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#1
Hi All,
Let's start from the beginning. I own a second hand Hyundai i10 Asta model November 2008 (I bought it in November 2015 ODO 51k). First time the problem started in May 2016 it was extremely hot outside, the outside temperature could have been around 42'C we were 4 passenger in the car, and the AC working. I was standing in the signal as soon as I put it in 1st gear pressed the gas car died, I tried starting the car it started but with a bit of hesitation. Now the car was behaving erratically I switched off the ac the condition improved but I can feel the hesitation of the car, the car would die as soon as I turn on the AC put into forward gear, I tried to keep it revving by varying the accelerator, this also didn't help in gears, but it seem to idle properly. I called my mechanic he told don't drive the car and tow it into his garage. But i drove the car in evening to home without any issues but I avoided the using the AC.
The next day I took my car to garage he did a scan , didn't give me the fault code but told me it's a problem with Idle speed actuator or MAP sensor. He told me he will clean both and if it doesn't work he will try replacing the sensors. Somehow I was not convinced about this hit and trial. So I thought i will take a second opinion. So I went to Hyundai ASC but it was very hard to explain the problem , since the problem was intermittent, any how they told me it's maybe ignition issue changed spark plug and and cable. After this one fine day returning from office I face the same problem. I directly took the car to my local mechanic after checking he took out the fuel pump and did bench test of fuel pump( never recommended since it may damage pump), he told me it's the problem of ISC valve, he will replace it, he replace the ISC with a substitute one he had and told me to drive the car for a week if it worked I need to pay 4k for ISC(I kept the original replaced it again since this didn't solve my problem).
The problem appeared again on a afternoon after driving only half a kilometre in peak to peak to peak traffic, some how I took the car to mechanic this time he called his electrician he checked and told me it's a faulty ecu, but he can repair it. But I didn't agree with him as I design a automotive electronics components and I know what kind of test it goes through before production, there are chances that a lose soldering when hot or water damage in ECU can be a problem but in my case I didn't think it is possible because the ECU is located inside cabin. I was frustrated I plan to the sell the car, but somehow the engineer in me stopped me, think its only a problem I need to find a solution apart from electronic I have interest in mechanics. So I started my own diagnosis.
I ordered a basic scan tool from Amazon, based upon review, to see the fuel trim. The problem didn't appeared in winter so I had to wait for summer. One fine day the car was fully loaded and I was on my way to Delhi. After 30 km of driving the problem appeared again this time I was ready I parked my car at the side of road with engine start and AC.Put the scan tool the short term fuel trim was around -24.5 and the o2 sensor was reading constant .9 volt. This mean I was running too rich. I know only two possible causes of this either leaking fuel injector purge valve and faulty 02 sensor (please correct me if I am wrong I am only an amateur). I focused on the purge valve this is because the problem was during summers. I opened the purge hose it created a huge vacuum leak . Then I closed the inlet with finger with the help of cloth I almost burnt my finger a word of caution. The short term fuel trim and o2 reading returned to normal. Then I put the back the hose on opened the gas cap pressed the inlet it again created huge vaccum leak this proved the purge valve was wide open and dumping extra vapour. Finally one last test open the purge valve and blow air through it ,ideally it should be closed and air should not blow. My purge valve failed that test too replaced it from Mayapuri at 700rs . Now my car is OK I drove it into bumper to bumper traffic, finger crossed till now didn't faced the problem again.
Hope this article help someone.
Let's start from the beginning. I own a second hand Hyundai i10 Asta model November 2008 (I bought it in November 2015 ODO 51k). First time the problem started in May 2016 it was extremely hot outside, the outside temperature could have been around 42'C we were 4 passenger in the car, and the AC working. I was standing in the signal as soon as I put it in 1st gear pressed the gas car died, I tried starting the car it started but with a bit of hesitation. Now the car was behaving erratically I switched off the ac the condition improved but I can feel the hesitation of the car, the car would die as soon as I turn on the AC put into forward gear, I tried to keep it revving by varying the accelerator, this also didn't help in gears, but it seem to idle properly. I called my mechanic he told don't drive the car and tow it into his garage. But i drove the car in evening to home without any issues but I avoided the using the AC.
The next day I took my car to garage he did a scan , didn't give me the fault code but told me it's a problem with Idle speed actuator or MAP sensor. He told me he will clean both and if it doesn't work he will try replacing the sensors. Somehow I was not convinced about this hit and trial. So I thought i will take a second opinion. So I went to Hyundai ASC but it was very hard to explain the problem , since the problem was intermittent, any how they told me it's maybe ignition issue changed spark plug and and cable. After this one fine day returning from office I face the same problem. I directly took the car to my local mechanic after checking he took out the fuel pump and did bench test of fuel pump( never recommended since it may damage pump), he told me it's the problem of ISC valve, he will replace it, he replace the ISC with a substitute one he had and told me to drive the car for a week if it worked I need to pay 4k for ISC(I kept the original replaced it again since this didn't solve my problem).
The problem appeared again on a afternoon after driving only half a kilometre in peak to peak to peak traffic, some how I took the car to mechanic this time he called his electrician he checked and told me it's a faulty ecu, but he can repair it. But I didn't agree with him as I design a automotive electronics components and I know what kind of test it goes through before production, there are chances that a lose soldering when hot or water damage in ECU can be a problem but in my case I didn't think it is possible because the ECU is located inside cabin. I was frustrated I plan to the sell the car, but somehow the engineer in me stopped me, think its only a problem I need to find a solution apart from electronic I have interest in mechanics. So I started my own diagnosis.
I ordered a basic scan tool from Amazon, based upon review, to see the fuel trim. The problem didn't appeared in winter so I had to wait for summer. One fine day the car was fully loaded and I was on my way to Delhi. After 30 km of driving the problem appeared again this time I was ready I parked my car at the side of road with engine start and AC.Put the scan tool the short term fuel trim was around -24.5 and the o2 sensor was reading constant .9 volt. This mean I was running too rich. I know only two possible causes of this either leaking fuel injector purge valve and faulty 02 sensor (please correct me if I am wrong I am only an amateur). I focused on the purge valve this is because the problem was during summers. I opened the purge hose it created a huge vacuum leak . Then I closed the inlet with finger with the help of cloth I almost burnt my finger a word of caution. The short term fuel trim and o2 reading returned to normal. Then I put the back the hose on opened the gas cap pressed the inlet it again created huge vaccum leak this proved the purge valve was wide open and dumping extra vapour. Finally one last test open the purge valve and blow air through it ,ideally it should be closed and air should not blow. My purge valve failed that test too replaced it from Mayapuri at 700rs . Now my car is OK I drove it into bumper to bumper traffic, finger crossed till now didn't faced the problem again.
Hope this article help someone.
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