Engine Miss & Petrol Smell In Cold Start

LancerL · August 4, 2015

I have Corolla CE110 and from recent some times when it start for the first time of the day (specially cold weather) it starts in one turn, runs rpm nearly 1,500 and then a engine miss comes for like 10 seconds then disappear. At that time if I bent down and smelled silencer it gives a little Petrol smell. But in next second the miss disappear, it smells as perfectly normal with water steam.

No issue in pulling power or anything else and no different in fuel economy also.

Only observation when engine hot and with A/C off there is slight vibration sense on steering wheel. That also random and not always.

Is this something that I have to pay attention or it could be something that is normal. But I haven't experience this before.

Please share your comments.

LancerL · January 1, 2016

Hi all, sorry for the long silence...

At last I found which was causing above miss in cold start and the petrol smell :pardon:

You might remember that I did a DIY fuel injector cleaning sometime back?

One thing I found while I was re-fixing the injectors to the inlet manifold is that one or two Orings which seals injector to the inlet manifold was loosen.

Since that was a afternoon and I was tired with cleaning, I did not bothered to visit any auto part shop to replace those.

But with further reading of the forum for similar incidents faced by other members, I got a clue that this might due to sucking excess air from the loosen Orings to the particular cylinder or two which cause a lean mixture.

So the oxygen sensor which detects it, signal injectors to flow more fuel as it thinks the mixture is lean, when mixture is too rich due to above, it will cause an imbalance which we called it as an Engine Miss Fire and smelled un-burned petrol from the tail pipe.

So that coming weekend I again removed injectors and taken out all inlet manifold side Orings and took it to a Auto part shop, cost for four Orings was just Rs. 85/- so I brought another set for further use.

Replaced all four Orings carefully, cleaned manifold holes with throttle body cleaner and a paper tissue and reinstalled injectors back to the manifold.

Disconnected positive battery terminal for a while to reset ECU and reconnected and start the engine and let it to worm up and had a decent drive about 15mins with A/C off.

Its almost nearly two months by now to the job and I have never got this miss and petrol smell again.

So my final conclusion was that this was due to one or more vacuum leaking Oring from inlet manifold.

Project was so interesting although it took lot of time but the satisfaction I got out of this cannot me measured by money.

But if I took this to a Garage for the same, my total bill would exceed Rs. 10,000/- for sure including a tuneup, replacement of Plugs, Fuel filter, Air filter and etc...

Thanks a lot for all of you who has given advises and directions to get this success. :yahoo:

Crosswind · August 5, 2015

How can you get petrol smell from a diesel car?

If your car is the petrol version of 110, I would say its normal for an old car and nothing much to panic. Rust in petrol tank/petrol lines due to years of poor quality petrol can cause the misfire (and many other reasons due to wear and tear) makabasses removing the termostat valve could be another reason. The bottom line is its something expected of an old car.

However, if it is CE110, i find it strange indeed!

Edited August 5, 2015 by Crosswind

Kavvz · August 5, 2015

How can you get petrol smell from a diesel car?
If your car is the petrol version of 110, I would say its normal for an old car and nothing much to panic. Rust in petrol tank/petrol lines due to years of poor quality petrol can cause the misfire (and many other reasons due to wear and tear) makabasses removing the termostat valve could be another reason. The bottom line is its something expected of an old car.

However, if it is CE110, i find it strange indeed!

Did you ever get around to investigating the petrol smell you mentioned in your car? ( the Mazda I think it was...)

Crosswind · August 5, 2015

In my case the smell is in the cabin. It's still there and didn't really investigate. Will probably do so this weekend.

aps · August 5, 2015

CE110 - petrol ?

btw since u still smell petrol, check following

1. Throttle Body - if not clean for more 10,000Km clean it check for vacuum leaks

2. Plugs - check and replace if necessary, (if not used same brand heat range difference apply)

3. Scan - check for any error codes ,

4.If u think all above expensive just remove ur car battery negative wire and leave it for over night then re-plug, you may feel like issue fixed, but it may come again, if so start from step 3 to 1

LancerL · August 5, 2015

Sorry it is AE 110.

Rumesh88 · August 5, 2015

I have Corolla CE110 and from recent some times when it start for the first time of the day (specially cold weather) it starts in one turn, runs rpm nearly 1,500 and then a engine miss comes for like 10 seconds then disappear. At that time if I bent down and smelled silencer it gives a little Petrol smell. But in next second the miss disappear, it smells as perfectly normal with water steam.
No issue in pulling power or anything else and no different in fuel economy also.

Only observation when engine hot and with A/C off there is slight vibration sense on steering wheel. That also random and not always.

Is this something that I have to pay attention or it could be something that is normal. But I haven't experience this before.

