When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Bog in warm weather - ignition timing waaaay retarded
I have read a gazillion threads (on at least 4 sites) on what seems to be this very topic, with no real consensus as to what the cause is.
If this has been hashed out and definitively solved (i.e. works for everyone) already, forgive me and point me to the true solution. I have read of guys replacing all sorts of parts (mostly to no avail) and I do not wish throw parts at it blindly to find a solution.
Background: 2007 F150. Phaser lockouts installed, no tune. CEL lit with P0011 and P0021. These two are expected and are no big deal.
Since the lockout install, the truck has run fabulous. Truck is mostly used for around town trips and performance has been as good as expected.
Lately, once the engine gets to 19x° degrees and the outside air temp is higher than it has been and I have driven it around town for an extended period of time (read: high underhood temps), when accelerating from a stop, the ECM pulls a MASSIVE AMOUNT (to a max of around 10° ATDC at times) of ignition timing until it reaches 2800-3000, then it returns to a normal amount of advance and accelerates fine. At times, it will launch fine with a normal amount of advance only to retard the timing to stupid levels before you reach the other side of the intersection. I have also noticed that when these condition are met, the timing at idle will be low (7-9° BTDC) or somewhat irratic (10-20° BTDC).
This seems to be directly related to temperature and/or open/closed loop operation. When engine temps and OAT (outside air temp) is low, the truck runs fantastic, so I am going to rule out any sort of condition (such as clogged/melted cats) that would be present and constant during both modes of operation.
I have read the "airbox foam replacement" thread, so I checked my airbox yesterday. It appears to be in decent condition and I remain skeptical that an air leak around the filter would produce such a result.
As a possible additional clue to this puzzle, when I view codes with Torque Pro, there is a P2006 hiding in there. I say 'hiding" because this code does not show up with my Actron code reader and does not set a CEL. I don't know if this is a cause/result or even related to this issue. However I tend to agree with F150Torqued that this code is a bit strange since the CMCV's are connected (verified mine are still both connected) and move in unison. The ECM has no way to directly monitor right and left CMCV position individually so it would have to use other clues to trigger this code.
From reading, this P2006 code can have it roots in a MAF sensor problem of some sort so it may be the underlying issue with the bog/retarded ignition timing as well. Monitoring the MAF and IAT with Torque Pro however does not show any values that seem to be out of the ordinary in my opinion.
I am going to continue to monitor this issue and will try to update this thread with my findings.
Torque Pro screenshot while accelerating. Note timing at -3.5° (3.5° ATDC).
Last edited by BigBlockRanger; 04-25-2016 at 10:56 AM.
Drove to lunch, truck ran like a top, but coolant temp only got to 185° and the IAT was reporting sub 100° intake air. Idle advance was in the neighborhood of 12-15°. Really started to think maybe unplugging the MAF and plugging it back in may have fixed the issue, but it was not to be.
Driving back, it ran good most of the way until the coolant temp was in the 194° and the IAT was around 114°. Pulling up to a stop light I noticed the timing was bouncing around from 7° to 22° and all points in between. As soon as I started accelerating, sure enough, it was pulling timing back to negative values again.
This is very interesting, I posted the same or very similar symptoms earlier this month thinking I had a MAF sensor issue. I have since replaced the MAF and TPS with some improvement but not total cure. My issue started as the temps got warmer and I had taken a trip to Fla. Look at the Vacuum and see if there is something funny going on with it when the issue surfaces. I just learned about these apps and will be ordering a Bluetooth OBDII adapter soon so I can more intelligently look at whats going on. Keep us posted.
Drove around some on the way home this evening to see if it would do it again. It did.
I drove to a parking lot where I shut off the truck and then unplugged the MAF. I started the truck and initially thought it was going to run fine, but as soon as I turned out of the parking lot and accelerated, it fell on its face. I turned the corner and returned to the parking lot where I shut it off and plugged the MAF back in.
Truck ran completely different and did not pull timing. The rest of the way home (with IAT's in the 130's and ECT in the high 190's) it mostly ran fine. At one light it did the bouncing timing thing again, but as soon as I accelerated away it recovered and ran nice. One other time as I started to accelerate, it retarded the timing briefly, then jumped to normal levels.
