Poor running after pressure washing engine

[PCF]

My daughter is driving a 2004 Vue with the 2.2 L 4 cylinder and manual transmission, 109,000 miles.

As I have done many times, I pressure washed the engine this morning. Upon starting, the engine ran very poorly, barely would accelerate to 4000 RPM, and smelled like it was running rich.

Although the MIL light has come on, there are no codes when I hook up the Actron.

It seemed to run better after a few hours of sitting. The MIL light is still on, however the engine does not seem to be running at full power. The Reduced Engine Power light is not on.

What's going on here? Any advice?

[fdryer]

As many times as you successfully pressure washed the engine without any issues, this last one may have caused electrical/electronic problems from water/moisture intrusion somewhere. To add insult to injury, there seems to be an undercurrent of Vue members with hit or miss decoding when using generic readers. It would help to know what error code(s) are stored. While not promising anything, Autozone may be able to read your Vue.

Usually, engine pressure washing is avoided unless done carefully to avoid all electrical/electronic connections. This makes it almost unavoidable with our engines heavily dependent on electronics. What this boils down to is most likely disconnecting each connection in the engine area (battery negative cable disconnected first) and blow drying one connection at a time to dispel any liquid deposits. While canned air is ok, a small air compressor will do with low air pressure. 120psi is not needed here, just 30psi will do. If you have a large air compressor, either dial down the pressure or use an inexpensive adjustable nozzle to restrict air pressure. Even a straw will work to concentrate mouth pressure to these opened connections. WD-40 helps to dispel water too while adding a protectant coating. Use sparingly.

Hopefully this is all that's needed and if it corrects the poor running then either modify your engine washing technique or hand wash with a soapy bristle brush to gently scrub off dirt and grime. WD-40 is a water displacer and if sprayed on each connection, may ward off water intrusion the next time pressure washing is done. A gentle water spray is all that's needed to rinse soapy water.

[PCF]

How do I get the connectors off of the ECM/PCM?

[fdryer]

VERY CAREFULLY! I would leave these connectors for last and at least until you've done all other connectors first and then tried another engine start to see if blow drying worked. The ecm connectors are specially made because of design considerations to work semi-permanently in the harsh environment of an engine compartment. Most connectors used now are weather proofed against water and moisture intrusion but aging from normal wear and tear plus weathering will cause issues eventually.

If yours are similar to most GM ecm/pcm connectors, there's a clamping action using a lever and cam design to each multiple pin connector that requires prior knowledge of how they work before attempting a disconnect. The lever is used to release clamping pressure via cam action on each side of the connector to allow a disconnect. A metal or heavy plastic strap is levered from one side to the other to release a connection. This allows applying even force to all the pins without cocking the connection and causing more grief. This is not normally done unless absolutely necessary as these connectors are weather proofed against water/moisture intrusion. I've washed my L300 over the years, carefully, and did as suggested without problems but do know that there may be a day when something will go wrong. I've never had to meddle with my ecm and it sits over one corner of the engine block so it does get wet. I try to refrain from directing water onto this expensive module.

If anything, just try blow drying the engine area with compressed air. I've used a small air compressor that pushes about 45psi to blow off dirt prior to engine washing. Blow drying with compressed air may be all that's needed with carefully aiming the nozzle and moving it continuously over every wire connection without forcing water into these connections. Wear goggles as dirt always finds an eye to blind.

[PCF]

Duly noted. After the metal clamp is released upward, the connectors just pull straight up?

[fdryer]

Its actually one motion that releases clamping force, disconnects and separates the female connector from the male pins while maintaining alignment. The reverse should occur to align all pins with two hands - one to work the lever and the other to guide and hold the connector/wire harness in alignment. Mark each connector before disconnection (at least one side) - nail polish on the connector and adjacent ecm side so there's no ambiguous confusion created.

If you perform any ecm disconnect, be sure battery negative is disconnected first as all ecm's retain memory power like radio preset memory; only part of the ecm is powered up at all times like radio memory while ignition switching powers the main ecm module like providing radio power. Disconnecting battery negative removes all power.

Be aware that once an ecm disconnect occurs, customized engine parameters are erased and the engine will default back to factory programming requiring a short period of engine running/driving. This is similar to resetting error codes where the engine needs a few miles of driving for the emission self tests require a full drive around to meet emissions testing before state emission inspection. There may be a small period of erratic engine behavior as the ecm learns to adjust and modify/customize parameters for optimum engine/transmission shifts.

[PCF]

OK, here's what I've done so far.

- Cleaned all the connectors and blew them out with compressed air
- New spark plugs - it needed them from the mileage and also the look of them once they were removed
- Removed the battery power overnight to reset the computer

On a test drive this morning, it started up fine but ran a bit rough on idle. It just doesn't seem to have enough power on acceleration, like one or two cylinders are not firing. It seems to be running "rich" as well, from the smell of unburnt fuel.

During the road test, the MIL light was on, sometimes flashing, indicating a misfire condition. But the Actron scanner, when it connects and reads, does not return any trouble code.

