Throwing codes after pressure wash

bigbandwith · Mar 11, 2010

96 GT throwing check engine codes P1443 P0136 P1131 after degrease and pressure wash of motor. Are any of these related and are they the result of the pressure wash or degrease solution?

Ateup · Mar 11, 2010

I wouldn't think pressure washing an engine would be a good thing to do.

sneaky98gt · Mar 12, 2010

P1443: incorrect evaporative system purge control valve flow
P0136: O2 sensor circuit low voltage (Bank 1, Sensor 2)
P1131: O2 sensor indicates lean

Sounds to me like you could have knocked off a vacuum hose somewhere, which is causing it to run lean. The codes don't show it (in this particular case), but getting the COPs on these cars wet can make them go out as well.

deftsound · Mar 12, 2010

First of all, i wouldn't recommend using a pressure washer to clean the engine, I like to use a very light mist from a garden hose when i do mine.

Second, its been my experience that every-time i clean the engine if you don't make damn sure its dry as a bone it will misfire until the spark plug holes where the cops sit in are completely dry. You most likely got some water sitting in a couple spark plug holes causing hte cops to misfire. Use an air compressor or wet dry vac on blow mode to really dry those spark plug holes and see if that doesn't fix your problem.

Kilgore Trout · Mar 12, 2010

Never use high pressure water on the engine! I wash my engine all the time but never with high pressure and I have to remove water from the plug wells every time I wash it.

GettinThere · Mar 12, 2010

deftsound said:
First of all, i wouldn't recommend using a pressure washer to clean the engine, I like to use a very light mist from a garden hose when i do mine.

Second ... Use an air compressor or wet dry vac on blow mode to really dry those spark plug holes and see if that doesn't fix your problem.

Kilgore Trout said:
Never use high pressure water on the engine! I wash my engine all the time but never with high pressure...

+1

Simple Green and the shower setting on the garden hose nozzle work well. A little elbow grease is needed to wipe down the engine bay (especially the black plastic and rubber parts) to really make it look good. A leaf blower works well in drying the engine bay. Start up the engine and let it idle for 10-15 minutes while drying with the blower. Then drive it for at least 10 minutes to finish drying it off.

Two things lead to problems after washing the engine bay: high pressure water and not thoroughly drying the engine.

bigbandwith · Mar 12, 2010

I have cleared the codes several times, several days after the wash, engine dry. They keep coming back. Which one would you tackle first so that it might be causing the others?

sneaky98gt · Mar 12, 2010

bigbandwith said:
I have cleared the codes several times, several days after the wash, engine dry. They keep coming back. Which one would you tackle first so that it might be causing the others?

I would check the vacuum on the engine first. Very easy to do, and cheap to fix if that is the problem. Advanced Auto will probably do it for you, for free, if you don't have a vacuum gauge.

As for the COPs getting wet and how to check them, pull the spark plug wires off one at the time. If the motor runs worse after you take one of them off, then it's not that one. If it stays the same, then that one is the problem.

I still think it's something to do with the vacuum. I wouldn't think it would throw lean codes because of misfires due to the COPs. If they were the problem, I would have guessed that it would throw a misfire code or something like it.

wmburns · Mar 12, 2010

EVAP purge troubleshooting 1996 Mustang

Tackle the EVAP purge problem first as it could cause the others. IMO, either the following has happened:

The EVAP flow sensor is wet.
The EVAP vaccuum line has become disconnected at the TB, EVAP purge sensor, or EVAP purge solenoid.
The EVAP purge solenoid is stuck open.

It is also possible that water is in the engine electrical harness (most likely the big connector in the rear right hand engine bay) and this is causing both of the problems.

With regards to the EVAP purge system on the 1996 Mustang. I know from first hand experience that it can be difficult to work on. The system throws similar DTC's for problems with the EVAP flow sensor and the solenoid. Making it necessary to "guess" which part is bad. Further, it takes an extended drive cycle test to "prove" any repair as effective.

The evidence points to a vaccuum leak which means that either the vaccuum line is disconnected/leaking or the solenoid is stuck open.

However, if this were my car, I would also disconnect the large engine harness connector and blow it out with compressed air. Disconnect the battery negative before starting. Also consider re-greasing the electrical pins. Use silcone di-electric grease such as used on spark plugs.

HW8 DTC P1443: VISUAL CHECK OF EVAPORATIVE EMISSION SYSTEM
Continuous Memory Diagnostic Trouble Code (DTC) P1443 indicates an Evaporative emission control system or evaporative canister purge valve (mechanical) malfunction.

Possible causes:
-- Damaged EVAP canister.
-- Pinched, plugged, blocked, cracked, cut or disconnected fuel vapor tubes/hoses between the fuel tank, EVAP canister, EVAP canister purge valve, purge flow (PF) sensor, and the engine intake manifold.
-- Damaged EVAP canister purge valve.
-- Damaged PF sensor.
-- EVAP CANISTER PURGE, or PF circuit shorted to VPWR.
NOTE:
Fuel saturation of EVAP canister cannot be effectively checked by the canister weight or intensity of odor (smell).
l Check for kinked or pinched fuel vapor tubes/hoses between EVAP canister, EVAP canister purge valve and engine intake manifold.
l Check for cracked or smashed EVAP canister.
l Is a fault indicated?

