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Mon Feb 23, 2004 12:37 pm

I just had a set of injectors cleaned and the results surprised me: I was expecting horrible pre-test results after years of sitting idle but either Bosch engineering prevailed or the injector cleaners I've been using have been working. Everyone has seen the gas tank photos. Luckily the fuel filter and pressure regulator (which is still icky) kept the sludge away.

I had one leaking o-ring and only fair spray pattern on all injectors. After the cleaning, the spray patterns were restored to normal (vast improvement) and the injectors all flowed within 1% of each other (slight improvement). Based on my exprience with fuel injector cleaners they seem ineffective compared to ultrasonic cleaning but I still think there is some value to them. On the jap car in the family it's a wonder tonic: the pinging at high rpms goes away immediately. On the bus the effect is a little less noticeable (can't rev as high?) although there is an apparent octane boost you can feel because it goes away when you refill the tank.

I would hazard a guess that the store bought additives are good for keeping residue buildup at bay but there are limits to how much they will improve the spray pattern. At $6+ for a bottle of Techron concentrate per oil change I figure that it's more cost effective to get them cleaned every couple of years simply because the techron won't cure o-ring leaks, clogged inlet screens and restore the spray pattern 100% which is key to atomization of the fuel.

We'll have to see what mileage increase if any the cleaning results in after the engine goes back in the bus. Even with a mere 1 mpg increase that would recover the cleaning costs in less than 600 miles at todays insane gas prices.

I used Cruzin Performance in MI for $11 each. It's the best price and their service is excellent. The two well known shops, Coast Fuel Injection and Marren Fuel Injection both wanted $25-30 per injector. I did find a local place called Ole's Carb that said they'd do it for $75 but they wanted to see the injectors first so I lost confidence in them and passed (they were more expensive anyway). Just mentioned it if you live near San Bruno and can drop by.

Mon Feb 23, 2004 2:39 pm

ratwell wrote:
or the injector cleaners I've been using have been working.
<snip>
Based on my experience with fuel injector cleaners they seem ineffective compared to ultrasonic cleaning.

I can't figure out if this is an endorsement to continue with the Techron treatments or go straight to ultrasonic cleaning for my CIS system.
Would an ultrasonic cleaning perhaps cure a leaky injector?
Colin

Mon Feb 23, 2004 3:40 pm

Amskeptic wrote: Would an ultrasonic cleaning perhaps cure a leaky injector?
I have no experience with K-Jet or cleaning those injectors. All I know is from books and looking at my friend's Rabbit once in a while (not much). Bus injectors work on a completely difference principle: pulsed vs. continuous.

If crud was keeping an o-ring from sealing under X bar of pressure, the cleaning could dislodge it, maybe not. You'd best ask someone who cleans them for a living or ask a clubmember.