Misfire already

MikeB · December 27, 2012, 01:12:38 AM

So I grabbed my MSD DH and setup some pids to go and log the Flex. I've gotten on this thing a few times, but tonight I got on it and heard audible knock followed by a misfire on cylinder #3. I drove around until it got out of limp mode and eased into it. No issues. Got on it a couple times with no issues. Hit it hard one more time and got a code for random misfire. I will swap out the plugs this weekend and move the coil on #3 to another cylinder, but I'm worried that this is fuel related. I will check with my powertrain warranty to see if injectors are covered, but if not, how hard is it to replace one?
Also, I saw 9psi at WOT and my WB EQ ratios were at .75 - .8 the times when there was no knock / misfire. They are right around 1.0 while cruise. Am I really reading 18-19:1 AFR? or am I supposed to multiply EQ ratio by stoic and not divide? If that were the case I'd be 11.0 - 11.7.

EcoPowerParts · December 27, 2012, 08:01:15 AM

Quote from: MikeB on December 27, 2012, 01:12:38 AM
So I grabbed my MSD DH and setup some pids to go and log the Flex. I've gotten on this thing a few times, but tonight I got on it and heard audible knock followed by a misfire on cylinder #3. I drove around until it got out of limp mode and eased into it. No issues. Got on it a couple times with no issues. Hit it hard one more time and got a code for random misfire. I will swap out the plugs this weekend and move the coil on #3 to another cylinder, but I'm worried that this is fuel related. I will check with my powertrain warranty to see if injectors are covered, but if not, how hard is it to replace one?
Also, I saw 9psi at WOT and my WB EQ ratios were at .75 - .8 the times when there was no knock / misfire. They are right around 1.0 while cruise. Am I really reading 18-19:1 AFR? or am I supposed to multiply EQ ratio by stoic and not divide? If that were the case I'd be 11.0 - 11.7.

Yes the gas is usually that bad but just in case take it to the dealer, the injectors are covered under the warranty.
You will be seeing 11.4ish at WOT and cruising will be 14.7 even under part throttle from what I've seen so far. The DI setup allows it to run LEAN at cruise and part throttle, way leaner than expected.

MikeB · December 27, 2012, 09:18:11 AM

My Flex already has 77K miles on it, so no factory warranty. The place I bought it from has a powertrain warranty til 100K. What I realized is that the problem only happens if I jump on it at a real high RPM. If I get into it at anything under 5K it is fine. That almost leads me to believe it is either an issue with the factory tune or maybe spark getting blown out.

According to my DashHawk, my Wideband EQ ratio was right at 1.0 while cruising. It was at WOT where it would drop to .75 - .80 and stay there. I read on a forum that you calculate AFR by dividing 14.67 by the EQ ratio. There is no way that the motor would even run that lean at WOT. If my multiply the EQ ratio by 14.67 I get a AFR number that makes sense.

MikeB · December 28, 2012, 12:33:27 AM

Update:

So I went over the Flex today and found a couple things. First, the spark plugs were the newer style and looked good, but were gapped between .038 and .040. I went ahead and threw the Autolite XP5364's in (gapped at .030). The next thing I noticed was what I consider too much oil residue and pooling throughout the IC pipes. I saw a drop just before the throttle body and a bunch of residue there. I noticed some in the pipe coming off the rear turbo to the IC. When I pulled the inlet on the rear turbo it was pretty dry, I didn't bother with the outlet since it faces straight up. I pulled the inlet on the front turbo and it had some residue. I pulled the outlet on the front turbo and quite a bit of oil drizzled out. At this point I'm suspecting the CCV is sucking a good bit in. So I cleaned out what I could and put it back together.

So I fire up the car and drive around. I already notice more throttle response and it is just smoother. I hammer it a few times and it pulls harder. The DH shows that I'm solid at 20 degrees of timing with boost around 11.5psi at the top of the gears. Long high gear pulls show AFR starting and 11.7:1 in the beginning and it richens up all the way to 10.7:1 at the top of the gear where the boost is at its highest.

I was not able to get it to misfire, however I was able to get a couple random shudders here and there on my second drive. I was not monitoring knock (not sure which PID), but I'm sure that's what it is. The AFR seems stable, but the timing would drop from 19-20 to 10 (sometimes lower) for a couple seconds and then everything would recover. Based on that, I'm guessing that this is not a bad injector or plug / coil type issue as the problem would be consistent and not completely random. I'm guessing that the motor is sucking in some oil and if enough hits a cylinder at once it will cause detonation.

So at this point I'm going to get my catch can on the CCV, get some seafoam in the next gas tank, clean out the IC pipes the best I can, and seafoam the motor. I will keep an eye on things for the next couple weeks and see if oil is still pooling. If so, I will work on getting the dealer to replace the turbos using my powertrain warranty.