Please share your comments.

While I agree with what others have pointed out above, the slight vibration could be due to an issue with one of the sensors like TPS or MAF. Of the two TPS is the easiest to test (just a resistance measurement over its movement range) and the most likely to fail intermittently (because it is mechanical) and also the relatively cheaper one to replace. Hence while you are at it get the TPS also tested. It is normal for the air/fuel mixture to be rich on cold start and become lean as the engine warms up.

LancerL · August 7, 2015

Did a scan from a Bluetooth ODB2 tool I ordered from eBay and no error codes found.

LancerL · August 7, 2015

While I agree with what others have pointed out above, the slight vibration could be due to an issue with one of the sensors like TPS or MAF. Of the two TPS is the easiest to test (just a resistance measurement over its movement range) and the most likely to fail intermittently (because it is mechanical) and also the relatively cheaper one to replace. Hence while you are at it get the TPS also tested. It is normal for the air/fuel mixture to be rich on cold start and become lean as the engine warms up.</p></blockquote>

If TPS or MAF defective that should indicate Check Engine or should be found on the scan?

If air/fuel mixture rich when starting, can it be smelled Petrol or visible black smoke?

Edited August 7, 2015 by LancerL

Rumesh88 · August 7, 2015

If TPS or MAF defective that should indicate Check Engine or should be found on the scan?
If air/fuel mixture rich when starting, can it be smelled Petrol or visible black smoke?

Marginal or intermittent faults in sensors will not necessarily show up in a scan. Your TPS should be a four wire one which is essentially a variable resistor (3 wires) with a homing contact (additional wire). If you are doing a DIY test all you need is a multimeter to measure the resistance and continuity. Read the TPS part number and search the Net for its pin-out config. You should get a reading of around 3 - 5k Ohm for the total resistance but what's more important is the smooth variation in resistance over is movement range without abrupt changes in resistance in between. TPS units usually tend to fail intermittently in their movement close to idle position because that is the range which is mostly in use during an average drive. As for the air fuel mixture at cold start, it should not be rich enough to produce black smoke but if you sniff the exhaust fumes you can clearly identify the smell of a rich mixture burning. However this is subjective and the sense of smell is extremely sensitive.

Edit: Since you have a scan tool with you connect it in the morning and check if the air temperature and coolant temperature values are approximately correct at cold start.

Edited August 7, 2015 by Rumesh88

LancerL · August 13, 2015

Marginal or intermittent faults in sensors will not necessarily show up in a scan. Your TPS should be a four wire one which is essentially a variable resistor (3 wires) with a homing contact (additional wire). If you are doing a DIY test all you need is a multimeter to measure the resistance and continuity. Read the TPS part number and search the Net for its pin-out config. You should get a reading of around 3 - 5k Ohm for the total resistance but what's more important is the smooth variation in resistance over is movement range without abrupt changes in resistance in between. TPS units usually tend to fail intermittently in their movement close to idle position because that is the range which is mostly in use during an average drive. As for the air fuel mixture at cold start, it should not be rich enough to produce black smoke but if you sniff the exhaust fumes you can clearly identify the smell of a rich mixture burning. However this is subjective and the sense of smell is extremely sensitive.
Edit: Since you have a scan tool with you connect it in the morning and check if the air temperature and coolant temperature values are approximately correct at cold start.

Hi Rumesh, thanks for your valuble inputs. I didn't had a time to check the TPS but I was able to test the the air/coolent tempreture at cool start and it was low like enviorment tempreture (I canno't remember the figures) and when i start the engine it went up gardually.

One more thing I did apart all above is I have removed two plug wire tops ( I could not remove other two as it was so tight) cleaned the rubber with a dry towel and re fixed. Also I coulden't remove plugs as I didn't had that thin box wrench. After it I observed that I didn't get the miss or the petrol smell.

Had a run to Matara on highway and back to colombo also and still it looks fine.

I doubt it was due to a loosen plug wire.... Anyway will keep posted the status.

Thanks

LancerL · September 4, 2015

I got the miss again about two weeks ago. That was a night and I checked to see what could be done on next day morning and found that one injector power wire has been tensioned by the accelerator cable by some way.

So I have corrected it and as a extra mile.I've remove all injector power connectors and clean with a contact cleaner and refixed.

Up to now it didn't given any miss as before.

But the slight idle vibration is comes and go time to time. As discussed in another topic was able to pull all plug wires today and planing to clean both plugs and it's top on tomorrow.

Will keep update the status once that is done.

LancerL · September 7, 2015

Cleaned the plugs and wires. No miss found up to now but slight vibration in operation temperature is still there...

It feels to the steering wheel and floor board well.

Could that be due to one or more injector?