Anyway, I am going to keep observing data streams until I hopefully find the one that is triggering this anamoly.
Today I learned to datalog with my Torque and it is quite interesting. I saved the files and then emailed them to my laptop and viewed them using www.datazap.me, which really works fantastic.
I was able to log both "normal" and "retarded" modes in the same log file. On the left side of this screenshot you can see that the bright green line that represents ignition timing advances when the throttle is opened and rpm starts to increase like it should. The truck runs great when in this mode.
Now, just to the right of the flat section you can see that when the throttle is opened and rpms starts to increase, for some reason the ECM pulls a ton of timing, retarding it to -5 degrees or more. This makes the truck feel doggy and sluggish.
The vacuum line is a calculated value from the ECM and it is interesting that once it kicks into retarding mode, the spike at initial throttle opening increases a good bit.
I guess I need to datalog more paramters so I can see a clearer reason why it suddenly goes from advancing to retarding.
This is really interesting, all the drop offs in timing seem to correspond to increases in throttle position, MAF level and the "calculated" vacuum. The vacuum should not go up like that until the RPM goes up substantially. It almost looks like the ECM is miscalculating. I expect to get my OBDII Bluetooth adapter today and will share anything I gather as well. I have noticed by letting off the throttle some it picks up acceleration, or if I hold the position for a few seconds it will pick up as though it has to catch up (or it could be the fact the RPM increases) I was hoping there was a vacuum sensor that might be clogged or slow to respond delaying the system responding to increased throttle. I wonder if the knock sensor might be causing the retard of timing?
Knock is one of the additional parameters I would like to log as well as throttle pedal position, throttle body position,vss and catalyst temp. I would really like to log commanded AFR or lambda, but those both stay at 14.7 and 1 all the time on mine, so I have to wonder if the PID in Torque is configured correctly.
Short Term Fuel Trims can be monitored to determine open loop and closed loop operation. (open loop they should be constant, closed they should be fluctuating) So I will add that to my logging.
You're already way beyond me technology wise, but my first suspect would be the knock sensor. I think its failing when hot. Keep us posted, I would like to know the outcome.
I'm about 97% sure this is an open loop/ closed loop issue. According to this, the ECU needs these 3 parameters to be true before it will switch to closed loop.
When the engine is first started, and rpm is above 400 rpm, the system goes into 'Open Loop' operation. In 'Open Loop', the ECM will ignore the signal from the Oxygen (O2) sensor and calculate the air/fuel ratio based on inputs from the coolant and MAF sensors, but mostly from a pre-programmed table in the memcal.The system will stay in 'Open Loop' until the following conditions are met:
1. The O2 sensor has varying voltage output, showing that it is hot enough to operate properly. (This depends on temperature)
2. The coolant sensor is above a specified temperature about 40oC/104oF.
3. A specific amount of time has elapsed after starting the engine. (some say around 700 seconds, but this could vary by model)
The specific values for the above conditions vary with different engines and are stored in the mem-cal. When these conditions are met, the system goes into 'Closed Loop' operation. In 'Closed Loop', the ECM will calculate the air/fuel ratio (injector on-time) based on the various sensors but mainly the O2 sensor. This allows the air/fuel ratio to stay very close to 14.7:1.
This screenshot is from a few minutes ago when I was sitting waiting to pick up my kid at school. Most of this is me sitting idling in neutral. Note that the timing is wandering a little, but is generally pretty consistent. Just after the weirdo spike (what the heck?) I put it in gear, held my foot on the brake (note the area where the rpm drops down) and the timing just goes bonkers. Once I put it pack in park, the timing stabilized somewhat. Weird stuff, but definitely interesting.
It gets even weirder. After I posted this, I turned on the O2 voltage log and both upstream O2's are showing zero volts for most of the log. Near the very end of this datalog, 1300 seconds after engine start, they suddenly start showing voltage. Maybe it was just an error in the datalog, idk. I'm going to do another log to see of they are working properly.
Last edited by BigBlockRanger; 04-28-2016 at 09:31 AM.
04-25-2016, 10:53 AM
Bog in warm weather - ignition timing waaaay retarded
