Check engine light flashing at high RPM

[Epetes]

I have a 2005.5 S4 with about 105k miles on it. I usually drive it pretty tame and am pretty easy on it. I have noticed though if I put in sport mode and really lay into it the check engine light comes on (flashing). Of course when that happens I lay off of it and just when I am about to pull over the light will go away (after about 5-10 seconds). The light stays off from that point on. Here is a copy of the one scan I did after this happened last time. Has anyone else ever had this happen or have any idea what would be causing this problem? I have never had it happen when I am not in sport mode. I'm researched the codes and am seeing that fuel injectors seems to be a similar theme among them. Looking in my Bentley manual I see that testing the fuel injection system and actually getting to the injectors themselves seems like quite the job and the testing requires special tooling.

17819 - Secondary Air Injection System; Bank 2
P1411 - 002 - Insufficient Flow - Intermittent
17831 - Secondary Air Injection System; Bank 1
P1423 - 002 - Insufficient Flow - MIL ON
17537 - Fuel Trim; Bank 2 (Mult)
P1129 - 002 - System too Rich - Intermittent
16559 - Fuel Trim; Bank 2
P0175 - 002 - System Too Rich - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - - Intermittent
16689 - Cylinder 5
P0305 - 001 - Misfire Detected - Intermittent
16692 - Cylinder 8
P0308 - 001 - Misfire Detected - Intermittent
16691 - Cylinder 7
P0307 - 008 - Misfire Detected - Intermittent
16687 - Cylinder 3
P0303 - 001 - Misfire Detected - Intermittent

[q_dubz]

Lol getting to the injectors takes like 1 min, it's just a pain to pull them cause the o-rings get stuck.

Anyway flashing CEL is immediate and constant misfiring. Check ALL your plugs. Swap coil packs from left side of engine to right and run the car again and see if the miss moves.

And no one say SHIT ABOUT SOME DAMN CAM ADJUSTER until the simple test have been completed first!

[q_dubz]

Also check block 032 and see what your fuel trims sit at for me.

[Epetes]

I'll check the 032 block tomorrow and let you know.

I'm glad to hear about the injectors. I just took a quick look in the manual and the 1st three steps for removing them are 1) remove residual fuel pressure, 2) drain coolant, and 3) remove intake manifold.

I'm new to this engine and to the S4 so I have a lot to learn. Thanks

[q_dubz]

pull fuel pump fuse. start car and let it die. Pressure is gone. disconnect fuel feed. unbolt fuel rails...pull HARD AS HELL AND *EVENLY* spray injector bases with WD40 and let it sit prior to pulling...

[kevinye77137]

Lol getting to the injectors takes like 1 min, it's just a pain to pull them cause the o-rings get stuck.

Anyway flashing CEL is immediate and constant misfiring. Check ALL your plugs. Swap coil packs from left side of engine to right and run the car again and see if the miss moves.

And no one say SHIT ABOUT SOME DAMN CAM ADJUSTER until the simple test have been completed first!

Its probably your cam adjusters. Gotta pull the engine or its donzo

[jakeoboy67]

might be a longshot, but I experienced about the same thing 2 years ago.
there was some power loss at high rpms , but it became way worse in the following days.
no codes for injectors or timing. . .
new spark plugs -no change
the misfires did NOT follow the coils as I moved them around

the next day I got left stranded on the side of the road with a engine running on 3 cylinders.
no codes except for misfires/SAI insufficient flow

the culprit : both cats were falling apart and restricting the exhaust progressively worse.

[Epetes]

I took it out for a drive starting with a cold engine and here are the readings once it reached operating temp. I drove for about 15 minutes. I drove normal until the engine was warmed up, then switched it to sport mode once and hit the gas. Once I hit about 4800 RPM the light flashed. A couple minutes later I was in regular drive mode and I downshifted until I got to about 4800 RPMs and it came on again, so as I was thinking, sport mode doesn't make a difference. I then parked it, put it in neutral and went up to 5500 RPMs and didn't get the light.

'032
Adaptation (Idle) Adaptation (Partial) Adaptation (Idle) Adaptation (Partial)
Bank 1 Sensor 1 Bank 1 Sensor 1 Bank 2 Sensor 1 Bank 2 Sensor 1
% % % %
0.2 9.4 0.6 -6.3

I also cleared the codes prior to this test drive and this is what popped up after the drive. The coolant fan is unrelated (I know what that one is about).

6 Faults Found:

18354 - Control Module 1 for Coolant Fan
P1946 - 002 - Defective
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 -
16692 - Cylinder 8
P0308 - 001 - Misfire Detected
16690 - Cylinder 6
P0306 - 001 - Misfire Detected
16691 - Cylinder 7
P0307 - 001 - Misfire Detected
17819 - Secondary Air Injection System; Bank 2
P1411 - 002 - Insufficient Flow

[kevinye77137]

First I would buy redline fuel system cleaner and see if that works to clean out injectors. Then switch coils around on each cylinder. Replace spark plugs while you at it since its not that expensive or difficult to do. also take a look of the small vacuum three way split lines and see if there is a crack

[Epetes]

First I would buy redline fuel system cleaner and see if that works to clean out injectors. Then switch coils around on each cylinder. Replace spark plugs while you at it since its not that expensive or difficult to do. also take a look of the small vacuum three way split lines and see if there is a crack

That sounds like a good plan to me. Since I live in the middle of crap hole North Dakota I'll have to order the plugs and wait for a few days. I'll hopefully report back next weekend. I am just go ahead and order the fuel injector o rings/pintle caps and have them cleaned too since I don't know a lot on the history of this engine. I think I'll also do the JHM intake spacers while I'm doing all of this.

