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Both mechanic shops claim that my valves only need to be touched if they're making noise in that that cannot be the rough idle problem..... As I went through the forms that seems to not be the case... What is the deal with mechanics thinking that they can talk down to you and that's just the way it is...?
With a rough idle bad enough to cause the car to stall I would recommend inspecting the black plastic intake plenum directly on top of the engine. It has a large vacuum line on it hidden by the firewall.. I'll see if i can get it up in the service manual. I believe it's the pcv breather hose going from the valve cover to the intake plenum.
In one of the many times i've adjusted the valves I left this hose unhooked and the car barely started, idled horribly, and freaked me out. It's easy to forget if having an off day because it's a short hose and once the plenum is put back on you can't see it. I doubt it could be IDed by going around the bay listening for vacuum leaks because of its location.
To get at this hose you have to take the intake plenum off. it's not hard to do, i believe you just unbolt the intake plenum and unbolt the throttle body from it, leaving the throttle body's coolant lines attached. Honda's gaskets are reusable (I love them so much for that) and everything can simply be put right back on.
I'll try n be back soon with service manual images n torque specifications should you need them.
tools needed are 3/8 ratchet, 6in extension, I believe 10mm and 14mm sockets, and some pliers to compress the hose clamp on the vacuum line.
Back from the Shop, they said the nothing is wrong with my car... Illustrated that there's black chalk all up in the exhaust pipe... Does it not entail the car is running rich? I can smell gas when I start it up first thing!
Of course it's hot outside and the damn thing won't stall out, so they won't do nothing about.
They charge me $60 to do nothing but check all modulars on a scan tool 🤷 I could have spent $60 and gone and bought one! Smh.
Long day. And can you post a vid of your idle on youtube?. If it isn't a totally rough like yer concerned about driving it, it's likely not the breather I was directing you towards.
i'll see what documents i can pull you, but cant really move forward with confidence if the work's being outsourced. Perhaps you can find an independent mobile mechanic? May not be so burnt out.
For what it's worth I empathize a great deal. My Tacoma has a mildly rough idle, idle vibration in drive. got it checked by a dealer and a separate shop, all said it's fine. By their mark, i'm sure it is. It runs, no codes. 🙂 But if you put your head against the headrest while in gear at a stop light your eyes will shake in your skull once idle drops to 600-650.
I'll get it though! Just a matter of time.
the idle isn't rough all the time... It feels like it's being choked and to much air or fuel entering the combustion... No codes Stored nor A light is on. Even after is warms up you can feel the motor rumble is it slows down to 0mph. 😩
I've got some documents for you, but I'd like to go put my hands on stuff n take some pictures before making recommendations. One of the things we're always concerned about is proper spark plug installation, and this may be yet another case of that tired old topic especially considering that yours were just replaced. That would be assuming that the fault did not precede the services rendered (air filter, tb cleaning, spark plugs.) If the poor idle did precede the services, then we have something interesting. I hope it's easy!
Besides the idling, the car drives alright? That would further encourage us to assume a vacuum leak, since engines run primarily on vacuum while idling (or so's my understanding.)
That'd be good news. The mention of fuel smell and the presence of excessive carbon in the exhaust would lead us to believe the engine is running rich. Here's a list of common causes:
Faulty MAF Sensor
Faulty O2 Sensor
Faulty MAP Sensor
Faulty Engine Coolant Temperature Sensor
Bad Intake temperature sensor
Faulty Fuel Pressure Regulator
Bad Fuel Injector
But I don't think any of those are likely unless you have reason to be suspicious of one of them. I've had no parts failures on my 2012 besides the struts/shocks What could be happening is that air is coming in through the intake, passing the maf sensor, then leaking out through an improperly seated boot, gasket, or vacuum line. The computer sees the air come in and adds fuel, but the appropriate quantity of air isn't making it to the cylinders at idle. It'd be weird if your mechanics didn't notice such a thing though. Still need to know if the symptom came before or after someone messed with stuff, although if it came before this may become a real headscratcher. Hopefully someone smarter than me chimes in. My head's been out of automotive for the past several months.
