Help: E85

[BTLD_LS1]

Hey guys I decided to make the change to E85 in my car and I have no idea what went wrong. I have a dyno jet wideband commander installed and have been running the car in open loop as I have not installed a bung for the wideband yet.

So I changed the tune to reflect 9.8:1 A/F and loaded it in. Fired the care up and let it warm up to about 180 where it normally runs. the wide band was reporting 16:1 A/F. I tried to change the air fuel ratio via VCM Scanner and no change what so ever while changing the number reflected on the narrow or wideband. I then tried changing the spark advance using VCM Scanner using the absolute, plus, and minus options, no change again to the commanded spark shown. However I was able to check and clear DTC codes (Cam position sensor code)

I drove the car down to the end of the street and back and just goosed it a little to see what it would do and the narrow bands went rich like they should and the wide band reported about 11:1 A/F.

I am using the Weiand LS intake and just replaced all the gaskets. I have the brake booster running off the back of the intake, the other port plugged. On the front of the intake I have one port plugged the other going to the emissions crap on the drivers side. I have a breather on both valve covers and the fresh air port on the tbody going to the second port on the passenger side valve cover.

Do you guys think maybe its a vacuum leak causing the lean condition at/off idle? Any ideas on what would cause the tool in VCM Scanner to not function like they did? Is there anything that jumps out as glaringly wrong with my tune?

I have attached my tune below and the log file. Sorry I forgot to stop logging so between frame 1800 and 2600 there is no data.

One more question, I'm running an xpipe on the car, should I install the wideband at the X, or on one side or the other, and if a specidfic side, is there a preference for tuning?

[Ls1c5vette]

I would not tune until you get a bung in for the wideband, I would not trust the readings you have now.

[BTLD_LS1]

I welded the bung in 2 days ago, about 6" back from where the xpipe joins the header and im still getting crazy lean readings. I also installed 2 new narrow band sensors and enabled LTFT and its locking at plus 25 at idle and still lean, not sure WTF happened. The car was tuned in really well on 91 always 14.5-15 on the wideband at idle and pretty much idled between 1300 and 1400 with no surging or hunting like a lot of cars with big cams, but now it is all over the place and will hunt / surge up to 500 RPM sometimes....

[murphinator]

when you say you changed afr you mean engine>fuel control> stoich afr ?

[BTLD_LS1]

correct

[Ls1c5vette]

Have you tried to add some to your VE table? Are you SD or do you have a MAF (I would pull your tune but im at work)?

[BTLD_LS1]

Thanks for the replies. I am still running a MAF, but I found the main issue. I was backing out of the driveway Sunday morning and the car totally died on me. Checked at the rail and had no fuel. So I pulled the fuel filter and still no fuel. So I pulled the pump out and the short rubber line from the pump to the outlet was split almost the full length. Replaced the line and now my fuel trims are back in line.

I'm still having a huge issue getting the car to idle correctly tho. If I set the idle screw to where the car will idle when cold (1100-1250), once it warms up the idle creeps up to about 2000. If I set the screw once its warmed up so that the IAC is reading about 180 and idling in that same range, then let the car cool down, when I start it back up, the IAC will max out and the car will not idle without opening the throttle manually to about 2-3%

[SSUte01]

With a cam like that your IAC is going to run out of useable range pretty quickly, not too sure how extreme that may be in this case, but I wouldn't resort to drilling the blade unless there is no other option. I have run into this more than once on pretty big cammed setups.

Set your hot idle so that idle voltage is somewhere around the 0.55V mark ie not too high, otherwise you can run into other issues and aim for a reasonable IAC count when hot and no A/C, somewhere around 30-60 so you the IAC has room to close to prevent hanging or similar.

Now use afterstart enrichment adder which just adds to your OLFA to add more fuel which will lower the requirement for air (desired idle airflow, richer will lower this - try it) from the IAC, I would thinking yours will need an EQ Ratio of around 1.3 (maybe more or maybe less, use the adder to achieve this) for initial cold start up and taper down to 1.0 (ie so no adder) at hot start.

You will have to tweak the delay and decay settings until you're happy. I usually start somewhere around 100-200 camshaft revs for delay at cold and more or less nothing at hot start and fairly gradual decay.

This will give you more head room at the cold end of the IAC range (well technically not more room but less requirement - same result). I am deliberately being general and not giving step-by-step with numbers because each setup will vary and very little to be learned from that.

All the above is based on the assumption that your VE is accurate and RAF is sorted. You will obviously have to re-do the RAF if you are changing the blade setting, but you've already done this. Also in case you are bothering with it, forget about Closed Loop with your setup, unless you have different sensors or move them into their intended heat range and even then I am doubtful they'd cope.

So, even if you are not actually achieving Commanded AFR = Actual AFR during startup, don't worry, add more commanded fuel (not airflow model changes) until your IAC can supply enough air when fully open (310 steps) to sustain cold start up without using the pedal.

Hope that made sense.

An idle log of

- Engine RPM
- Desired Idle
- Dynamic Airflow (g/sec)
- Idle Desired Airflow (g/sec)
- DynCylAir (g/cyl)
- ECT
- IAT
- Idle Advance
- IAC
- Desired IAC (not essential)
- O2 Voltage (indicative of either rich or lean - doesn't need to be quantitative)
- WB (if you have it, it is very handy, but not essential if you've already nailed the airflow model)
- Commanded AFR
- STITs
- LTITs (P/N or Gear, whatever you are doing at the time)

That's about it all I can think of off the top of my head

Best of luck

[BTLD_LS1]

Thanks for the reply. I will try your suggestion.

