Had injectors rebuilt and the engine runs worse? What's goin on!?
 

Had my injectors rebuilt at a reputable Bosch shop nearby in Worcester. Purchased NOS Bosch France nozzles from a forum member and had them installed to cure my nailing problem. Car has 200k miles and the injectors are original, so I figured what the heck.

Re installed and the car runs worse.
- misses on startup a few times (didn't before)
- smokes more at idle
- idles worse
- accelerates worse

Ran the car hard for a 100 miles on the highway with no improvement.

What the heck could be going on?

Didn't change anything else on the engine except the heat shields.

Thanks much in advance,
dd

PS Im having the worst luck with this thing!

I'm not sure about the french nozzles, but I know several people have not been happy with the Bosch nozzles.

That sounds like a tough problem to figure out. One possibility would be renaming the car. It could feel like and oddball in Boston. How about "Clam"?

Did you put the heat shields in correctly? Any chance you may have flipped one?

liet-
Heat shields are 100% in correctly. I took extra care since one of the old heat shields was not in correctly.

Car is from dallas/forth worth and still has its texas registration stickers on it, so I thought the name fit....must of been a bad choice :-/

But seriously, if a injector pops and sprays correctly, how can it be bad right off the bat?

Sounds to me like someone botched the rebuild. Those symptoms sound like bad spray patterns.

Sounds like the "reputable shop" is the problem here.

Had the pump timing ever been tweaked while running the old/bad injs?

Not by me. I have checked it using the drip method and determined it is close - within a couple degrees. My chain stretch is somewhere in the 4 degree range.

Ill call gthe shop today and see what the deal is.

I have had no other reports of the nozzles being bad, having had several other batches go out to people.

It would be good if the shop volunteered to set each injector up for you and show you the spray pattern. They should do this if you report problems.

Personally, I am aware that there are honest and dishonest people in the automotive repair business. Unless you really know the people you dealt with, then you don't really know what they could have done. For example, keeping your nice new French injector nozzles for themselves and subsituting Indian nozzles for your rebuild. That's a horrible thing to think has happened, and I mention it just as a possibility if you happen to open one of the injectors yourself for inspection. It could happen on purpose or by mistake.

I don't have the nozzles in front of me to look at, and can't remember if they have identification on them to let you be sure that your nozzles were used in the rebuild.

So, that gives you two avenues to investigate: Verify the nozzles and verify the spray patterns.

Otherwise I believe you should have reasonable confidence the nozzles I shipped you are good. I sure expect them to be as I have a reserve supply for my own cars.

Ken300D

Take the injectors back for another check. There is a very small possibility that someone tweaked the pump for individual bad injectors but not very likely. Did they check the old nozzles for spray and pop pressures before changing the nozzles?

I doubt they did this - I'm sure they just rebuilt with the nozzles I gave them.

Ill give them a call this afternoon.

Update
 

Took my injectors back to the shop. They invited me back into the shop to watch the pop and spray without me even asking.

Watched them pop and spray the five. Great pattern, and popped right at 135 bar. They're fine.


So...........who's got the RIV tool again? :D

Time for chain timing, pump timing, compression. My theory is the PO advanced timing to compensate for early popping injectors. So I need to set it back.

So yes, you CAN have your injectors rebuilt and your car run worse. Unless I have done something else stupid, which is certainly a possibility. But there wasn't much to mess up reassembling and I went really slow.

dd

Good luck, keep us posted.

Most injection shop workers know nothing about the type of injector in our cars. If you ask them what they are going to do to your injectors and they do not specifically mention "pintle holes", keep looking.

As I left I commented how I was being careful checking since they probably don't see these that much. The guys who rebuild them said 'you'd be surprised, I see them all the time'.

These guys seemed to know these real well. The proof is in the pudding, right? I mean if they popped and sprayed correctly, what else is there?

At the shop where I took mine, they would only test the old mechanical types. Like what many of us have.

Are your PC balls intact? If you still have the problem pull the GP's and verify that it is not a compression issue. Did you correctly torque (and not crossthread) the injector lines?

PC balls - all of them look good by the descriptions I have read.

Harbor Freight compression tester is enroute.

I think I have done the lines correctly. Certainly none of them cross threaded. Will take extra care in reassembly.

Thank you for the ideas - its gotta be something.

Maybe its time for the Marvel Mystery Oil down the injector hole treatment - I have many other thing to check before doing this, but maybe it cant hurt since the patient is open.

If you check and reset the injection pump drip timing. Yet engine still runs badly you may wish to check the milli volt output of each glow plug looking for any major discrepency. Swap glow plugs and injectors into the strange reading cylinder if one is indicated. .
If problem remains and compression across the engine is simular. Someone has probably tweaked the element on the pump or that specific element is defective in some way. Perhaps even just wear from use. If nothing else the careful testing will indicate the pump at fault or clear it. Also the increased pop pressures might be at the edge of what the pump is willing to easily supply on perhaps one element.
There is a slight chance if the problem is broken down to one cylinder you might be able to correct it yourself. There would be nothing really lost as otherwise the pump is on the way out to a shop for a check. If it proves to be the fault by test.

