Running water/meth injection? Check your FPR spring! Carnage inside.
 

With many/most modified FD guys running some kind of injection at this point I'm posting this here for more visibility. Taken from my recent build thread post:

https://www.rx7club.com/build-thread.../#post12241979

Public Service Announcement to those running Water/Meth Injection:

.....be aware that all of that nice fluid that steam cleans your internals and helps prevent detonation also gets into every single UIM/LIM sensor and boost reference hose :shocking: :crzyeye:

Not my usual quality of pictures, but this carnage was found inside my Aeromotive FPR..... they were kind enough to send me extra new springs if anyone else is in need. I recommend adding this to your list 'Annual FD Checks' for those running this setup. Also a consideration to run a filter inline much like our factory setup on the MAP sensor.

It's worth noting that at WOT and 20 psi boost, rather than the 62ish psi i normally see, on a third gear pull the car hesitated until I quickly got out of it. Peak hold gauges showed--- 48 psi peak fuel pressure. Not cool at these boost levels. Happily idle is fine and vacuum is the same. If anything with the new spring and freshly set 43.5 psi of base fuel pressure, the car runs stronger and better than ever. Score one for RxParts apex seals, water injection, and an engine built by Goodfella's Garage :bubrub: :D

Looking at the details and picking apart what might have happened: I've had this setup for around four years or so, so the spring gradually corroded, weakened and then finally snapped. My FPR is mounted down low and further downstream on the back of the secondary fuel rail. If mounted up high on the front of the UIM as is the old school method, maybe the issue may not gotten so bad so quickly. Props to FortyOunce for his Sherlock Holmes aid in figuring out what exactly happened :icon_tup:

https://www.rx7club.com/attachment.p...1&d=1514464903

https://www.rx7club.com/attachment.p...1&d=1514464903

https://www.rx7club.com/attachment.p...1&d=1514464903

shame they didnt offer a stainless steel spring especially with injection and e85, I wonder if e85 users should also inspect?

get em coated before reinstalling..

coated with what though? anodize?

whichever provides the least effect on spring ratings if any... electroplating.. anodizing.. powder coating.. etc

you would think some oil in the fuel would help with that

thinking out loud here but do water guys "winterize" their cars? what keeps everything from freezing up if you dont store the car in a heated space?

^wiper fluid is what's typically used in place of water :icon_tup:

Thanks for the tip, guess I better check that out. The FPR in my FD is located on top of the motor, so it will be interesting to see how it looks.

Thanks for the heads up. Mine is on the firewall, highest point. But running a weak mix about 25%. Might be worth putting some sort of moisture trap inline?

when dormant in an unheated garage wiper fluid can def freeze, it has frozen on my pickup on certain occasions and I drive it all winter

Wiper mix is crap due to dyes and other junk in it. It might not be distilled water.
I run distilled water with pure meth, 50-50. Only safe way to go.

But it is your choice to be less safe.

If you get the -20 winter stuff it shouldn't be a problem. I don't drive the FD in freezing winter weather of course but have never had an issue in unheated garages.

I've run wiper fluid consistently since about 2003, never had a single issue at all. I also had the opportunity to tear down my old engine that I had sold to a guy. He promptly did multiple burnouts on an empty gas tank a few months after buying the short block. Zero issues inside the engine due to dye, suspect undistilled water or any assortment of junk. Just warped apex seals :)

Same thing happened with my SX Performance FPR but I was NOT running water. The corrosion was not as bad and I found it before the spring broke. The FPR was about 8 years old and had been sitting for about a year so I attributed it to the humid climate of the gulf coast.

Agree. I'm normally just distilled water with an in-line filter, and the car is in a heated space over the winter. But out of an abundance of caution, and b/c I pull it outside occasionally to work on something else, I fill up with straight -20 washer fluid in late fall. Never had issues.
"But it's your choice to be less safe" :)

hmm would this also happen on a stock FPR?

I'm wondering the same thing.

I am curious; how much of this was caused by water/meth injection and how much is caused by moisture in the fuel lines due to ethanol in the gasoline?

GoodfellaFD3S does your FD sit for long periods for "winter"? Or is the weather too damn nice out your way? :nod:

The reason I ask is because I know a lot of classic muscle car guys out here that avoid gas with ethanol like the plague; due to its ability to absorb water and corrode lines throughout the winter months.

I guess time will tell on my build as I only run ethanol free gas.

Just my 2c, Tom

there are guys who have been running only e85 for years and years now, on many different platforms.
I would think we would have heard more about it by now if it were a cause of concern and companies would start developing more e98/85 or even e10 safe products
maybe the issue really is the fact you are running water through the system?

Would there be a way to plumb the FPR boost reference line upstream from the water injection?

Don't believe so, the injection needs time to atomize and the boost reference has to be post-TB.

As commented above, I have experienced corrosion but not failure. In service for about 8 yrs and sat for about 1 yr. Only driven 3,00 miles a year- NEVER injected any auxiliary fluid. It would be nice if some other folks would pop the top off their aftermarket FPR's to see if there is a difference in surface corrosion between the water and non-water users.

I replaced this one in 2011. It has been sitting idle over 5 yrs needing a motor. I'll open it up for a look when I start working on revival of that FD to see if how it looks.

Jack, mine looks way more Fubar'ed than yours bud. Does this mean I win the prize :rofl: :D

Could just spray some silicone lube in the reference port time to time?

Since the OEM FPR is sealed, there is no chance to inspect it. Makes me wonder about the suitability of this mod over the long haul, although the benefits that it can have are well known that would all be negated when the engine blows due to low fuel pressure from a compromised fuel pressure regulator spring.

Would this be a problem with just distilled water I wonder? Methanol is very corrosive, for sure, so if only water was used would this be a safer condition long term?

Where's the reference, downstream of the injectors? Fuel or additives affecting the spring, has me a touch skeptical I must say, unless the diaphragm is slightly perforated....hot/cold condensation taking place I could believe.

The mention of anodised steel springs along the way - that's a no - unless there's an aluminium spring out there somewhere. Electroless nickel maybe, but cheaper to replace springs every few years!