S5 Turbo cranks (sometimes) but does not start.

After trying a few times, the key stops working. It suddenly goes loose in the cylinder and the idiot cluster doesn't come on. In this state, the key can easily be moved clockwise all the way, offering no resistance. Oddly, it starts working again as expected after a while.

The wiring to the ignition switch is in pretty bad shape.

Are these related? Have any of you guys experienced this?

 

The ignition switch is "el fucko". It's caused by people having 8,000lb key chains and it wears the contacts and return spring out.

As far as the wiring for the ignition switch, Mazda decided to make the ignition switch harness 50ft long, so most installers will install alarm and remote start modules on the ignition switch side of the plug as the main ignition plug is barely accessible.

 

Thanks! Do I need to replace the whole cylinder assembly or just the switch?

I don't have a super heavy keychain but I'll try to take some keys off haha

 

I think the first thing is to fix the lock/cylinder, it's what turns the contact on the switch.
If the key is just rattling around, the switch doesn't have a chance to work and may in fact, be perfectly OK.

 

the lock cylinders actually usually arent the culprit in these cars, though in some cases i have seen them to the point you dont need an actual key to get them to turn but anything that slides into the slot. the issue you are having sounds like a faulty switch.

 

Thanks for the responses guys!

I'm kind of grasping onto the hope that it's just the ignition switch since it's cheaper and easier than replacing the key cylinder as well. However, I'm a little dubious because the key (when it's not working) doesn't have the mechanical return to the "on" position when you rotate it to the "ignition" position. Is this a red herring? Is that spring-like return to the On position somehow governed by an electrical current?

 

no, because the return to start from crank is actually part of the ignition switch, and why i said it is the most likely cause according to the list of symptoms given.

it is easy to disassemble the switch, just do it in a room that has very little in the way of shooting parts to get lost in... lol. not that it is such a boobytrap but there is a lot of copper strings and springs in there.

 

if you are worried about re-keying the cylinder is isnt hard. You can easily do it yourself.

Put the new key cylinder on a bench and remove the tumblers, It's going to be like a puzzle. Stick your original key in and drop the tumblers in. For the key to work, the tumblers need to be siting flush with the cylinder. Unless you get lucky, they won't be correct the first time but you can rearrange them until they all sit flush. I really isnt that hard.

 

for reference, i'm talking about the electrical switch, not the cylinder which is just an extension shaft that only turns when a key is put in.

the switch is just a plastic housing which holds several spring loaded contacts. if the housing gets cracked, the contacts get jammed, the contacts are burned from excessive loads or the old wiring, etc, etc, etc then the switch fails to work. i have cleaned them before, but that only works if the switch is in good enough condition, most of the time the contacts are extremely worn out and carboned up after 100k miles.

 

Thank you guys! I really appreciate the help!

 

So I finally got the replacement switch, but I managed to break off the stud for the little breakout harness with the button on it that attaches behind the ignition column while trying to remove the metal fastener.





Does anybody know what the purpose of this switch is?



It has a solid green wire and a red wire with a yellow stripe coming out of it.

I figure I have two options here:

1. Super Glue it
2. tap a stud into the ignition cylinder and secure it with a nut

As janky as it is, I'll probably end up going with option 1 unless I can find a good reason not to, so I'm trying to figure out what the purpose of this switch is.

Does anybody here happen to know?

 

I did the same thing and just cut it off the harness.
It doesn't affect anything electrical in the switch itself.

 

That's keysense. it tells the cpu to gripe at you when you have left the key in the cylinder and you open the door., assuming you cpu still works properly.

 

Thanks guys! I replaced the ignition switch and it's completely solved that particular electrical gremlin.

However, the car still doesn't start.

I tried for a good half an hour and made some observation (percentages are based on feeling lol):

20% of the time, it just cranks
75% of the time, it sounds like it's soooo close to starting, but is just spinning too slow
5% of the time it starts! goes up to 2k with me trying to spam the gas pedal, then immediately dies whether or not i am touching the gas pedal

When it does fire up brieflly, thick white smoke comes out of the tail pipe like the car just took a hit from an e-cig:



The smoke dissipates pretty quickly and it doesn't smell like coolant. That's pretty normal for a fresh rebuild, right?

I'm a little stumped. I just replaced the fuel pump last weekend and the spark plugs and wires are new.

Has anybody seen this kind of behavior? Is it just a matter of not getting fuel/spark? Could it be timing or low compression?


To be totally transparent, I took the car to a mechanic to rebuild the engine and he ended up being a total POS once the car didn't start up immediately after the rebuild. No need to tell me how much of a mistake that was, but I'm trying to get this car on the road again. Jury is still out on the quality of the work he did do.

The car ended up sitting for about 9 - 10 months after the engine itself was rebuilt and installed.

 

Could be a slow starter. Could be low compression which makes the hard to start. If the car does start it would probably be best to let it run for a long time so as to break in the engine as opposed to just starting and turning the engine off.

 

i would ignore the smoke for now, could be coolant in the exhaust from a previously bad engine.

sounds like the car has vacuum leaks which is why it is stalling after a startup.