Rough Idle (cold) & Poor gas mileage

[Dwaite7133]

Never had a problem with my 2000 Explorer Sport(2WD) (43000mi.) until recently, symptoms may or may not be related.
1) Rough idle (feels like it's rocking from side to side) after starting for about 5 mins. EFI cleaner (gumout) no help.
2) Insufficient heat from heater. Temp gauge always reads cold. (Coolant flushed and changed) No improvement in heater output or idle-but old coolant had that "congealed sour milk" look on underside of radiator cap. My guess is that it was original (7 years old coolant)

This car was bought a few years ago with very few miles (or maintenance) on it. Oil is changed religiously every 3 mos since I bought it.

With only 44k on this truck but most parts (plugs/wires) original to the truck, what would be a good place to start?

Any help would be appreciated.:exp:

 

[rmcknight]

you have a vacuum leak, probably in the plastic air intake (as this is common).
you are not getting enough vac to open the heater control valve (at front lower of engine).
the reason its after 5 mins is thats when engine control switches over to the sensor control, no longer in startup mode. and you are sucking in un metered air, thus getting a very lean mix, thus getting the plugs very hot, and missing.

there is a cheap kit to fix that issue. It is a SOHC engin is it not?

 

[steventadams]

change the plugs, wires, clean the IAC, MAF, change all fluids. For gas mileage do a search for aldive's "quest for 30". he makes 30mpg on a 2wd v6 like yours...

 

[ThePhoenix]

why would bad plug wires make for a lean engine....just curious because someone said that to me about my lean condition.

wouldnt weak spark make for a rich condition as fuel wouldnt burn?

 

[Dwaite7133]

Not Sohc

Thanks for the help
Engine is not a SOHC, it's the other V6 EFI-don't really know what to call it-OHC?
Anyway, along with the poor gas mileage, rough idle, and low heater output, I have noticed a strong sweet (best way to describe it) smell near the exhaust which is new, meaning I never noticed that before. Not a gas smell, not a burning oil smell, just...well sweet smell, and not a good kind of sweet smell.
Once again, thankls for the help.:exp:

 

[ThePhoenix]

OHV - over head valve

 

[maximus44]

Uh oh... isn't the only sweet smelling thing from the truck the engine coolant?

 

[ThePhoenix]

i believe so...but at the back of the enigne, by the new exhaust....could be a cover and not a head gasket

 

[Redneck0907]

ThePhoenix you had a sick mustang... sad to hear its totaled.

as for the poor mileage/rough idle. check your codes. autozone reads them for free. also try to clean the MAF sensor. this can be done by removing the sensor and spraying it with CNC mass airflow cleaner, or brake cleaner. do not touch the sensor wires very brittle! heater issue could be the blend door but not so likely judging by the smell you get. you could be burning antifreeze off in your exhaust, meaning a bad gasket possibly or worse a cracked block. good luck!!

 

[Redneck0907]

cracked block would cause all three too by the way due to lack of compression on a cylender. then when the truck warms up rough idle may go away as the heat seals the crack up.

 

[Dwaite7133]

Thanks, I'm going to start with plugs/wires and a code reading at autozone. Wouldn't coolant in the oil show up as bubbles on the dipstick? Wishful Thinking?

 

[alohamonte]

$4 fix

try this long shot... change the thermstat

my 98 ran rough, got terrible mileage, and had a temp gauge that would barely move... that is until i spent the 20 mins needed to replace the 'stat.

gauge works, warms up in 3-4 mins, and gets much better gas mileage.

 

[ThePhoenix]

thanks Redneck!

alohamonte, are you saying your car was constantly running in warm-up mode? Ouch!!

 

[alohamonte]

yup

exactly what i'm saying. i never owned a vehicle that would run cold and show cold on the temp gauge when the thermstat fails so i didnt suspect it for a long time. finally i realized that the radiator water wasnt circulating and it fixed a lot of problems!

i bought the X about 2 months ago for $3k, price reduced because the temp gauge and the gas gauge didnt work. I replaced the tstate and the gas cap and now both gauges display properly and it runs like a champ.

 

[aldive]

Take a look at http://www.explorerforum.com/forums/showthread.php?t=169335&highlight=quest

Good luck ...

 

[Dwaite7133]

Quick follow up:
Rough idle at start up seems better after plugs and wires changed. Plug from #3 cyl. fouled with oil-all other plugs had normal wear.

Next I changed thermostat (old one looked siezed up) Had warm air out of the blower for about 5 mins. while I "test rided" my #20 torx back to autozone for a #20 security torx. Then back to cool air from the heater.

Also changed air filter and cleaned the MAF sensor. Am I missing anything before I start changing the heater core? Someone suggested a vacuum leak and I haven't looked into that yet.
Before I changed the plugs I got 104 miles on 1/2 tank of gas = 12MPG!

 

[momerath71]

try this long shot... change the thermstat

my 98 ran rough, got terrible mileage, and had a temp gauge that would barely move... that is until i spent the 20 mins needed to replace the 'stat.

gauge works, warms up in 3-4 mins, and gets much better gas mileage.

My temp gauge gets into the normal range, but just barely--does this fall into the above category? And would that account for the coolant smell in the exhaust, or is that a separate issue? Mine only smells that way for the first minute or so of operation, then it goes away.

Thanks!

 

[Dwaite7133]

Coolant smell went away after the plugs were changed. To address the heat, I assumed the blend door was broken, but it wasn't. The only thing that brought back heat was new anti-freeze, flushing and back flushing the core, and springtime
Gas mileage still sux, but I am attributing that to a 2-3 shift flare in the transmission.

 

[momerath71]

Well, I guess we'll see then, 'cuz I just replaced the #3 plug after it threw a misfire code. Maybe I solved all three (rough start, misfire, coolant smell) all in one go? Neato.

 

[Dwaite7133]

Very interesting. I had a check engine light and it came up with a cyl 3 misfire too! I pulled the plug, checked for a spark (there was a spark) and put it back in. Check engine light went off the next day. I put some techron Fuel injector cleaner in and the light has stayed off.