So I took my 93 RX-7 to hyperfest on Saturday to show the car, on the way back its pouring down rain really bad so I'm only going about 55. After a 30 minute drive to the gas station, filling up on gas and putting in some oil (i had 1/3, and added a quart just to be safe) we drove about 10 more minutes when I heard a loud pop sound. The guy in front of me thought someone blew a tire, I thought it was lightning or something but then about 10 seconds later the engine starts lurching and hesitating as if I were lugging it really really bad, so I downshift and it keeps on doing it and then just dies. I drift it to the side of the road where it proceeds to not start up, my friend says there is white smoke coming out the exhaust when I try to start it. I figured I had just blown an engine. We towed it back to my house and the next morning when I went out to show my dad the damage the car started right up. Not only that but it held idle and ran smoothly. I was shocked.

The car has been driving since then perfectly normal (well, as normal as it was) just like it used to with seemingly no changes. I have turned the turbos all the way down(6-7lbs) and havent been boosting much but it really doesnt seem much different at all. The vacuum is normal, the boost is normal, the idle is normal, the drive is normal, nothing is different from when I drove it last week.

So my question is what happened to my engine that night? My dad thought it could have been water that got into the engine. I have no idea.

My mods are:
ported engine with 3mm seals rebuild was roughly 5,000 miles ago by rotorsports racing, bonez dp, hiflow, and exhaust, ebay intake with K&N filter (the intake sits in the engine bay, so im not sure how it got water in it) M2 large smic, 850cc primary, 1200 secondary, pfc, walbro fuel pump, unorthodox main pulley, non-sequential turbos, manual boost controller set to 10lbs, fresh plugs/wires/idemitsu oil

Thanks guys!

 

Wow, maybe water got splashed onto a sensor or something. Check the ECU for ghost codes, I guess, and if you want to be extra sure, run a compression test.

Another possibility is a nice fat backfire, but that wouldn't explain the lugging engine.

Are you running the stock underbelly pan?

Dave

 

I'm thinking that since you were driving in a downpour, you probably somehow got some moisture in your CAS connectors, or the sensor itself.

 

I called rotorsports earlier today, they are kinda boggled by this too. They thought that I it might have been a loose wire somewhere or an exposed wire that could have gotten a little wet. A real mechanical failure doesnt make sense since it starts, drives, and holds vacuum perfectly fine, and theres no smoke either.

I am leaning towards the idea of water getting splashed in either the intake or on a sensor, I've never driven the car in rain that bad ever before (and after this never will) so that could be why it had never happened before.

I am running the stock undertray but the car has an aftermarket front bumper so it doesnt mate up perfectly (that and there are a few zip ties holding it on temporarily until I can make some new brackets)

If it is something electrical it wouldn't surprise me, it isn't the first time the wiring has been faulty.

 

It was definitely related to some water entering your electrical system. Even if you'd got a bunch of water in the intake, your engine would have easily burned it off, and it wouldn't have died on you as you described.

The reason I'm theorizing that it was the crank angle sensor is that the "pop" before the engine died could be a sign that the ECU was initially given a bad timing signal. It became totally confused by the engine timing signals it was getting, so it shut everything down.

 

What do you consider to be normal as far as it holding vacuum and idling nicely? What's the vacuum reading at idle after it's warmed up?

Tim

 

lol, now i know this is noob but make sure you check map sensor.. hte loud pop could have been a back fire. Personally when it starts raining and im in my rx7 i pull over, put the cover on it and have my insurance company pick it up and take it to my garage, i have free 150 mile tow range with USAA. Takes an extra 30 minutes or so but, its peace of mind..

 

Most likely you drove through a puddle and water was thrown up on the plug wires at the plugs. This shorted some of them out for a while which caused the unburnt fuel to explode in the exhaust system. The next day the wires were dry.

The plugs being on the side of the engine are more vernerable to this compared to other engines.

Has happened to me a few times since owning a RX-7 since 1983.

 

if there is white smoke then some how water got into ur engine

 

and the pop could have been raw fuel being dumped into the exhaust, causing a backfire?

 

That's what I'm theorizing.