99 sport runs like garbage

[stonerboys]

hey guys, I revived my old 99 sport a few months ago because I was in a bind and needed a vehicle. After it had been sitting for almost 3 years because of a bad tranny, I scarfed up a used one for $100 , and put it back on the road. This was back in June. It was occasionally started and let ran for minutes at a time for the timeframe that it sat. After putting a new motorcraft fuel filter, coil, plug wires (all from rockauto), and 6 new Autolite platinum plugs in it it was running good. The check engine light has been on for a few years but it always ran fine...until a few days ago. If you let it sit for a few hours, upon startup it idles erratically and smells like raw gas and has a miss. At first it was only doing it upon startup and had an occasional miss while driving, so I went and took it to auto zone, had them pull the codes and they said MAF sensor. So I changed it, seemed to run real good for a day or two. Now coming home from work this morning it was missing the whole way home and had little to no power. I’m assuming the smell of fuel is from an incomplete burn. Maybe try changing the plugs because they had to burn off 3 years worth of junk from it sitting and are possibly fouled from a dirty maf sensor? The plugs I took out before putting in the above mentioned autolites had no electrodes left on them at all. Going to go and try checking the codes again tomorrow but the other day I think it was an evap canister code and O2 sensors ( I changed both upstream ones already and codes are still there)? I know it needs some exhaust work too but it’s just a beater so I really don’t care just want it running full power again. Any thoughts or ideas/input guys?? Kinda leaning towards plugs since it happens under a load-while it’s driving and revs just fine and seems to have almost full power in park. Explorer is a 99 sport with the 4.0 OHV, 159k miles

 

[Macgiobuin]

Sounds like the idle air control valve. Get some Sea Foam, cut the top off a soda can, put the IAC valve in the can, fill it with Sea Foam, let it sit over night. Tooth brush it out. Pour 95% of the sea foam back in the can. It'll last a long time.

 

[stonerboys]

Sounds like the idle air control valve. Get some Sea Foam, cut the top off a soda can, put the IAC valve in the can, fill it with Sea Foam, let it sit over night. Tooth brush it out. Pour 95% of the sea foam back in the can. It'll last a long time.

I cleaned it with throttle body cleaner or carb cleaner when I first got it back on the road again because it was all carboned up, maybe I’ll check it again. Thanks!

 

[410Fortune]

WHAT? Do not buy any more parts!!

Okay so if your check engine light is on the computer is storing codes, telling us what the actual problem is
Throwing parts at it is not the correct way to read the codes.
The Autozone guy that scanned your car is selling you parts, instead of buying them WRITE DOWN THE CODES and come back here

Do not mess with the IAC (idle air control) valve yet.
Do not replace any parts, GET THE CODES

My guess is You have a SOHC 4.0L Engine since like 85% of all 99 sport had that engine, the other option would have been the OHV or PUSHROD 4.0.
So which engine do you have?

You said you replaced the oxygen sensors and no change. Why did you replace them? Let me guess the 02 sensors were reading a lean condition? Codes P0171 and Po174? ring a bell?
This would mean the 02 sensors are doing their job and telling you there is a problem, it does not mean go buy new 02 sensors.
I bet you need intake plenum gaskets....but lets start with the codes you have in memory

 

[974X4BLACKSPORT]

Put a fuel pressure gauge on the fuel rail (if possible) and check the pressure while driving under all load conditions, especially WOT. A vehicle that has sat for three years is going to have some sort of gunk in the tank from either bad gas, or tank corrosion, unless measures where taken to prevent this at time of parking.

 

[stonerboys]

Hey guys so I pulled the codes and have the following:

P0171- fuel system too lean (cylinder bank 1)
P1451- EVAP system canister vent solenoid circuit malfunction
P0136- HO2S-12 (Bank 1 sensor 1) circuit no activity.

For now I’m going to try and clean and put the original MAF sensor back on and maybe check the plugs. Any ideas???

 

[MrQ]

For the first and last codes, I would say you might have a bad O2 sensor.

 

[stonerboys]

Sounds like the idle air control valve. Get some Sea Foam, cut the top off a soda can, put the IAC valve in the can, fill it with Sea Foam, let it sit over night. Tooth brush it out. Pour 95% of the sea foam back in the can. It'll last a long time.

Just changed it because it was all sludged up and the gasket for it was completely gone. Idles better but still has a miss to it

 

[stonerboys]

For the first and last codes, I would say you might have a bad O2 sensor.

I changed both of the upstream ones on the manifolds a few months ago when I put all of the ignition parts on it but I did not change the downstream one because I could not get it to come out. The explorer needs a muffler because it’s blown out but I don’t think that would make it run noticeably horrible right? Just louder that’s about it

 

[swshawaii]

Explorer is a 99 sport with the 4.0 OHV, 159k miles

Very LAST sentence in OP. I'd do a smoke test.

