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Ep 82 Cold Start Vibration


amad
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So this problem still persists after many days at the garage and at the electrician.

My car is a starlet ep 82 , 1994 automatic.clocks 105000 kms.

On cold starts the car vibrates in "D" or "R" with AC on when brakes are engaged.If i let it go, then no vibration.

with out AC or in "N" or "P" it runs without a hustle.

This vibration fades away after 5-1o mins on the run.After that no problem at all.

Engine tune up done at Nishanthas in Borelasgamuwa.He asked me to replace the throttle body as well. I did that also.

Your valuable comments are mostly welcome. Any good mech plus a electrician to solve this matter?Thank you.

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after change the throttle body if it's remain same i feel it's something related to your auto box.

vibration meaning a sudden drop & increase your rpm level?

rpm level does not fluctuate.The whole steering rack and the bonnet tends to vibrate.

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rpm level does not fluctuate.The whole steering rack and the bonnet tends to vibrate.

that means car has a RPM meter, can you see a noticeable(100-150 ) RPM difference between N,P and R,D, please specify the values.

normally when engine operates at very low RPM engine mounts cant tolerate the vibration.

if your car engine operates at correct RPM then there is a "mechanical" reason for vibration (like bad engine mount, gear box mount .....)

if the RPM is too low then your ECU might get wrong inputs due to some issue (sensor failure, malfunctioning something in fuel path or lot of other possibilities).

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that means car has a RPM meter, can you see a noticeable(100-150 ) RPM difference between N,P and R,D, please specify the values.

normally when engine operates at very low RPM engine mounts cant tolerate the vibration.

if your car engine operates at correct RPM then there is a "mechanical" reason for vibration (like bad engine mount, gear box mount .....)

if the RPM is too low then your ECU might get wrong inputs due to some issue (sensor failure, malfunctioning something in fuel path or lot of other possibilities).

car does not have a rpm meter.Mech and myself does not pick any rpm fluctuations.

It is noticed in cold starts if i switch off the AC the vibrations fades away.

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It should be engine/transmission mounts or bearings if no sensor has failed...may be something related to a/c compressor giving a hard time for the engine when engaged..check whether the ac belt is too tight or old....

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It should be engine/transmission mounts or bearings if no sensor has failed...may be something related to a/c compressor giving a hard time for the engine when engaged..check whether the ac belt is too tight or old....

The vibrations fades away after 5-10 mins.

Thank you for the advice. i will look into that matter.

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The vibrations fades away after 5-10 mins.

Thank you for the advice. i will look into that matter.

If it's mounts vibrations should happen all the time...did your mechanic scans your ecu?There is no reason to change the throttle body without a good reason...it's better if you can find a good garage who can test all the sensors...

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car does not have a rpm meter.Mech and myself does not pick any rpm fluctuations.

It is noticed in cold starts if i switch off the AC the vibrations fades away.

AC+ R,D will increase the load to the engine.

sometimes this might nothing do do with "cold start".

cold start means first time you start after few hours. then your alternator also consume additional power from engine (that's why alternator belt make noise when starts vehicle and got disapear after 10-20 seconds).

now AC+ R,D +Alternator will increase the total idle power demand.

but anyhow this demand should be provided at same idle RPM (more power at same RPM).

option is that ECU should detect this and it should increase the throttle position internally (not mechanically) with the help of other components(ex: AC idle up).

but due to some problem, your car ECU doesn't do this or additional power demand is too heavy from the level that ECU can handle .

check your battery also, if it drains out quickly, that is also probable root cause.

try to do what Rumesh said

Edited by MV-5
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If it's mounts vibrations should happen all the time...did your mechanic scans your ecu?There is no reason to change the throttle body without a good reason...it's better if you can find a good garage who can test all the sensors...

es.He did scan the ecu, and there were no errors.

The ECU it self had some problems few days back.And Nishantha did repair the ecu.

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Get the ECU scanned when the engine is cold (at ambient temperature) and ensure that the coolant temperature is correctly read. I hope the idle control is working OK.

