Diesel Fuel Injection System Help Desk

**Dieseldude** · October 20th, 2006 09:40 AM

Originally Posted by mad_max168

Dieseldude,

What happens with a diesel engine with a too lean fuel mixture?
Low fuel setting = low power.

What happens with it if its too rich?
High fuel setting = a bit more power, but a lot more on fuel consumption, black smoke, and engine wear.

Diesel injection pumps are adjusted to strictly conform to manufacturer's test data, no more / no less. This is called calibration. Authorized injection pump service shops have the necessary calibration info for various injection pumps.

Whats the difference with an advanced injection pump timing and a retarded one? Injection pump timing is the exact point when injection begins, often expressed as a specific crank angle before top dead center, eg: 20 degrees BTDC.

If the engine's specified injection timing is 20 degrees BTDC, putting the timing on 21 degrees or more would be advanced, and putting it at 19 degrees or less would retarded.

Any info on these is highly appreciated. Thanks.

Good questions.

**mad_max168** · October 20th, 2006 03:52 PM

Dieseldude,

I have some followup questions on my previous questions:

What happens with a diesel engine with a too lean fuel mixture?
Low fuel setting = low power.
Would there also be a possibility of overheating of the engine on such condition upon acceleration?

What happens with it if its too rich?
High fuel setting = a bit more power, but a lot more on fuel consumption, black smoke, and engine wear.

Diesel injection pumps are adjusted to strictly conform to manufacturer's test data, no more / no less. This is called calibration. Authorized injection pump service shops have the necessary calibration info for various injection pumps.

Whats the difference with an advanced injection pump timing and a retarded one? Injection pump timing is the exact point when injection begins, often expressed as a specific crank angle before top dead center, eg: 20 degrees BTDC.

If the engine's specified injection timing is 20 degrees BTDC, putting the timing on 21 degrees or more would be advanced, and putting it at 19 degrees or less would retarded.

Would advancing the timing of the injection pump give better engine response? Would it also consume more fuel? Will it cause faster engine wear and overheating?

How about retarding the timing? Would it cause sluggish engine performance? Would it consume less fuel? Will it cause engine to overheat and faster engine wear?

Any info on these is highly appreciated. Thanks again.

**Dieseldude** · October 21st, 2006 08:27 PM

Originally Posted by mad_max168

Dieseldude,

I have some followup questions on my previous questions:

What happens with a diesel engine with a too lean fuel mixture?
Low fuel setting = low power.
Would there also be a possibility of overheating of the engine on such condition upon acceleration?
No.

What happens with it if its too rich?
High fuel setting = a bit more power, but a lot more on fuel consumption, black smoke, and engine wear.

Diesel injection pumps are adjusted to strictly conform to manufacturer's test data, no more / no less. This is called calibration. Authorized injection pump service shops have the necessary calibration info for various injection pumps.

Whats the difference with an advanced injection pump timing and a retarded one? Injection pump timing is the exact point when injection begins, often expressed as a specific crank angle before top dead center, eg: 20 degrees BTDC. If the engine's specified injection timing is 20 degrees BTDC, putting the timing on 21 degrees or more would be advanced, and putting it at 19 degrees or less would retarded.

In the same way, setting the timing at 30 degrees BTDC would also be advanced (more advanced), and timing it at 0 degrees TDC would be retarded (more retarded). Engine performance degrades as injection timing drifts further from specs.

Would advancing the timing of the injection pump give better engine response? Would it also consume more fuel? Will it cause faster engine wear and overheating? This will depend on how far timing has been altered.

How about retarding the timing? Would it cause sluggish engine performance? Would it consume less fuel? Will it cause engine to overheat and faster engine wear? Same answer as above.

A diesel engine operates on various speeds and loads, which require variable timing. Most injection systems can dynamically change injection timing to suit the engine's operating condition. Emission laws on noise and exhaust pollutants also have an influence on the timing specification. The engine manufacturer considers these variables and determines the optimal injection timing for a specific engine model and power rating.
Any info on these is highly appreciated. Thanks again.

Have a nice day.

**promdiboy** · October 22nd, 2006 06:23 AM

sir diesel dude I went to two diffrent shops for calibration, had them quote me the price and parts. 4m40 ITD engine why is it that their parts to be replaced are not the same. same price 17k. shops are denso banawe and central diesel clinic.

**Dieseldude** · October 23rd, 2006 12:09 AM

Originally Posted by PROMDIBOY

sir diesel dude I went to two diffrent shops for calibration, had them quote me the price and parts. 4m40 ITD engine why is it that their parts to be replaced are not the same. same price 17k. shops are denso banawe and central diesel clinic.

