MY buddy's Hyundai Sonata was running fine, then as we pulled up in the driveway he said there was problems as I was getting out of my car. I asked what, he said listen and started the car. It made a terrible loud rattling and shaking noise, and it wasn't methodical. Very random. It was a very audible sound over the belts and normal engine noise. The car stalled out and died after 30 seconds. I had him start it again, with me holding the throttle partially open to see if more gas would make it start, but nothing. After a few more tries the car just wouldn't start. The starter was fine but there was no ignition. So I pulled out my OBD2 scanner and scanned for codes. There was a p0421 code and that's it. I was stumped. It could be many things: no fuel. no spark. no air. I'm gonna try to take off the intake so that we can rule out the air filter being clogged up. PLEASE HELP ME. I really need to help out a friend here. I know it's not a Honda, but I really am stumped and am willing to try anything.

 

hmmm Honda tech doe not Hyundai think you'd get better luck in GDD. I don't even know if that's 4 cyl or 6 those cars are NOT close to a 92-00 civic.

 

Well then pretend it's a honda. Pretend MY 95 civic is doing this. What would you check?

 

Well that code is supposed to be for the down stream 02 on the cat could be seriously clogged take it out(the cat) and see what happens

http://www.obd-codes.com/p0421

 

Would that prevent the car from even firing?

 

shouldn't be but that's the code's definition. this is where the complications come in does this thing have a dizzy ?

 

Yes. It does. I was thinking that maybe the dizzy failed and it's not getting spark. Maybe thats what went down. To your knowledge is there a code for that or a way to 100 percent be sure of that as the issue? I don't wanna **** him over. I'm usually right when it comes to cars, but his car is very cramped under the hood (unlike our spacious hondas).

 

There is no code for a bad coil/igniter afaik. what you CAN do is 1st just use a spark plug tester to see if it gets good spark if so that's not the issue. 2nd you can test the coil by stress testing with a HEI tester.

 

I don't have ANY mother ******* testers at all. No voltage testers, sp testers, and I have no idea what a HEI tester is or a stress test is. And autozone is closed right now.

 

well.... there's not much you can do then other than check grounds and inspect visually that everything is connected tight(plug wires, plugs to the starter things like that).

 

Thanks for your help mang.