M70 injector testing, replacement, etc

[LappingLuke]

Hey again... I pulled my bank 2 plugs to investigate a light/kinda random idle misfire yesterday and found 2-3 of them were kinda wet but the color all looked pretty normal. Wondering if I might have some bum injectors with lousy atomization causing a crappy burn at idle. The car has 137k miles on it now and I bet they're original. Do you guys think having the injectors tested would be a valuable exercise? If so, is rebuild a possibility? If not, what replacement should I get? I think I remember seeing something about 1 hole vs 4 hole injectors for M70. I'll do some research this morning while my California friends are waking up and getting their coffee.

Luke

[jimmythefish]

Hi Luke,

While I was doing every maintenance thing I could think of to my 850 with 96K, I had the injectors cleaned and refurbished. The person I used was Jim from Injector Repair LLC, 518-,956-0014 It took a few weeks because COVID was messing everything up but he sent pictures of the results with information on the before and after performance of the injectors. At 137K and possibly original injectors it might be good to have them replaced or at least cleaned, tested, and refurbished as necessary. Honestly, after I have gone through my 91 850i 6 spd, my new motto for that car is, “if it hasn’t been done by now it probably needs it done”. I know that doesn’t answer your direct question, but that is what I did for the car…cost me a little over 200.00 I believe.

….disclaimer: this comment was posted from Arizona with no coffee yet…..

James

[LappingLuke]

Thanks! That helps a lot! I agree with your motto about doing everything that hasn't been done. Definitely the case for my car at this point. I keep replacing 30 year old parts and it keeps getting better! Imagine that!

[rogbmw]

Thanks for the contact on the injectors. How much was the service.

[LappingLuke]

Jimmy said costs him a bit over $200 which checks out on the company website which says $17 per injector. Unless someone like cartoonz comes in and says don't do it I'm planning to pull mine Sunday or Monday and get them in the mail.

[petejk]

That’s a great price for a refurbish of all 12.

Another option - new Bosch 62415 4 hole injectors from Rock Auto for $33 each.


Sent from my iPhone using Tapatalk

[LappingLuke]

Another option - new Bosch 62415 4 hole injectors from Rock Auto for $33 each.

I noticed that too. Did our cars come with a 1 hole injector? And is the 4 hole a meaningful upgrade for double the price?

[LappingLuke]

Found this video comparing 1 hole to 4 hole injectors for Jeeps... pretty interesting

https://youtu.be/bHf-6ohkgbA

[petejk]

I don’t think they’re a significant upgrade, but replacing 30 year old parts with new genuine Bosch parts could give a certain peace of mind.


Sent from my iPhone using Tapatalk

[cartoonz]

Bill Fox still has a few sets of the upgraded Bosch injectors, I believe. They are more than $17, maybe less than $33, and brand new and work perfectly.

[LappingLuke]

Oh yeah? And how can a prospective injector buyer contact Mr Fox?

[Max Lumens]

Please contact him directly at maxlumens@finemotoring.com. Injectors are $440 per set of 12, including shipping in the US.

[CD05001CIA]

Bill Fox still has a few sets of the upgraded Bosch injectors, I believe. They are more than $17, maybe less than $33, and brand new and work perfectly.

Oh now, come on, Harold isn't the final last word on everything. But for Harold.... HIS BETTER HALF IS!

[LappingLuke]

Hm looking back thru my records Alex put the 4 hole injectors on it around May of 2016 which comparing to other records just before means these injectors have under 30k miles on them. Maybe something else is up or maybe I should just have them tested...hmm

[jimmythefish]

Hi Luke,
30K and almost 6 years ago, maybe consider some other reason. Consider checking spark plug wires and coils. Have the TBs been rebuilt? I know your MAFs have been rebuilt ����. Injectors would be a consideration if the car sat for a long time and maybe poor gas quality fouled some of them, otherwise that is low mileage and short time for trouble.
James

[LappingLuke]

Jimmy I feel the same way. Might be something else afoot but I will have to think really hard about what the missing piece is at this point. Here's the roundup of everything I've had to do to the car since Jan 2021...