Yes the Idle control valve is working fine.

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then i think "AC+ R,D +Alternator" load is too heavy.

if it is AC: then compresses produce too much resistance

Alternator: check the battery first and Alternator .

R,D : that means auto gear box has some kind of issue (which is not probable).

Still engine mount possibility is there . when Alternator extra load has been released (after 5 min) you might not feel the vibration level.

Edited by MV-5
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then i think "AC+ R,D +Alternator" load is too heavy.

if it is AC: then compresses produce too much resistance

Alternator: check the battery first and Alternator .

R,D : that means auto gear box has some kind of issue (which is not probable).

Still engine mount possibility is there . when Alternator extra load has been released (after 5 min) you might not feel the vibration level.

Engine mounts are intact, the mechanic said. Thank you for the comment. I will check these.

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Yes the Idle control valve is working fine.

Scanning will not help at all unless it is done at cold start in your case. Are you sure you did the scanning when the engine is cold and did the scanner indicated correct coolant temperature when it was cold? This is very important because according to OP your engine slows down on light loads when the engine is cold. If the ECU sees a high coolant temperature when it is actually not it cannot enrich the mixture while the engine is cold. Check the reading of intake air temperature reading too to see if it is abnormal. You will not get any error codes for the above two readings unless of course they are totally off the mark.

Edited by Rumesh88
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Scanning will not help at all unless it is done at cold start in your case. Are you sure you did the scanning when the engine is cold and did the scanner indicated correct coolant temperature when it was cold? This is very important because according to OP your engine slows down on light loads when the engine is cold. If the ECU sees a high coolant temperature when it is actually not it cannot enrich the mixture while the engine is cold. Check the reading of intake air temperature reading too to see if it is abnormal. You will not get any error codes for the above two readings unless of course they are totally off the mark.

I will ask the mechanic to check these things. Thank you for the reply.

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I will ask the mechanic to check these things. Thank you for the reply.

Ask the mech to check the coolant temperature and intake air temperature when the engine is cold and before starting the engine. Then start the engine and take another reading. Take down the two sets of reading and post here to compare them. If your mech changed the throttle body without trying out these things he is just a makabass with a scanner in his hand but certainly not a mechanic.

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Ask the mech to check the coolant temperature and intake air temperature when the engine is cold and before starting the engine. Then start the engine and take another reading. Take down the two sets of reading and post here to compare them. If your mech changed the throttle body without trying out these things he is just a makabass with a scanner in his hand but certainly not a mechanic.

any gud mechanic that u know? This guy turns out to be useless .

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Well that's a tough question and in this case ideally you need someone willing to come to your place and do the scan when the engine is cold. Otherwise you will have put your engine in a refrigerator for sometime after driving to a garage :speechless-smiley-004: .

Let's see if other members can come out with a contact of a mechanic willing to come to your place. BTW wh are u located?

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Well that's a tough question and in this case ideally you need someone willing to come to your place and do the scan when the engine is cold. Otherwise you will have put your engine in a refrigerator for sometime after driving to a garage :speechless-smiley-004: .

Let's see if other members can come out with a contact of a mechanic willing to come to your place. BTW wh are u located?

Rather than putting the engine in refrigerator, i prefer park the car overnight at the garage and let mech check in the morning.Im from Nugegoda:)
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help anyone?

Mileage and the idle speed are not related. But due to wear and tear sometimes it could be difficult to run the engine smoothly at the recommended idle speed. Then of course you need to set it slightly higher until you decide to rebuilt it. However at a genuine mileage of 100,000 km a Toyota 4efe type well maintained engine should run smoothly even for another 100,000 kms.

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@ Rumesh an all;

I also feel very slight (I feel it when I stay fully aware) shaking near 1000 rpm when it comes down from above in cold start with AC off. In normal driving can't feel it with or without AC on. Engine mounts and spark plugs recently replaced. Is it alarming something or it just maybe the inherent frequency of the vehicle to oscillate with engine frequency?

Edited by Charith H Jayasinghe
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