Strange issue that only happens when it’s raining.
Thread Starter
Cruising
Joined: Jul 2022
Posts: 11
Likes: 2
From: South Jersey
Strange issue that only happens when it’s raining.
Hey all, so I have an 02 convertible. A little while ago I had a set of headers, and x-pipe installed and since then I’ve been experiencing this issue. Now it took a while to realize that this issue was specifically related to when it’s rains but there is no doubt now that something is happening when the undercarriage gets wet…. So when it gets wet, the car starts to misfire to such an extent that the car is un-drivable. I had an event where, during a heavy downpour, I was forced to leave it at a shop to see if they could figure out the issue (before I realized it was water related) and they swapped out the wires and plugs and changed the exhaust manifold gaskets with better ones since what was there was super thin. Now when I picked the car up on a sunny day it drove fine so I thought it was fixed but next time it rained the issue returned. Long story short, I’m looking for thoughts on what it could be. My thought is the O2 sensor or wires are getting wet and causing the issue. What do y’all think?
Drifting
Joined: Sep 2022
Posts: 1,460
Likes: 1,128
Yeah, kind of sounds like an electrical short from water getting to an exposed circuit.
Would take some thorough investigation, looking for a possible harness rub through or burn through or compromised connector.
Would take some thorough investigation, looking for a possible harness rub through or burn through or compromised connector.
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
Never seen an O2 sensor when wet causing misfires but if there are misfires is the MIL illuminated ??…can can try misting some water onto the engine when running and do that in a dark garage and see what happens…you won’t get a definitive answer here.
Melting Slicks
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From: North Coast
Drifting
Joined: May 2008
Posts: 1,695
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From: Denver, NC
Hey all, so I have an 02 convertible. A little while ago I had a set of headers, and x-pipe installed and since then I’ve been experiencing this issue. Now it took a while to realize that this issue was specifically related to when it’s rains but there is no doubt now that something is happening when the undercarriage gets wet…. So when it gets wet, the car starts to misfire to such an extent that the car is un-drivable. I had an event where, during a heavy downpour, I was forced to leave it at a shop to see if they could figure out the issue (before I realized it was water related) and they swapped out the wires and plugs and changed the exhaust manifold gaskets with better ones since what was there was super thin. Now when I picked the car up on a sunny day it drove fine so I thought it was fixed but next time it rained the issue returned. Long story short, I’m looking for thoughts on what it could be. My thought is the O2 sensor or wires are getting wet and causing the issue. What do y’all think?
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Tech Contributor
Joined: Jan 2007
Posts: 19,470
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From: Dyer, IN
Hey all, so I have an 02 convertible. A little while ago I had a set of headers, and x-pipe installed and since then I’ve been experiencing this issue. Now it took a while to realize that this issue was specifically related to when it’s rains but there is no doubt now that something is happening when the undercarriage gets wet…. So when it gets wet, the car starts to misfire to such an extent that the car is un-drivable. I had an event where, during a heavy downpour, I was forced to leave it at a shop to see if they could figure out the issue (before I realized it was water related) and they swapped out the wires and plugs and changed the exhaust manifold gaskets with better ones since what was there was super thin. Now when I picked the car up on a sunny day it drove fine so I thought it was fixed but next time it rained the issue returned. Long story short, I’m looking for thoughts on what it could be. My thought is the O2 sensor or wires are getting wet and causing the issue. What do y’all think?
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Thread Starter
Cruising
Joined: Jul 2022
Posts: 11
Likes: 2
From: South Jersey
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
the shop scanned the codes and found that a couple of cylinders were misfiring, the plugs and wires were original, one wire was damaged and a couple of plugs were fouled. All of this was shown to me prior to approving the work. Also the head gasket was what came with the headers and it was super thin and crushed so I had a leak. I think while they did the work, the wetness dried and mad it appear that what they did solved the problem but either way the work still needed to get done at some point; probably by the guy that installed the headers but he’s a whole other story.
Thread Starter
Cruising
Joined: Jul 2022
Posts: 11
Likes: 2
From: South Jersey
TBH, I don’t have that information. If I recall, it was showing misfires in bank 1&3 but that’s as far as I got with that because issue isn’t with the engine but rather because of something (O2 sensor or pigtail) getting wet causing the misread that’s causing the misfire. I just don’t have the time or a lift to diagnose this positively. I’m looking for anyone that might have seen where water could make an O2 sensor do what I’m describing and what the fix was.
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
TBH, I don’t have that information. If I recall, it was showing misfires in bank 1&3 but that’s as far as I got with that because issue isn’t with the engine but rather because of something (O2 sensor or pigtail) getting wet causing the misread that’s causing the misfire. I just don’t have the time or a lift to diagnose this positively. I’m looking for anyone that might have seen where water could make an O2 sensor do what I’m describing and what the fix was.
Race Director
Joined: Oct 2004
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Or maybe bank 4, which the "stealer" owns. Seriously, I do wish the OP luck. I'm having my share of bad luck lately with codes and wiring, and it totally sucks. I'm convinced that, eventually, it'll be electronic and wiring issues that will take the C5s/C6s off the road, NOT mechanical ones. Actually, I'm really surprised that someone hasn't reverse engineered the SWPS (SAS) and the EBCM. Hell, it's getting tough to find quality 1997-2000 key fobs, ignition switches, fuel senders, TPMS, etc.
Running Guns & Moonshine
Joined: Aug 2001
Posts: 12,665
Likes: 7,300
From: CT
You don't need a lift. You can drive it up on a friend's lawn with a divot and slide under there or buy a jack and some stands. Even rent them.
If it was reporting banks, it could be one or both O2s feeding infinite rich or lean if shorted I suppose. Likely the connectors were allowed to flop loosely and melted through the harness connector if leaning against the pipes near the frame. Absolutely could be that.
Another thing to always verify, not that it applies in this case necessarily, but with so much work right there are the grounds at the block secure.
If you're paying people to do this work...... My only advice then is to reach out to your local state Corvette Club and seek a referral to the best shop in your area so you only have to buy once and cry once.
If it was reporting banks, it could be one or both O2s feeding infinite rich or lean if shorted I suppose. Likely the connectors were allowed to flop loosely and melted through the harness connector if leaning against the pipes near the frame. Absolutely could be that.
Another thing to always verify, not that it applies in this case necessarily, but with so much work right there are the grounds at the block secure.
If you're paying people to do this work...... My only advice then is to reach out to your local state Corvette Club and seek a referral to the best shop in your area so you only have to buy once and cry once.