[Element24]

Im having negative fuel trims on the short and long term fuel trims on my new to me 2004 honda element. Im getting negative 12 on both long and short term but no engine codes and I do have a rich smelly exhaust.

These readings are at idle and improve somewhat on acceleration but still negative like 5. I have brand new denso upstream.

Will adjusting my valves since I dont know the maintenance history possibly help with my rich condition? has anyone ever had a rich condition from out of adjustment valves? Exhaust valves too tight? I have no noticeable engine noise right now except for what might be a slightly noisy power steering pulley noise when warm.

Thank you in advance.

 

[Rustedwrench]

If the air-fuel sensor and lambda sensor are working properly the most common thing I think would be a leaking evaporative system purge valve. If you locate a hose from the vapor cannister to the purge valve you can block it by squeezing it closed with the appropriate type of pliers. Failing that you could disconnect the hose coming from the vapor cannister and see if the idle fuel trims change. If so you may find engine vacuum leaking through the purge valve and pulling fuel vapors into the intake when connected.

If the problem is long term the engine oil may be fuel contaminated with fuel. This is less likely but this can be test by removing or blocking the pcv hose from the pcv valve to the intake manifold.

 

[Element24]

Yes my upstream is brand new denso as that was my first attempt at this. My condition is definitely at idle because when cruising down the street or highway i get negative 1 to 5 but when at a stop light it goes negative 12 long term and short. I'll try that purge test and also I noticed today that at idle, when my rpms would drop to 600 to 650 my negative trims would go more negative but then my rpm would jump to 750 and my negative trims would go to like negative 5 or 7.

Do you think this could be a throttle body issue but I have no codes no stalling and I only feel the idle change a bit when it drops to 600 just sitting at the light but no sign of stalling at all. Also when it drops rpm sometimes out of the blue my torque app would read open loop low temp but I've never had a problem with my temp readings always around 185 to 190 steady. Thank you.

 

[Element24]

Update:

I wanted to update this old post of mine since I really dont like when I search issues and the original poster never updates with the fix.

I was chasing a rich condition with no code on my 2004 honda element as I
was running both short term and long term values of negative 14 at idle and with almost no improvement cruising.
I started with changing the upstream air fuel sensor, evap purge, map sensor, spark plugs, air filter, and fixed a small exhaust leak I was having.

Nothing worked so since this car is new to me with 150k miles I decided to Adjust the valves myself using this amazing website as there is a great tutorial here and it was very easy.

Well glad to say this has solved my rich condition. Immediately and after a few days of heavy driving, I noticed a huge improvement on my fuel trims. Im now at short term and long term very close to plus and minus 6. And adjusting the valves was my fix. They were tight especially the exhaust side. Some youtube famous mechanics didnt think it would solve my rich issue and wanted me to check my fuel pressure but im glad I watched one youtuber that said it fixed his crv with the same engine. Only problem im having now is that my exhaust is still a little smelly but im thinking now that its just burning oil since I have to put in half a quart every 1000 miles it seems. I changed the pcv with no change so thats my next goal to fix or just keep adding oil as there are no exterior leaks that I can see. Thanks to everyone and this amazing site.

 

[UtahJohn]

I want to add a data point. I have a 2005 M/T with 215k miles. I bought it in July, and the rich smell was getting worse and worse. The front trans mount was bad, and I replaced that in October.

I read an obscure post somewhere that if the front mount is bad, it allows the engine to rock fore/aft, which quickly wears out the collector doughnut (from exhaust manifold to flange before converter). I inspected mine and it was completely shot; HUGE LEAK! $50 in genuine Honda parts and an hour's work and it was changed, and THEN my fuel trims went back to ~0. I picked up a couple MPG too.

 

[Element24]

I want to add a data point. I have a 2005 M/T with 215k miles. I bought it in July, and the rich smell was getting worse and worse. The front trans mount was bad, and I replaced that in October.

I read an obscure post somewhere that if the front mount is bad, it allows the engine to rock fore/aft, which quickly wears out the collector doughnut (from exhaust manifold to flange before converter). I inspected mine and it was completely shot; HUGE LEAK! $50 in genuine Honda parts and an hour's work and it was changed, and THEN my fuel trims went back to ~0. I picked up a couple MPG too.

