engine light

[Daly]

About 3 days ago upon starting the VX the rpm went up and down 3 times from 900-2200, then everything fine.
Today engine light went on. RPM's only upon start up fluctuate from 900-2200Driving around RPM's fine. Come to stop and they are fine. It doesn't occurr every start up, but now with engine light on I know something needs to be fixed.
Any one experience this and solve problem?

[vt_maverick]

Get your CEL code (Advance/AutoZone will scan it for free) and that will help the diagnosis a lot.

[jeeperkate]

Mine did that same thing, but I never had a CEL come on. I had to clean out or replace the Idle Air Control Valve (IAC). Maybe your MAF? The CEL code would be really helpful!

[Daly]

I will go into have it diangnosed.

What is MAF?

Where is Idle air control valve located? Easy replace?

[circmand]

I will go into have it diangnosed.

What is MAF?

Where is Idle air control valve located? Easy replace?

It probably is not an EZ fix. JK do a search on MAF Mass Air Flow or Idle air control valve both have better directions in the how to than you are likely to get here and judge based on you ability. It may be something as simple as a cut in your air hoses letting too mauch air to gas mixture.

[CoastieCosta567]

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[Daly]

Took VX in for computer scan got a PO171 on one bank.
Mechanic says wouldn't be MAF or IAC if only one bank effected. Thinks ignition coil might be bad and one cylinder missing.
Sound feasible?

[Mile High VX]

Possible...could also be the intake manifold or a vacuum leak.

[CoastieCosta567]

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[SilverBullet75]

I just did a Google search of P0171:

NOTE: This is "universal" info on the code...

System Too Lean - Bank 1

The following is an overview of P0171 check engine light code possible causes.

Fuel System:

Leaking or faulty fuel pressure regulator
Plugged or dirty fuel filter or lines
Fuel pump weak or defective check valve
Injectors leaking or faulty
Low fuel pressure or running out of fuel
Leaking EVAP system components
Faulty FRP (Fuel Rail Pressure Sensor)

Air Intake System

Vacuum leaks
Contaminated, damaged or faulty Mass Air Flow sensor
PCV valve leak or stuck open
Air induction turbulance caused by wrong filter
Oil dipstick not seated
Air leaks after the Mass Air Flow Sensor (MAF)
Oil coated aftermarket air filter

Exhaust System

Any exhaust leak before or near the oxygen sensors

EGR System

Vacuum line disconnected from EGR System Module (ESM)
EGR valve, tube or gasket leak
EGR vacuum regulator valve leaking

Secondary Air Injection System

Mechanically stuck secondary air injection valve

[Y33TREKker]

How many miles currently on your VX, and when was last time you changed fuel filter, air filter, etc?

[Daly]

86k on vx. Checked for vaccum leaks.
Going to change the air filter, gas filter, pcv valve, ignition coil (expensive little buggers) as one is pretty surely bad, and spark plugs.
If they don't fix it, will move on to a couple of the other possibilites.
Certainly a lot of choices to fix, would have been nice if the code was a bit more specific.
I was surprised at the prices of the replacement parts. Went through Merlin of course. MAV, O2 sensors, coils all over a hundred bucks each. Even the spark plugs were expensive.

[Zu4two]

Does your VX make a farty kind of sound during acceleration? I would check the mounting of the EGR valve and the attachment of the tube coming off the passenger side exhaust manifold that feeds the EGR valve. Letting air into the exhaust stream can fool the O2 sensor into thinking the bank is running too lean and then the computer tries to richen up the lean cylinders. This causes the idle to vary and then the computer tries to compensate with the IAC.

[Daly]

No farty sound. When driving all is fine, maybe a little miss when idling at stop.
Main thing is the revs going up and down on start up and solid engine light on.
should be changing some parts next week will update.