The problem was already of occurrence.. sad to say. I wanted the dealer to check the live data modulars and not just run an modular check! They are incoherent to listen to what the customer wants because they are busy and don't want to waste their time! BS. They're reading through the forms I found multiple suggestions of valve clearance is being out of spec and making the car run rough. I'm just hesitant that I might break something going they far. But it's almost worth it at this point, because I'm not paying them another $60 to plug in a scan tool.
Valve clearance adjustment is a reasonable task with the right tools and instructions. I could likely tell you if a valve adjustment is necessary or could be beneficial. I'd need you to take and post a video of your own engine's sound though, preferably with the hood open.
I also took some pictures showing some vacuum line connections. My vacuum lines are modified so they will look different from yours, but they connect to the original locations. Reach your arm around the engine to to place your finger where my finger is located in the image. there's a vacuum line that it's resting on. ensure that it's connected. This vacuum line will look different from yours. Still, there will be a hose there. verify that there's no leak. Once again, verify no leak.
I can't assure 100% that these images will be quite like what you see. I noticed that you stated your car is an 08. 08 is first generation, and I'm showing a 2012 which is second generation. Different engine.
Based on what you said I'm still confident that there could be a vacuum leak
I've got some documents for you, but I'd like to go put my hands on stuff n take some pictures before making recommendations. One of the things we're always concerned about is proper spark plug installation, and this may be yet another case of that tired old topic especially considering that yours were just replaced. That would be assuming that the fault did not precede the services rendered (air filter, tb cleaning, spark plugs.) If the poor idle did precede the services, then we have something interesting. I hope it's easy!
Besides the idling, the car drives alright? That would further encourage us to assume a vacuum leak, since engines run primarily on vacuum while idling (or so's my understanding.)
That'd be good news. The mention of fuel smell and the presence of excessive carbon in the exhaust would lead us to believe the engine is running rich. Here's a list of common causes:
Faulty MAF Sensor
Faulty O2 Sensor
Faulty MAP Sensor
Faulty Engine Coolant Temperature Sensor
Bad Intake temperature sensor
Faulty Fuel Pressure Regulator
Bad Fuel Injector
But I don't think any of those are likely unless you have reason to be suspicious of one of them. I've had no parts failures on my 2012 besides the struts/shocks What could be happening is that air is coming in through the intake, passing the maf sensor, then leaking out through an improperly seated boot, gasket, or vacuum line. The computer sees the air come in and adds fuel, but the appropriate quantity of air isn't making it to the cylinders at idle. It'd be weird if your mechanics didn't notice such a thing though. Still need to know if the symptom came before or after someone messed with stuff, although if it came before this may become a real headscratcher. Hopefully someone smarter than me chimes in. My head's been out of automotive for the past several months.
I'm not a mechanic but. The BEST clue was the smell of fuel
Check the oil dipstick does it smell like Gas. Check it from the CAP too do it with the engine off and then start the car and re check for the smell of fuel.
Can you notice fuel dripping from the exhaust?
My first guess bad injector stuck in the open position.
The 2nd guess is more common Loose spark plug no spark that's why you smell fuel. It could also be a bad coil not getting a spark and dumping fuel down the exhaust.
I'm not a mechanic but. The BEST clue was the smell of fuel
Check the oil dipstick does it smell like Gas. Check it from the CAP too do it with the engine off and then start the car and re check for the smell of fuel.
Can you notice fuel dripping from the exhaust?
My first guess bad injector stuck in the open position.
The 2nd guess is more common Loose spark plug no spark that's why you smell fuel. It could also be a bad coil not getting a spark and dumping fuel down the exhaust.
*Solved*
The exhaust valves were completely closed tight! It idles good without trying to stall now.
05-20-2021, 11:42 AM
What could be happening is that air is coming in through the intake, passing the maf sensor, then leaking out through an improperly seated boot, gasket, or vacuum line. The computer sees the air come in and adds fuel, but the appropriate quantity of air isn't making it to the cylinders at idle. It'd be weird if your mechanics didn't notice such a thing though. Still need to know if the symptom came before or after someone messed with stuff, although if it came before this may become a real headscratcher. Hopefully someone smarter than me chimes in. My head's been out of automotive for the past several months.
