Phungalis

Hey fellow s2k owners, I hope some people on the forum can help me out. I have searched and tried many of the suggestions on this forum regarding misfires. The car only has 50000K (an 05 AP2) and suddenly started to get the "poof poof" sounds coming from the exhaust. As I searched this board, there are many suggestions as to how to narrow this down. I have tried many, and so far still have the problem. I will try my best to list what I have done in detail below.

Engine idles rough and exhibits a popping or poofing sound from the exhaust. If it is allowed to idle for 3-4 mins the rough idle will go away for another 2-3mins and return, the cycle will continue indefinitely. After driving the vehicle and coming to a stop at the lights the rough idle and poofing can be heard and also felt as the engine idles rough. If I drive again and then get a chance to pull over in the parking lot, the engine will idle rough until a few minutes have passed. The cycle then begins with the rough idle for a few minutes, followed by no rough idle for a few minutes as stated above.

Periodically a CEL will be thrown

I have responded to this problem by doing the following.

1. First codes thrown P0300 - Random Misfire, P0302, P0303, P0304 (Misfire on cylinder 2,3,4)
Action Taken: Changed Air Filter, Cleaned IAC Vavle, removed fuel injectors to be flow tested - came back clean showing no problems. Cleared codes
Result: Engine idled fine for a 10 minutes after resetting ECU. Went for a quick drive, rough idle returned and exhaust poofing remained.

2. Action Taken:Had the valves adjusted - The mechanic said some valves were a bit tight, some a bit loose. He also said he believes the primary 02 sensor to be the problem as the car is constantly adjusting the fuel to the injectors going from a bit lean to a bit rich in endless cycle. Again, he is only making an educated guess based on his preliminary tests. I also notice that at idle the rpm gauge fluctuates from lets say 8 bars and then 10 for a couple minutes and then from 10 back to 8 bars, as if it was seeking. (not sure exactly exactly in rpms, since i'm basing this on my memory and it has been a long day)
Result:Idle becomes a bit smoother but problem still exists

3. CEL arises again a few weeks later Code P0303, and P0304.
Action Taken: This time I start to try a few more things suggested on the boards. Changed out the coil packs with new Honda OEM coil packs, and changed out the spark plugs from the aftermarket Denso iridium's to Honda NGK original. Inspected spark plugs, spark plug on cylinder 3 and 4 smelt like fuel, but were in very good shape.
Result: No change - car idles and exhibits the same problem - rough idle periodically, and the poofing sound remains.

4. CEL P0303 arises
Action Taken:This time I do nothing, since I have no time with work, CEL goes away and stays off for 2 weeks.

5. CEL P0303 arises with P0135 - Sensor 1 Bank 1 heater circuit on 02 sensor. (There is a Honda specific code for this as I pulled the code, however I have lost that code since it has been erased off the code reader)
Action Taken: I check the 02 connection and connector - looks fine. I then order a new Denso 02 sensor and change out the old primary 02 thinking that is probably the cause of all this.
While I'm doing this I also do a compression test and get readings 240, 240, 250, 240 (Cranked engine 5 times, followed typical instruction for doing a compression test) Test results seem high as other members here say readings usually lie around 200 - 220. Am I doing something wrong? If I hold the rpm around 2500-3000 the putting sounds coming from the exhaust are still there but get louder. The engine however feels normal while driving.

Result: So far P0135 has not returned, however, regarding the original problem remains.

6. CEL comes back on a week later with P0303 and P0304 (misfire on 3 and 4)
Action Taken: I pull the codes and also the FF data. The data is shown below

BOTH P0303 and P0304 FF Data. ALSO there are pending P0303 and P0304 which has the exact same FF data as shown below.
Fuel Sys 1 - CL
Fuel Sys 2 - N/A
Calc Load (%) - 37.3
ECT Temp (Celsius) - 86
STFT B1 (%) - 3.1
LTFT B1 (%) - (-2.3)
MAP (kPa) - 37
Eng RPM - 1357
Veh Speed (km/h) - 0
Spark Adv (Degrees)- 27.0
IAT (Celsius) 62
TPS (%) - 9.8

I am now stuck and am not sure what else could be the problem. I am not a professional mechanic by any means, so I may be missing something here.
Other threads suggest it may be the ECU that has fried as a result of the problems above, overworking the unit. Is this even possible? Or a vacuum leak somewhere. Car engine is not modified and is stock. The only modifications ever installed to affect the engine were headers, test pipe, exhaust, which have been removed and returned to stock.