Could it be the coil pack is now damaged, and not getting a spark to two of the plugs? How do I check that?

[fdryer]

Perhaps the engine washing and misfiring were coincidence.............

The easy way to find a misfire on your engine would be to remove the ignition coil pack off the top of the engine when you replaced the plugs, remove the plugs for inspection. One look at each plug compared to the other should tell you which plug/cylinder is misfiring. Good plugs/cylinders firing would be tan colored with few deposits. Black, wet deposits indicate oil/misfiring. Google spark plug reading from any major plug manufacturer for plug charts.

Examine the ignition coil pack extension tube connectors, coil pack, and ignition control module sitting in the coil pack. All are suspect for misfiring. Misfiring, if allowed to continue will let unburned fuel into the exhaust system and burn in the catalytic converter - cooking the catcon prematurely with raw fuel will destroy it in as little as 50 miles of driving with the MIL indicator constantly flashing. If unsure of whether the ignition control module or coil pack, replace both.

[RedGeminiPA]

You're most likely not getting codes because the Service Vehicle Soon light is the one coming on. They have to be read by advanced readers like the GM Tech II at a GM dealer. Service Engine Soon light is usually read by most common readers.

[PCF]

The only light that is coming on is the Service Engine Soon light.

[fdryer]

You're not alone as there are many Vue owners having trouble with (generic) Autozone readers not decoding SES indicators. The wrench indicator does require better ($) readers but in general the SES indicator is supposed to be easily read by most readers since its emissions related (misfiring).

If you find a reader capable of decoding your Vue DTC's, the most likely error codes will be P0300-P0304. P0300 is a general misfire condition while P0301-P0304 will indicate which cylinders are misfiring. There may be other error codes too but that's more guessing.

[PCF]

Replaced the ICM, now it runs perfect. The MIL light (Service Engine Soon) is still on, but my Actron does not read any DTC code. I tried a newer Actron unit, but it failed the ISO link.

Thanks for all your help, it's fixed!

[fdryer]

Great!? Leave the SES indicator alone. It will reset on its own after three or more engine restarts/drive cycles. If you reset it manually then the engine computer has to run though all its emissions self tests before allowing you to pass state inspection, if its due. This way, the engine computer logs how many times the engine runs without misfiring before it decides to reset the SES indicator. Big Brother as it were.

[BobbyP]

Great thread!

A couple months ago I carefully cleaned the dust from my engine compartment with my air compressor, dialed down like fdryer suggested.

This Honda engine has been the cleanest engine I ever owned.

[PCF]

Well, a month later, the car runs perfect, driven daily. But the SES light is still on, and the Actron still reads no codes.

How do we reset this light so that it is not on all the time?

[fdryer]

Well, unfortunately for you and many Vue owners, there seems to be a mystery why some store readers are unable to retrieve the error codes. You're not alone and may have to try several auto stores before finding a reader that can retrieve stored codes. Another issue is that what ever is turning on the SES light, the error is real and hasn't been corrected. Something else is wrong. Hopefully you find a reader to decode the error(s) and try resetting. Real errors will return as soon a reset is done.

Other than using a reader to reset the SES light, you can always pull battery negative for 30 seconds to reset the light. Be forewarned that the next start up may turn on the SES light again - this will mean a current issue not yet addressed. A more refined reset without losing the radio presets would be pulling one or more ecm/pcm fuses where error codes are stored.

[RedGeminiPA]

When I bought an aftermarket gas cap for my '04 due to the original wearing out, that's when my SES and SVS lights started coming on.

I bought a new cap from a GM dealer, put it on and left it alone, and the lights went off on their own after a few drive cycles. Codes were still stored, but not active.

In other words, my problem was corrected by the gas cap. Since the problem was solved, the diagnostics check at startup knows it's fine, and the lights no longer come on.

If it's been a month for you and the light is still on, you have something wrong that needs addressed.

Do you have an Advance Auto Parts near you? They've been able to read SES codes on my Vue until I bought my own scanner. Autozone scanners seem to be notoriously bad for some reason.

[pdough]

I'll chime in just for kicks, since I've never had luck with Actrons on the Vue... You said you replaced the ICM and all was good except for some lights that wouldn't go out. Are you checking fuel mileage and if so what are you getting? A bad ICM might have caused poor fuel mixtures that may have pushed the catalytic converter or down stream O2 sensors to their limits. At 100+ thousand miles the O2 sensors are ready for replacement. Only way to know for sure is to take it to GM and have them read the code.

Don't throw parts at it. As much as I still hate to say it, go to GM or another shop that has a Tech II to read the codes and know for sure.

[marvin_smith]

Now a days people go for pressure washing as it is most affordable and provides better service. It's a safe method but turn down pressure a little.
This is the best way to clean home and vehicle. In fact It also removes mold and mildew. This may also increase the value of your home or vehicle.

[wolfman]

Disconnect the Negative battery cable overnight. That should clear the SES light. Then just wait to see if it comes back on.