How to reduce Hydrocarbon count in older car for RTA passing?

[Gaurav]

I have 1999 Mitsubishi Pajero 3.5 SWB very sparingly used and though it's driven very less, it gets spoiled sitting idle and collecting dust. Last week took it for a renewal and RTA failed with 1600+ HC (Hydro Carbon) Count. Ideal should be 400-600 and max 800 for RTA passing in Dubai. 

Dropped the car with 45 years old experience garage in rashidiya: Cars Clinic aka Salim Ali Bin Haider Garage with the explanation that everything is fine in car except the HC count, hence please advise how to bring it down. Next day got a quote of 3,000 AED for changing many parts and sensors but without a guarantee that this 3K expense will bring the HC down or not. Collected the car today after paying 250 AED for diagnostic services for receiving 3K quote as spending so much w/o any confirmation was a pointless game.

Went to Karama Mobil 1 (before sana signal) and got the Oil and filter change and detailed cleaning, went for passing and HC was lower to 1200. ENOC guys in aweer advise that the neighboring garage can clean the throttle body and sensor and that brought down the HC to acceptable range and finally Tasjeel passed the car after a week of hassle.

• Mitsubishi Oil filter: 33 AED
• Mobil 1 - 5,000 Oil: 115 AED
• Full wash:  45 AED
• Throttle body cleaning: 30 AED
• TOTAL: 223 AED 

I like to know from other people experience, what all more I can do to further to reduce the HC count? And how I can avoid similar situation in future for less driven car? 

I have already order from Habtoor new air filter (100 AED) and throttle body Idle speed control servo kit (800 AED) but both are out of stock. And now with above latest development does it make sense to change these or not...? Please advise.

[nutbolt]

Haven't you ask them what they will do in 3K, I mean breakdown of items and see if it really make sense or it's just a milking cow usual behavior.

For reducing HC, for sure get the air filter changed and also see some good mechanic to diagnose the Vacuum leak or additional air going from some seals. Idle speed control sensor should not be changed unless car showing some error code for that specific item.

For less driven car, I would have suggested that to put the fuel treatment bottle (STP or cyclo) from eppco emarat for 50 bucks in quarter tank and drive at 140 to get rid of all carbon deposit before you hit Tasjeel.

[amitaj]

Was there any error code shown in scan tool reading....? If none, then there is nothing seriously wrong and all what you have done should be enough. It's just that drive car once a month for more than 30 minutes at high speed on highway of 120 or above.

[treks]

 

 

 

Hi Gaurav,

I'm afraid that I pushed the wrong button here, hence the empty quotes. Sorry about that.

However, high hydro-carbon counts are a feature of older engines, and there will come a point at which there is nothing you can do to pass and emissions test as the tests are getting more stringent as time passes.

In the meantime though, bear the following in mind when using older cars, like your Pajero.

1.) Hydro-carbon counts depend on the quality of the combustion process. Thus, with cars that are not used often, the lubricating film on the cylinder walls eveporate, which means that the rings are not able to seal properly, at least until a new lubricating film has formed, which can take a few hundred kms. In practice, this means that some oil escapes past the rings, to be combusted with the air/fuel mixture.The best remedy is to use the car more often, and to use the best quality oil available. 

2.) On older engines, it is quite possible for oil to leak into the cylinders past the valve-stem seals when it is not used for some time. You don't need much oil in the cylinders to raise HC counts-just a few micro-drops is enough, and it can take several hunderd kms for this oil to burn off. If this is the case, you might notice some blue/white smoke when you start the Pajero, but the amount of oil in the cylinders might be so small that you may not actually see the smoke. It might be worth your while to have the cylinder heads removed to replace the valve guides, and valve-stem seals. The other option is to drive the vehicle more often to prevent oil build-up in the cylinders due to leaking valve stem seals.

3.) Keep the air filter clean to maximise airflow.

4.) Replace the crankcase ventilation valve to enable the engine ventilation system to function properly. Clogged crankcase ventilation valves is the leading cause why cars of all makes fail emissions tests all over the world.

5.) Replace the plug wires to ensure you get a proper spark to the spark plugs. Plug wires deteriorate over time, and a weak spark equals poor combustion, which means high HC counts.

6.) Replace the sparkplugs with the best available, as opposed to the most you are willing to pay for spark plugs. Plugs with platinum or irridium electrodes are the best, and they last forever.

7.) Have the injectors tested to check their spray pattern. Poor atomisation of the fuel causes poor combustion, and high HC counts.

8.) Have the injector pulse-width checked. The pulse width is the amount of time the injector stays open to inject fuel, and it happens sometimes that injectors get sticky, which is when they inject more fuel than they should, and especially when the engine is cold.

9.) Have a compression test done. Compression on all cylinders should be within 5-, 7% of the values for a new engine, and all cylinders should be within 3-, to 4% of each other.

I hope that helps.

[Gaurav]

Thanks Treks, this issue has been already resolved last month, by the things that I mentioned earlier. 

I'll keep your wonderfully detailed advise handy for the next time as I'm sure my this brat is always mischievous than my all other good boys.

[Rahimdad]

Wow, this is amazing read. All I did with my Land Rover Discovery 1 was to take it to this shop in Hor Al Anz and get them to put in the fuel injector cleaner direct within the engine by replacing a few hoses with their machine. It cost me AED 200 and they took about 30 minutes to run the solution through the engine and walla, I sped up home and 2 days later went to Tasjeel and got it passed without any issues.

[Gaurav]

5 minutes ago, Rahimdad said:

Wow, this is amazing read. All I did with my Land Rover Discovery 1 was to take it to this shop in Hor Al Anz and get them to put in the fuel injector cleaner direct within the engine by replacing a few hoses with their machine. It cost me AED 200 and they took about 30 minutes to run the solution through the engine and walla, I sped up home and 2 days later went to Tasjeel and got it passed without any issues.

Please share the contact as my Pajero passing due next month. I might need them

[Rahimdad]

I have forgotten the name of the garage and lost all their contact details, however whenever you want to go just give me a shout and I will be ready to take you there. I still remember the garage and I will take you there whenever you need.