4G92 low idle RPM after changing alternator

[jebatdex]

Guys

I just had my alternator replaced. After that, I see my idle rpm is very low, around 500 (before this ok, around 1k). During alternator installation, I see the mechanic remove both terminals of the battery too.

Is it because of the ECU being reset? How to get it to normal idle rpm? Should I go to workshop, spend RM50 for them to properly set my ECU back (using that device which they plugged in it under the dashboard, I duno the name )? Appreciate all inputs. Thanks.

 

[vr2turbo]

Guys

I just had my alternator replaced. After that, I see my idle rpm is very low, around 500 (before this ok, around 1k). During alternator installation, I see the mechanic remove both terminals of the battery too.

Is it because of the ECU being reset? How to get it to normal idle rpm? Should I go to workshop, spend RM50 for them to properly set my ECU back (using that device which they plugged in it under the dashboard, I duno the name )? Appreciate all inputs. Thanks.

As far as I know that is only for diagnostic when engine check lights comes on, and not for tuning.
4G92 I think can tune idling if same as my 4G63. Just turn the screw on throttle body....

 

[john_unai]

i thought OBD can adjust rpm, they just adjust the rpm reading on the the OBD..:questionmark::questionmark::questionmark:

 

[jebatdex]

I think, i will clean the TB and see how. Is rpm still low, will adjust the screw on the TB a bit. Never touches that because before this, idle rpm is good. After remove the battery, ECU reset, than idle rpm drops.

Another question, on the TB, there is 3 vacuum hoses marked P E A. On mine, only P & E is connection, but A got nothing (no hoses connected to it). Is that normal?

 

[vr2turbo]

I think, i will clean the TB and see how. Is rpm still low, will adjust the screw on the TB a bit. Never touches that because before this, idle rpm is good. After remove the battery, ECU reset, than idle rpm drops.

Another question, on the TB, there is 3 vacuum hoses marked P E A. On mine, only P & E is connection, but A got nothing (no hoses connected to it). Is that normal?

I remember mine two are used and the one not used is plugged up with a cap

 

[m a v [3] r i c k]

Try driving your car around for 1 week or so and then see if it gets better. I don't know what is going on at the ECU but based on my personal experience, after a battery disconnection (change), my car will consume more petrol for the first tank and gets better eventually. Engine idling too will be affected.

I would say you should just drive your car as how you used to for a week or so before you waste any unnecessary money.

 

[vr2turbo]

Means let the ecu learn back....

If that is the case, in future for any battery change, link a good battery on when removing old dead battery.....

 

[jebatdex]

Try driving your car around for 1 week or so and then see if it gets better. I don't know what is going on at the ECU but based on my personal experience, after a battery disconnection (change), my car will consume more petrol for the first tank and gets better eventually. Engine idling too will be affected.

I would say you should just drive your car as how you used to for a week or so before you waste any unnecessary money.

OK then... will do. Thanks

 

[Izso]

jebatdex - your issue settled?

 

[jebatdex]

I cleaned the tb (as much as I can becoz I didnt take out the tb, just remove the plastic hose from the air intake), and I adjust the screw on the tb a bit, rotate counter clockwise about 100deg. Now, idle is fine. I dont know whether this will make my fc worse or not, since this is regard as manual setting, not computerized. Hopefully the fc is not much affected. I usually get 11cents/km for highway, and 14cents/km for urban driving, with current RM1.70/l fuel price. Lets see during this raya, will travel from Johor to Perak

 

[vr2turbo]

I cleaned the tb (as much as I can becoz I didnt take out the tb, just remove the plastic hose from the air intake), and I adjust the screw on the tb a bit, rotate counter clockwise about 100deg. Now, idle is fine. I dont know whether this will make my fc worse or not, since this is regard as manual setting, not computerized. Hopefully the fc is not much affected. I usually get 11cents/km for highway, and 14cents/km for urban driving, with current RM1.70/l fuel price. Lets see during this raya, will travel from Johor to Perak

Should not affect your fc unless you tune idling very high and you idle most of the time in traffic....lol

 

[jebatdex]

Should not affect your fc unless you tune idling very high and you idle most of the time in traffic....lol

OK then.. so I shouldn't be worried much. :proud: thanks

 

[Shinjite]

OK then.. so I shouldn't be worried much. :proud: thanks

As long as your idling is all A-OK even with the air-conditioning turned on. Everything will be fine. Before going on a long trip back for Raya, do a regular service check up to make sure everything runs as intended

 

[vr2turbo]

As long as your idling is all A-OK even with the air-conditioning turned on. Everything will be fine. Before going on a long trip back for Raya, do a regular service check up to make sure everything runs as intended

Mine the FICD a bit KO already, so without air con now higher a bit, then air con cut is just nice.....lol