washed under hood and now really rough idle HELP

[specialized7]

Ok this is driving me nuts.
Yesterday i was washing this truck and decided hey why not spray the engine down to.
so i used this engine cleaner stuff just spray it on wash it off. i rinsed it pretty good because i hate the smell.
Anyways fast forward 2 hours later and i start it up idles good but starts chugging up uptil about 3000 rpm. I figure it will clear up and it somewhat did so i left it over nite.
This morning i start it up and the Check Engine Light is on and really rough idle bouncing from 1000 to 500.
So i took the battery cable off and let it sit for an hour. i put it back on and drove 50kms no check engine light but a really rough idle.
if the light comes back on ill have to get it scanned.
But for now , does anyone have an idea on whats wrong?
Thanks guys

 

[specialized7]

i changed the plugs and wires about 4 monthes ago because i had a dead plug in cyl 5
and it idles just like it did with the dead plug.
i dont think the plugs would go bad that quick?

 

[specialized7]

on a sidenote i pulled out a jeep liberty tonite

 

[blakshukvw]

Get the codes. You obviously have a misfire from getting the ignition wet under the hood. If you have a distributor, remove the cap and clean well inside even using brake clean to remove any water. If you have coilpacks, you probably just found a weak one. Replace as necessary. Next check your wires.

 

[rhauf]

washing under the hood often results in electrical problems. (although a clean engine IS nice i admit) i try to avoid engine washing as much as possible.

oh, and those engine cleaner/engine degreaser products destroy rubber (such as insulation on wiring) so unless you want a bunch of wires with cracking/rotting insulation, i wouldn't recommend engine cleaners. remember, if they dissolve oil and sludge, they'll also break down other petroleum based products, such as rubbers and plastics.

 

[specialized7]

ya i wont be using that stuff again, and im not sure what i have its a 4.0 ohv.
i kinda looked around and theres 6 wires plugged into the top of what i thought was the distributor they all look good, i changed the plugs and wires not long ago i was washing in the front wheel wells really good and with the body lift you can basically see the sparkplugs from the side, im wondering if maybe i blew a bunch of water into the plug boot?

 

[rhauf]

let it dry out more. maybe unplug the "big" connectors on the wiring harnesses (where the wiring harness connects to the engine) make sure it's plenty dry inside (let them sit for a day, or hair-drier them) and plug them back together.. that thing you're describing is the coil pack. unless it's soaked with water, it's not causing this issue. it'll probably be fine once it drys out really good

 

[specialized7]

ill give that a try tomorrow morning.
would the engine misfire only at idle?
because it feels like it has lots of power but anything below 1000 rpm is rough.

 

[rhauf]

it depends what connection/sensor is shorted with the water.. it's throwing off one of the engines readings, so (in this case) it wont idle smoothly. just let it dry out really good.

 

[specialized7]

alright thanks man ill give it a try in the morning

 

[Sbyrne97]

poor idle and reving would not usually be diagnosed with an electrical problem unless your mass air flow or Idle air control sensors were damage...if it is misfiring you would here a popping noise from under the hood you did not mention this in your first posts. Idle and stalling are result of a intake or manifold leak. The engine is sucking in air from a place other than the intake and the computer cannot respond with the mass air flow because of the air is getting passed the mass air flow sensor.

What you need to do is get a can of carb cleaner and spray it around the main places there could be a leak (ie. intake, Throttle body, intake manifold, and vacuum hoses) and see if the idle changes. Its kind of a hit or miss, but when it does change you'll know you have a leak at that source.

Believe me I thought it was a good idea to spray my girlfriends 1993 chevy lumina with a pressure washer and it idle and stalled for a weak before I realized the intake manifold gaskets were bad

also if you washed the engine while it was still hot then you could have damaged the egr which can affect your idle as well

odds are its your idle air control if it seems to be fine above 1000 rpms, there is a thread around here on how to clean it out as well as the sensors inside of it. If you damaged to a point of no return then youll have to pick up a new one.

 

[Joe Dirt]

You've got water in an electrical connector, probably in a plug well, or someplace else creating an arcing issue or a misread on a sensor. Next time plow them off with an air compressor immediately after, and don't wait 2 hours to start the truck. Needs to be started right away and left running until the water evaporates from the compartment heat.

Best bet- just use simple green and a rag- 10+ year old electrical connectors don't like that type of onslaught, and will lead to premature failures. Sure a lot of people have no issue with a EC wash, but a lot do- but I haven't heard of anyone dealing with a misfire or running issue when using a rag and some simple green.

It'll eventually go away once the water evaporates in most cases though.

 

[specialized7]

well had it scanned and the wires tested turns out there was 3 wires that were shot, and a dead plug.
i just did plugs and wires in it 3 monthes ago?
anyways i changed all that and shes running smooth now

 

[Joe Dirt]

The arcing from the water could have ruined some of the wires- that happened to one of my friends- or the wires could have been touching the manifold and melted perhaps? Seen that too...