Possibly my most embarrasing troubleshooting moment

Vulture

Vulture

TJ Enthusiast
Supporting Member
Joined
Aug 17, 2016
Messages
263
Location
Indiana
So, last Wednesday I posted here about a problem I was having with my TJ revving to the limiter instantly on startup. Thanks millions to mrblain, 89sandman and jeep_boss for their reply's and advice trying to help me solve this problem. I want everyone to know that I've been a maintenance worker most of my life so I like to think I'm not a total moron when it comes to troubleshooting problems. Just goes to show you how wrong you can be!
Here's the sequence of events. I took a systematic approach to solving the problem, I checked the throttle cable, unhooking it from the throttle body bellcrank and making sure that it wasn't binding and it was totally free. I crawled, stooped, crouched, stretched and contorted myself into a pretzel under the dash and engine compartment trying to find a vacuum leak. I couldn't perform the usual vac-leak check with propane or whatever because the engine was revving as soon as you started it. I removed the throttle body, cleaned it, cleaned the IAC, checked the TPS, made sure all the gaskets, o-rings and stuff were not leaking. No luck there. I read everything I could online about this issue, I read everything I could find in the Factory Service Manual about all the suspected components. I finally decided that it might be a problem with the PCM so I disconnected the battery on Friday night and left it off over the weekend. ( I know that's not necessary but Soaring season started this weekend and I was at the airport every day.). Yesterday, I went to work on the jeep again, hooked up the battery, started the jeep and she started and idled perfectly. Hurray!!! Then I touched the gas pedal and whammo, high revs again. About now, I'm getting pretty pi$$ed off. I grab a screw driver and flashlight and start searching again under the hood. I then move to the cabin to go through the vac leak check thing. Again. Drop my screwdriver on the drivers side floor, reach in to retrieve it, look up, and there it is, right in front of me. Moron. Nincompoop, Idiot. Novice. Now remember, I've been under the dash at least 567,842 times checking vac lines and in all that time I didn't notice this!!!
The floor mat, while behind the clutch and brake pedals, was in front of the gas pedal!!!! And THAT was what was messing with the throttle.
As you may notice I spent a whole day debating with myself on whether I should post this and confess to such colossal blunder. Hopefully, you all get a chuckle out of it. Basic troubleshooting: always check all the simple stuff first!
 
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We can all relate, @Vulture. God bless you for being honest enough to follow up and post your findings.
Some get their answer and are never heard from again, at least till their next problem.
We're a bunch of troubleshooters who like to solve problems and reading about your experience makes us better diagnosticians. :)
 
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Throughout my tech career, I have had to troubleshoot extremely complicated issues in very large scale environments. Over the years, I have truly adopted the principles of the 7 layer OSI model, where layer 1 is the "physical" layer and on the other end of the spectrum, layer 7 would be the application layer, where protocols such as HTTP live.

I always start troubleshooting by inspecting layer 1 - many times, the problem had stemmed from something being physically wrong. It's hilarious in retrospect thinking about a dozen or more highly paid engineers chasing down a problem and arguing about something that actually wound up being an unplugged cable! :D
 
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I was trouble shooting a garden tractor once... Could not get it to run. I was convinced the timing was off ( fresh rebuild). Went through a long process because it had been running! Turns out, i had only put a little gasoline in it at the beginning. I ran it out and didn't check it again. Turns out, gas is pretty important!
 
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How 'bout having a 5 year old show you up? I could get my '86 Toyota Supra to start and run for about two seconds, and then it would die. I had been messing with it for about 30 minutes when my five year old son came out and started watching me. After a couple of minutes, he said "The big hose isn't on, Dad." I thanked him, and dismissed it without even looking at what he was talking about. A couple minutes later, he repeated himself, and I again sort of just let it go. By the third time, just to pacify him, I firmly attached the "big hose" which had somehow worked its way loose, leaving a slight gap from where it attaches. You know where this is going. Fired up the car, and it idled beautifully. I went out, detached the "big hose" again, and the car wouldn't stay running. The hose was to the MAP system. Yup. That'll teach me! This old man heaped loads of gratitude on his boy that day!
 
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I started working on alarm systems years ago and after installing for a few years went to the service dept. A well respected senior tech pulled me aside and asked me how I was doing. While things had been okay I’d just gone thru a call where I ran myself to hell and back chasing a problem that didn’t exist. I’d finally figured it out but had wasted hours. He just smiled at me and let me know that it happened to everyone and as soon as you thought you were above making that kind of mistake you were bound to get humbled again, quickly. He was right.
 
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