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UPGRADE from Silly Question Thread - Check Engine Light Troubleshoot
So maybe I'm just being paranoid, but I feel like this is more than just a silly question; and I'm sort of stumped. Not that it is that difficult to stump me on these topics, but still...
the tl;dr version is my check engine light came on after driving for about 30 miles, turning the engine off and on a couple times, and filling the tank up with 12 gallons of gas. Ignition was weaker than usual, but I was able to drive back the 30 miles on pins and needles to get home. Car did not seem out of sorts besides the slow RPM decrease, despite the check engine light.
Unplugged battery and waited 30 minutes. Didn't do anything. Restarted the car and the idle is very wonky with osccilation (see second video). RPM's weren't coming down when the clutch was depressed (see first video).
And now I'm worried my car is sick...
NON-TL;DR version with videos:
Hay Carumba. So took the car out on a 30 mile jaunt over to Vallejo. Was waiting in line for Costco gas behind two of maybe the stupidest people ever, who couldn't figure out how to 1. pump gas 2. Get their cars to turn on and move out of the way.
Anyway, the car idled for about 4 minutes before I just shut it off and waited another 4 minutes before idiots moved along. When I restarted the ignition wasn't like it typically is (first try, fires up) and was kind of half-assed. It stalled and I restarted, turning the key for a half second longer than I usually need to and the car came to life.
Pull up, pump gas, get chatted up by a couple folks asking about my car. I get back in to restart the car and to avoid embarrassment of having it stall again, I give it a little gas. Engine ROARS everyone thinks I'm a douche.
I do my shopping, come out, car starts up again somewhat anemically, and then the check engine light comes on.
I limp home keeping tabs on the temp and trying to keep the engine under 3K revs.
I noticed that the "return to neutral" is WAY slower than before. Like the gas just keeps coming into the engine even when the gas pedal is not depressed. I made the video to capture what I'm talking about. Any ideas? My first thought was a distributor belt may have finally gone out, but really that's just because it's the only thing I can think at this point. It's almost like I have an extra-heavy flywheel or something all of the sudden. Idle, power, etc are all seemingly normal.
Sherlock Holmes observation: I did have a lot of trouble filling the tank up to 12 gallons today. The cutoff valve on the gas nozzle kept kicking on, and I had to fill up by manually holding the nozzle open and reset it every 10-30 seconds when the cutoff kicked in. When I pulled the nozzle out, there was a more than insiginficant amount of gas that was outside the metal flapper, almost like the gas wasn't flowing down quickly enough. Now I'm thinking Tank Venting Valve or Idle Speed Control activation?
Sucks I don't have a diagnostic computer at home., but lucky I have RL. Will a fouled ISV trigger the check engine light? Planning on doing this:
I don't have any brilliant ideas, but I'm in SJ near Campbell, and I have the scantool. I might be able to help you run a scan this weekend if it would help. Where are you in the east bay?
Oh that would be awesome. I'm in Berkeley, right by the Claremont Hotel/UC Berkeley. I'm actually heading down to SJ on Saturday to meet some folks, but won't be able to bring the Porsche (for obvious reasons )
As an interesting aside, I did pick up a portion of a guys wine cellar and now I'm quite well stocked in that department, happy to trade wine for help!
fwiw my 91 came with a faulty dme relay. from the factory. it had a 944 part number on it.
there was a recall, of sorts, at some point in time.
replaced relay. end of problem.
^^ Thanks! Swapped out the DME and started the car. Sounds a lot better. Check engine light still on, so unplugged the battery and will wait for computer to restart to see if that was the solution. Should know in the next 30 minutes.
I was half way to pulling out the ISV when I figured out I should probably wait until I figure out what the issue is before doing something that's going to take a while and patience. I also opened up my old DME relay (944 part number) and it smelled EXACTLY like the Laphroig double cask I had yesterday. No visible signs of burning though.
Engine is running a lot better but check engine light is still on . Looks like I'll have to see if I can get a diagnosis done. Member on here might be helping me out in that dept!
Wow, my fellow droogs, I am happy to report I figured out what was wrong.
So first, I was able to figure out the code from doing the "pedal to the metal" method when the ignition was on, but engine off. I got the 1115 error code (4 slow flashes followed by 5 fast ones), which is for the Idle Speed Contact Break.
Based on comments from Pelican to check with the throttle WOT and closed to listen for microswitch activations led me to believe that wasn't the problem. What I DID notice, however, was that my sound deadening had fallen to a point where it was covering the top of the throttle. LO and BEHOLD, after removing the sound deadening around the throttle, giving th spring a spray of WD40, and moving it back and forth a couple times, started car with no issue, and more importantly, NO CEL.
Love simple fixes. Moral of the story is pull that crap sound deadening stuff out to the extent possible!!!
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UPGRADE from Silly Question Thread - Check Engine Light Troubleshoot
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