Rumesh88 · September 8, 2015

Cleaned the plugs and wires. No miss found up to now but slight vibration in operation temperature is still there...
It feels to the steering wheel and floor board well.

Could that be due to one or more injector?

Possible. ECU assumes an identical fuel delivery from all injectors at a given RPM. So if one injector is delivering more fuel or has a residual leakage, the ECU will try to correct the situation by reducing the injector timing in all. Although the injectors are individual, sensing (MAF, O2 sensor) is common. Hence a problem with one injector may cause engine imbalance and vibration. Since you are using your own OBD tool can you post the short-term and long-term fuel trim values and O2 sensor readings (Lambda value) at idle? Wait for 30 seconds or more on idle after engine has fully warmed up before taking the readings.

Edited September 8, 2015 by Rumesh88

DVT · September 8, 2015

CE110 - petrol ?
btw since u still smell petrol, check following

1. Throttle Body - if not clean for more 10,000Km clean it check for vacuum leaks

2. Plugs - check and replace if necessary, (if not used same brand heat range difference apply)

3. Scan - check for any error codes ,

4.If u think all above expensive just remove ur car battery negative wire and leave it for over night then re-plug, you may feel like issue fixed, but it may come again, if so start from step 3 to 1

This refers to point number 2.

After 55 thousand KM running I sent my sportage ( Petrol) to change ATF oil and do a engine tune up ( including plug replacements) to agents (KIA) last Friday.

Experienced the same - bad petrol similar smell coming inside and could not bear with it. Called the agent and they wanted me to take the vehicle to check on monday.

Before taking it to check on Saturday , there was a bad miss when tried to start the vehicle and engine was unstable. Took her to closest garage to see what they have done for my vehicle. Noticed that two plus are not fixed tight. Did the needful and ..

Then the engine became stable and no fuel smell.

My question - Can loose plugs cause fuel smell inside vehicle ? or was it another reason ?

LancerL · September 9, 2015

@DVI Loosen plugs can make fuel smell as it leaking air fuel mixture out from cylinder at compression stage.

Check your A/C vent set to fresh or recycle, if it is fresh obviously it sucks air from engine compartment side where it could smell petrol.

If it is recycle, then there could be a gap or a hole somewhere it leaks air to inside. Also could be a bad door beading.

DVT · September 9, 2015

@ lancer L , Thanks

LancerL · September 12, 2015

Possible. ECU assumes an identical fuel delivery from all injectors at a given RPM. So if one injector is delivering more fuel or has a residual leakage, the ECU will try to correct the situation by reducing the injector timing in all. Although the injectors are individual, sensing (MAF, O2 sensor) is common. Hence a problem with one injector may cause engine imbalance and vibration. Since you are using your own OBD tool can you post the short-term and long-term fuel trim values and O2 sensor readings (Lambda value) at idle? Wait for 30 seconds or more on idle after engine has fully warmed up before taking the readings.

@Rumesh88 thanks for the post

Got a free time today only to take readings.

Attached below screenshots of short-term and long-term fuel trim values after about 30mins drive and kept idle for about 1minute with A/C off.

I have taken Timing advance and Engine RPM reading also for further findings.

I could not find the O2 sensor reading with the tool.

Please click on the image to view.

Is this within the safe zone?

If not what are the values should be?

Edited September 12, 2015 by LancerL

Rumesh88 · September 12, 2015

Thank you for the readings. STFT and LTFT values are close to zero and that means they are OK. BTW did you check/clean the PCV valve recently? If not first check the PCV by opening the oil cap and holding a sili-sili bag a bit taut over the opening fully sealing it. While holding it start the engine (of course you can do it while the engine is running but you will get a few oil droplets thrown out). Now the part which is held taut over the oil cap opening would flutter to the beat of the engine but you should be able to see a concave shape indicating a net vacuum inside the engine.(What happens is because of the pressure peaks produced by blow-by fumes as each cylinder fires, you get the sili-sili bag to flutter up and down but if the PCV is working you should get a net vacuum). If you see a convex shape of the bag remove and clean the PCV and the connecting hose (check for cracks and leaks on the hose). If you find them really dirty with carbon and oil deposits there is a good chance that the oil baffles inside the cam cover are clogged up too. But that's a bit more work. If your instability is due to a dirty PCV cleaning it would solve it. Keep ur observations posted.

