don't be put off by some comments you may hear.