96 Blazer starts, engine surges then dies

[abominus]

When I first turned the key I heard a snap/bang sound, then smelled the acrid smell of something electrical. "That's not good," I said. So naturally I tried it again. The engine started immediately, but the it surged (RPM revved up) on its own, and then it died. It will do this consistently. If I tap on the gas I can keep it from stalling, but then it just surges again and then wants to die. Very cyclical.

I have a computer code reader, but, frustratingly, no code comes up. Any ideas what to look for? Looking under the hood I don't see any little mushroom clouds or bomb craters...

-Doug

[BlazerLT]

Is the check engine light on?

Checked the fuses?

[abominus]

Originally Posted by BlazerLT

Is the check engine light on?

Checked the fuses?

No "check engine" light. Fuses good. Humma.

[BlazerLT]

Was the smell in the engine compartment or the cabin?

[abominus]

Oddly, I smelled it in the cabin. Sounded like it came from behind the dash so I wouldn't rule out fm under the hood. ODBII reader links with computer (yay, at least the computer still exists) but comes up with NO CODES. Checked fuses again, no problems. Will check throttle sensor next, if I can find my multitester...

[BlazerLT]

I think the ignition switch shorted out.

[abominus]

Originally Posted by BlazerLT

I think the ignition switch shorted out.

That's an interesting idea that fits the known facts (I've since not found any dead sensors). But how would a shorted ignition still allow the engine to start at all, much less run cyclically? I would think either the starter wouldn't engage, or the ignition wouldn't turn on at all. The cyclical surge/stall thing is confusing me.

If the problem IS a shorted ignition switch on the steering wheel stem (or under the dash), is that pretty much a "dealership only" repair? Or can a weekend mechanic (I mean, mechanically-inclined) person (me) handle it? Any special tools or "gotchas"?

-Doug

[abominus]

Well, I replaced the ignition switch (ugh) but the symptoms didn't change. Any other ideas out there? No check engine light, no codes come up on the computer -- but based on the snap I heard, and the smell, the failure probably has an electrical component.

Otherwise I'm going to have to get it towed to a dealership

[rlith]

Silly question, have you checked all your fuses? (pull them all and if needed meter them for continuity). Do you have an aftermarket stereo/amp system? Disconnect it for the moment. Have you added anything else that possibly would hinder it...(remote starter, alarm, keyless entry etc)... Have you sniffed around the cabin to see if there is a stronger odor of electrical burn in certain areas? (eburn smell doesn't go away easily, it tends to stick to the plastic and what not, try to zero in on it)

[abominus]

Thanks for your thoughts! Not silly at all...Yep, did all the above -- except meter the fuses (which I'll try). Blazer is all stock. No lingering smell to help out. Guess I can go back to testing engine sensors individually, but at this point I'm running out of ideas. At least Autozone took back the new ignition switch.

[abominus]

It turns out that it wasn't the ignition switch (although that sounded like a good possibility) but a bad INJECTOR. I don't know why that would cause the engine to cycle RPMs and not provide an error code, nor how that relates (if it does at all) to the "snap" and electical smell I smelled at the time it happened. But as I limped it to a repair shop (after a while it became somewhat driveable) I finally did get an error code, P0300. The shop swapped out the injector (and another that had logged a few misfires) for the tune of $700. OUCH. But it runs perfectly now.

Thanks for the suggestions, guys -- it just wasn't what we thought it was this time.

-Doug

[BlazerLT]

Next time bro, do the work yourself.

Pay them for the diagnosis and have it towed to your place to replace the parts, much much cheaper.

[blazee]

Welcome back LT.

$700 to replace two injectors??? That means you paid them $600 for 1 1/2 hours of work. For $400/hour I hope they at least gave you a kiss and supplied the lube.

[BlazerLT]

Originally Posted by blazee

Welcome back LT.

$700 to replace two injectors??? That means you paid them $600 for 1 1/2 hours of work. For $400/hour I hope they at least gave you a kiss and supplied the lube.

Yip, that was a scam, the injectors are 50 a piece.