Any insights into this problem and help would be greatly appreciated.

P

franky

so looks like no more misfire in cylinder 2 then, right?

as far as compression goes, the #s are good.

when you reset the the cel, let it idle for a good 10-15minutes for the ecu to relearn its idle spot. if you drive it after you just clear the code, the ecu will not and can not establish a good idling.

as for the ff data, looks like the rpm is high during idle.

Phungalis

Thanks for responding! Misfire in cylinder 2 never came back. I will try what you have suggested and see if the CEL comes back. I was also glad that the compression was good, however this problem leaves me stumped. What could be the cause of a high RPM in the FF data? I remember clearly that the most recent CEL that came on was when I was at a stop light.


Does anybody else on the board experienced this, or may have suggestions?

T-Smac

IAT is high and the MAP is reading low. Should be around 55-75 kPa at idle. I would guess a small vacuum leak.

I would hook a vacuum gauge to it and see what you are getting

Phungalis

Thank you T-S.M.A.C I will try that as well.

Just as I got home today the cars feels worse and the idle is getting much more rough and that roughness is consistent instead of on and off. CEL comes again on with misfire this time on cylinder 1 now! The problem seems to be moving without me touching anything.

Second code, and this one is new, is a DTC enhanced code 71-01 which encompasses 1. Misfire on cylinder one and 2. SHIFT SOLENOID VALVE MALFUNCTION?!? Why would this code suddenly appear? This is frustrating to the point I'm just starting to laugh LOL

Triptafan

I have been having the same random misfire codes for the last uear or so.. Every 4 months to be exact. Changed plugs, map whacked, valves adjusted, etc.. I have a mechanic that swears its a bent valve but I have never over-revved so I chose to change the injectors.. I used rockauto return and rebuild.. Granted, I never had a starting problem but the first set they shipped me were faulty as my starting became troublesome so I had them ship me a replacement set, installed this past Friday and It starts fine and idles better than it has in months.. All in all it was only $117 plus the shipping charge to send them the cores.. Now I will wait for a code with fingers crossed that the re-manufactured oem injectors did the trick.. Just a suggestion.. Worth a shot..

Phungalis

Hey Triptafan,

I have a mechanic that also says it could be a bent valve, but how if the compression numbers come back fine?
I purchased this from the first owner that says this problem started happening to him, they replaced the injectors with brand new injectors, and it solved the problem 20K kms and has now returned as I have the car...........

As suggested by some members here I've tried resetting and allowing the ecu to relearn for 10-15 mins. I've also tried my friends 04 AP2 MAP sensor, since I thought this may be a good way to tell if the MAP is all funky - no change, problem is still there. I have also swapped out my new 02 sensor for the OEM old 02 sensor - car seems to idle differently but nonetheless the initial rough idle still remains.

ONE THING I DO NOTICE is that the putting/poofing sounds from the exhaust ARE NOT THERE WHEN THE ENGINE IS COLD, it only comes on once the engine is warm. (This is why I initially thought it was the 02 and purchased an aftermarket OE DENSO). Should i fork out the dough and get an original Honda 02 sensor? Some say aftermarket OE, even from an OE manufacturer is no good. The original one on the car now is NTK Japan

kolyan2k

Why not let Honda senior tech try to troubleshoot the problem....I read here that some around the corner mechanics don't do a proper job adjusting valves.

I had the same problem with misfires at 30k miles and its all good now after Honda adjusted them.

Today my dads Jeep started throwing multiple misfires, hope its only plugs or coil packs at most

Phungalis

Just called a friend at a local Honda dealership, and he has said that the valve adjustments may not have been done properly. I'll take it there is see how it goes!

jeggy

Your battery posts are clean and tight right?