Yes
REPAIR fuel vapor tubes/hoses as necessary. If EVAP canister is cracked or smashed, GO to Powertrain/Engine System Group, Evaporative Emission Section in the Workshop Manual. If components are replaced, GO to «HW42».

No
For Escort/Tracer, Mustang, Thunderbird/Cougar, Ranger, Aerostar:
GO to «HW11».

fiveoho · Mar 12, 2010

even tho i wouldnt be using a pressure washer, this is a prime exampe why im scared to clean my dusty motor

bigbandwith · Mar 12, 2010

harness is dry. Found a disconnected vac line by the harness. line coming from the firewall to a small plastic module and then to the throttle body. Hooked it back up and now the motor still running rough. Took it off and motor still rough. Doing a vac check? How much should I be pulling?

Kilgore Trout · Mar 12, 2010

fiveoho said:
even tho i wouldnt be using a pressure washer, this is a prime exampe why im scared to clean my dusty motor

Take a look at the gap under the leading edge of your hood. If you ever drive in the rain, due to the hood design, water just flows into the engine bay and across the top of the engine. So its not like its going to stay dry no matter how often you clean it. For the most part all connections are water resistant but not completely water proof.

One should absolutely wash their engine it is not that great of a risk in my opinion. Here are a few steps I like:
-spray whole engine bay down with 303 Aerospace Protectant
-drive a few days, preferably in the rain
-wash cold engine and bay with garden hose and car wash soap with old wash mitt
-spot clean and spot dry to remove water spotting from glossy/noticeable areas
-check plug wells and remove the water that always gets in there
-also like to remove battery and air intake so I can clean below them

This works best for a relatively clean engine. For a very dirty one you would have to use a spray degreaser instead of the car wash soap. When spraying degreaser avoid spraying the cowl in the area of the vent air intake. If you get that degreaser stench in your ducts it will be there forever. Do not ask me how I know this...

trinity_gt · Mar 12, 2010

As if it needs saying again: Don't pressure wash modern EFI engines. Although the electrical connectors are weather resistant, they aren't pressure-washer proof.

Because it's a 96, you won't have COPs, you'll have coil packs. I'd remove the plug wires from the coils and from the plugs and ensure that they are dry. If they're wet inside the boots, given them a quick spritz of WD40. Check also that the spark plug wells in the cylinder heads don't have any water pooling in them. If you find any, use compressed air to dry out the affected wells. Smear some dielectric grease on the contacts of the plug wires and re-install.

You may need to check other electrical connections for water infiltration. Fuel injectors, TPS, IAC, alternator and so on. If you find water in any of them, daub up the worst of it with a paper towel, again spritz them with WD40, smear a tad of dielectric grease on the contacts and re-assemble.

Get under the car and check the O2 sensor connectors the same way.

A potential problem here -- and why you want to displace the water with WD40 and use the dielectric grease -- is that the water, unless it was very soft, contains minerals and salts. When the water evaporates, it leaves the minerals and salts behind as a crusty film that can often be corrosive and cause connection problems later. High-impedance connections like O2 sensor signal lines may also be affected by the conductivity of the salts. You need to make sure, then, that there's no water left in any connector that got sprayed.

bigbandwith · Mar 12, 2010

I promise I won't pressure wash the motor again..

Thanks for all the tips. With that being said, what vacuum reading should I be pulling on a stock 96 GT? I replaced both the EVAP solenoid and sensor and now I am throwing only code P0353. No more P1443 P0136 P1131 but am I making progress?

wmburns · Mar 12, 2010

P0353 misfire #3

Misfire cylinder #3. Wet coil, or wet spark plug well or wet boot.

After doing the repair, how did you do the drive cycles? Does the ODB2 scanner show "readiness tests complete"?

The reason I ask, it has been my experience that an extended drive cycle is needed to for the EVAP purge routine to complete.

>>>
P0351 Through P0360 - Ignition Coil A through J Primary/ Secondary Circuit Malfunction

bigbandwith · Mar 12, 2010

It is actually no spark on cylinder 7 and one other on same side. It has been 10 days since the motor was washed so I am guessing I should go for a new coil pack.

bigbandwith · Mar 25, 2010

One code left..still getting p1131

Got rid of the evap codes but still getting p1131. Swapped only the wires to the O2 sensors from bank 1 to bank 2 and vice versa and no change? Didn't move 02 sensors as couldn't get bank 1 out. If it was an 02 sensor prob shouldn't it read lean bank2? Any thoughts before changing the 02 sensors?

wmburns · Mar 26, 2010

blow dry the O2 connectors

One of the causes listed for the DTC is water in the connector. Take the connector apart and blow out with compressed air.

Suggest doing this for the O2 connectors and the large main engine connector. Also consider re-greasing the pins with di-electric grease (same kind as used on spark plug boots).

Throwing codes after pressure wash

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