Hyundai

Hyundai Repair Questions? Ask a Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

Hyundai

I have a 05 Chevy Aveo. I 't ask Chevrolet people because it

Customer Question
I have a 05 Chevy...
I have a 05 Chevy Aveo. I don't ask Chevrolet people because it is a korean car. I have this missing like shaking at idle speed and I have changed more than 10 new or used sensors and I tested compression of each cylinder which they all around 125psi. The shaking is caused by timing constantly jumping between -2 to 5 . I tried disconnect different sensors and only got a stable -5 after I disconnect idle control valve.
Submitted: 1 year ago.Category: Hyundai
Show More
Show Less
Ask Your Own Hyundai Question
Answered in 2 hours by:
2/19/2016
Hyundai Mechanic: 350matt, Engineer replied 1 year ago
350matt
350matt, Engineer
Category: Hyundai
Satisfied Customers: 22,168
Experience: Mechanical Engineer BEng Hons22 years experience in car engine industry, 10 years in formula 1
Verified

Hello

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattenedpiece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth cleaning out the idle speed control motor / valve as these get clogged up with carbon and some brake cleaner washed through helps free things off.

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

Air leaks are very temperature dependent as gaps can open or close up as things expand with heat, so the weather and engine temperature can effect them.

This leads them to be quite intermittent in the case of mild leaks

its also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue

On no account touch the sensor wires with anything physical as they are extremely fragile

Ask Your Own Hyundai Question
Customer reply replied 1 year ago
Hi. I am a mechanic myself and this car is really tough for me . It's not lean condition. It's rich. I checked fuel pressure it is normal at 65psi.I added propane gas to vavuum port there was no change on idle speed. OBD live data show long term -17 so engine is rich. also I can smell the rich exhaust. This engine doesn't have an air flow meter. it's only have a MAP sensor. The idle is so bad and I can't sell it. it drives fine . no lost power anything. I changed used ECM and throttle body with idle control and TPS. I changed new crank sensor, cam sensor,air tem sensor, o2 sensor. new coil pack , new wires and spark plugs. The shaking was caused by unstable timing which will stable after idle speed reach 1200rpm or above . Do you know what sensor input can makes computer constantly adjust timing at idle speed? I changed a used ECM and there's no change in problem so the ECM is not at fault.
Customer reply replied 1 year ago
I checked compression and all 4 cylinder at 120 psi. vacuum gauge reading is low but not fluctuate. There is no OBD code except P0300. There is no missing code such as p0301, p0302 ,3030,304.I also took fuel rail out and tested by crank engine. there is no leaks and at 4 injectors have same spree patterns.
Hyundai Mechanic: 350matt, Engineer replied 1 year ago

Hello

the idle speed ignition timing will move around quite a bit as the ECU uses ignition timing to control the idle as well as moving the throttle variation of about 8-10 ° is normal

I'd check over the MAP sensor connection and wiring and also if its connected to the inlet manifold with some rubber hose then replace this too

Ask Your Own Hyundai Question
Customer reply replied 1 year ago
The wires ok. if the wires is bad then there would be a code. also if the MAP sensor has problem it will have bad acceleration which this car doesn't have.
Hyundai Mechanic: 350matt, Engineer replied 1 year ago

Hello

is this the version with the MAP sensor on the bulkhead and joined to the manifold by a rubber tube ?

if it is then check the condition of the tube for leaks, cracks and blockages as these can all create this issue

if not and its the one where the sensor is directly on the manifold then that won't be the issue

Ask Your Own Hyundai Question
Customer reply replied 1 year ago
I just checked the vacuum hose for the MAP sensor by blowing it use my mouth and NO restriction. No cracks in good condition. Since the car don't have air flow meter so the MAP is very important. The engine will stall immediately if I disconnect either the hose or wires. This proves nothing wrong with MAP sensor.
Hyundai Mechanic: 350matt, Engineer replied 1 year ago

Hello

OK in that case have you tried replacing / checking over the coolant temp sensor?

as this has a strong effect on the fuel mixture strength

if you were to disconnect it the ECU should revert to using a default value of a warm engine so I'd try that next