Edited September 12, 2015 by Rumesh88

LancerL · September 14, 2015

Thank you for the readings. STFT and LTFT values are close to zero and that means they are OK. BTW did you check/clean the PCV valve recently? If not first check the PCV by opening the oil cap and holding a sili-sili bag a bit taut over the opening fully sealing it. While holding it start the engine (of course you can do it while the engine is running but you will get a few oil droplets thrown out). Now the part which is held taut over the oil cap opening would flutter to the beat of the engine but you should be able to see a concave shape indicating a net vacuum inside the engine.(What happens is because of the pressure peaks produced by blow-by fumes as each cylinder fires, you get the sili-sili bag to flutter up and down but if the PCV is working you should get a net vacuum). If you see a convex shape of the bag remove and clean the PCV and the connecting hose (check for cracks and leaks on the hose). If you find them really dirty with carbon and oil deposits there is a good chance that the oil baffles inside the cam cover are clogged up too. But that's a bit more work. If your instability is due to a dirty PCV cleaning it would solve it. Keep ur observations posted.

Thanks for the post, sure will keep posted

With regard to STFT and LTFT values, does that mean the injectors are in proper order?

Rumesh88 · September 14, 2015

Thanks for the post, sure will keep posted
With regard to STFT and LTFT values, does that mean the injectors are in proper order?

For you to confirm the proper working of injectors and the sensors (remember they do not operate in isolation) you need to perform a few more tests not just STFT/LTFT on idle alone. That includes revving up and checking how fast the fuel trims adjust themselves at different RPMs etc. Also unless you monitor and analyze the exhaust fumes with an external tester, with OBD information alone you cannot accurately diagnose a marginal issue like this one. If you want to test the injectors for their accuracy in fuel delivery it has to be done on a external rig like one shown in http://www.asnu.com/. However, your car is doing OK at least on idle so check the other things like small air leaks etc. Another place where an air leak can occur is the injector seating which tends to crack under heat stress.

cefiroA33 · October 8, 2015

Hi guys.

I have a small issue with respect to the engine of my Nissan Cefiro A33 petrol 2L V6 which I thought I would share with you for your expert advice.

Recently I carried out a major repair to my engine with repairing all the oil leaks replacing oil seals and o rings etc. Also I replaced 3 out of 6 ignition coil plugs with Nissan genuine ones (But purchased from Pioneer motors) and also I did a complete tune up of the engine including throttle body cleaning etc.

After that I went on a trip to Yala and after say 175 miles of travelling I experienced there is a sudden drop in the RPM when it reaches the 2000 mark and it comes with a misfire in engine as well ( I felt the vibration in the car when engine misfire). However this issue only came when the RPM was increasing gradually and when it was suddenly raised to 2000 - 3000 no such thing occurs.

After returning I have been running for almost 1000 kms now but so far nothing has improved but i have noticed that even if the vehicle is in parked mode and accelerated gradually till the rpm reaches 2000 the sudden drop in the RPM is experienced between 1500 - 2000 range.

You guys being the experts would be able to identify the issue easily and please enlighten me.

Thanks and regards

Sierra Charlie · October 8, 2015

Hi guys.
I have a small issue with respect to the engine of my Nissan Cefiro A33 petrol 2L V6 which I thought I would share with you for your expert advice.

Recently I carried out a major repair to my engine with repairing all the oil leaks replacing oil seals and o rings etc. Also I replaced 3 out of 6 ignition coil plugs with Nissan genuine ones (But purchased from Pioneer motors) and also I did a complete tune up of the engine including throttle body cleaning etc.

After that I went on a trip to Yala and after say 175 miles of travelling I experienced there is a sudden drop in the RPM when it reaches the 2000 mark and it comes with a misfire in engine as well ( I felt the vibration in the car when engine misfire). However this issue only came when the RPM was increasing gradually and when it was suddenly raised to 2000 - 3000 no such thing occurs.

After returning I have been running for almost 1000 kms now but so far nothing has improved but i have noticed that even if the vehicle is in parked mode and accelerated gradually till the rpm reaches 2000 the sudden drop in the RPM is experienced between 1500 - 2000 range.

You guys being the experts would be able to identify the issue easily and please enlighten me.

Thanks and regards

maybe a dead spot in the TPS? Did it happen on the E01 where you have to maintain a constant speed?

cefiroA33 · October 8, 2015

maybe a dead spot in the TPS? Did it happen on the E01 where you have to maintain a constant speed?

Thanks Charlie for your reply. Well this did not happen on the E01. Drive on the E01 was smooth. Actually this happened in Hambanthota where the roads are very similar to E01 and the drive is exactly like on the E01. I did not change the throttle position sensor recently as well. can a scan recognise this error?

Rumesh88 · October 8, 2015

Sierra Charlie is right. This could very well be a TPS fault but it is unlikely to show up in a scan. Is your TPS three/four terminal and built into the throttle body?If that is the case you need to be absolutely sure of the fault (cos replacement would be expensive) which can be confirmed with a simple multi-meter by observing the resistance change as the throttle moves from closed to wide open position.