98 STS Engine Dies for no apparent reason

[hondo69]

I have a 1998 STS and have recently had an issue where the car dies for no appparent reason. Happens sometimes when I first start the car, sometimes when I park and other times when I am just driving along--Engine dies, dashboard goes black, a little hairy at night on a back road. I have seen the posts for FPR failure, checked it, no leaks. Also saw the posts for CKP failure, but wasn't sure if this was common on 98's. Checked the codes...nothing triggered.

Also, I notice a little engine "stumbling" at higher speeds...not like a bad coil pack, much more subtle. Also, sometimes the idle is slightly rough nad sometimes it is smooth.

Any ideas?

Car has 102k and is in otherwise great condition.

A

[Ranger]

The symptom you describe is a common CKP failure. It does not always set a DTC. That said, it is not common on the '98's. Much more so on 2000-2003's. No DTC's makes it much harder to diagnose. Check the battery cables and grounds.

[submariner409]

Curious........Most of the CKP complaints occur during warmup at slowdown for traffic or a light...........and sometimes during changeover from closed to open loop, generally at low speeds.

What about throttlebody and IAC (Idle Air Control) port cleaning? Are new spark plugs in? (102k is overdue....... DELCO 41-987.)

And, yes, do a complete battery cable cleaning. How old is the battery?

BTW, when it's running on the open road, what is the DIC battery voltage, day and night?

[CadillacSTS2003]

CKP sensors

[hondo69]

Thanks for the responses. I will replace the CKP's...BTW does the 98 N* have 2 CKP's like the 2000 and up? If so are they identical?

To clarify, the problem does tend to happen frequently when slowing down to make a turn or when pulling into a parking place. In addition, there are times when I try to start it, it fires up and then immediately shuts down. This can happen 2-3 times, then it starts and runs normally.
Not sure about the Battery age or cables and grounds...but will check them this weekend, while replacing the CKP's and posts the result.

Finally, I notice that when I first start it, the dash board lights sequence through (ie. ABS and Airbaig lights come on and go off) Sometimes if i sit still I can observe the lights cycle through again, similar to a computer reboot, the ABS/Airbag lights come on, the compass in the rearview mirror goes off, then it "reboots" and the compass comes back on and the ABS/AIrbag lights goe off.

Not sure if this is relevant, but thought I would mention it.

[hondo69]

Thanks for all of the advice. Replaced the cam sensor and the 2 crank sensors. Also , cleaned the throttle bdy...had a lot of carbon from 100k miles of no cleaning. Problem seems to be better, however, it appears as if the ignition switch is also bad. Sometimes when I turn the key just prior to engaging the starter, no dash lights illuminate. If I turn the key off then back on, they will sometimes light other times not. Jiggling the key will sometimes make the dash lights come on. In any case, when they do not light the car doesnt start and I have to play with it to get it to start. I have ordered a new one and will post the results.

[CadillacSTS2003]

check your battery terminals and cables before you throw money at it
usually (i say from experience) when the ign switch starts to go, youll get random and weird warning lamps on the dash

[submariner409]

FWIW, my car had a warranty ignition switch replacement at ~3,200 miles in late '02, original owner in Staten Island. Complaint was dash indicator problems.

[Ranger]

Engine dies, dashboard goes black

The symptom you describe is a common CKP failure.

In rereading this, I stand corrected. A CKP failure will cause the engine to die, but the rest of the electronics will stay unchanged. Your problem does seem to be more ignition switch related. Sorry for pointing you in the wrong direction.

[chubbyranger]

Seems to have been a few bad ignitions lately:

http://www.cadillacforums.com/forums...placement.html (Ignition switch replacement)

[hondo69]

Thanks for the replys. Ordered the switch from rockauto and will let you know how it works out.

[Mister Moe]

I just replaced my switch today - for reasons similar to yours. Sometimes, after turning the key to the ON position, the dash would be dark - no lights at all. Then, although the engine would crank, it would not start. Turn the key to OFF, back to ON, the dash would come on and the car would start. The bad one was when everything - dash and engine - just quit on the highway. Then it happened a couple more times, it was as if the ignition had been turned off. So, I have replaced the ignition switch, I hope the problem is solved but I won't know for a little while.

Good luck and let me know if your problem is solved by replacing the switch.

Moe

[hondo69]

Replaced the ignition switch and it looks as if this was the problem. I noticed that the switch contacts where the two main plugs connect were discolored as if there were a lot of current being drawn through the switch. Hope this helps other that are experiencing similar issues.