98 Ranger XLT 4x4

[dougs55]

Ok, I posted this same info in another spot but maybe this forum is better to get a quick response since there are more folks looking.

I am at my wits end with my Ranger, over the last 90 days I have replaced or checked everything below and now it has a high idle, rough cold start and check engine light on ---again! Anyone got any ideas since I have virtually replaced everything that I can think of?

Mass Air Flow Sensor
O2 Sensors (All Three) Downstream twice
Electronic Computer Module (Mounted in Firewall)
EGR Differential Pressure Switch
Fuel Pressure Checked – 62 PSI
Right Crash Sensor Module replaced
Changed Vacuum hoses on EGR Valve
Replaced Fuel Filter – Twice
Checked for vacuum leaks and replaced the intake upper intake gaskets
Verified EGR valve is free and working
Replaced heater hose valve
Gas Cap
Cleaned the throttle body with TBC
Replaced Throttle Position Sensor

 

[Ranger Al]

Did you get error code that prompted your check engine light?
What engine do you have?
Is it a Flex Fuel model?

 

[James86]

I had a phantom check engine light that made my truck run like shit for a week. shop replaced O2 sensors, did smoke test in intake.... came up empty handed. Turns out, bad tank of gas. I had switched from E85 to gas that winter, and the CEL would either say bank 1 lean, bank 2 lean, or both, so O2 sensors were suspected, then maybe a vacuum leak. I ran that tank empty finally and put E85 back in, cleared the CEL and it never came back. Never hurts to check the stupid stuff.

 

[FritzTKatt]

Since you hit pretty much everything... how's the idle air control? Just a thought...

 

[tmcalavy]

Is it the 4.0 engine, if so no suggestions. If it's a 3.0, check the underside of your air intake tube right up next to the intake and back at the airbox...when they rot through on the underside it's very hard to find until you pull it and stick your finger throught it. And like Fritz said, check the IAC. Might also seafoam the intake, gas tank, and the crankcase and do an oil change after. How's your mpg since this started?

 

[97RangerXLT]

If the CEL is on, that is where to start. Don't throw parts at it until you know that the part is bad.

James86 has a good point. check the gas, you might have a bad tankful. run it out and put fresh gas in.

AJ

 

[dougs55]

It's the 4.0 and the P0171 and P0174-lean both banks are the two error codes that have haunted me since day one.

 

[James86]

Other than the bad gas, I guess you could try a smoke test on the intake to see if you missed something like a breather hose, intake hose, vacuum lines (don't forget the extra ones for the vacuum hubs since you said you have a 98 - there's a solenoid under your airbox for the 4WD) etc. Not to mention all the fun little lines for your HVAC controls in the dash. If both banks are running lean, I'm guessing vacuum leak, but I had the same issue just from bad gas.

 

[97RangerXLT]

It's the 4.0 and the P0171 and P0174-lean both banks are the two error codes that have haunted me since day one.

Check the gasket between the fuel rail and the lower intake. this will require removing the upper intake to get to, but there was a TSB for this on teh 1997 4.0. your 1998 might just have the same issue. basically part of the gasket between the ports in the intake breaks loose, allowing unmetered air to go in, causing your lean code. the gasket is pretty cheap, and while you have it apart you can do the valve cover gaskets as well. because of where the gasket breaks, a smoke test or just eyeballing it you will not see anything.

http://www.therangerstation.com/forums/showthread.php?t=94437

This will let you know what you are getting into

AJ

 

[bmerr98]

I had a lean condition a while back on my 1998 4.0. Turned out to be a bad egr valve. The diaphragm had worn out and anytime it tried to cycle the valve the CEL would come on and usually stay on. Replaced the egr valve and it's all good in the hood. Found the leak when I had it smoke tested.

 

[dougs55]

I guess the EGR valve is the only thing I haven't trplaced but when I put a vacuum test on it it held good with no loss of pressure.
Dropped the TB in a jug of carb cleaner to see if maybe there is just a piece of carbon causing the butterfly to stick.

 

[James86]

I am curious if you checked the vacuum lines for the 4WD system... seems like people forget about the lines for all that jazz on PVH systems - as far as I can recall there are lines to the 4WD solenoid, then lines to each hub.