Help with drowned injection???

[Daryl Adams]

Here's my situation. Tell me what you think. I was in my SPF MKI (injected) a short distance from home when I was hit by a massive thunderstorm. Driving along I first noticed some backfiring on the over-run when shifting. Then, after a short stop to wait for traffic, the engine began missing. Things got progressively worse as I limped home, and the engine finally stalled in front of my garage. I let things cool down and dry out for a few hours and tried to re-start. Things were obviously not right, and I think I had a back-fire through one of the injector stacks, so I just put her away and called the engine builder (Roush). While awaiting their reply I've been trying to figure out what might have happened. My take is this:

The O2 sensor is mounted at the junction of the "bundle of snakes" right below the ventilation opening in the rear deck of the MKI. I'm betting the icey cold thunderstorm deluge was running down the back of the car and dumping down directly onto the O2 sensor which in turn started enriching the fuel mixture (causing backfires). Then, while stopped for traffic, the situation worsened and the plugs began to foul when I pulled away. As I limped home the whole system probably fouled out, perhaps even trashing the O2 sensor, to the point where the ECU doesn't know what is going on at all, and nothing works. I'm interested in other opinions and tactics. First change spark plugs and try again? Can I test the O2 sensor somehow?

[Big-Foot]

Change the spark plugs first.. Sounds like you may have fouled a couple of them..

Then I would pull the distributor cap and blow it out with compressed air or spray down the insides with WD40. Let air out a little before you re-install.

[kgschrader]

Daryl,

I would guess you don't have a distributor.... since you have an EFI setup.
But I would agree with changing the plugs first. Been there, done that with backfiring etal while tuning my car.

You should be able to check the O2 sensor if you know what kind it is and what it reads in open air. For example, my Bosch wideband reads about 21.7 AFR in air when it's reading correctly after it's warmed up.

I'm not familiar at all with the Roush system you must have though...

You might have to remove the sensor to have it checked.

Have you checked the ignition coils and their wiring? Where are the ignition coils mounted with your setup? Can they get wet?

You know... just like wet plug wires on a distributor system.

Hope that helped a little... I'd be interested in seeing how the Roush system is set up in your car. Got pictures of where the ECU, coils, etc. are mounted?

Oh, and how is the system triggered? Could the crank sensor, or whatever tells the EFI where the engine is at any given time, have gotten wet?
Checking the plug connection and sensor there might also be a good idea.

Regards,
Kirby

Originally Posted by daryl adams

Here's my situation. Tell me what you think. I was in my SPF MKI (injected) a short distance from home when I was hit by a massive thunderstorm. Driving along I first noticed some backfiring on the over-run when shifting. Then, after a short stop to wait for traffic, the engine began missing. Things got progressively worse as I limped home, and the engine finally stalled in front of my garage. I let things cool down and dry out for a few hours and tried to re-start. Things were obviously not right, and I think I had a back-fire through one of the injector stacks, so I just put her away and called the engine builder (Roush). While awaiting their reply I've been trying to figure out what might have happened. My take is this:

The O2 sensor is mounted at the junction of the "bundle of snakes" right below the ventilation opening in the rear deck of the MKI. I'm betting the icey cold thunderstorm deluge was running down the back of the car and dumping down directly onto the O2 sensor which in turn started enriching the fuel mixture (causing backfires). Then, while stopped for traffic, the situation worsened and the plugs began to foul when I pulled away. As I limped home the whole system probably fouled out, perhaps even trashing the O2 sensor, to the point where the ECU doesn't know what is going on at all, and nothing works. I'm interested in other opinions and tactics. First change spark plugs and try again? Can I test the O2 sensor somehow?

[Mike Trusty]

Most of the Roush motors use the Accel system and only trigger a distributor and coil with the ECU. I would start with checking for moisture in the distributor cap like Big-Foot suggested. I have seen this quite often in Pantera's where water hits the header and the steam finds it's way into the distributor cap. It gets progressively worse as you described as more and more moisture condenses inside the cap and forms little carbon tracks.

Kirby: You would be right for our systems with individual coils and no distributor. It just depends on what Daryl actually has.

You can also check the output of the o2 sensor with a voltmeter. The output is different for different types of sensors but with the right information you could check the unit in free air as Kirby suggested with a voltmeter.