Rebuilt DKs (Dragon840)
New fuel pumps (Dragon840)
Rebuilt MAFs (Injection Labs)
Mated electrical connection for #3 injector (yes, LOL)
12 BKR6EK plugs
CID sensors both banks (genuine BMW)
Verified 12 plug wires resistance (wires and distributors relatively new prior to my purchase, dragon840)
Verified both banks fuel pressure regulators appeared to work correctly

So as far as fuel, air and ignition the fundamental requirements for engine operation, I feel like I have covered it pretty close... I might need to smoke test the intake or something but dragon840 did the top end reseal on this engine not all that long ago as well and the plugs being a little wet on inspection tells me there probably isn't a vacuum leak. Non-car people (my fiancee for example) wouldn't be able to detect the misfire at idle (but I verified it using the dollar bill tailpipe trick) and the engine has perfect manners under load so whatever is wrong, its only *barely* wrong. I just wanna get that last 1-2%!

[Max Lumens]

IMHO- Calculate how many times your injectors fire in 100,000 miles. IIRC it’s around 70 million cycles each. And recognize that there’s no such thing as a rebuilt injector. Since they’re hermetically sealed, they can’t be opened up in order to replace components. All that the “rebuilding” vendors do is clean them and replace screens and o-rings, then sort them by flow by picking thru the pile for a batch with similar results. They have still cycled many millions of times and whatever wear has occurred is still present.

[jimmythefish]

Hi Luke,
I am certainly not the one to solve this, however, I am just going through my checklist when I was solving the issues with my 850….unfortunately still a work in progress….long story.
I would assume if Dragon850 did the intakes (he is the man!) , he probably did valve covers and set the timing too? Have you done any computer diagnostics, INPA, to check the values…that might give you the best information on what is needed.

Also, I did not see coils on your replacement list, are they original?…they do fail over time as well….could be a good “maintenance item” to change anyway if original.

[01BMWs]

I had my injectors cleaned instead of buying new for my 540. I think the cost of cleaning and new o-rings for all 8 was the equivalent to 1/2 the cost of new injectors. 5 injectors increased more than 4% each, over 20% cumulative.

InkedInjector cleaning receipt_LI.jpg

[LappingLuke]

Thanks for sharing the data. Curious what symptoms you experienced that lead you to send them off and what improvement you realized after install.

[CD05001CIA]

Thanks for sharing the data. Curious what symptoms you experienced that lead you to send them off and what improvement you realized after install.
...
Mated electrical connection for #3 injector (yes, LOL)

The "didn't get the connector seated" thing plagues all of us at one time or another. Don't feel special.

[LappingLuke]

My car still misfires at idle, throws CEL for lambda regulator stop and shows full negative adaptations on both banks in INPA. I've verified or replaced virtually everything that affects engine controls, yet this is still an issue with fueling. I've come to realize my car has BMW injectors 1731357 which crosses to Bosch 0 280 156 346. These have a 162cc/min flow rate vs the stock 152cc/min flow rate. Is that difference enough to cause issues? From reading some other threads, it sounds like the OBD1 controllers have pretty limited ability to adjust back to stoich in the face of less-than-ideal conditions.

[Timm]

Yes, pretty little adjustment and a change of 6% would cause havoc!

[LappingLuke]

Thanks for the confident feedback Tim. Having done pretty much everything else imaginable at this point I think I need to get back with Bill and take him up on his suggested injectors.

[LappingLuke]

Interesting that others have talked about running 17lb or even 19lb injectors on otherwise stock M70s with no mention of idle manners except stinky exhaust...thats quite a bit more even than the 15.4lb I have now vs 14.5lb stock. I ordered a set of 14.3lb Bosch injectors from Bill basically hoping at this point that I have failed/leaky injectors on both banks....

https://www.bimmerforums.com/forum/s...s-17-and-19lbs