Have a 2006 ford escape, at idle the engine will run around 1000 rpm's and then regularly dip down 500 rpm's. Through the intake i can here a distinct "thwap" when the RPM's dip.

Only codes are

P0113 and P2196

Problems accelerating sometimes, Took it too a shop they said bad exhaust valve on the backside of the engine either 1-2-3. They said needed engine work, but said they didn't know where the bad valve was so i don't even know how the made the determination. Vac gauge at idle also indicates bad valve.

However, when i give it even the smallest amount of gas possible the engine smooths out and vac gauge reads totally normal and steady.

Any ideas?

Dave

 

P0113 - Intake air temp - P0113 Ford Intake Air Temperature Sensor Circuit High Input OBDII Engine Light Trouble Code | Engine-Codes.com
P2196 - Bank 1 O2 Sensor - https://www.autocodes.com/p2196_ford.html

Compression/leakdown tests would definitely show leaking valves.

 

So importantly you aren't getting any codes pointing to the idle being out of range so those idle speeds would seem to be commanded to me. Not sure what the noise is but the a/c pump engaging could be the source of sound and a momentary drop in rpm.

Either code source could give you a hesitation when accelerating, I'd suggest either troubleshoot the codes or reset/clear them and troubleshoot any new codes it throws up.

Not sure how a vac gauge on a running engine would show up specifically an exhaust valve issue (and even more so on which bank)??? But a leakdown is the way to go to confirm it as suggested above. It may be as simple as a leaking lifter at idle but the clearance comes back when off idle with higher oil pressure and flow. BUT as both the code issues ould also cause the running problem I'd troubleshoot those first.

 

You have an O2 showing RICH condition... due to ??? - bad O2? bad wires? short? The computer also indicates the incoming air temperature is showing HOT (ambient warm?) all the time. Unless you are in FL or another warm state, the IAT should indicate ambient, and warm up as the engine & manifold warm up. The computer takes the previous as errors, and may be ignoring those sensors and making it up on the fly, using 'stored' parameters it thinks will work.
I would take a look at the O2 sensor wires, checking for shorts(where the heater volts cross into the sensor volts), chafed wire insulation, etc. I would also check the IAT wires, the same way(though it does not have a heater). There may just be something wrong with the wires, both, I think, on the back side of the engine.
That said, an exhaust valve that leaks would have a putt-putt-putt out the exhaust for each misfire. mmmmmmPUTTmmmmmmPUTT, etc. A bad valve will likely misfire more regularly if it is really bad. Hydraulic lifters should provide enough exhaust flow at idle you'd not worry about collapse due to lowered oil pressure. Higher rpms might be more problematic.
Check also that the EGR is not flowing at idle as it will mess up the idle badly.
The computer needs to know the air temp & O2 readings to do its job. Beyond that, it is guessing. Fix the IAT & O2 problems first, then go from there.
Your 'mechanics' didn't want to remove the upper air intake to do a compression test and verify that there was a bad valve leading to poor compression. How much did they get paid to guess? Must have a 1 in 3 chance of being right...
Did this slowly come into its condition, or was it a BAM, now it is running poorly?
tom

 

I'm in Hawaii, so the ambient air temp is indeed high, Ill check wires to see if any shorts could be present. I've reset codes and will re-run in the near future, wonder if some were not residual. The noise is not so consistent as "putt-putt-putt out the exhaust for each misfire. mmmmmmPUTTmmmmmmPUTT", and when I give it even the smallest amount of gas possible the engine smoothes out and sounds great. The shop actually didn't charge me anything (so I'm not out there). They basically just said bad valve, we don't do engine work, you need a new engine take it here..... When I asked which valve they said on the backside but we don't know which one, could be 1, 2, or 3, so I actually don't know how they even made the determination.


This happened all at once, wife was driving said it was having some stalling issues between 45 and 50 mph. when I got in it I immediately noticed the idle issue and noise.

 

Additionally just discovered the problem gets a ton better when I turn the ac off, will still see very infrequent rpm/vac drops but with ac on its much more regular? Thoughts?

 

You may have a vacuum leak due to deteriorated tubing. There are several vacuum lines attached to the intake manifold that could cause misfire. The MAF measured air coming in, and a leak in the manifold is not measured. The misfire will leave O2's in the exhaust. That should make the computer add extra fuel, trying to make up for the extra oxygens that didn't get burned... not because of lack of fuel but because of lack of combustion.
I would not trust your "mechanics', or their diagnosis as it appears they put limited effort into determining the problem.
You noted it ran better with the A/C off. There is less load on the engine as the compressor clutch is not energized, thus leaving the compressor at rest. The IAC - Idle Air Control - is supposed to raise the idle speed in response to more load, such as A/C or power steering pump, or putting the transmission into a driven gear R/D/etc.
Note the rpm on the tachometer, then put the transmission in gear. The idle may drop a bit, but should recover to a hot idle of about 750 rpm.
Have you ever changed the spark plugs? They should be changed before that recommended 100k mile mark, as the electrodes will be past the suggested spec at least 10k before that. The job of changing them is not difficult, but you'd need small mm sockets, an extension, and a ratchet. A torque wrench would be recommended along with a set of 'upper intake manifold' gasket - about $8-10. Spark plugs recommended would be Autolite or Motorcraft - the latter being OEM, so match what you take out.
tom

 

SO here's the deal, when I re-ran codes after a re-set and driving for a while, I've got no codes at all, so I think the two that I listed above were risdual from before I bought the vehicle, I've driven it a good distance and still no codes at all.


I'm still getting occasional rpm drop at idle, and trouble accelerating between 45-50 mph.


If I hook up the vac guage, I'm getting an inconsistent drop of ~5, but then a return to normal.


To make things more complicated the problem is only there at startup. If I rev to the rev limit and then let it come back down the problem goes away.


When I turn my A/C on the problem comes right back, but is better again when I turn the A/C off.


I've swapped out the IAC as it was suggested that might be the problem but no change.


Additionally I'm getting a little exhaust suction when the RPM drops, but I can get the car to run awesome, stead vac, no suction at exhaust, so long as the a/c is not running.