I have a 97 Honda Accord ex, and no matter how hot or cold it is outside, if the car hasn’t been ran in more than an hour or two, it needs 5 minutes to warm up, (RPMs go down to 500, then rev up to 1200. That’s how I know I can go) or else when driving it will stay in first gear and not allow me to go faster than 20 MPH. My mechanic said that the codes P0171 and P0505 came up. Also, the gas milage is terrible, even after my fuel filter was changed. Help?
After finding those codes, all that your mechanic did was change the fuel filter???
I think the first step is to find a new mechanic.
The P0505 code indicates a problem with the Idle Air Control Valve (IAC) or its wiring, and the symptom of wildly varying idle speed is totally consistent with a malfunctioning IAC.
The P0171 code indicates that the engine is running on too lean a fuel/air mixture, and this can have various causes, including (but not limited to) a vacuum leak, a bad O2 sensor, and a weak fuel pump. A good mechanic can figure out the exact cause of the problem, but from the information that you provided, your mechanic is not up to the task.
I suggest that you use the “Mechanics Files” link at the top of this page to find a recommended mechanic in your zip code.
Edited to add:
As to the transmission problems…What did you find when you checked the transmission dipstick?
What can you tell us about the level, color, and odor of the trans fluid?
When was the trans fluid last changed?
Did you use genuine Honda fluid for the last trans fluid change?
While this is just speculation, I think that this car may be the victim of long-term lax maintenance, in addition to the probable IAC issue and other problems.
THANK YOU SO MUCH!!! My mechanic said he didn’t know what the IAC code meant, nor what to do about it. Maybe I should find someone new…sigh Just ballparkin’ it, how much do you think it may cost to fix the IAC issue?
And when I checked the trans fluid, it was a kind of dark pink color, no odor, and there was a sufficient amount in there. I have no idea when the last time it was changed, I bought it as-is a few months ago.
Your mechanic has no clue, and you think that you should find a new one?
Why would you even consider staying with an incompetent mechanic, rather than finding a new one who actually knows what he is doing?
If the IAC can be cleaned, or if the problem is a bad wiring connection to the IAC, the cost should be fairly low. If the IAC needs to be replaced, then you are probably looking at a total bill in the area of $400.
The actual cost for IAC replacement will vary somewhat, depending on the area of the country where you live. However, you need somebody who knows what he is doing for this task, as well as for diagnosing & fixing the lean fuel/air mixture problem, so you really need to divorce yourself from your current mechanic right away.
When–hopefully–you take the car to your new mechanic, have the transmission serviced also.
I say this because, if you don’t know the maintenance history of the car, then you have to assume that NO maintenance has ever been done. Make sure that he drops the transmission pan, changes the filter, and changes the trans fluid, using ONLY genuine Honda fluid. Other fluids can lead to transmission damage, and an overhauled transmission will cost more than the car is worth at this point.
And, speaking of not knowing about a vehicle’s maintenance history, unless you know for sure (from hard copies of repair invoices) that the engine’s timing belt was replaced within the past 5 years or so, it is now due–or more likely overdue–for that vital maintenance. When a timing belt snaps (with no warning whatsoever), it causes catastrophic engine damage on an “interference” engine, such as the one on your car.
Replacing the timing belt is not something that you can afford to dither about, as the damage from a snapped timing belt will lead to repair bills that would likely exceed the book value of the car. So, if money is really tight, I suggest that you ignore the drivability issues for the time being, and focus on replacing the timing belt and having the transmission serviced.
All told, your likely costs for timing belt replacement, transmission service, and the drivability issues is in the neighborhood of $1,200-1,500, so you have to put things in priority order, and the timing belt and transmission service have to take priority over the drivability issues.
Sorry for the reality check…
Consider him divorced. And I will ask (my new mechanic) to do these things specifically.
THANKS SO MUCH. You’ve been beyond helpful.
It doesn’t need an IAC and your mechanic may have a problem with communication more than he has a problem with diagnostics. If you mechanic tested the fuel pressure and found it low, then a new fuel pump or fuel filter would be in order, but if he didn’t test the fuel pressure first, then he isn’t performing all the correct diagnostics.
He should be testing the vacuum in the intake manifold first. The P0171 could be due to a vacuum leak, insufficient fuel pressure, a defective fuel injector or mis-adjusted valves. The fact that this only occurs when the car is cold causes me to be concerned about the valve lash adjustment. If this is off for too long (not really that long actually) it can result in burned valves. BTW, check your owners manual and you will see that a valve lash inspection is required every 30k miles.
This can also cause the P0505 code. A clod idle problem can also be caused by a defective fast idle thermo valve. Your mechanic should remove the air intake duct from the throttle body and then with the engine running, put his finger over the lower port in the throttle body. If the engine speed drops, first check that the coolant system is bled properly. If so, the fast idle thermo valve is bad. It is located under the throttle body. This test is done with the engine warm.