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Symptom:
Intermittent '4-cylinder like power' on acceleration around 30 mph, 1800-2500 rpm.
Will then clear up after 10-15 seconds and suddenly boost feels great and *generally* stays that way (although there are times of felt power loss that occur randomly). No codes in ECU or TCU.
Logged conditions during occurrence:
TPS 80-90%
Boost 11 psi
LTFT 0.78%
IAT under 90 deg F
Timing 0 to -1
Fuel pressure 76 psi
Replaced in last year: Plugs, MAP sensor, O2 sensors, IAT sensor, Knock sensors, Cam and Crank sensors. Fuel pumps done a few years back. NOTE: I recently found that the adapter harness wasn't installed by the dealer, connectors looked good, installed harness and fuel pressure seems good. 76 psi which then drops down to around 60 psi under WOT (keeping in mind my 550cc injectors).
What am I missing? Timing is what I'm most concerned with, but just about every log out there is under full boost pulls and focused on higher rpms. I'm in 3rd or 4th gear at low rpms so I'm not sure if timing close to 0 is normal...I have STAR and have been running a bunch of their component tests but it seems everything is checking out. Any thoughts on things to try or log? Do our cats ever go bad and cause intermittent exhaust blockages without any noise? I only have primaries left after putting in an x-pipe.
Timing seems real low. If you could show a spread sheet of the log it would help a lot more and this way we can see what's going on before and after.
The sampling rate of our OBD2 drives me crazy, since this only lasts for so long. Here's a quick one from my drive into work an hour ago, the acceleration/issue happened near the end of the log, timing numbers before seem pretty normal to me.
Monitor throttle position sensor for "glitches". Fuel pressure gauge taped to windshield; monitor for fuel pressure drop during periods of low power. Best to you on solving this. Please post findings.
Edit: knock sensor malfunction?
Monitor throttle position sensor for "glitches". Fuel pressure gauge taped to windshield; monitor for fuel pressure drop during periods of low power. Best to you on solving this. Please post findings.
Thanks, I definitely will. I did the fuel pressure drive yesterday and the gauge didn't waiver, stayed right at 76 psi (and I did get it to act up on me too).
I did get a TPS glitch logged once, it spiked to 100% under light throttle pulling away from a stop, but the consensus I was given is that it was normal due to programming when the supercharger engages and the bypass valve closes to equalize pressure in the supercharger. It timed with the clutch engaging and given my recent logs showing good boost and a somewhat steady, mostly open TB (which is stock) I'm not sure trying another would do any good (but it's one of the few things I haven't tried either!).
And new knock sensors last month, I had that same thought. The STAR test for them is to stab the throttle and see if the voltage jumps above .3v or something like that. I did that, and they basically didn't respond, so put new ones in.
I also need to see why I have no load ranges learned beyond n1 in the sensor adaptation, I've tried the 'sensor rotor adaptation' twice now and it doesn't seem to take. To get 50% load and 2100rpm in 3rd gear I basically have to powerbrake while driving at 45 mph to load up the motor, which is annoying and really gets the brakes hot
Last edited by GinDistiller; 06-24-2020 at 08:02 PM.
The sampling rate of our OBD2 drives me crazy, since this only lasts for so long. Here's a quick one from my drive into work an hour ago, the acceleration/issue happened near the end of the log, timing numbers before seem pretty normal to me.
Can definitely see when you hit the peddle and boost your timing just goes to 0 or 1deg.. Thats really strange. I had a tune which was made for altitude and then when I relocated to sea level I would never see over 10 deg timing, tried everything to get that increased, and only thing that sorted it was a new tune for the new pressure the car was in.. Sorted. But I don't think this is your issue here. Curious to learn of your findings
OK, more info as I narrow down a direction to go with diagnosis:
We're in agreement the timing is the culprit of my problems. As far as I know, timing is affected by: IAT, Knock, Coolant Temp, Spark, RPM, Load, MAP readings, and Fuel Injection. All of these things are consistent for me, Coolant and IAT temps normal, boost matches TPS and actual throttle input, and fuel injectors and plugs are newer. Fuel trims seem good, and still no codes present.
So to me that leaves the engine thinking, or detecting, detonation or knocking. It do not feel any kind of misfire, and hear no audible knock. Knock sensors are new and reactive.
