Could be all kinds of things. Fuel pump giving up is my first guess.
this post was submitted on 07 Nov 2023
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Second guess- failing/loose crank position sensor or other critical sensor.
That would be my first guess. Fuel pumps usually don't go out sporadically. Should have still been a readable code in there, though.
Every dying fuel pump I've dealt with was hard to start, but ran fine once running.
The ones I've seen usually just die. Engine cranks but won't start. Or it will start a few times till it gives up the ghost.
I'm not mechanical in any way but it sounds very similar to what happened to me. It turned out to be some issue with the transmission. There is something called overdrive or something like that where when you go in 4th gear it engages and you get better highway fuel economy. The problem was it would engage but would get stuck and not disengage which would stall the engine (and shake the car violently) when coming to a stop. I took it to a mechanic and they gave me an option. Fix it for 2000 or disconnect it for 100. I disconnected it and I lost maybe 1-2mpg while driving freeway. Some cars have a button to turn off overdrive so you could try that if yours does.
I just looked up your owners manual and you have a switch on your shifter knob to turn off overdrive.
That sounds like the torque converter lockup clutch. The torque converter is a fluid coupling between the engine and transmission. It will always have some slip. In the 80s they started putting clutches in them to get those 2 mpg you described. Yours must not be disengaging properly, I've never seen one fail like that.
Yeah like I said I am dumb when it comes to cars and this was years ago so I may misremember. All I know is that if I got my car up over around 50mph it would shake violently and stall when I stopped. Then if it sat for 10-20 minutes it would be ok again (until it got in 4th again). I do know they disabled something that reduced my mpg slightly and I never had the issue again for the 2 years I still had the car. Again I don't remember 100% but I think he literally just unplugged a cable. Charged me 75 for diagnostics and 25 for labor.
Actually reading your comment again "Torque Converter" sounds really familiar so that's probably it. If we are running a pool I got $5 on stuck torque converter lockup clutch.
I do have an overdrive switch, and when it's on it shows up on my dashboard. It wasn't on, it's not something I use but I've accidentally switched it a couple of times.
I've never heard anything about a "Torque Converter" on my car, but I'll keep that in mind as a possibility. Thanks
Flashing check engine light means you have a severe misfire.
Probably a coil pack
That could definitely do that. Had that happen to my GTI; I pulled over as soon as I was able to and parked the car. I checked on an OBD II reader, and the light and shaking was caused by misfiring. I replaced all the coil packs, cleared the code, and it's been fine since.
I'm a mobile plant mechanic, but would it run fine before driving?
As in idling and reving?
Knowing that would help diagnose between drivelin issues or engine issues.
Transmission could be fucked or the engine is getting hot and seizing.
Yes, letting it idle and revving wouldn't make it shake. The first mechanic tested that for about 15 minutes. The engine was cold by the time he arrived though.
Hmm, seems drive related then so i would say transmission torque converter perhaps. They cause shaking and stall out engines. Or perhaps kickback valve.
It might be a misfire on one of the cylinders. Try to find somebody with a scanner. It would be interesting to see what comes up
misfiring, could be coils, plugs, injectors, could be worse (like a bad piston could be blown engine, not unusual for a Hyundai) unlikely fuel pump IMO.
I have a 20yo car with a bad torque converter that I'm dragging my feet in replacing.
It shakes at stops and to get it to stop shaking I shift it to neutral. Your car is in the shop so you can't really make that test.
Fuel sensors can cause some funky things though. Give fuel when it shouldn't and not give when it should. It will cause misfires that way.
Driving with faulty parts will cause other systems to fail. It's usually better to replace things sooner rather than later.
Like a lot of people here, my first thought is misfire, which means either plugs, cables, or coils/coilpack.
My second thought is it could be a vacuum leak.
I've reading a bit after all these answers. I figure coils or plugs would show up on a scan, which the roadside mechanic did and only turned up the already known fuel sensor issue, as I mentioned on the post.
I'm starting to get the feeling it might be something transmission / torque related, which I hope is not the case as it sounds very expensive.
You are the first one suggesting vacuum leak, will keep in mind. Cheers
Yeah, a couple months back I was doing some work on my car and when I was done I did a test start and it started right up. The next morning though it wouldn't start. After giving it a little gas I could get it to...idle, per say, but it sounded terrible. Like Satan spray-shitting hammers and nails into a sheet-metal toilet. At that point though I was able to look in the engine bay with the car running and I could hear an audible hissing - the vacuum line going to the brake booster snapped in two. It must've been torqued weird when I was moving the intake manifold around. I rigged it back together, it started up great, and I went straight to the hardware store to replace the hose
It sounds like what happens in a manual if you bottom out your RPMs in gear. Maybe your car isn't shifting down or disconnecting the gear properly, especially if it happened while stopped.
It's not possible to guess with certainty, but my guess is a failing ignition coil pack. The oil and battery lights are just because the engine was off.
Worst case would be if your transmission fluid leaked out, then your transmission would be shot.
Best case would be an issue with your spark plugs, then it should be good to go after replacing them.
Most likely case is a problem with wiring or electronics, which could be very easy or very hard to fix.
Blinking check engine = pull over and call a tow truck. You'll do even more damage by continuing. As for shaking, it could be a bunch of things and I'm not going to speculate beyond what other people have commented.
Sounds like it's shifting into a higher gear too quickly, getting stuck in a higher gear, or shifting at the wrong times, an issue with the transmission.
Traction control can cause the tires to refuse to move if youβre on a slippery surface like snow.
One of these will immediately tell you with a free app
He said he already scanned it, so it won't tell him anything he doesn't already know. I actually do have one of those though, albiet with some other Chinese branding. It's not very durable as I've already had to replace it, but it's cheap so who cares? It won't pick up manufacture specific codes though, just obd2