Ask Your Own Hyundai Question
Customer reply replied 1 year ago
The live data OBD scanner tells the engine coolant tempreture. I observed coolant tempreture before I started the engine and it match ambient tempreture after an overnight cooling down. I will give it a try anyway.
Hyundai Mechanic: 350matt, Engineer replied 1 year ago

understood

good luck

Ask Your Own Hyundai Question
Customer reply replied 1 year ago
Disconnected the coolant sensor and it didn't make any different . Also when coolant tem sensor disconnected live data show -40F so is not warm engine.
It is random miss fire at idle only. ECM never set up any cylinder miss code. It drives fine.engine mechanical should be ok otherwise it won't accelerate.
I re-checked vacuum leaks with a stethoscope and no leaks. very small intake manifold .
I switched new and old o2 sensor and they make no different. the old o2 is only has bad heater
Hyundai Mechanic: 350matt, Engineer replied 1 year ago

Hello

Ok is this still on a manual / cable throttle?

if so they I'd suggest to clean out the throttle body with some brake cleaner and a lint free rag and also disconnect the ISCV and set the closed position of the throttle so you can get 650-700rpm

the reason for doing this is to try and incrase the flwo of ait into the inlet manifold to try and improve combustion.

Ask Your Own Hyundai Question
Customer reply replied 1 year ago
None of your suggestion worked. You said at beginning erratic timing is normal and I think you are wrong. The erratic timing causing the missfire. I don't now why and that is why I am spending money here to find the answer but you have not give me a answer yet. Can you transfer me to other expert because I am going to rate you 1 star since your answers have not helped solve the problem.
Hyundai Mechanic: 350matt, Engineer replied 1 year ago

understood

good luck

Ask Your Own Hyundai Question
Ask 350matt Your Own Question
350matt
350matt
350matt, Engineer
Category: Hyundai
Satisfied Customers: 22,168
22,168 Satisfied Customers
Experience: Mechanical Engineer BEng Hons22 years experience in car engine industry, 10 years in formula 1

350matt is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry.

Stephanie PElm City, NC

used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future.

David L.Richmond, TX

9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much.

PhilMarysville, CA

Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible.

CharlesWalnut Creek, CA

As a single woman, I really appreciate an excellent and affordable opinion.
Thank you Geordie, I will not hesitate to contact justanswer in the future!

SueCharleston, WV

Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff.

JimCastleberry, FL

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

< Previous | Next >

Meet the Experts:

George H.

George H.

Hyundai Technician

2,104 satisfied customers

Hyundai Gold certified, ASE Master tech 15+ years

Ron Z.

Ron Z.

- Hyundai Tech -

634 satisfied customers

18+yrs experience. State Inspector and Hyundai Diagnostics

Chris (aka- Moose)

Chris (aka- Moose)

Technician

570 satisfied customers

16 years of experience

K. Wiggins

K. Wiggins

ASE Certified Technician

342 satisfied customers

ASE Certified Technician, Associates Degree in Automotive Technology, 15+ years in the trade

Mike Kelly

Mike Kelly

Hyundai Mechanic

259 satisfied customers

17 years experience as an auto mechanic, foreign and domestic. 5 years running my own repair business.

