Help, LS8 left us stranded

J

jderou

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We were driving down the interstate yesterday and the car fell flat on its face. The details:

2001 LS V8
Car will start, rev up as normal, then idle drops down to a low rough idle which slowly gets lower and lower till it dies. Throttle input does nothing.

I pulled all the coils off, on the passenger bank the 2nd from the front had lots of oil, 4th from the front had a little, the rest were dry. I pulled the two plugs to drain the oil. replaced plugs and coils and started the engine. No change in behavior, but did get lots of smoke, so that would tell me at least one of the two coils is working correct? Just for fun I tried swapping some of the coils around to see if it behaved differently, no change.

Fuel pressure: 40 before starting, once it starts it goes down to about 30, then comes up to about 35 while idling roughly. Replaced fuel filter today.

I talked to the dealer, he doesn't think it's the coils or the fuel pump (I'm not convinced either way), he said it sounded like one of the engine sensors. I haven't been able to check codes, as I can't drive it to have them checked. I may be able to borrow a code reader, I will look into this tomorrow.

Anyone have any ideas?

Thanks,
Joe
 
maybe vacuum leak or bad IAC - so you are getting too much air in stalling the engine. the IAC can stick - and if it's too open or too closed that will be your issue.
 
Also check the MAF sensor and check for exhaust restriction.
 
Well you need new valve cover gaskets. And you might need to replace some of those coils.
It's a really bad idea to drain oil from the plug wells into the cylinders by pulling the plugs. Roll a paper towel around a 3/8" ratchet extension, slip the extension out while you hold the towel to keep it from unraveling, then drop it down into the plug wells where the oil is. I used the nice absorbent blue shop towels to do that and it worked great. Once most of the oil is gone spray some brake cleaner down in there and do it once more to get the cleaner out and that should get it all.

Other than that I'm with these other guys on the vacuum leak. The lack of change when giving it throttle could point to a bad Throttle Position Sensor, but I don't think that would cause it to stall.
Make sure your intake tube is tightly clamped onto the throttle body, and the MAF sensor housing by the air filter box.
 
Wow, thanks for the quick responses guys. I'm going to try and pull the codes tonight.
This is my first ford product so I'm a little ignorant of the vacuum systems, where would be a good place to start? since it won't run for long on its own, it'll be tough to listen for it.

Also, what is the IAC?

I will post back when I get codes.
 
the IAC - Idle Air Control valve - it is on the side of the throttlebody, it allows some air to 'sneak' past the throttleplate when the plate is closed. So when you are stopped - and foot off the gas - the car would stall because no air can get in - but the IAC has a little motor in it that continually adjusts (based on your idle rpm) to open a air bypass allowing air araound the throttleplate.

If it is stuck closed - you stall without having to keep you foot on the gas pedal a little.

if it is stuck open - you have a huge vacuu, leak and the car stalls no matter what you do with the throttle.
 
Failsafe in mine was I could start it, and then once the RPM came down from the start it'd shut itself off with all sorts of warnings from the dash.


Turns out the seals on one of the intake silencer chambers came apart and was letting in a ton of unmetered air so it went into failsafe.
 
Ok, so it didn't throw any codes. But I tried a couple things.
I disconnected the big hose to the IAC, it started and ran smoother for a couple seconds, but shut off suddenly (assuming because no air was moving through the snorkel).
Next I tried unplugging the MAF. It will run like this, it runs crappy, but it runs.
So does it sound like the MAF is bad?
 
It could just need cleaning. It could also be that it is not metering all of the air because there is a leak somewhere. Check for that too.
 
when you unplugged the IAC hose - did you plug the ends up?

if you plug the ends - and the problem changes - that will tell you if the IAC is stuck open.
 
you've got to be kidding me. I took the MAF sensor off and there was a little bug on the wire, a little blast of air to clean it off, put it back together and it runs great! That bug cost me $150 in towing!
For one thing, how did a bug get in there, for another thing, what are the chances it would end up on that little wire?
I guess that's where the saying "its got bugs" comes from.
I appreciate everyone's help in steering me in the right direction!

Joe
 
good for you. check for holes in the air filter.... just in case. I hard shell bug at 100mph can get into areas...
 
jderou said:
you've got to be kidding me. I took the MAF sensor off and there was a little bug on the wire, a little blast of air to clean it off, put it back together and it runs great! That bug cost me $150 in towing!
For one thing, how did a bug get in there, for another thing, what are the chances it would end up on that little wire?
I guess that's where the saying "its got bugs" comes from.
I appreciate everyone's help in steering me in the right direction!

Joe
Click to expand...

Interestingly enough, my 06 LS stalled on me while pulling on to the interstate about a month ago. It turned out to be what looked like lady bug remains stuck on the MAF.
 
at least it was a little inspiration to do some maintenance. VC gasket, air filter, etc.
 
In my case, the bug got in because i didn't have the cover to to air filter box snapped all the way down. (One snap was okay, the other wasn't.) The tow didn't cost me anything as it was covered by Lincoln. The dealer that it was towed to, however, did charge about $100 to find and remove the bug.
 
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