In STAR, I looked at the 'Smooth Engine Running' test, and according to WIS values over 3 m/s^2 indicate a cylinder fault, and I have random cylinders going over that value, some go as high as 10 at times, some in negative 3-5 values, it's all over the board. When looking at the fault counter screen however, all cylinders show 0 faults all the time. It does say a prerequisite of the smooth engine test is having the sensor rotor adaptation learned, which it does not appear mine does, so I'm not really sure using that test is accurate. I can't seem to get mine learned however - all I see on that screen is n1 in load rage 2. I've reset it, followed the directions to learn by holding over 2100rpm at 50% engine load for 30 seconds (which requires me standing on the brake while driving, I don't see any other way of achieving this next to finding a ski slope to drive up!), still says 'NO' on the learning screen.
I'm stumped - is there something preventing rotor adaptation and causing the car to revert to a 'safe' map of timing? Should I ignore the sensor stuff and assume that maybe there is detonation happening for some reason?
I'm going to see if anyone in my neighborhood has a compression test kit I can borrow, at least eliminate the last mechanical component I can think of. I also checked injection times on both banks and they match, so that should rule out a timing chain jumping a tooth as well.
Here's the sensor rotor adaptation screen, I've seen one other post asking about it but never saw a response. And one video online showing another E55 with more values filled in. This hasn't changed in over 1k miles for me. Normal, or concerning?
Last edited by GinDistiller; 06-25-2020 at 03:20 PM.
OK, more info as I narrow down a direction to go with diagnosis:
We're in agreement the timing is the culprit of my problems. As far as I know, timing is affected by: IAT, Knock, Coolant Temp, Spark, RPM, Load, MAP readings, and Fuel Injection. All of these things are consistent for me, Coolant and IAT temps normal, boost matches TPS and actual throttle input, and fuel injectors and plugs are newer. Fuel trims seem good, and still no codes present.
So to me that leaves the engine thinking, or detecting, detonation or knocking. It do not feel any kind of misfire, and hear no audible knock. Knock sensors are new and reactive.
In STAR, I looked at the 'Smooth Engine Running' test, and according to WIS values over 3 m/s^2 indicate a cylinder fault, and I have random cylinders going over that value, some go as high as 10 at times, some in negative 3-5 values, it's all over the board. When looking at the fault counter screen however, all cylinders show 0 faults all the time. It does say a prerequisite of the smooth engine test is having the sensor rotor adaptation learned, which it does not appear mine does, so I'm not really sure using that test is accurate. I can't seem to get mine learned however - all I see on that screen is n1 in load rage 2. I've reset it, followed the directions to learn by holding over 2100rpm at 50% engine load for 30 seconds (which requires me standing on the brake while driving, I don't see any other way of achieving this next to finding a ski slope to drive up!), still says 'NO' on the learning screen.
I'm stumped - is there something preventing rotor adaptation and causing the car to revert to a 'safe' map of timing? Should I ignore the sensor stuff and assume that maybe there is detonation happening for some reason?
I'm going to see if anyone in my neighborhood has a compression test kit I can borrow, at least eliminate the last mechanical component I can think of. I also checked injection times on both banks and they match, so that should rule out a timing chain jumping a tooth as well.
Here's the sensor rotor adaptation screen, I've seen one other post asking about it but never saw a response. And one video online showing another E55 with more values filled in. This hasn't changed in over 1k miles for me. Normal, or concerning?
To take possible detonation out of the equation, try adding some octane booster or like 100 octane fuel or something.. Basically get your fuel rating higher and see if it has any effect on your timing at WOT.
I've tried the octane booster with no change. Just did compression test, pretty much 165 across the board, cyl 4 was 155 and a few were closer to 170 but overall well within acceptable ranges.
However - being that my plugs aren't that old, they looked a bit 'rough' coming out for the compression test, and I passed a thread earlier that mentioned counterfeit NGKs. I bought these on Amazon in December from a 3rd party vendor, and the threads don't look quite right! Going to the Oreillys after lunch to compare against a Genuine as they have them in stock. Boy would I be happy if it was just crappy Chinese spark plugs!
GOOD LORD. It was the spark plugs (knocks on all the wood in case some re-learning issue comes back). They were good fakes, it took comparing them to the real ones to really see the difference but missing dimples on top, an extra hash mark on one side of the 'Japan' marking and the threads were lower quality. These were the NGK Iridium 1 step colder plugs.
Never trust 3rd party Amazon vendors to send you genuine things! I'm just glad I caught it before one catastrophically failed and took out my motor.
I now have trouble keeping traction in comfort mode with moderate throttle, and that's how it should be! It must have just been poor enough ignition at times to screw with the timing tables, but not bad enough to set misfire codes.
Awesome, good find and catch.. Glad you back in the game and no serious damage caused!!! Have fun and thanks for reporting back. Always good to have history and diagnosis here for future references...
06-24-2020, 03:56 PM
and thanks for reporting back. Always good to have history and diagnosis here for future references...
