Diesel Fuel Injection System Help Desk

[Dieseldude]

Hi DieselDude,

I seem to have a problem with my 98 BMW725 TDS...the problem is at idle...there is so much fuel knock, my question...is there a quickfix to this...like diesel fuel additives/conditions that can minimize or eliminate it. Petron's Diesel Booster might help. I've tried it.

About the fuel knock, its only present at idle around 800-900rpm. If I just tap the accelerator very lightly to keep it at 1000rpm the knock is totally gone....if I pump the accelertor several times very very quickly and let it idle it will idle without the knocking sound for about 2 seconds and the the knock returns... Knock is probably due the present cooler temperatures, as well as lower compression pressure due to normal engine wear.

I also would wnat you to know the car has no problem at all, power is good, not much smoke emited when driven hard. This seems to be normal for Rovers....

Another concern of mine, the car does not start quickly even when already hot, it will take 2 to 3 revolutions before the engine fires up...Whats your suggestion? Again this is normal, especially for high mileage cars, slight drop in compression pressure......

I believe you have a shop...are you capable of rebuilding the pump and are the parts available if ever I have it done? Could the injectors be a possibility or is it the pump, or thats just normal for older cars? Yes we are a Bosch Diesel Center, and we service this pump type. You have an EDC (Electronic Diesel Control) pump. Parts may have to be ordered from Germany though. I don't think your fuel injection system needs service; your condition is normal.

[jpn]

Hi DieselDude,

I seem to have a problem with my 98 BMW725 TDS...the problem is at idle...there is so much fuel knock, my question...is there a quickfix to this...like diesel fuel additives/conditions that can minimize or eliminate it. Petron's Diesel Booster might help. I've tried it.

About the fuel knock, its only present at idle around 800-900rpm. If I just tap the accelerator very lightly to keep it at 1000rpm the knock is totally gone....if I pump the accelertor several times very very quickly and let it idle it will idle without the knocking sound for about 2 seconds and the the knock returns... Knock is probably due the present cooler temperatures, as well as lower compression pressure due to normal engine wear.

I also would wnat you to know the car has no problem at all, power is good, not much smoke emited when driven hard. This seems to be normal for Rovers....

Another concern of mine, the car does not start quickly even when already hot, it will take 2 to 3 revolutions before the engine fires up...Whats your suggestion? Again this is normal, especially for high mileage cars, slight drop in compression pressure......

I believe you have a shop...are you capable of rebuilding the pump and are the parts available if ever I have it done? Could the injectors be a possibility or is it the pump, or thats just normal for older cars? Yes we are a Bosch Diesel Center, and we service this pump type. You have an EDC (Electronic Diesel Control) pump. Parts may have to be ordered from Germany though. I don't think your fuel injection system needs service; your condition is normal.

Dude,

Thanks a lot for the info...I have been already searching the WEB for weeks only to find out I got the aswers from a local site....I read this whole thread from the beginning...THUMBS UP...for the time you put on to answer questions.....!!!

[batosai]

Sir DD thanks for enlightened me. So there's a purpose pala kung bakit nila nilagay ung EGR. I'll just leave it as it is..

* CJPAMA

Why not try to drop by at central diesel it is located along Quezon Ave near the capitol medical center. Mga expert tao dito pag dating sa mga Injection Pump. Hope this will help you.


Thanks and more power!!!

[jpn]

Knock is probably due the present cooler temperatures, as well as lower compression pressure due to normal engine wear.

Sir,
I notice my engine temp is always below 1/4....I highly suspect that the previous owner/mechanic probably removed or did something to the thermostat....I wonder if I put back the thermostat to maintain normal engine temp. would this probably lessen the fuel knock at idle?

By the way I did put the petron power booster and yes it did make a difference already...it silenced the fuel knock noticebly...thanks!!!

[Dieseldude]

Sir,
I notice my engine temp is always below 1/4....I highly suspect that the previous owner/mechanic probably removed or did something to the thermostat....I wonder if I put back the thermostat to maintain normal engine temp. would this probably lessen the fuel knock at idle? Doing this will not totally remove engine knock. But it might shorten the knocking time as the engine will reach operating temp sooner.

By the way I did put the petron power booster and yes it did make a difference already...it silenced the fuel knock noticebly...thanks!!! Good...

[chitobarba1972]

Sir Jake "DieselDude", my wife brought our crosswind XUVi 05 A/T at your shop last September due to high fuel consumption. Initial diagnosis by one of your personnel is that our unit is still running fine and only needs replacement of OEM air filter. He mentioned that our consumption of 6km/li on city driving (Galas QC to Don Bosco Mandaluyong in Kalentong around 8.5km back and forth) is just right due to short distance runs and traffik. Our current milage is at 89k and as per previous owner, it has not undergone any calibration of injection pump. Smoke is only visible during start-up in the early morning and after that no-smoke can be seen. Unit has not experienced overheat and change oil and filter * 5k and OEM air filter * 10k. I'm just a bit worried about its fuel consumption coz base on some Isuzu forums, normal FC for such models (A/T) at city driving is at 8 -10 km/li. Would you recommend for an injection calibration or injection to engine timing?
By the way I just replaced my TPS sensor / potentiometer due to error detected which caused blinking of my "Check Trans" and it was done by Isuzu Manila after running their diagnostics tool. So far error solved but still my FC is a bit high. They also informed us that they adjusted the TPS for better shifting. Kindly assist me on this...

Thanks in advance sir Jake!!

[Dieseldude]

Sir Jake "DieselDude", my wife brought our crosswind XUVi 05 A/T at your shop last September due to high fuel consumption. Initial diagnosis by one of your personnel is that our unit is still running fine and only needs replacement of OEM air filter. He mentioned that our consumption of 6km/li on city driving (Galas QC to Don Bosco Mandaluyong in Kalentong around 8.5km back and forth) is just right due to short distance runs and traffik. Restricted air filter is the main cause for smoke and high fuel consumption. I believe that 8.5km is fine for city driving. What is your FC on highway?

Our current milage is at 89k and as per previous owner, it has not undergone any calibration of injection pump. Smoke is only visible during start-up in the early morning and after that no-smoke can be seen. This is normal.

Unit has not experienced overheat and change oil and filter * 5k and OEM air filter * 10k. Good,

I'm just a bit worried about its fuel consumption coz base on some Isuzu forums, normal FC for such models (A/T) at city driving is at 8 -10 km/li. Would you recommend for an injection calibration or injection to engine timing? FC is influenced by many factors; driving style, parasitic loads, timing, pump calibration, etc. Timing can be checked on engine. Pump calibration can only be verified on the test stand. So this is up to you.

By the way I just replaced my TPS sensor / potentiometer due to error detected which caused blinking of my "Check Trans" and it was done by Isuzu Manila after running their diagnostics tool. So far error solved but still my FC is a bit high. They also informed us that they adjusted the TPS for better shifting. Kindly assist me on this...

Thanks in advance sir Jake!! You're welcome.