Does IAC cause this

[JusTheUsual]

I'm driving 55mph. I stomp on gas, revs go from 2k up to 3k and that's it and like almost no more power is added after stepping on gas from driving at constant 55mph.

 

[ranger7ltr]

Not likely...

The IAC or Idle Air Control is just that...A device to regulate air into your engine around the closed throttle valve into your engine to modulate and regulate the engines' idle ...

Sounds like you have a possible fuel delivery problem, an exhaust restriction, or perhaps worn operational components[ wires, plugs, filters, brakes, gaskets,sensors] that are not performing to standard...

Do you have any pending or set codes in the ECU? If so, resolve those and go from there... If not, when were your plugs, wires, filters replaced? Are your brakes dragging and if you run an automatic what is the condition of the fluid and filter? If you run a manual, does your clutch slip?

I have a 99 Sport that I don't routinely drive anymore and even though it sits a lot I have to do maintenance on it just like I drive it daily to expect it to perform to standard...In the last 2 years I have only put 10 miles on it but I tune it, change filters, maintain tire pressure, replace oil and filters in the engine and the trans, and replace intake gaskets that looked great but were starting to leak...

 

[JusTheUsual]

So a bad IAC or dpfe wouldn't cause the engine to do that than? I thought I read on here where someone had a problem like mine and it was the IAC as the problem. I have a newer TPS, all new gaskets and wires and plugs and fuel pump and the compression checked and fuel pressure checked a couple weeks ago. But I never gave it a lot of gas until now. I just cruised and never floored it especially at highway speeds until now

 

[JusTheUsual]

171 and 174 I believe is from bad exhaust manifold gaskets and/or holes in headers. I know passengers side is definitely gasket and also maybe hole in headers but drivers side is either or. you can hear the ticks underload but not idle. 455 I have no clue where its coming from and now 306pending. Why pending and this is a new code. Is 6th cylinder by pas. or drivers side firewall

 

[ranger7ltr]

Your ECU is telling you something...

The codes you have are telling you information on how the engine is running..
P0171 and P0174 are mixture too lean codes...When a vehicle has the fault code P0171 and or P0174, it means that computer can no longer automatically adjust the mixture between air and fuel. Code P0171 applies to Bank 1 and P0174 applies to Bank 2. And I do believe a leaky exhaust, leaking intake manifold gaskets and vacuum leaks can cause this...So can low fuel pressure from a dying pump or clogged fuel filter...Oh injectors that are not working properly can cause this too...When the code says that the Fuel System is "too lean," it means that the computer has been adding more and more fuel, which is called Long Term Fuel Trim.

P0306 is a cyl. #6 misfire detected and P0455 is a gross evap system leak...Either a plug, plug wire, lack of fuel from the injector, or a dead cylinder will cause this code...And cylinder #6 is the rear drivers side hole...P0455 is usually caused by the vacuum lines on the evap canister valve leaking, the evap canister valve under the battery leaking from battery acid, or the evap canister itself under the back of the truck...

One thing I should ask is whether you have the OHV or the SOHC engine...

171 and 174 I believe is from bad exhaust manifold gaskets and/or holes in headers. I know passengers side is definitely gasket and also maybe hole in headers but drivers side is either or. you can hear the ticks underload but not idle. 455 I have no clue where its coming from and now 306pending. Why pending and this is a new code. Is 6th cylinder by pas. or drivers side firewall

 

[JusTheUsual]

Well can rule out anything with fuel or compression since those tests tested out fine. The plenum has new orings along with the fuel manifold when I replaced a injector.. All of these things were done with in the past few weeks.

Oh the reason why I asked about 306 is the pending part. I never seen a reader say the cylinder and say pending. Why is it say pending

 

[ranger7ltr]

Pending codes...

The computer detects something "wrong", but the error usually has to be present after a few driving cycles before it turns into an "actual" code that triggers the Check Engine Light. Otherwise, if the code goes away before that, then the computer shrugs it off.

I understand your fuel pressure and compression were tested but what was the fuel pressure when tested?? If it was not 65-72 psi it is too low...And I would verify the plugs, wires, and injectors again just to rule out that misfire as SOMETHING is causing a random miss...

Well can rule out anything with fuel or compression since those tests tested out fine. The plenum has new orings along with the fuel manifold when I replaced a injector.. All of these things were done with in the past few weeks.

Oh the reason why I asked about 306 is the pending part. I never seen a reader say the cylinder and say pending. Why is it say pending

 

[JusTheUsual]

New fuel pump and fuel tank less than a 1k miles ago and the fuel pressure was at 62 which is fine. That's with the gas leaking out at the guage of the tester because its not sealing right. So gas is ruled out completely along with the compression being at 150 on all cylinders. New injectors. New wires, plugs and coil.

Now you see why this is a mess and why I am leaning towards sensors

 

[Turdle]

po455 and the lean codes "could" be connected.

There could be a vacuum leak to the evap.

Can't find the thread right now but there have been several posts about the vacuum solenoid under the battery tray. You need to check it out real good. I remember the post saying you had to remove it to see the hole in it caused by battery liquid dripping onto it and melting a hole.

306 code could possibly be caused by a bad spark plug, or even a fule injector mis firing.

Is the PCV valve fitting tight?

When you did the intake gaskets dod you replace the green egr tube o ring?

 

[JusTheUsual]

po455 and the lean codes "could" be connected.

There could be a vacuum leak to the evap.

Can't find the thread right now but there have been several posts about the vacuum solenoid under the battery tray. You need to check it out real good. I remember the post saying you had to remove it to see the hole in it caused by battery liquid dripping onto it and melting a hole.

306 code could possibly be caused by a bad spark plug, or even a fule injector mis firing.

Is the PCV valve fitting tight?

When you did the intake gaskets dod you replace the green egr tube o ring?

Yeah I never knew about anything under the battery. going to have to check that out. don't know what its called or does or anything.

PCV valve is new and about 5kmiles on it. Looked fine a few weeks ago when replacing the top end gaskets. yes and new green oring egr tube with the other gaskets with injectors.

Im liking the reading of the 455 could be related or connected to causing the lean codes.

 

[Turdle]

The thing under the battery is the vacuum purge solenoid valve for the EVAP ( fuel tank pressure vent).

http://www.obd-codes.com/p0455

Hope this helps. At lest it is something to eliminate.

 

[JusTheUsual]

I just remembered the old known problems with explorers...the gas filler neck. I remember that being rusted some and moved the rubber line up some and clamped it but the rubber line is so malformed im sure some air or whatever its not a complete seal. So im sure 455 is from that. Never wanted to pay $125 for new rubber line that I cant find anywhere else plus another $90 for filler neck. So im sure that causes 455 and I did that a couple years ago.

That still wont cause the rpm and power problem with 174 and 171 though. Oh and have to look into pending 306