I haven't looked at the plugs and I just bought the car a few months ago so who knows how many miles they have on them. Hopefully it ends up being that simple.

Thanks for all the suggestions so far.

[Epetes]

I replaced the spark plugs and swapped the coilpacks from one bank to the other. I then took cleared the codes from the week of driving while I was waiting for parts (which included 5 codes on the fuel system being too rich and too lean). This time when I floored it went to about 5500 RPMs before it shifted and one the way down the light came back on flashing. When I scanned it I only had one cylinder misfiring. It was #6 which appeared in one of the scans before.

The intake spacer kit didn't come complete so I am waiting for the remaining parts and then I'll clean the injectors and go from there. All of the plugs looked pretty decent but I changed them anyways.

I'll report back once the injectors are checked out.

[QIKRNU]

Check out http://www.mrinjectorparts.com/ . They do cleaning/servicing as well. I got an injector rebuild kit for < $40 shipped.

[Epetes]

I finally got around to working on this (my wife had foot surgery so I've been pretty slow at getting anything accomplished). Anyways, I am amazed the car even ran. I found about 5 intake bolts on the passenger bank of cylinders loose (less than finger tight). The vacuum line behind the oil filter was either not connected or was hanging on by a thread. I ended up cleaning all of my injectors and checking flow. They all look good. I also replaced the pintle pins and orings. I figured the loose intake bolts were going to be the culprit for sure but alas, they weren't. I test drove it for a few miles last night and it seemed to run with slightly more power but again when I stepped on it I got the engine light. Two cylinders were misfiring but nothing about the fuel system. So I cleared them and swapped the coilpacks on those cylinders that were misfiring with cylinders that weren’t misfiring again. Then I ran it again and of course got the light. When I scanned it this time I got misfires on the same cylinders plus fuel issues again. Here is what I got today…
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 -
16690 - Cylinder 6
P0306 - 001 - Misfire Detected
17536 - Fuel Trim; Bank 1 (Mult)
P1128 - 001 - System too Lean
16555 - Fuel Trim; Bank 1
P0171 - 001 - System Too Lean
17537 - Fuel Trim; Bank 2 (Mult)
P1129 - 002 - System too Rich
…so now I am wondering where to go from here. I don’t want to start shot gunning parts at it due to how expensive these parts are. If it is this dreaded cam adjuster wouldn’t I be getting codes specifically related to the cam? Any more suggestions?

[Epetes]

I have been doing some reading up and I am thinking I might take a look at the cats as Jakeoboy 67 mentions. But, does anyone have a way to inspect the cam adjusters and other common failing components without heavy disassembly (like a borescope - which I have access to), or some other way to confirm for sure before going to the extent of pulling the engine?

[Epetes]

I should also mention that I swapped injectors on the cylinders that were throwing the misfire code routinely with the ones that never did and it didn't make a difference so I am reasonably certain at this point that it is not an injector issue. Also the fuel pump sounds healthy but I do wonder if it could be on it's way out. Now I am routinely getting codes for too rich and too lean on both banks and the check engine light will come on and stay on within about 10 miles of driving. The check engine light still flashes when I hit about 5000 RPMs under load (from the misfires).

I can not hear any of the misfires and I can't hear any chain slapping or anything like that.

[q_dubz]

Your cel is flashing for the misfire, that's it.

Now it seems to have isolated to cyl6 after unplugging and swapping everything around. I'd venture to say you have a bad connector contacts or wiring leading up to the connector. Remove the red plastic shielding and inspect.

As for your cam adjusters it would be an all the time misfire and all of the failed bank's cylinders. But you can always check the readings with vcds it's one of the measuring blocks between 90 and 100 IIRC.

One thing you can try is take cyl6 and tighten the plug gap up to around .030, if the coil pack is doing a poor job due to wiring then a tighter spark gap will lessen the strain on it.

[Epetes]

I'll check over the wiring. There are a couple of connectors where the previous owner broke off the little lock tabs so I might as well replace all of those to ensure they are getting locked on. With the screws holding the harness in place they feel pretty solid but I should definitely take care of it before jumping to other conclusions.

It hasn't always been six. Since I have changed the plugs I have scanned about every 15 or 20 miles of driving and out of my scans I've had 8 scans and here is what I have had. It seems to me like whatever is making bank 1 lean is possibly creating the misfires but it’s interesting that bank2 is rich half the time too (and lean once). I was planning on getting piggies from JHM sometime in the distant future, do you think I should push that forward and see if it is the cats getting backed up that is causing all of the mixture problems and my lack of power? I’ve never driven another S4 for comparison but if I compare it to acceleration videos on Youtube, it is nowhere near as fast as it should be.

P0300 – Random Misfires – 6 times
P0305 - #5 Misfire – 2 times
P0306 - #6 Misfire – 5 times
P0308 - #8 Misfire – 1 time
P1128 – System too lean, bank 1 – 7 times
P0171 – System too lean, bank1 – 7 times
P1129 – System too rich, bank2 – 4 times
P0175 – System too rich, bank2 – 4 times
P1138 – System too lean, bank2 - 1 time

[Epetes]

I'm updating this so anyone researching it in the future can see what the final fix was. The left precat was half blown out on the back side (front side looked great) and those pieces of the precat blew back into the main cat and plugged it up. I fixed that problem and all of my issues went away. I took it for a 15 mile test drive last night and it ran amazing, far better than it has ever ran since I have owned it. All fuel trims are now between -1% and 1%.

Thanks for all the help and suggestions.