Is injector opening pressure adjustable?

[RufusTheDufus]

I have the head off my engine at the moment and figured it's a good time to test my injectors. I bought one of those bench mount pump type injection testers. Very easy to use and setup.

5 of my 6 injectors open at 1875-ish PSI. One of them doesn't open until 2250 PSI. This could be part of my rough idle problem. Is there a way to adjust the opening pressure down?

I had these injectors rebuilt less than 20K miles ago. I'm very surprised there is such a difference. (I didn't own the injector tester when I had them rebuilt otherwise I might have caught this problem if it existed back then.)

I need to check the FSM to see what the opening pressure is supposed to be set at for the H diesel.

 

[gerg]

Where did you get your tester? This is something I have been interested in doing for a while. My dad use to be a truck driver and would always get the guys to bench test them after rebuilding before installing them. More often than not one or two of them were out of wack.

 

[RufusTheDufus]

I ordered it on Ebay. Brand new was like $200. The instruction manual was in Italian though.

I disassembled the injector, cleaned up the slight carbon on the tip and soaked it in Diesel Purge overnight. Reassembled it and now opens at the same pressure as the others.

 

[tmarx]

.. . Reassembled it and now opens at the same pressure as the others.

And is the rough idle problem gone ?

 

[RufusTheDufus]

I'll know after I put the cylinder head back on the engine. It's still at the machine shop.

 

[PERUVIAN]

For the record.. you can totally change the opening pressure of the injectors.. But the question is if it is the correct thing to do.. By messing with the pressure you could be actually messing with the timing as well ( pressure gets there early or late of what it was designed ( initially timed ) for which means the fuel enters the cylinder off of the point where your engine wants it ( timing ) .. you also have to look at if you set them to open very high.. the pump might struggle to get the pressure that high to begin with to even open the injectors-

 

[Kynot62]

Opening pressures are adjusted by changing the shims inside the injector housing. Commonly done to bring them into spec. Yes you need to fix that one that opens too high and maybe all the others as well.

Are you sure you can trust that tester? The max psi for a new or old injector should only be 1778psi according to the 1980 B series manual for B,2B and 3B

From the manual new injector 1636-1778 psi opening pressure
reused injector 1493 - 1778psi

Sorry I don't know what the H injectors open at

Tony

 

[canucksafari]

I picked up one of these testers from a friend back East who is importing. You'll need to get a shim kit. I still have to get around to ordering one from Hiflo in Australia. You'll also want to have some new tips on hand along with new washer sets. On my Td4.2 you can boost the pressure a bit and also advance the timing a bit too. On the same engine, the breaking pressures vary depending if the engine is turbocharged or not. Not sure if their would be any differences with an engine with an inline pump verses a VE type pump. A good diesel tuner just doesn't go by what the book says. They play with it a bit - some just by adjusting and driving and others on a dyno. It is also important to make sure your tappets are adjusted properly before making any changes from factory specs.

 

[RufusTheDufus]

My pump and injectors were setup for a turbo. I had them serviced at the same time by an outfit in Portland, Oregon. I can't recall the name of the business but I do recall that Lynchmob uses them for his diesels. Maybe they set the pressure a little higher than stock for me? (The H matches the specs for the 3B.)

It is possible the tester is a little out of whack though it did have an Italian certificate of calibration in the package when it arrived. I was just concerned that I had one injector opening at a much higher pressure than the other 5. Now that they are all consistent I'm not too concerned. But I do wonder what was causing that injector to stick closed. There wasn't a lot of carbon buildup or any obvious contamination.

I should have it running again tomorrow. Style waiting on the head gasket sealer to arrive today.

 

[RufusTheDufus]

And is the rough idle problem gone ?

Yes, the rough idle is gone now. I don't know if it was the injector or the head gasket. Both were fixed at the same time.

 

[iglux]

Opening pressures are adjusted by changing the shims inside the injector housing. Commonly done to bring them into spec. Yes you need to fix that one that opens too high and maybe all the others as well.

Are you sure you can trust that tester? The max psi for a new or old injector should only be 1778psi according to the 1980 B series manual for B,2B and 3B

From the manual new injector 1636-1778 psi opening pressure
reused injector 1493 - 1778psi

Sorry I don't know what the H injectors open at

Tony

Hi I have engine knocking on my BMW X5 40d 2011 I take out this injector and I go to injector to be checked all 6 and 5 of them Is number.1-2-4-5-6 psi 2250 excesive fuel ! INJECTORS NOT HOLDING PRESSURE & OPENING PRESSURE TOO HIGH and number 3 injector I was INJECTOR FAILED ON ELECTRONIC SOLENOID FAILURE I buy other injector number 3 and install back all of them still same knocking anyone help me please or advise I need to fix other 5 injector to be at normal pressure what you suggest me to do guys

 

[rick_d]

what you suggest me to do guys

Don't revive a 13 year old thread?

Rebuild all injectors and get back to us with a new thread.