So my 2005 HAH with 110,000 miles has started doing what appear to be tiny little backfires. Typically when I am cruising at like 30-40 mph and then hit the gas, I get this little 'poot'. Not a big loud backfire, just a little one. Barely noticeable, especially if you are rocking out with the radio.

It seems to be getting a little worse over the past few weeks and it seems my mpg has dropped a couple points as well. The car is running fine, starting fine etc

Anybody ever had anything like this?

 

Hi I have a 2007 HAH and I'm having the same problem. It's starting to get worse and seems to happen more often in hotter conditions. I currently have 62,000 miles. Backfire is coming from the exhaust although I originally thought it was in the intake. It started as a slight poof as you explain and has gotten louder. I actually originally thought it was motor mounts or maybe transmission issue , but as it has started to happen more often I have realized that's definitely a backfire and occurs just as shifting into 2nd gear or as cruising at 30-40 mph and go to accelerate, there is a very slight his hesitation then the back fire. Not sure where to start on this, I just changed the air filter about 2 months ago but no change. Does anyone have any additional information? I have seen a couple posts in regards to similar issues , but they seam to die as a post and never get an actual solution to the issue. Anything would be helpful at this point, as it gets annoying when it starts to happen more often and the MPG go down a decent amount as I have realized when ever the poof occurs the car drops out of assist and runs only on the engine for the duration of the gear the transmission is in.
Thanks Julio Garbalosa

 

Yes, I forgot to mention the fact that it seems to happen only when the day is like 85 degrees or hotter. Good call.

I took mine in and the dealer seemed fairly sure that my problem was the air filter box that had not been properly reassembled by yours truly when I changed the air filter. He said hot air was leaking in the box from the engine compartment and screwing up the mass air flow sensor, causing the backfires and the reduction in gas mileage. He says this is fairly common because the air filter box is such a bugger.

Now, since that day the temps out here have been unseasonably cool, so I don't know if they backfires went away because we fixed the problem, or because the temps have been cool. Waiting for a heat wave to be sure.

You might ask your dealer to make sure the air filter box is reinstalled completely and correctly.

 

TSB 09-069 goes for popping noise.
July 21, 2011
Applies To:
2006-07 Accord Hybrid - ALL

Popping Noise During Light Acceleration
(Supersedes 09-069, dated September 9, 2009, to update the information marked by asterisks)

REVISION SUMMARY

*Under WARRANTY CLAIM INFORMATION, the flat rate time was changed because the MVCI updates control modules more efficiently.*

SYMPTOM

A popping noise similar to a backfire is heard in the intake system at low speeds and light throttle.

PROBABLE CAUSE

As the variable cylinder management (VCM) system reactivates cylinders, compressed air built up in the cylinder is released back into the intake manifold producing a "pop."

CORRECTIVE ACTION

Update the PGM-FI software.

SOFTWARE INFORMATION
HDS Software Version:2.018.016 July 2009 (white) or later

Control Module (CM) Update:
Application Version V6.17.08 or later
Database Update 24-JUN-2009 or later

To avoid an incorrect repair that would not be covered under warranty, use the software version listed above or a later version.

 

Thanks for the TSB information, looks like I will be taking mine in to the dealer sometime next week to see if than can perform that update.

 

Hmmm...I am not getting the "pop" noise yet. I have a 2006 HAH with just 170k on it.

Should I also update the PGM-FI software anyway? I am just afraid it makes my HAH worse off as it is running "optimally" right now.

Thoughts?

 

If it aint broke, don't fix it...

 

So I just got mine back from the trip to the dealer, the updated the PGM-Fi and the IMA software. I have only felt it do the back fire 2 since I got it updated on Tuesday @ Rick case Honda. 114.00 diagnostic fee and they waived it cause the mechanic could not duplicate the issue but still did the updates for me. I noticed an imitate difference in the hybrids activity. Now while on the hwy 75-80 mph , if I press lil more than slightly it easily goes into assist mode and previously I noticed very little hybrid movement while at high speeds. If its not broken I wouldn't mess with it, but those of us having the backfires or poofs I would def bring up the TSB # to the dealer and ask them to update the IMA and PGM-FI. I got lucky and didn't have to pay the 114.00 but it is well worth it I am more I love with my accord now and it's only been 2 days * Happy Camper

 

More assist sounds good. I am curious about how the update is affecting your fuel efficiency. With more assist, I would expect mpg to go up some. Please keep us posted on changes in performance, especially in fuel efficiency. I have experienced misfires only twice in the last 6 years, so not eager to update but if the update brings other goodness with it, I will be all for it.

 

Well I already have my IMA software updated last year when I have an issue I thought was with the IMA system. After 2 visits, they ended up changing the PDU (Power Drive Unit) to see if it fixed the problem. The problem repeat so that got me pretty upset. What I am about to tell you the cause of it will be laughable. All this time, the cause of the problem is all due to a bad 12V battery that have a bad cell. The 12V conventional battery I used was what I thought an upgrade for the HAH...a BRAND NEW Optima Yellow Top Deep Cycle battery.

Never would I have thought that there is a defect in the Optima battery! It is so expensive and BRAND NEW that I slipped my mind...that's the last thing I thought it will go wrong. I use a voltmeter to test it finally and only then realize it is only giving me 10.3V constant.

That's why the IMA system keeps detecting there is a fault!

What gives? I am not saying I don't recommend the Optima Yellow Top battery at all. In fact my other 2 cars I have also uses Optima batteries. It just so happen I got a lemon...what are the chances, eh?

Anyhow to cut it short, during this process of elimination the IMA software was updated as part of the troubleshooting process of over 1 month going to the dealer 3 times! Fortunately I have Honda Plus Extended Warranty so all this I was covered.


My experience with the IMA software is also POSITIVE. Since the update, I find my HAH actually "assist" more and more willingly to do so. The charging of the battery also increase as well.

Overall, I will say it gave the HAH an extra fuel saving of 0.5L/100kms advantage on average since the IMA update all season long. I was satisfied. Winter is more noticeable in Toronto Canada climate as we had one of the most harsh winter last year.

And all proud HAH owners, consider we are lucky the IMA update actually worked better than before.

I have a friend who have a 2009 HCH (Honda Civic Hybrid) and it latest software update actually decrease the fuel economy by almost 1L/100kms! But I know Honda was trying to save the IMA battery of the HCH as they have numerous complaints of failed IMA batteries...so the IMA software actually changed the behavior of the IMA system to drain the IMA battery less overall in prolonging the battery.


So my final say is...thanks for the tip of "If it aren't broken, don't fix it"...but I do highly recommend all proud HAH owners to update the IMA software!

I will NOT update the PGM-FI software though as I aren't broken.