E85 Injector Build-up / Gunk

[n2xlr8n]

Originally Posted by Phatron

Yes.

The way u said it made it seem like You couldn't run pump because u would knock at 25psi.

Open map. Multiply injector scaler by 1.3, zero the wgdc...boom 5 second pump gas map. No more dirty Injectors.

Now, that's worth the money

Thanks!

S.

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[vicious_fishes]

is there an injector/fuel system cleaner we can just run through that will get rid of this stuff?

[choi0706]

Originally Posted by n2xlr8n

Great info, thank you.

Has anyone determined if the Lucas Safeguard E-85 product has PEA?

+1............

[Nuke209]

Originally Posted by Phatron

Yes.

The way u said it made it seem like You couldn't run pump because u would knock at 25psi.

Open map. Multiply injector scaler by 1.3, zero the wgdc...boom 5 second pump gas map. No more dirty Injectors.

and no adjustment for timing map

[wrxsubiemod]

That's a good question but your running 0 wgdc on a pump map to clean the injectors. Its a nice map for those purposes. The load cells should do most of the work I assume unless your running a huge waste gate spring. I wish I knew about tuning so all this is an assumption

[Phatron]

I should go back and edit all these posts....people are taking it as "this is how i tune cars"....it was just a suggestion for a simple pump gas map to put around on not in boost.

Nuke, what do you need to do to the low load timing? it really all depends on how the e85 map is setup.....but you can run craploads of low load timing on pump too....i was running 52* on my STi for 6 years on 91 oct. stock 06-07 WRX's run 55*.

If you're going to make a pump map you should just change everything anyway.....its not like it takes hours and hours to change the boost, timing and fuel maps over.....it can be done in several minutes.

My comments in this thread were just a simple solution for someone that really doesnt know what they're doing.....and obviously (at least i thought) not the way i do things or recommend people do things. If you do what i suggested in this thread and get into boost, then you're most likely going to knock like a mofo....especially if your switching to 91 oct.

[NoGraffix]

I'm worried that this buildup might be the cause of my issue. Ever so often I'll go to downshift into 2nd attempt to rev match and nothing. The rpm's simply wont climb and the engine makes a noticable misfire sound. I've ordered new plugs in fear that they might be the issue but the current ones look clean. I haven't had time to pull the injectors to check for any gunk, but I'm going to switch over to my 93 map this weekend and run a tank or two of 93oct through the system. I'll report back in a week or 2 with my results.

[kpluiten]

Originally Posted by arghx7

I went ahead and posted this on EvolutionM in their two big threads on this issue.

I am an engineer, and I have been following industry developments in alternative fuels. As I mentioned in an above post, GM had a production port injected turbo flex fuel engine all the way back in 2007. It was a Saab variant of the Ecotec engine family. Saab did extensive testing on a lot of boosted E85/Flex fuel issues and published some work on it. See Bergstrom, "The New ECOTEC Turbo BioPower Engine from GM Powertrain," 2007 and Bergstrom, "Alcohol Based Combustion Engines - Challenges and Opportunities," 2007. Deposit formation is one of the dirty little secrets of E85; another is pre-ignition.

GM found the exact deposit problems many of you are experiencing. I have read a lot of different ideas on here about the nature of the problem and I have read a lot of speculation about solutions for it. Here is what we know for sure about the deposit issue, based on GM's internal research.

Chemical Origins of the Deposits

The deposits primarily consist of "Poly Iso Butylene," or PIB, a cleaning additive in the gasoline portion of commercial E85 blends. As far as we know, the ethanol itself doesn't directly cause this type of problem with injector and valve deposits. This PIB additive was never designed for use in high ethanol concentrations.

PIB is designed to soften engine deposits, but below a certain concentration (by total fuel volume) it is actually counter-productive. What happens is that with insufficient PIB by volume, the normal valve deposits don't soften. The PIB actually combines with these normally occurring deposits and makes build up worse.

Running PIB-free E85 is basically impossible in a practical sense. GM engineers ordered special batches of PIB-free E85, but in the real world the E85 still becomes contaminated with PIB because the entire fuel refining and transport infrastructure has traces of it. Still, with this very low PIB concentration E85 deposits can still occur at similar rates.

A lot of people on here have speculated something along these lines.

Effect of Drive Cycle

Deposit formation is highly dependent on vehicle use and overall drive cycle. This whole issues is complicated, but aside from the makeup of the actual E85 blend, drive cycle is the #1 factor in these deposits.


Bergstrom, "The New ECOTEC Turbo BioPower Engine from GM Powertrain," 2007, Internationales Wiener Motorensymposium 2007, p. 29

On the left is a multi-hole type (not pintle type) fuel injector after 15,000 km running a GM in-house designed drive cycle to simulate major stop-and-go city driving. On the right is the same type of injector after 60,000km in a high-speed (mostly highway) drive cycle. Both engines were running the same commercial E85 blend in Sweden, consisting of 95 RON fuel and denatured ethanol.

Drive cycle variations may not explain absolutely everything but it is a reasonable hypothesis for why two vehicles running the same E85 blend can have such variability. This can also partly explain why somebody doing a lot of highway driving (rural driver or suburban commuter) who always runs E85 may never experience noticeable deposits.

Using Fuel additives and Normal Gasoline blends

There are a lot of fuel additive blends out there and they change all the time so I can't speak for all of the various formulations. What we do know based on GM's research is that PolyEther Amine or "PEA" , which can/used to be found in Techron products, cleans valve deposits but does not clean injectors with this problem. In fact, too much of fuel system cleaner could make the problem worse.



So how do we clean up the deposits if an engine is prone to them for whatever reason? Put "normal" gasoline blends in the tank and it will go away within 1 tank. You don't even need to pull the injectors.



Most of you already knew that. It's not really news; it just confirms with reliable sources what has been widely understood.

Conclusion

So yes, I didn't have any earth-shattering solutions to present, but I did clear up some of the mechanisms for this deposit formation. The deposits are caused by the gasoline portion of E85. The two biggest factors in deposit formation are the additive mix in the fuel and the way you drive the vehicle. Fuel system cleaner products are innocuous at best, counter-productive at worst. The type of injector or fuel system you run might matter some but they are not part of the mechanism of deposit formation.

So if you figure out that your engine is prone to these deposits, be mindful of stop-and-go traffic and put gasoline in your engine sometimes to clean it out.

Hope that helps.

Great information. Thank you. (I know this is an older post)

[SenorDucK]

Originally Posted by NoGraffix

I'm worried that this buildup might be the cause of my issue. Ever so often I'll go to downshift into 2nd attempt to rev match and nothing. The rpm's simply wont climb and the engine makes a noticable misfire sound. I've ordered new plugs in fear that they might be the issue but the current ones look clean. I haven't had time to pull the injectors to check for any gunk, but I'm going to switch over to my 93 map this weekend and run a tank or two of 93oct through the system. I'll report back in a week or 2 with my results.

how'd the 93 for a few tanks turn out?