Wow thanks for the info and I would like to ask if there is any symptoms when the front motor mount is shot since I feel no vibration whatsover. My donut you mention is definitely leaking exhaust in that area since i tested it using an air compressor and soap and it bubbled up there. But my problem there is that the previous owner had her catalytic onverter stolen but the shop actually welded on there own pipes with aftermarket cat and the surface where the donut and the exhaust manifold and pipe meet is not leveled its sorta on an angle so nothing I could do but replace the whole pipe and I ordered one online for 100 with catalytic. But im goingto actually swap my cat to the one from canada im getting by cutting it out and welding it myself since all i really needed was the pipe from the manifold to the cat. Do you have a diagram pointing me to this exact location of the motor mount just to double check? and yes I still want to get my fuel trims near 0 but with the age of the vehicle and previous neglect, im very happy with negative 6 right now. Burning oil is my only problem now. Thank you.

 

[Fleetw00d]

Front mount is number 8. Low on the front of the transmission housing just to the right of the engine/transmission interface (looking from the front of the vehicle).

 

[UtahJohn]

You can shine a flashlight from top/left and barely see the mount. Have someone rev the engine, or load it (in drive, brakes on (BE CAREFUL), see if the engine moves more than "a little". The front mount is a 15min swap from below with wrenches.

 

[psschmied]

Im having negative fuel trims on the short and long term fuel trims on my new to me 2004 honda element. Im getting negative 12 on both long and short term but no engine codes and I do have a rich smelly exhaust.

These readings are at idle and improve somewhat on acceleration but still negative like 5. I have brand new denso upstream.

Will adjusting my valves since I dont know the maintenance history possibly help with my rich condition? has anyone ever had a rich condition from out of adjustment valves? Exhaust valves too tight? I have no noticeable engine noise right now except for what might be a slightly noisy power steering pulley noise when warm.

Thank you in advance.

Fuel/air mix isn't determined by the valves, just the completeness of combustion. Exhaust valve being too tight would be an exhaust restriction that would cause a perceived loss of power during acceleration.

It's less likely that the intake valves being much too tight would cause incomplete combustion than the problem being caused by a bad oxygen sensor telling the ECM to do the wrong thing.

 

[Element24]

Fuel/air mix isn't determined by the valves, just the completeness of combustion. Exhaust valve being too tight would be an exhaust restriction that would cause a perceived loss of power during acceleration.

It's less likely that the intake valves being much too tight would cause incomplete combustion than the problem being caused by a bad oxygen sensor telling the ECM to do the wrong thing.

I understand your skepticism but this really fixed my over negative 16 or so at idle fuel trims. Nothing else was done other than adjusting the valves and im now in a lot better negative 6 fuel trims and better at idle. Look up on youtube there is a guy that had a similar problem like me on a crv with same engine and he also fixed his rich condition adjusting the valves. He was surprised himself and he was talking about it being related to the vacuum and valves being related. Ill look for it and post it if you like but it for sure fixed mine.

 

[smilley772]

Update: I wanted to update this old post of mine since I really dont like when I search issues and the original poster never updates with the fix. I was chasing a rich condition with no code on my 2004 honda element as I was running both short term and long term values of negative 14 at idle and with almost no improvement cruising. I started with changing the upstream air fuel sensor, evap purge, map sensor, spark plugs, air filter, and fixed a small exhaust leak I was having. Nothing worked so since this car is new to me with 150k miles I decided to Adjust the valves myself using this amazing website as there is a great tutorial here and it was very easy. Well glad to say this has solved my rich condition. Immediately and after a few days of heavy driving, I noticed a huge improvement on my fuel trims. Im now at short term and long term very close to plus and minus 6. And adjusting the valves was my fix. They were tight especially the exhaust side. Some youtube famous mechanics didnt think it would solve my rich issue and wanted me to check my fuel pressure but im glad I watched one youtuber that said it fixed his crv with the same engine. Only problem im having now is that my exhaust is still a little smelly but im thinking now that its just burning oil since I have to put in half a quart every 1000 miles it seems. I changed the pcv with no change so thats my next goal to fix or just keep adding oil as there are no exterior leaks that I can see. Thanks to everyone and this amazing site.

thanks for your post, I am having the same problem and tried everything to correct negative fuel trims, and was aware of honda exhaust valves tightening up,but was not sure if this affected negative fuel trims, will soon correct this.

 

[kumarcherry2]

thanks for providing update, i have a similar honda engine with similar issue and ill try out too