The BBK throttle body I am using has 2 predrilled holes in the housing itself. The one on the left going to the fresh air for the PCV system and the center one being blocked off by the gasket on the backside by default. I have since cut the gasket out allowing for free airflow from this hole to the intake

[MikeGyver]

I put a F.A.S.T. 102 on my truck, and the airhole to the idle air motor was that small. I hogged it out as big as I could on the inlet and outlet sides. It still needs to be bigger for under +- 30°F starting, but at least the IAC start dropping now after the motor gets above 50-60° ECT. With the hole that small, IACs stayed at 310 until the motor was pretty close to fully warm. I'll find the pics and post them in a minute.

[MikeGyver]

Inlet before:
Inlet after:
Outlet before:
Outlet after:

[BTLD_LS1]

Wow I didnt even think about that thanks for the tip, Im gonna look at this as soon as I get home!

[Sherminator]

Wow, that cam is not doing you any favors power wise. That thing is way to big for this setup.

[BTLD_LS1]

no doubt I could make more power with a smaller cam, but I love how the car sounds and pulls up top

[Ls1c5vette]

Wow, that cam is not doing you any favors power wise. That thing is way to big for this setup.

I just noticed how big it is, thats serious duration, enough for a 454!!!

no doubt I could make more power with a smaller cam, but I love how the car sounds and pulls up top

LOTS more power on the table with a smaller cam

[BTLD_LS1]

I know you guys are purely trying to offer constructive advice, and I appreciate that, but the issue is not "why does my 10:1 motor with a cam for a 454 make 400 HP running rich?", its "why wont the POS idle all of a sudden?"

However, I followed MikeGyver's advice and looked into the inlet hole on the throttle body. The hole itself is not very large at all and I determined the advice provided to me by BBK on getting the car to idle was inaccurate at best. I was advised by tech support to cut out that area of the gasket to allow the air to bypass, however, all I was doing was bypassing the IAC, which explains why the damn thing wouldnt idle right now. I swapped the gasket out for an uncut one last night and opened the hole up slightly, as my small drill bit set only goes so large. I put everything back together and let the car warm up. I set the idle screw so that the IAC count was very low at idle and this seemed to help a little, however, the car will not start when cracking now without opening the throttle, but I think this maybe a result of too much fuel.

I have attached a couple log files, the tune and the config file, let me know what you guys think.

[BTLD_LS1]

Also, of note, around frame 1600 on the 'crank' log I began to drive the car around the block. You will notice the LTFT locks at -1.6, pretty much the same as on 91, with a command AFR of 9.82, but once I decel and idle at the stop sign, around frame 1800, the command AFR jumps to between 8.13 and 9.12 at idle.

Also another thing i noticed, but didnt log and will try to tonight, is when power braking the car between about 2800 and 3200 RPM the AFR goes crazy rich and the wide band gets pegged at about 11.8:1. However, while bringing it up through the RPM range, the AFR gets progressively richer in the 13.2-12.8 range until u hit that point and then it just bottoms out instantly, once u make it through there it goes back to about 12:8:1. Im waiting on an email from dyno jet that will *hopefully* contain a firmware for the wideband commander to make it read correctly when logging for E85 to make it easier to judge the AFR. Is this possibly the cross over point from using the MAF to MAP?

EDIT: looking at the tune I have the PE delay RPM at 2800 instead of the stock 3200, probably the reason that the car goes so rich there

[BTLD_LS1]

Actually I think I might see the problem, which is totally my fault, the LTFT shows to be disabled in the tune. I remember disabling them a while back when I had the wideband in the narrowband location. Im gonna enable the LTFT and reset it and see what happens.

Also looking at the tune. I have the target idle speed set at 1500 (????) in the tune, but it was commanding 1200 in park?

[BTLD_LS1]

Ok I think I got a good start on sorting out my idle issues. I enlarged the feed hole for the IAC to just over 3/8 of an inch and loaded the attached tune. the car fired up immediately without use of the throttle. Let it warm up and turned the idle screw out about 3/4 of a turn. car seems to idle pretty good in drive and in park.

Im thinking there is still something I need to change in the tune as the idle desired airflow and the Dynamic airflow should be equal is that correct? Also my LTFT on the 2 banks range from about 5-16% difference, do you think that indicates a possible vacuum leak on the bank 2 side?

I also tried adding about 8* timing at idle and the car idled much higher but also was adding about 14% fuel, am I better off with more timing and fuel or less timing and less fuel at idle?

Anything obvious that I should be looking at in my tune? Im using the same config file as above.

[Mr. 2008 SS]

E-85 tune,
1.Did you fix the idle problem?
2. Set the fuel table?
3. What reading on the wide band O2 in part and full runs?
4. What is your base timing and advance?
5. Was it diffcult to set up your base tune for E-85?
6. I am in the Norheast and I need to talk to some one with E-85 tuning experience.

2008 Trailblazer SS LS2, K@N, Flowmaster cat back AWD

Thanks,
Mr. 2008 SS