Thanks barry. I will check that out. Oh man, if someone tweaked the induvidual elements.... The paint has long since worn off I think. Specs of it are left.

I now suspect more than a few mechanics have quietly tweaked these old pumps over the years. The only problem I have is trying to decide what they used for a guide. Unless there was a serious knocking problem on one injector I can think of no other easy guide in their time. I always hoped they at least tried another injector first for the troubled cylinder.
There has been some limited success correcting one element at home. But if the glow plug voltages are all over the place and verified to be so with a known good set of injectors and fairly even compression across the engine. The pump needs service. All depends on what the milli volt spread is after all the variables are eliminated.
I have also suspected injection pumps not being in the best condition as a primary cause of low milage sometimes between simular models of 123s. Especially the 240ds. A reported 20 percent difference was a little too great for just general manufacturing tollerances alone I think.

I got to thinking what exactly is a known good set of injectors? It has to be a set where you can prove their output is pretty well identical to each other for the whole set at true operational speeds.
You know new nozzles have to kind of seat themselves or self lap in over a little time. The manually operated injector test stand does not cover all the variables as it is just a static test of the nozzle. Your running engine is the true dynamic test. I would run the rebuilt injectors for say 1000 miles and see if they settle down. On reflection this is the most probable senario in your case.
If not or you do not wish to wait you can do a dynamic test by moving all of the injectors to the same cylinder one at a time. They all should exibit the same milli volt output on that cylinder or the one or ones that do not are either off on dynamic pop pressure or leaking at dynamic run rates.
This is a test I suggested as a standard awhile ago for a suspect set of used injectors in an engine before sending them out. If all injectors produce the same voltage in the one cylinder they are all equal and there is no reason to send them out. This dynamic test is far superior to a manual test stand any day in my opinion.
Older ideals die hard even if the logic of the new is pretty sound. Only careful well thouight out application is really required for great accuracy. We as amateur mechanics usually have the time or will swap time for money as it is a hobby.
Again there can be a world of difference between an injector opening and closing on a manual test stand say at a five to ten times rate per minute and one opening and closing at hundreds of times per minute. It's by comparison like a static balance of a tire compared to a dynamic balance.

Barry,

Your ideas and thoughts make total sense to me. I also read up on the millivolt method and that makes a lot of sense as well.

I will check and correct overall timing, but I am not going to go overboard before a 1000 mile run in on the injectors as you suggest. That makes a lot of sense. I am interested to millivolt my GP's.

The diesel tech even stated that new an injector will pop at 135 bar, and used it will go down to the 120-125 bar. Of course this also has timing implications.

Is there one spot that describes your set up and where to put the test probes? Thats the only thing I'm confused about. Im guessing the GP relay harness area? What size condenser/capacitor did you use?

dd

The original erratic voltmeter readings were traced to the normal resistance in the engine grounds. If you ground the negative probe to the engine head instead of the negative battery terminal and the other or positive lead on the glow plug or it's contact in the wiring harness the problem is gone.
The milli volt thing will always be a good approach for certain problems when applied correctly. A large diesel mechanic could not function without the equivelent of being able to measure the exhaust temperature on any given cylinder. Even a general understanding someday will save an individual money and time.
This is a non destructive form of testing. Even just a great tool to unplug your glow harness and read all the individual cylinders once a year and record them. Therafter any change by any one cylinder you might want to quick check for a fault. Might just be a glow plug that has changed output values with age even. It's strong point is for tricky problems as an additional tool perhaps. At the same time checking out a set of injectors is well within it's sensitivity range as well.

Forgive me for asking, but do you see any leaks when the car has been run for a while (10 mile drive or so). Reason I ask is that I just changed my injector nozzles and didn't clean the housing out as well as I could have and the injector body leaks where the two pieces screw together. Also I notice wet looking prechambers. I get a rough start everytime with this because the fuel system looses prime. So... if you have any leaks this may also be a problem.

One other note on my last post... In the Haynes manual if you look in the symptoms area at the begining of the book it says that rough starting can be caused by leaking injectors.

I'd really clean out the mating area of the prechamber and injector and put a few drops of diesel on each before you torque them back in. There has to be NO leak in that fitting.

Thanks for the tips 777, Ill look into it when I reassemble tonight. I had a bit of a leak going on but I think it was due to my return line end cap leaking.

Spray volume, sealing and spray pattern are the most important. Once again, just because they claim to do a large volume of business does not mean they do anything right. Do your homework and quiz them before you let them work on your injectors.

The leak they are talking about is leaking past the needle seat into the combustion chamber ( effectively changes the timing ), not leaking out on top of your engine.