MikeB · December 29, 2012, 11:06:29 PM

Update:

So I see that the PCV has some kind of catch can / filter device and that's cool, but I still can't get over the fact that there is a straight tube from the other breather to the inlet pipe. With the crankcase pressure under boost and the vacuum being pulled from the turbo inlet I'd bet lots of oil gets sucked in. We decided to take a trip up to Flagstaff today, so I quickly grabbed a catch can I had laying around and ran some hoses to it from the valve cover and inlet. So far so good. I hammered it several times up the hill and no shudder. No knock. Timing and boost stayed steady. So we'll see if that fixes it.

EcoPowerParts · December 30, 2012, 03:42:04 PM

Do you have a link to the catch can? I should probably do that on my car as well. Can you take some more pics of where you attached the lines from the catch can to the intake/valve covers.
Thanks!

EcoBrick Bob · December 30, 2012, 08:10:49 PM

RE. : Catch Can...

I asked that question back in 2010 when I bought my Brick.

Ford built in a catch can in the back valve cover, that catches the breather oil and lets it flow back into the engine, which is what I do (pour it back in) in my G8's that have catch cans that I installed.

On the front of the engine, there is a plastic hose that goes between the valve cover and the front turbo intake, that could possibly blow some oil.

Several of us have installed a vent filter on the valve cover. And then we put a rubber cover plug on the other end on the inlet piping to the turbo. If anyone needs me to take a pix... I would be happy to do that tomorrow.

MikeB · December 30, 2012, 09:37:02 PM

I will have to see what kind it is and get back to you. I had it laying around for a couple years and someone gave it to me. Its a nice one though. Just take the line off that goes between the front valve cover and the front turbo inlet tube. There is a nipple on each end that you can just clamp a hose onto. Just run a rubber hose from each end to a port on the catch can.

If the motor is under boost, the turbo inlet is going to be sucking a lot of vacuum and all that oil vapor and splash will go straight in.

The Turbo Buicks have a similar setup. They block the inlet tube and put on a valve cover breather as well, however with the lack of crankcase evacuation, the end result is blown rear main seals over time. That's why I opted for the catch can. I use a LS1 electric smog pump on my GN that runs off a boost activated switch.

MikeB · January 10, 2013, 01:17:45 AM

Update: After the tune I have the #3 misfire again and it is repeatable at WOT. Since I swapped plugs and moved coils, I'm assuming that I have a fueling issue. Since it is #3 over and over, should I replace the #3 injector?

EcoPowerParts · January 10, 2013, 08:18:59 AM

Have you verified your findings with Torrie? Also I would try adding some E85 to your fuel and see if it disappears. There's a station on 46th street & Chandler that has it - Valeros. To start off I'd try 1 gallon to every 5 of gas that equals 93 octane.
http://www.intercepteft.com/calc.html

MikeB · January 10, 2013, 09:57:29 AM

I'm going to email my log to Torrie and see what he can find. It seems like something caused it to go lean. Adding E85 means that AFR at WOT is going to have to get richer. Right now he is commanding 11.7:1, which seems a little lean to me. Anything leaner than 11.4:1 in my GN and I get knock. That is with meth injection though.

EcoPowerParts · January 10, 2013, 10:26:16 AM

E85 will let you run leaner, won't take long and you'll know within 10 minutes if it made a difference. Our gas is just THAT BAD, my F-150 EB had a ton of problems with the 91 tune just because of our gas, I'd throw a 93 tune in it and E85 but my wife would have problems mixing so I just leave it stock.

MikeB · January 10, 2013, 11:15:15 AM

I'd rather just work around our gas. Besides, adding E would require you to add more fuel since it has less BTU's. If you add 25% E85 to your E10 mix, you get about E22.5. This increases your octane to 93, but stioch AFR changes from 14.63 (straight gasoline) to 13.36. If you multiply that by the standard .8 EQ ratio you get 10.7:1. So really you would want to richen your fuel mixture to handle the different fuel and add timing for the added octane.

E10 likes around 11.2:1 at WOT. This is what I run on my GN. If I hit 11.4:1 or leaner I get knock. I know, different animal but still. I was able to run 11.7:1 no problem with straight gas.

MikeB · January 10, 2013, 11:17:19 AM

Torrie sent me another tune with 11.17 commanded. I'll log that and see if I still have issues. I will also monitor fuel pressures this time around and look for any drops.

turbodave · January 11, 2013, 07:56:30 AM

Quote from: MikeB on January 10, 2013, 11:17:19 AM
Torrie sent me another tune with 11.17 commanded. I'll log that and see if I still have issues. I will also monitor fuel pressures this time around and look for any drops.

Good Mike!! As you and I are quite familiar with by now, anything leaner than 11.4 on a forced induction WOT run is going to be too lean on straight gas (no meth). Throw meth at it and you'll need to tend into the 10.9 range.