headlight on, idle revs goes down? updated 16/11/2009!

[altong0840]

hi~i got a D15B4 twin carb EG, recently 2 problems on the car, seach nothing on the forum, so open this topic


problem1 : Fast idle not work, the idle up to 1400rpm after warm up in P gear
but drop to 900rpm in D gear, is it normal>???

problem2: idle 900rpm without headlight on is smooth~ but feel stall and drop to 700rpm after turn the headlight on/the fans/any electric stuffs...


it is twin carby engine but running a ecu to control the fuel/air mixture, but no iacv on it~ so is there anyway i can anything to fix the problem??cheez




[SIZE="6"]I just check the voltage by the mech shop and it shows that


P gear(0 rpm), no elec load, battery 12.5V
P gear(1400rpm), only start the car, no other elec load, battery 14.0V
P gear(1200-1300rpm) , start the car and and headlight, no other elec load, battery 13.8V


so the professional told it is not about the alternator, is about the carby setuP~


thanks everyone!

UPDATE :16/11/2009


thanks for everyone in here first, recently i had been replace my ground wires, the one relate to the headlight, low the idle to 1200-1250rpm when P gear

before replace the ground wire: 1300 RPM (P gear) drop about 300rpm when headlight on

after replace the ground wire: 1200rpm (P gear) drop about 100-200 rpm when headlight on, 950 RPM in D gear when healight off, 700-800 RPM in D gear when headlight on

so it seems like getting fix~ but the auto choke still need to be check~

will update ASAP i found the problem

[V73C]

Maybe battery or alternator ?

[riruiz_88]

when u start the engine when its cold, the revs under normal conditions should be roughly 1300RPM. then as the engine starts to get warmer, the revs drop down to 900RPM. this is normal.

your problem is the alternator. as you turn more electronics on, it puts too much load on the alternator. you need to replace or rebuild it. do this simple check.
-use a volt meter and measure the volage at the battery when the car is off. a good battery should indicate above 12V.
-start the engine and let the engine warm up to operating temperature. then rev the engine to 2000RPM and turn on the headlights (need 2 people).
-now check the voltage at the battery, should be roughly 13.9V to 15.1V.

let us know how you go with that.

[OMG.JAI xD]

Go fuel injected.

[altong0840]

but my rev normally 700-800when it is dead cold in D gear 1300-1400 rpm in P gear

the rev will back up to 900rom in D gear 1300-1400 rpm in P gearwhen it is warm...

i will check it asap and let u know~cheez!

[altong0840]

i thought there are something on the engine will detect the elec load and provide enough power~hahaha

so u means it is only 3 part relate to the elec provide

1. battery (start the car)
2. starter
3 alternator

i checked the battery it seems ok i bpught it band new 3 months ago
but don't have the meter things to check the alternator.

so do u think the problem will fix/better if i replace the alternator ?

thank you so much man!

[altong0840]

Go fuel injected.

i love to get a D15B7 vtec
but 1.5 EFI is not in australia.....

[ep3_ctr]

yeh sounds like the alternator, to double check inspect your battery's voltage and terminal connections while the engine is idling. use a multimetre and look for a reading between 13.8 and 15 volts. If the reading dips to 12.8 to 13 volts your alternator may be gone

[riruiz_88]

haha dude thats what i just said

[altong0840]

but my rev normally 700-800when it is dead cold in D gear 1300-1400 rpm in P gear

the rev will back up to 900rom in D gear 1300-1400 rpm in P gearwhen it is warm...

i will check it asap and let u know~cheez!

[OMG.JAI xD]

i love to get a D15B7 vtec
but 1.5 EFI is not in australia.....

Get a d15b7 with a d16y vtec head.
Or better. get a d16y1/8.


Most carby systems are mechanical. All about mixture adjustments.
As long as your engine doesnt stall. I see no problem.

[altong0840]

Get a d15b7 with a d16y vtec head.
Or better. get a d16y1/8.


Most carby systems are mechanical. All about mixture adjustments.
As long as your engine doesnt stall. I see no problem.


isn't that the D15B4 use the ECU to control the mixture?

[altong0840]

I just check the voltage by the mech shop and it shows that


P gear(0 rpm), no elec load, battery 12.5V
P gear(1400rpm), only start the car, no other elec load, battery 14.0V
P gear(1200-1300rpm) , start the car and and headlight, no other elec load, battery 13.8V


so is it mean the alternator worn? cheez

[MRGRIM]

those voltages at your ALT are spot on ...
batt with car off cvaan drop as low as 11v this is normal
at charge after start it can be between 13.2 and 14.8
these are the voltages that your after for a healthy ALT.
BUT THIS DOES IN NO WAY MEAN ITS CHARGING WITH GOOD CURRENT.
VOLTAGE IS ONLY HALF THE STORY AN ALT MUST PUT OUT GOOD CURRENT

if your not having starting probs and if when the car is at idle and you put on the head lights and they dont get much brighter when u up the revs this is good as your ALT is doing its job..

regarding your idle ..
from what you said its an AUTO so in Park your rev's will be higher than in drive as there is no load on the motor at "idle"
1400 in Park is correct 900 +/-50 rpm in Drive is also correct
if the idle is droppng as low as 700 this would be the motor is cold also it should have an auto choke thermaticaly controlled these some times get blocked or corroded ..easy fix just clean or replace
another main reason for a drop can be timing, fuel mixture,can also be caused by a vacum leak from inlet to dizzy as there is no vacum to advance the dizzy due to load and being cold the rev's will drop.

a good tune and diagnostic look at it will find all these problem's and can be fixed easly...without any major exspence

Cheers
Grim

[~Sp33~]

Corroded ground wires can cause excessive load on the alternator too.

