'02 LS8 - Starting issues

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NascarGuy

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Been a forum member a good part of a week and spent most of it reading the forums concerning the gremlins I face with my LS8 but have not found all the answers yet so figured I would make my first post.

Purchased the LS8 about 3 weeks ago. It is an '02 with 101k miles on it. It had the usual misfiring issues as well as a few others so after reading around I spent a good part of yesterday replacing the valve cover gaskets, plugs, and coil packs which made a huge difference. I no longer have the misfire or hesitation issue but still have one that I thought this tune-up would eliminate. The car is still slow to start when it is cold; slow meaning that I have to turn it over for 10 to 15 seconds before it will fire up. Once running, it runs like a dream and once warm it starts fine. After completing the parts swaps yesterday I also disconnected the battery to clear all codes and then reconnect. I drove around for a bit then took the car to AutoZone to see if any new codes were in the system. Presently I do not have any engine lights or codes showing. Any help with this issue would be appreciated. Lastly I have to mention before I did the tune-up yesterday the car was also a PITA to start. It would take the same 10 to 15 seconds to finally catch.

Thanks in advance and thanks for all the great info.
 
cranks ok, but no ignition right?

So the starter is ok since it cranks. Then it might be the fuel filter needs replaced or the fuel pump is failing to prime, or maybe battery needs replacement. Since the car is nearing 10 years old, have you replaced any of these items? Oh!!! I forgot! the IAC valve could need a cleanout or replacement.
 
Here's two things to try.

1. Turn the key to run and wait five seconds. Turn it off, then back to run and wait five seconds again. Now turn it to start and see if it starts quicker. If it does (consistently) then your fuel pump may be failing and/or your fuel filter clogged.

2. Press the gas pedal 1/4 to 1/2 way down and try to start it. If it starts much quicker, then maybe your idle air bypass valve (aka IAC) is sticking.
 
Replaced the fuel filter this morning and same result. I located the IAC and tried disconnecting the large hose that loops to the air cleaner the the car would idle for a few seconds then stall. I then cleaned out the end I could see into, connected everything back up and same result. I also tried the "turn the key on and back" thing a few times and no luck. Wondering if it is vacuum or fuel pressure related. It seems like once pressure, whether positive or negative, is built up, the car starts and runs like a top.

Keep the ideas coming. I can get an IAC from RockAuto for $54 plus shipping but would rather not if not needed.

Thanks in advance
 
You can take the IAC off the throttle body very easily. Do that to clean it properly. The tube that runs to the passenger valve cover gets filled with oil gunk, too.
Get a replacement gasket for it, too.
 
Yes take it off to clean it.

use some carb cleaner to clean out the IAC really good from the inside. You will need to remove it first. The solenoid in the IAC may be getting ready or has failed. Its an easy fix, sooner or later it will go out leaving you stranded. Hey one more thing, on the drivers kick panel (left side) you will see a single switch opening, that is the accident cut off switch for the fuel pump. Make sure the switch is in the down position.
 
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How can one test the IAC to make sure it hasn't failed?
 
unknown

on my bimmer, i just unplugged the electric connector and the car would idle at 2000 rpm. Not sure about the LS, check the resistance, see if its open or shorted out. When my IAC crapped out, the car would crank, just barely start ignition then die, in order to drive it, I kept one foot pressed on the gas and the other on the brake or it would die. I just went to Napa and got another for about $50 and was done with it.
 
This may actually be the cause of my no start. I'm getting power to injectors, new fuel pump/filter, and no start. I was almost thinking crank sensor.
 
pektel said:
How can one test the IAC to make sure it hasn't failed?
Click to expand...

There are two ways that I know of.

1. Unplug the electrical connector while the engine is running. The idle speed should fall greatly and the engine may even stall.

2. If the engine won't start, hold the gas pedal down about 1/4 to 1/2 way and try to start it. If it starts okay and runs okay as long as you keep pressing the gas pedal part way down, then the IAC is a good suspect.

(Keep in mind that this all applies to the gen I only. The gen II does not have an IAC.)
 
Thanks joe. I was thinking there may be a resistance test with a multimeter or something. I can't perform the first test because my car doesn't start.
 
pektel said:
Thanks joe. I was thinking there may be a resistance test with a multimeter or something. I can't perform the first test because my car doesn't start.
Click to expand...

You could check the solenoid coil resistance, but that's not what I've ever seen fail. Instead, the valve fails mechanically.
The solenoid opens a small air valve. The small air valve controls air pressure on a small piston that opens the large air valve that controls idle air to the engine.
 
interesting note

another member had a similar problem and found a broken wire at the fuel pump connector. see current thread list for won't start
 
in the tank, actually. pull the rear seat. You'll see a rubber piece covering the metal. Remove that. You'll see 2 black plastic/rubber covers. The pumps are directly underneath those. My pump was on the pass. side.
 
Well, the saga goes on. I tried cleaning the IAC today as well as removing the butterfly but still the same. Will continue looking until one of these suggestions resolves the issue.
 
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