Misfire on E85

[Sgottlieb]

Hey guys

I have a strange problem ever since I have switched to E85.
I get a misfire at around 4000 rpm and about 19-21 psi of boost in 3rd gear also in 4th gear so pretty much any high load application. But 3rd gear is when the problem starts to happen.
My car is a SF5 forester with a link g4 ecu running a flex fuel sensor, five-o motorsport 1200cc injectors, aeromotive fuel pump, VF37 turbo, exhaust etc. Fully dyno tuned for the flex setup and MAP based tuning.

This miss only happens when the ethanol content is high. When running 98 or a lower ethanol content like 40% the miss doesnt happen.

Things I have looked at:
Changed spark plugs initially I was running heat range 7 now im running 6's on a standard gap which helped a little.
Changed my dwell times which has also helped a little.
Changed fuel pumps: from a walbro 255 to an aeromotive
Changed fuel filters
Changed my MAP limit
Checked for leaks
Changed the VAC/Boost line to the fuel pressure reg from side of the manifold to centre of the manifold.
When it was on the dyno the tuner tried to advance/decrease timing and also the same with fuel
Tried a different coilpack
Looked for boost leaks etc

Next is to look at changing the rocker cover gaskets and spark plug gaskets as my rocker is weaping a little.

Any help on this would be much appreciated. Next it will be heading to mechanic/tuner for more testing. Just wanted to see if I could sort out this issue before it has to sit in a workshop as the dollars tick up.

Thanks guys

[jaydece]

Simon? off side topic? you running the aeromotive 340lph???

I was running it until I read this on there site:

WARNING: If you plan to run E85 fuel you must be prepared to install proper filtration, and maintain it as frequently as every 10 run-hours. If not, Aeromotive does NOT recommend you the use of E85 with the 340 Stealth Fuel Pump. Aeromotive’s new product warranty assures the purchaser their 340 Stealth Pump will be free from defects in material and workmanship for one year from the date of purchase. Fuel pump failure caused by clogged/blocked fuel filters is not the result of any defect in the pump itself, and is not covered under this warranty.

http://aeromotiveinc.com/tech-help/frequently-asked-questions/faq-340-stealth-fuel-pumps/

point 9

unlike the DW65c which is covered under warranty with e85 fuel use...

back to your misfire issue? does your car come with AVCS?

what afr targets are you hitting when it does misfire? have you tried leaning/enriching it up to see if the misfire increases? or decreases?

are you using the oem setup coil packs?

is the misfire coming from a particular cylinder?

[dr20t]

As Justin said check fuel pump for lean out. Chef your wiring too

Failing that, change plug gap down to 00.28. If that doesn't work, get a set of spec c coils from rising sun Subaru. You're probably getting spark blow out.

Mick

[Sgottlieb]

Simon? off side topic? you running the aeromotive 340lph???

I was running it until I read this on there site:

WARNING: If you plan to run E85 fuel you must be prepared to install proper filtration, and maintain it as frequently as every 10 run-hours. If not, Aeromotive does NOT recommend you the use of E85 with the 340 Stealth Fuel Pump. Aeromotive’s new product warranty assures the purchaser their 340 Stealth Pump will be free from defects in material and workmanship for one year from the date of purchase. Fuel pump failure caused by clogged/blocked fuel filters is not the result of any defect in the pump itself, and is not covered under this warranty.

http://aeromotiveinc.com/tech-help/frequently-asked-questions/faq-340-stealth-fuel-pumps/

point 9

unlike the DW65c which is covered under warranty with e85 fuel use...

back to your misfire issue? does your car come with AVCS?

what afr targets are you hitting when it does misfire? have you tried leaning/enriching it up to see if the misfire increases? or decreases?

are you using the oem setup coil packs?

is the misfire coming from a particular cylinder?

Yea read that about it. Just have to see how we go haha
Nah unfortunately no AVCS Justin. Um im pretty sure its around the 11.8 -12 AFR. Cihan tried to lean/enrich etc to find out why it was happening. Unfortunately the link wont show me which cylinder it is. Standard coil pack.
Wouldn't have thought there would be a problem with the stock coil pack on E85 as im not pushing that much power?

As Justin said check fuel pump for lean out. Chef your wiring too

Failing that, change plug gap down to 00.28. If that doesn't work, get a set of spec c coils from rising sun Subaru. You're probably getting spark blow out.

Mick

Has been happening on bot the walbro and now the aeromotive? Also when the misfire occurs the AFR doesn't change or maybe it cant react that quickly?

If I change the plug gap to 00.28 will that affect driving when I am forced to run 98?
I have been thinking of spark blow out only think is that I would have thought the standard coil pack is good for something like 300kw or more?
Thanks for the responses guys

[jaydece]

I would try what dr20t mick is suggesting? easy test.....spec c coils or something better / equivalent?

As a safety measure? maybe compression test and leak down test the car? one less thing to worry about...

[Sgottlieb]

Alright I think gapping down would be the next step. Is 00.28 in inches obviously? so .7mm gap? im pretty sure thats my standard gap size?

[dr20t]

Sorry that was supposed to read 0.028"

Stock is 0.032 I think?

You could even gap down a little more but then you risk losing low rpm power/ torque

Just play around with the gap first before changing coils

Which plugs are you running? Try copper plugs not platinum with e85.

*Edit* - Also - the dwell time can only be played around with to a limit (irrespective of ecu changing) because the actual hard wiring of the coil packs will limit you - or so I've read.

With my setup I went with the spec c coil packs which are higher intensity discharge and dwell is lower from factory for spec c's.

*Edit 2* - one more question - have you checked the actual clips on the coil plugs? The electrical connectors sometimes break and a loose connector on one of the coils could be causing your issue.

[Sgottlieb]

Alright gapping is the first thing I'll try. Yep using cheap coppers as I've heard they give a better spark?

Yea have checked all clips and sanded the connection etc.
Really hoping that the change in gapping will solve my issues.
Thanks Mick

[dr20t]

Good luck

Please keep us updated as I'm keen to hear your findings

[Sgottlieb]

Cheers

Yep definitely will I've got some heat range 7 plugs that I might gap and try out? Or should I try standard 6's again?

[dr20t]

I reckon gap the 7's and see

[Sgottlieb]

Sweet. Will report back

[Sgottlieb]

Alright guys! Success!
Regapped the plugs to 0.610 as the ones that were already in there were at .7.

The car is idling better too and no noticeable loss of torque but thats just what I 'feel'.

Thanks guys really appreciate all the help.

Car now goes like a cut snake.

So gap is 0.610 on a heat range 7 plug NGK copper

[jaydece]

Alright guys! Success!
Regapped the plugs to 0.610 as the ones that were already in there were at .7.

The car is idling better too and no noticeable loss of torque but thats just what I 'feel'.

Thanks guys really appreciate all the help.

Car now goes like a cut snake.

So gap is 0.610 on a heat range 7 plug NGK copper

Xcellent!!!!!!

Great advice from mick as per usual

[dr20t]

Great result mate

And good pickup on the gap between 6 and 7 heat range