Promdiboy

You were probably given a high value estimate assuming that you just inquired, without the shop actually dismantling your pump. The actual & more exact estimate will be given to you upon opening the pump assembly, and actual inspection of parts to be replaced. Once the pump is opened then it is off calibration specs and you will have to proceed with having it calibrated.This is the reason why customers ask about the amount that they will more or less spend before deciding to proceed with the work.

Sometimes, it is just a difference of part description among shops. Send your pump to where you are comfortable with. Check out their facilities, and then decide where you want to have it done. Also ask about the length of warranties offered on their work....and compare.

**Hibiki** · October 23rd, 2006 10:41 PM

Sir DieselDude,

I had my Pump calibrated almost 3months ago. Last week the delivery valve leaked and I had to ask the calibration shop to check it. They replaced an o-ring in the valve and the leak stopped. After using the vehicle since then, I noticed that the engine became louder and consumes more fuel compared to before. Do you think there is some other problem with my pump? Perhaps the leak was just one symptom?

Thanks.

**Dieseldude** · October 24th, 2006 01:38 AM

Originally Posted by fuego4x2

Sir DieselDude,

I had my Pump calibrated almost 3months ago. Last week the delivery valve leaked and I had to ask the calibration shop to check it. They replaced an o-ring in the valve and the leak stopped. After using the vehicle since then, I noticed that the engine became louder and consumes more fuel compared to before. Do you think there is some other problem with my pump? Perhaps the leak was just one symptom?

Thanks.

So many things can cause the problems stated above such as: a faulty injection pump (improper calibration), wrong injection timing, bad injectors, etc. What is your vehicle? It could really be louder as the previously leaking fuel is now fed back to your engine. What was your previous fuel consumption, and what is it today after the leak was corrected?

Did the fuel shop pull down your pump to replace the o-ring? I am asking you this question because the pump may not have been properly timed during reinstallation.

I suggest you bring it back to the shop where you had it done, and ask for warranty service. Most shops give a 6 months warranty as we do.

**Hibiki** · October 24th, 2006 03:48 AM

Thank you for the response.

The vehicle is an Isuzu Pickup (4ja1). It was a bit loud as all Isuzu vehicles are but the idling was smooth. Now, it is loud and erratic (magaralgal). Before, I get 12km city driving and 14-16 hiway. As of yesterday, I'm getting less around 9km/liter mixed city/hway.

They did not pull out the pump when they replaced the o-ring. They just removed the delivery valve, replaced the o-ring, and then reinstalled the valve. They used a calipher to check the length of the protruding end of the valve screw (my guess is to approximate the amount of fuel delivery --- is this the correct way?)

You're right, i think I will bring the vehicle to the Calibration shop for another testing.

Thanks.

**2Dmax** · October 24th, 2006 08:19 AM

DIESELDUDE,

i have a ISUZU pick-up LS '94 model. engine is 4JA1. my problem is that my oil level keeps on rising. last change oil, we just used 4.5 liters of oil, and it was in the maximum level. then after 2 weeks, it was 1 inch above the maximum level. now it's 2 inch above the maximum. i consulted a mechanic and said that the diesel fuel might be entering inside the engine, mixing with my engine oil. pls help on this matter. thanks..

**Dieseldude** · October 24th, 2006 10:54 AM

Originally Posted by fuego4x2

Thank you for the response.

The vehicle is an Isuzu Pickup (4ja1). It was a bit loud as all Isuzu vehicles are but the idling was smooth. Now, it is loud and erratic (magaralgal). Before, I get 12km city driving and 14-16 hiway. As of yesterday, I'm getting less around 9km/liter mixed city/hway.

They did not pull out the pump when they replaced the o-ring. They just removed the delivery valve, replaced the o-ring, and then reinstalled the valve. They used a calipher to check the length of the protruding end of the valve screw (my guess is to approximate the amount of fuel delivery --- is this the correct way?)

You're right, i think I will bring the vehicle to the Calibration shop for another testing.

Thanks.

Fuego 4x2

Go ahead and have your pump re-checked under warranty claim. And ask for a retimining on engine upon installation. By the term "calbration" itself...would mean that your pump should pass all the specifications your pump has to adhere to as per OEM (Original Equipment Specications) No more no less... This spec sheet from the OE is given to authorized shops. Try to find out if they have this, otherwise it could all be guesswork. This spec sheet is particular to your pump assy. number which you will find in your pump data plate. If they have this, then you can be comfortable that they know what they are doing. Good luck