Injector question.......
 

Now maybe 7 years ago, my car was having a problem going up hills. To make a long story short, I found out that it was because I needed to do a Liqui Molly diesel purge on it.

Now maybe 2 years ago (5 years later), my car was having problems going up hills, I did a diesel purge on it, and the car ran fine again.

Now the car is having problems going up hills again, but it's only been 2 years since the last diesel purge. Since this time between needed cleanings is shorter, I wonder if my injectors need replacing? Maybe mine are just worn too much or something. I found that I can get the injector nozzles really cheap, like $10 a piece or something. Would that fix my problem, or should I just do another diesel purge? I know diesel purge is a cheaper way to go, I just didn't know if new nozzles would make a robust change in power or not.

1991 300d, 256,000 miles

I am speaking of vehicles that only use diesel fuel.

Personally, I am not sure what the diesel purges did to supposably fix the issues in the past.

Lots of diesel engines out there that never have any sort of purge done on the other than occasional additive in the fuel tank. When there is the slow down you are speaking of what I was taught is that it is most frequently a fuel supply issue.

Things that effect your fuel supply:
Plugged or plugging filter
Plugged or plugging fuel tank screen
If the fuel tank venting system is plugged
The fuel supply lift pump needs to be rebuilt
A problem with the fuel pressure relieve/overflow valve not holding the proper pressure (The spring inside gets weak over time, and some have plastic parts the warp or fall apart.
Crappy contaminated fuel

Unfortunately, there is no easy way to check the fuel supply pressure.

I would replace the fuel filters and see if the sutuation changes.

Have you ever adjusted or removed the ALDA? That's what finally cured my sluggish 91.

Nothing about injectors, huh?
 

I'm surprised nobody said anything about injectors.

No Alda removed
 

No, I never removed the Alda and I don't know how to adjust it.

They are not something I know cause the symptoms you mention.

One I missed was if there is an issue from the accelerator pedal to the throttle arm that keeps the throttle arm from going into the position it is supposed to be in that will slow you down.

What’s your process for doing the purge?
Are you replacing both filters afterwards?

The only "purge" I have ever done is when I change fuel filter is I fill it with ATF before installing it. ATF is 'extremely' high in detergents & it does work. I do this with both my MB & Blazer.

Probably because injectors won't cause the problems you're having. They'll cause noise, they'll cause smoke, they can cause rough running, but not low power.

You have a fuel starvation issue or a boost problem. You mention nothing about ever replacing the spin-on fuel filter. Low power is a classic symptom of one that's beyond time for replacement.

Process for the purge
 

There's basically only one way to do a purge. Disconnect incoming/outgoing fuel lines, put them in the diesel purge, and start the car. You don't have to use a full bottle. Half bottle will do about the same job.

Afterwards, change the filters.

Filters are replaced on regular basis
 

I replace the filters on a regular basis. I think the big one is supposed to be changed every 12,000 miles and the small ones 3x in between, so every 4k miles.

This is true. However in the interest of being thorough, it’s worth asking.

Being a 91, have you checked all the vacuum lines? The turbo wastegate is vacuum controlled instead of intake pressure controlled like the om617.

When I had my w124, I followed the vacuum controlled wastegate change over to pressure by following GSXR's write up on how to do that. I also did the EGR delete.

Seems if the injectors are the problem...
 

Purging them would have no effect.