Well.....bump that idea.....This is so frustrating.

 

I didn't read the whole thread, just the last couple posts and your first post.

I agree with mrfred on both counts.

Although, I have a question...what turbo are you running 27psi to redline? That doesn't sound like a stock turbo. You may be at your limits for the Walbro on E85 and that may be part of the problem.

For the surging, you can control it with ECU or EBC boost control. You may also want to try running a little more timing during spoolup, as less timing will simply cause boost to build earlier in the RPM range. Again, I wonder what turbo you are running here, as some are more prone to surge than others and need the anti-surge cover.

Edit: Just saw your sig, stating you have the green.

I did some quick calcs, and you should be able to get down to about 11.5 or so AFR on a maxed out green (old green) on E85 with a Walbro 255, assuming 14V at the pump. In reality, with stock wiring, it's most likely much less, closer to 12V. So, you may simply be approaching the limit for your pump. But, it's also possible that your pump isn't up to the task and needs replacement. Maybe do a rewire or test the voltage you get under WOT if you can.

 

I've encountered program corruption several times. Start with a clean slate and eliminate any possibility of that rearing its ugly head.

Consider a fresh fuel pump and upgrading the power wiring (direct to battery) and add a dedicated ground. Doing this can increase voltage at the pump by 0.5-1.0V, which is absolutely significant in your case. It sounds to me like a fuel delivery issue, although it shouldn't be at your power level (possibly failing pump or inadequate voltage). You need to be able to check the FP while under load.

The surging is likely a separate issue, so treat it as such.

 

Yeah...it is a green. It spools extremely fast so long as I am above about 3500rpm to start a pull. If I start the pull at say....2500 I get the cut out at the same location every time....at about 3000-3100 rpm. After that the car pulls like mad. Boost at this point is in the 18psi range.

For example...in a 4th gear pull at 3500 it will have 0 boost. By 3900 it is at 30psi then by 4100 it is at 33psi. It then tapers slowly down to 27psi by 5600 and holds this 27 to redline.

 

Well...I re-scaled the timing and fuel maps to give better resolution from 100 load out to 300 load (v7) by incrementing it by 10 load each cell. Timing is very conservative. The cut out condition is happening consistently below 3500 rpm and load can vary. Timing is almost always 1 degree.

For the first time I was able to make this happen at a throttle position other than WOT. Further aiding to the puzzle.

When looking at a log of a pull I can see that load drops considerably when the cut out happens. Fuel injectors are not bothered by it at all. There is a brief rich condition that occurs at the same time further proving that the injectors and fueling is not the problem.

So...I believe it has to be something electrical causing the problem.

Just for the hell of it I took off my APS bov and gave it a good rebuild/lube/sealing. I performed a little leak down test on it and it appears that the seal is starting to give way. It looses pressure over time.....albeit very slowly. Upon reinstall I tightened the adjustment a little further.

I also adjusted the WGA arm slightly looser. It was 2 1/2 turns tight. It is now only 1 1/2 turn tight. The looser actions may allow for smoother boost control.

For the inability to get the AFR to go lower, I believe I found the culperate. When I was doing the BOV reinstall I noticed that the hole for the valve cover vent was open on my perrin suction pipe. The line was just laying in the engine bay. I have reconnected the line as it should be. (Cross my fingers this works)

AFRMAP does match nearly perfectly for all conditions other than above 100 load. It is off by as much as 3 full points at peak load. (9.6 AFRMAP vs 12.7 WB)

 

After reading your description of the stumbling phenomenon, I just realized something...

I've experienced a part throttle stumble that occurs only with E85 and not gasoline. In my case, it's more or less takes place during tip in throttle, but it sounds similar enough to what you're reporting that I feel you should know about it. Two things I've observed about this is (1) it occurred most frequently when using a plug heat range one step colder than factory, and, (2) it sometimes reoccured when the plugs became tired.

I recommend buying an inexpensive set of BPR7ES plugs, and making a swap with no other changes. In my case, reverting to the factory heat range resolved the issue immediately. Why? In some cases, the colder heat range plugs apparently operate insufficiently hot to self-clean at lower loads with the lesser combustion temps of E85. This could be further aggravated by cams with considerable overlap.

If that doesn't clear it problem, bypass the HKS unit.

If it persists, change back to gasoline and check to see if the problem continues.

Definitely swap the plugs. I wouldn't be surprised if that cleared the issue.

 

That's good advice Ted. Not many people realize that E85 may run better with stock heat range plugs due to E85s cooling effects. Although I am only on a stock turbo, I run 30+ psi and I run the stock VIII iridium plugs and haven't had much problem at all. Only the coldest winter days (well below 0) running E85 did I have some breakup at higher loads.

 

Now to search for some NGK plugs. Seems none of the auto parts stores near me carry them.

My plugs are nearly new NGK BPR8EIX.

Guess it is worth a try.

 

Try Advance Auto Parts.

 

Dang guys, never thought of running the stock heat range plugs with the E85... that completely skipped my mind... Only a half tank of 93 left, then back to the sweet nectar!

 

If you are running the plugs I sent your they are br8eix, so they are 1.5 steps colder... get the bpr7eix, Advance or Autozone won't show those in the system, you will have to try Napa, Carquest or Oreillys/Shucks. I think the stock number is 4055...

 

Advance has the BPR7ES.....you have to cross reference the part number as 5534.

Guess I am off to the parts store.

Oh and thanks Freddie....I couldn't remember which ones they were.

 

Yes advance has the copper cores, and I could get them to pull up the bpr7eix in the computer but for some reason they were unable to get them, this was in Washington State and here in Florida now...

 

I've been running stock heat range plugs for a couple years now. Runs much better on E85 than the colder plugs.

 

Ok...just picked up a set of NGK BPR7ES (5534). I gapped them to .020. Once the car is cooled down I will throw them in and hope for the best.

Thanks to all of you. I appreciate your input. I only have a few weeks left to enjoy my car, then it is off to the land of sand. Oh joy.