103 injector replacement--worth it?

[Joe Bauers]

I have a 1989 300SE with 123,000 miles that runs well. Would it be worth it to change the injectors? My only complaint about the car is poor fuel economy, which my MB mechanic friend says is to be expected, given the weight of the vehicle. He doubts that new injectors would add much in the way of either performance or economy. If I did decide to do it, I would handle the job myself, so there would be no labor cost involved.

Anyone here have experience with this? Your opinions would be appreciated.

Joe B.

[104.992]

Good question. I think that the correct, and only sure, way to determine if your injectors need replacing is to look at the spray pattern. This involves taking the injector out, activating it into a recepticle and observing the spray. (I do not how to do this with your motor)

[ejboyd5]

The enemy of good is better! Leave well enough alone.

[lino]

I changed the injectors in my W201 and it did make a difference. I had taken off each and every duel related item in that engine and either cleaned or replaced it, because I was that obssesed with making the car run perfect. I chased after a dream. My recommendation to you is to try something like this first:

http://www.autobahnpower.com/products.asp?recnumber=92


Here it is from their homepage:
http://www.bgprod.com/bgprofessional/bgproducts/autofuel.html

[S-Class Guru]

Replacing injectors worked to fix my complaints.
I bought the set aftermarket, for approx $120.
I had a slight cold-start problem, it stumbled and chugged on start-up unless you pressed the accelerator.
Also had a slight roughness in the warm idle.
Replacing the injectors cured both of these.
It's a '91 300 SE, had approx 110k when I changed them.

Gas mileage didn't improve, though; still struggled to get 20 mpg on the road.
It's that super low gearing - 3500 at 70 mph.

The job is really simple - just be careful loosening the metal fuel lines - I suggest a wrap-around end-wrench designed for these fittings.

DG

[deanyel]

If your car is running fne and starting fine there's really no reason to do it. I would wait for the first signs of trouble. When some of them start leaking down it will be hard to start cold and will then run rough for a few seconds as the pressure to all injectors evens out. The 103 motors have about the cheapest injectors going - if you shop around only $20 to $25 each. As S Class Guru says it's a very easy job - and then you're good for another 100k to 150k without having to worry about it.

[Joe Bauers]

All comments appreciated. Right now, it starts fine in the cold, though there is a second or two when it runs a bit rough. Might be having the first signs of leak down. I'll see how it progresses and decide what to do by spring.

Thanks again.

Joe B.

[Duke2.6]

Dump a bottle of Chevron Techron into the fuel tank on the next filllup and leave the injectors alone.

Duke

[wbain5280]

Big car, small engine, CIS injection, poor mileage. I get about 22 mpg in mine. My 96 Volvo gets about 22 with Motrinic EFI.

[C Holmes]

I have a '90 300 sel with 128k klm on it. I have the leak down problem as it starts rough but soon smoothes out. BUT I get 28mpg hwy and a good 25 screwing around. I am very pleased with the mileage. Maybe consider a tune up.