HELP! Cleaned throttle body now crazy idle and check engine lights

[TonyWare]

Originally Posted by povy

Actually there's a vacuum line connection over by the PS pump. Check that and see if they are loose or cracked etc.

On the V6? There is a little "Breather" on the front but nothing major there. I removed the accessory belt to stop the PS pump from spinning and I started the car momentarily, the hissing sound was gone.

I am beginning to think that it has to do something with the torque converter. Even though it is totally unpredictable when the surge will start or when it will go away, I have noticed that sometimes when the car is in D and stopped, it wants to surge the RPMs, while if you throw it in N, still stopped, the surge goes away.

I did a tranny oil change recently and I think while the oil was flowing out maybe some crude oil stuff around the torque converter got somewhere it shouldn't.

For the seasoned mechanics... does my tranny theory make sense?

[povy]

Ah you have a v6. Sorry I thought you had the i4.

So your theory is that your torque converter is locking up at certain intervals?

When I slow down in my car I can feel surges every now and then almost like a downshift. Is that what you're referring to?

[TonyWare]

Nop. Suppose you are already stopped and in N. Once you put it to D it starts to surge. Also when you maintain speed and you throw it from D to N it keeps the RPMs high, almost at the same level as it was in D. Weird things are going on. I'll just do a transmission fluid change, change the filter and clean the celenoids and see if that fixes the issue. Still surprised to see no MIL codes thrown, the fuel trims perfect and no visible or audible vacuum leak. Honda better get that new generation Accord hybrid to Canada fast!! LOL because this one has to go, I think. I just had enough. This car has made a mechanic out of me. OK, I admit I have pushed it to the limits, but it was all worth it I think.

[povy]

Well the thing about your theory where you think it's the tranny is that the engine and the tranny are two totally separate "beings" technically.

The the tranny can be slipped into neutral and be freed but your engine can still idle at high rpm. This being your throttle body DBW system could be damaged like mine was just not as severely. Your fuel trims can be perfect yet there still be a problem with your TB actuator that controls the position of the butterfly.

The ecu controls both the engine and the transmission to work synergistically together.

If it sees that it needs more air ie when you slip in in gear to drive the ecu tells the TB to open more. Well if its damaged it can open too far then try to compensate by closing. This getting the surge effect.

Does that make any sense? Trying to help you as much as I can.

Been a mechanic for two years not quite "seasoned" though

[TonyWare]

Originally Posted by povy

Well the thing about your theory where you think it's the tranny is that the engine and the tranny are two totally separate "beings" technically.

The the tranny can be slipped into neutral and be freed but your engine can still idle at high rpm. This being your throttle body DBW system could be damaged like mine was just not as severely. Your fuel trims can be perfect yet there still be a problem with your TB actuator that controls the position of the butterfly.

The ecu controls both the engine and the transmission to work synergistically together.

If it sees that it needs more air ie when you slip in in gear to drive the ecu tells the TB to open more. Well if its damaged it can open too far then try to compensate by closing. This getting the surge effect.

Does that make any sense? Trying to help you as much as I can.

Been a mechanic for two years not quite "seasoned" though

Yes your theory makes perfect sense. I swapped with another v6 throttle body and still the same surge. Now, given that if I drive the car for about an hour in stop and go city driving conditions the surge goes away, that tells me there is a vacuum issue somewhere, probably related to metals and not hoses. The interesting part is yet another experiment I did to leave the coolant overflow cap open and the surge didn't occur. So I believe that there is a combination of issues. Hopefully I haven't blown a head gasket, but the oil I changed came out with no coolant visible in it. So, I suspect the two hoses under the throttle body. Maybe one of these two is inhaling air while the fluid is circulating.

Which way does the coolant flow in these hoses? From left to right hose or right to left? I have a bypass metallic thing I can by pass the throttle body and see if the problem persists.

I have to say, very challenging and learning experience so far, not frustrating really, since I am learning new things I didn't know before.

PS. By the way, I also changed the EGR valve and cleaned the passages, just in case.
PS2. Wish it threw a MIL code to really know whats going on! But not!

[povy]

Hmm I'm not really sure how the flow goes but I think it goes from top hose to bottom hose. At least that's the way if flows on my 4cyl.

Makes sense that it could be somehitng metallic. The expansion of the material when it's warm could seal the leak. I know that since i've done the TSX IM swap i kind of have a stutter at certain times until my engine gets nice and toasty then it goes away. Nice work checking the EGR. I know you'd think that since our computers are so sensitvie that it would throw a code... obviously the computer doesn't think the issue is that serious, though it may be extremely irritating to the driver

[TonyWare]

We all understand that it is not a good idea to throw parts on an engine until an issue is resolved... without proper diagnosis. So, the new EGR valve even though it didn't correct the issue at least I don't have to deal with that in the future.

I don't exclude the transmission yet, but I'll leave the "big ticket" items for later. First I'll eliminate the cooling system possible inhaling air from somewhere while the engine is cooling down through the various hoses and the bleeding screw on the block (I think thats a real issue since I removed it a few times and perhaps there was a gasket there?) and then I'll get a new gasket for the throttle body, even though spraying carb cleaner around there didn't indicate a drop in RPMs. Then if there issue is not resolved... I'll see if I can remove the selenoid from the tranny (the one on top) and test it... to be continued Worse case scenario: head gaskets! But the coolant doesn't seem to be escaping in the oil and after a quick oil change I did the old oil didn't have any water in it, plus the spar plugs are not squeaky clean to indicate that they are constantly washed with coolant... so I hope the head gaskets on both cylinder banks on the v6 are ok.

I hope this thread provides some benefits to others who if not yet, I am sure they'll encounter the same problem with their 7th gen in the future.

PS. Caution about spraying carb cleaner while the engine is hot and running... it may case fire.

[povy]

Just in case I missed it have you done the correct idle re-learn procedure per handbook guide?

Without the car throwing codes it's hard to say what the real problem is... Are you losing any fluid? If the coolant was getting into the engine you'd probably notice a decrease in the reserve/overflow tank. And small amounts of pure white smoke from the exhaust.

Really hope you get it fixed. It's hard to help out not actually seeing what's going on. Good luck!

[TonyWare]

Yep, I have a funnel I bolt on where the radiator cap is, fill it up with coolant, and let the engine warm up until the fans turn on twice (temp over 95oC) and then I let it cool down. The reservoir and the radiator haven't leaked anywhere, still the same levels.

Now, as the winter approaches up here in the true north and frozen (lol), I expect the car to cool down very fast after I shut down the engine. So I think it won't have any time to slowly inhale air in the coolant system, if indeed there is a coolant system vacuum leak. So as we hit sub-0 temperatures, if I see that the surging idle has gone away, that would be a good indication that the cooling system is inhaling air as the engine slowly cools down just like it slowly cools down in the summer time.

(I am having fun trying to figure this one out... I have another car so it doesn't really limit me. Plus, from what I have seen over the past couple of years, the '09 Pilot built quality of the J engine is much better than the J engine in the 7th gen Accord)