 

[stonerboys]

And just an update guys, I cleaned and put the original MAF sensor back in and it runs the same so I don’t think that is the problem either. I’ll be taking the autozone one back and getting my $100 back

 

[410Fortune]

PO136 low voltage from HEGO sensor bank 1 sensor 2 (SENSOR 2 downstream not sensor 1 like you typed)
PO171 Bank 1 lean

The low voltage is likely due to the lean condition

Lean condition can be leaky intake manifold gaskets, leak in the intake tube, or a large vacuum leak. Can also be a non firing injector on the bank 1 side and or low fuel pressure

P1451 You need to look at your canister vent solenoid as this code is a circuit malfunction and it is not working properly
The Canister Vent solenoid is mounted above the spare tire near the charcoal canister

 

[stonerboys]

PO136 low voltage from HEGO sensor bank 1 sensor 2 (SENSOR 2 downstream not sensor 1 like you typed)
PO171 Bank 1 lean

The low voltage is likely due to the lean condition

Lean condition can be leaky intake manifold gaskets, leak in the intake tube, or a large vacuum leak. Can also be a non firing injector on the bank 1 side and or low fuel pressure

P1451 You need to look at your canister vent solenoid as this code is a circuit malfunction and it is not working properly
The Canister Vent solenoid is mounted above the spare tire near the charcoal canister

Are the intake baskets hard to change? Visually they don’t look too awful bad

 

[410Fortune]

I was thinking about this and if your canister purge/vent had a large leak in it there could be a large vacuum leak causing the lean condition as well
So you SHOULD look into the P1451 asap.....

No the intake plenum gaskets are not hard to change, you do need some special tools to make it easier..
I can do them on a SOHC engine, upper and lower O rings in a few hours total job
If your engine is a OHV its even easier....

 

[stonerboys]

I was thinking about this and if your canister purge/vent had a large leak in it there could be a large vacuum leak causing the lean condition as well
So you SHOULD look into the P1451 asap.....

No the intake plenum gaskets are not hard to change, you do need some special tools to make it easier..
I can do them on a SOHC engine, upper and lower O rings in a few hours total job
If your engine is a OHV its even easier....

What does that canister look like? Problem is mine still has the spare tire underneath, I don’t have the jack handle to lower it because it was gone when I got the explorer, and I live in Pa so it’s nice and rusty and I kinda doubt I could get it down unless I cut it off somehow. Mine is the OHV 4.0, it doesn’t look too hard to get to all of the bolts and get the plunum off anyways. What is bank 1 too? Is that the drivers side upper O2 sensor?

 

[lobo411]

Rule #1 of auto repair:

When someone says "it's probably the MAF sensor," it's NOT the MAF sensor.

 

[stonerboys]

Rule #1 of auto repair:

When someone says "it's probably the MAF sensor," it's NOT the MAF sensor.

Lmao yeah you’re not kidding. Been there learned that!

 

[410Fortune]

Bank one is cyl 1-3 (pass side)
Bank two is cyl 4-6 (drivers side)

Bank 1 sensor 2 is your downstream 02 sensor, after the cat converter

I am pretty sure your 99 only has 3ea 02 sensors? not 4ea

You need to get that spare tire dropped if you want to fix this thing properly, try borrowing the spare tire tool you need or a junk yard?

The upper intake plenum on the ohv does come off rather easy, but you will have to mess with the large EGR tube on the drivers side
Plan to replace the intake plenum O rings and also the large EGR green O ring.
If you wanted to take it a step further you can also remove the fuel trail and injectors, clean them, put new O rings on them and replace the fuel rail gaskets.
Then a step further then that would be to actually test/clean each injector before re installing them
Its up to you how far you want to take this.......

USUALLY leaking intake gaskets will cause a lean condition on BOTH BANKS
So if it was my truck I would try to fix the EVAP system leak FIRST, then clear the codes and see if they come back.......

 

[donalds]

I am pretty sure your 99 only has 3ea 02 sensors? not 4ea

My 99 xlt has 4 if that helps

 

[stonerboys]

Bank one is cyl 1-3 (pass side)
Bank two is cyl 4-6 (drivers side)

Bank 1 sensor 2 is your downstream 02 sensor, after the cat converter

I am pretty sure your 99 only has 3ea 02 sensors? not 4ea

You need to get that spare tire dropped if you want to fix this thing properly, try borrowing the spare tire tool you need or a junk yard?

The upper intake plenum on the ohv does come off rather easy, but you will have to mess with the large EGR tube on the drivers side
Plan to replace the intake plenum O rings and also the large EGR green O ring.
If you wanted to take it a step further you can also remove the fuel trail and injectors, clean them, put new O rings on them and replace the fuel rail gaskets.
Then a step further then that would be to actually test/clean each injector before re installing them
Its up to you how far you want to take this.......

USUALLY leaking intake gaskets will cause a lean condition on BOTH BANKS
So if it was my truck I would try to fix the EVAP system leak FIRST, then clear the codes and see if they come back.......

Yeah, mine only has 3. The downstream one was the one I couldn’t get to budge because it’s pretty rusty and tight but maybe I’ll try to get it. And alright lll have to see if I can get the tire down somehow. Thanks for all of the advice!