Daniel

Daniel

Hyundai Technician

247 satisfied customers

Hyundai technician

Tim Mohr

Tim Mohr

ASE MASTER

237 satisfied customers

30 YEARS EXPERIENCE, FORIEGN AND DOMESTIC, GAS AND DIESEL

< Previous | Next >

Related Hyundai Questions
Hyndai santa fe battery light, brake light, and tsc light
Hyndai santa fe battery light, brake light, and tsc light are all on. While driving, it feels like the car is gearing down, like brakes are locking up. Now it will not start without hooking up battery… read more
Gunvir Singh
Gunvir Singh
1,712 satisfied customers
My 2002 Hyundai accent will start with the key when the
my 2002 Hyundai accent will start with the key when the engine is cool but not when it is warmed up . But I can roll and jump start it . I have changed the fuel pump and it didn't help. And today it q… read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
How much does it cost to ask a question about my 2000
how much does it cost to ask a question about my 2000 accent? … read more
nelson freitas
nelson freitas
Automotive Technician
Vocational, Technical or Trade School
83 satisfied customers
I have 2004 Hyundai Sonata and when you take off it shifts
Second opinion] I have 2004 Hyundai Sonata and when you take off it shifts up fine and then as soon as you get to 20-30 miles an hour it automatically downshifts to low very hard. Engine light is not … read more
Chris (aka- Moose)
Chris (aka- Moose)
Technician
Vocational, Technical or Trade School
570 satisfied customers
Cylinder 1 misfire. Only when i hit the gas hard and
only when i hit the gas hard and suddenly 95000 miles … read more
Chad Farhat
Chad Farhat
Owner
Associate Degree
4,017 satisfied customers
I am having more than usual vibration when the car is
I am having more than usual vibration when the car is in-gear-at-idle … read more
3pac2222
3pac2222
nissan master auto tech
Associate Degree
2 satisfied customers
2011 sunroof won't shut seams to get stack when around half
2011 sunroof won't shut seams to get stack when around half way closed. … read more
sprinkles08
sprinkles08
Technician
High School or GED
11 satisfied customers
When I am in a low gear let's say 1st my car almost redlines
When I am in a low gear let's say 1st my car almost redlines and I barely hit the gas pedal … read more
Pete
Pete
Independent Auto Technician
Vocational, Technical or Trade Scho
138 satisfied customers
2007 4 cylinder Hyundai Sonata: No brake lights at all,
2007 4 cylinder Hyundai Sonata: No brake lights at all, including high mount. Checked fuses, replaced switch on brake pedal. Nothing.… read more
baddad1
baddad1
technician
High School or GED
5 satisfied customers
Our original remote fob is fading so i purchased two new
Our original remote fob is fading so i purchased two new ones online only to find the box doesn't have a switch. How do I program the remotes? … read more
David Craig
David Craig
OWNER/MECHANIC
Associates
3,943 satisfied customers
Engine light is on and off again and again. 2096. 2011.
engine light is on and off again and again JA: Has your vehicle stalled? Has anyone run a diagnostic test to pull the trouble code? Customer: 2096 JA: What is the model/year of your Hyundai? Customer:… read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
Santa Fe 2003. Motor hood is locked. The latch of the motor
Santa Fe 2003. Motor hood is locked.The latch of the motor hood can not be released by pulling the lever. Likely the cable is broken.How can I open the motor hood? Is there an emergency mechanism to o… read more
Mechanic01
Mechanic01
1,160 satisfied customers
While parked in the garage, I've noticed an small oil leak
While parked in the garage, I've noticed an small oil leak under the right front. Do you know what it might be? … read more
3pac2222
3pac2222
nissan master auto tech
Associate Degree
2 satisfied customers
I HAVE A 2015 ELANTRA AND AM THINKING ABOUT INSTALLING A
I HAVE A 2015 ELANTRA AND AM THINKING ABOUT INSTALLING A BACKUP CAMERA. iS THIS POSSIBLE AND IF SO WHAT IS THE APPROMATE COST INSTALLED?THANKYOU.***@******.***… read more
AMEDEE
AMEDEE
AUTOMOTIVE TECHNICIAN
Vocational, Technical or Trade Scho
9,105 satisfied customers
I have a 2010 hyundai elantra the left side power windows do
i have a 2010 hyundai elantra the left side power windows do not work( driver and passenger). the right sides work fine. the left rear window works from the left rear door switch but not from the mast… read more
Chad Farhat
Chad Farhat
Owner
Associate Degree
4,017 satisfied customers
I am only getting heat on the drivers side passenger side is
I am only getting heat on the drivers side passenger side is cold air … read more
Ron Z.
Ron Z.
- Hyundai Tech -
Vocational, Technical or Trade Scho
634 satisfied customers
My car started smoking when I tried to start it. I checked
I checked the coolant and oil, both are fine. The miles are … read more
Peter Bagley
Peter Bagley
master technition
Vocational, Technical or Trade School
909 satisfied customers
2912 tuscon remote died daughter opened car with key but wil
hi 2912 tuscon remote died daughter opened car with key but wil not start, alarm goes off she is pregnant abd alone right now withthe car … read more
sprinkles08
sprinkles08
Technician
High School or GED
11 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x