[altong0840]

Corroded ground wires can cause excessive load on the alternator too.


bingo! it help the idle not drop so much as before!!! cheez

but still the long way to go~thx~champ!

[altong0840]

those voltages at your ALT are spot on ...
batt with car off cvaan drop as low as 11v this is normal
at charge after start it can be between 13.2 and 14.8
these are the voltages that your after for a healthy ALT.
BUT THIS DOES IN NO WAY MEAN ITS CHARGING WITH GOOD CURRENT.
VOLTAGE IS ONLY HALF THE STORY AN ALT MUST PUT OUT GOOD CURRENT

if your not having starting probs and if when the car is at idle and you put on the head lights and they dont get much brighter when u up the revs this is good as your ALT is doing its job..

regarding your idle ..
from what you said its an AUTO so in Park your rev's will be higher than in drive as there is no load on the motor at "idle"
1400 in Park is correct 900 +/-50 rpm in Drive is also correct
if the idle is droppng as low as 700 this would be the motor is cold also it should have an auto choke thermaticaly controlled these some times get blocked or corroded ..easy fix just clean or replace
another main reason for a drop can be timing, fuel mixture,can also be caused by a vacum leak from inlet to dizzy as there is no vacum to advance the dizzy due to load and being cold the rev's will drop.

a good tune and diagnostic look at it will find all these problem's and can be fixed easly...without any major exspence

Cheers
Grim

thz for the information!!!

follow your method, i test the ALT and it is fine~

but i read the manual that mention the idle RPM should only be about 1100rpm, when put in D gear it should be about 900 rpm.

anyway, how can i check is my auto choke working or not?

where is the auto choke located??

cheez!

[~Sp33~]

bingo! it help the idle not drop so much as before!!! cheez

but still the long way to go~thx~champ!

No probs, make sure you check all of them, not just the negative terminal on the battery. :)

[MRGRIM]

thz for the information!!!

follow your method, i test the ALT and it is fine~

but i read the manual that mention the idle RPM should only be about 1100rpm, when put in D gear it should be about 900 rpm.

anyway, how can i check is my auto choke working or not?

where is the auto choke located??

cheez!

i would like to help you..
i need a little more info re the car then ill look into it further for you
also when was it last serviced ?

[altong0840]

i would like to help you..
i need a little more info re the car then ill look into it further for you
also when was it last serviced ?


my car is 93 civic EG4 Twin carb D15B4 hatchback auto
done all the fuild and belts 3-4 months ago

[MRGRIM]

my car is 93 civic EG4 Twin carb D15B4 hatchback auto
done all the fuild and belts 3-4 months ago

?? was this done buy you or mech
did u replace the dizzy cap and rotor button?
reset timming ??
adjust valve clearance ??

[altong0840]

?? was this done buy you or mech
did u replace the dizzy cap and rotor button?
reset timming ??
adjust valve clearance ??

i actually replaced the long motor+Gearbox by porfessional~ so it had done water pump, belts, fuilds, tune up timing, air/fuel mixture~ but the carby set still the old one

it just recently replace the spark plug and Spark plug lead by myself, also the gound wire kit

[sultanaz]

hey ive got a problem with my new installed mongoose alarm, i got HIDS light with the car with i bought it, its a 1999 prelude vtir. I was driving 2 days ago with my HID lights on and forsome reason i dont think they are wired correctly, it looks bodgey but they work fine, i wna fix them tho. My problem is i was driving and the immobliser kicked in while i was driving me forcing me to stop and unlock the car and start it again. this only happened once, ive had the alarm for 1 week so far. i took it back and they had a look saying it was a voltage drop, I then discovered every time i turn my HID lights on my alarm box has a TICK noise ? i can hear my engine sound drop a little too, could my HIDS not being wired up properly have set a voltage drop which is my cause ? ive taken it to a electrician and they say if the battery and the alternator is reading fine then it could be the HIDS... Im just thinking could this be my cause ? possibly wired wrong ?

please help, in desperate need. its so frustrating.

thanks.

[~Sp33~]

Sounds like it needs a better ground.

[sultanaz]

thanks dude ay i really appreciate it ! im gna be putting better flow of power tommorow, 1 Gauge wiring from the alternator to the battery too for the +, and lyk heaps more Grounding, the HIDs look lyk there grounding is shit as . ill be working on it tommorow..

thanks heaps !

[cheapdouchebag]

i love to get a D15B7 vtec
but 1.5 EFI is not in australia.....

i have a d15b vtec efi. meh lol
in all respects, d16 vtec is almost identical in performance, on paper it wouldnt say that but.

could probably grab a d16 for cheap as chips