Rpm Goes Down For Head Light And Viper

[LancerL]

Dear Members, I'm experiencing an engine RPM drop on idle speed when I put Head/Tail lights or Viper on my car.

When I switch off one of them it will coming back to normal idle speed again…

What can be the reason???

Your valuable inputs please.

Thanks in advance.

LancerL

[Sylvi]

Dear Members, I'm experiencing an engine RPM drop on idle speed when I put Head/Tail lights or Viper on my car.

When I switch off one of them it will coming back to normal idle speed again…

What can be the reason???

Your valuable inputs please.

Thanks in advance.

Lancer L

'LancerL',

First of all please inform what make of car and engine CC capacity. I will give under the answer for your question.

This is very common in low powered engines.

Due to the engine, get loaded for extra Amperage drawn for your equipment. like A/C other electrical systems come on when the engine is running at low RPM.

You can notice this when the engine is on idling speed, if you on your A/C then engine idle speed will increase

This will not happen when you drive fast. Alternator needed extra power from your engine, to compensate the draw of current for extra load. Still there can be a little RPM loss but it is negligible due to high rpm on the engine.

I hope above explanation will give you answer for your question.

Sylvi Wijesinghe.

[LancerL]

'LancerL',

First of all please inform what make of car and engine CC capacity. I will give under the answer for your question.

This is very common in low powered engines.

Due to the engine, get loaded for extra Amperage drawn for your equipment. like A/C other electrical systems come on when the engine is running at low RPM.

You can notice this when the engine is on idling speed, if you on your A/C then engine idle speed will increase

This will not happen when you drive fast. Alternator needed extra power from your engine, to compensate the draw of current for extra load. Still there can be a little RPM loss but it is negligible due to high rpm on the engine.

I hope above explanation will give you answer for your question.

Sylvi Wijesinghe.

Dear Sylvi,

Thanks for the quick reply. It is Lancer Fiore 1400CC.

What you trying to say that the load giving to the engine by alternator is based on number of electrical equipments running at a given time?

In other words fewer lights and Fans low load and more lights and Fans high load??

Also on which stage I have to keep idle speed with load or without load and what is the recommended idle speed for this?

Regards,

LancerL

[Rumesh88]

I assume yours is a 1985-87 Lancer Fiori with 4G13/14 MCA-JET engine. This engine must be provided with an idle boost arrangement for headlight and the AC. As Sylvi has explained above it is those ancillary loads causing the engine to load at low revs. But this should not happen for it has been taken care of. I do not recall if a dashpot with a vacuum line and a electrically operated valve or a separate solenoid to carb was used (Like in Trad-Sunnys) for this purpose in this model, but I am positive that something must have gone wrong with the idle boost mechanism. What about the idle speed with AC on?. Check for loose vacuum pipes or electrical connector to either carb or vacuum valve that has come off.

[Sylvi]

'LancerL',

I explained to your post about RPM issue.

Rumesh88 had explained the other engine and carburetor working system very clearly.

Therefore you can combine both to gather you have a total explanation for your problem.

I hope the two posts are clear to you..

Sylvi Wijesinghe.

[LancerL]

Sylvi/Ramesh... I got the point, where as I was thinking it was a problem with the alternator..

Anyway Thanks for the prompt support..

[Rumesh88]

Sylvi/Ramesh... I got the point, where as I was thinking it was a problem with the alternator..

Anyway Thanks for the prompt support..

After all it is the alternator that loads the engine in response to any increase in electrical loads. If it loads the engine for increased electrical loads, then it is not a problem but shows that it is working properly. It is those other mechanisms which are supposed to boost the idle that seem to have gone wrong. One other thing to check if the supply to ignition remain within 13 to 14 volts when you put on your electrical loads while the engine is at idle. You may check this at the fuse box.