Please give me the benefit....

[cammerfe]

of your experience and thinking.

My '02 LS8 sport has +/- 150K on it. Battery is less than a year old. Largest size that'll fit in the battery tray. Connections clean and tight. Plugs have +/- 40K on them. Accel coils. Car has always started just fine in any weather.

Several days ago and then today it wouldn't start. Last Saturday it would fire a single plug about every three or four turns of the engine. Since it had been snowing the night before I hadn't stopped for gas and the tank was low. my first thought was that I might have got some water in it and froze a line. Fuel pressure gauge showed the usual jumping rapidly between 40 and 60 while cranking.

The cranking speed had started to slow so I jumped it and sprayed starting fluid in the intake duct through the thumb-size pipe that connects to the side of the throttle body. Although it didn't start instantly it did so within a few seconds and settled down to idle as soon as I re-connected to the TB. I went and got gas and drove it for 15-20 miles. All was well and it started just fine several times the next day.

Today I had the exact same experience. This car has always started just fine, regardless of weather. I didn't have jumper cables immediately available so the car has not been re-started. I did crank it long enough that just as I quit I noticed the 'swinging' tach and speedo needles that, I'm sure, are a sign of low voltage. The volt-meter shows about 11 1/2 volts with the key on.

Please offer suggestions. Since after starting the engine runs fine, I don't think I need to replace the coils again but I will put new plugs in soon. Anything else?

KS

 

[joegr]

11.5 volts is too low.
Check the voltage while it is running the next time you get it going. Maybe your alternator is failing?

 

[cammerfe]

Thanks Joe! Running, the voltmeter shows 14-14.5 volts.

KS

 

[joegr]

Thanks Joe! Running, the voltmeter shows 14-14.5 volts.

KS

Well, that's about what it should be. If your battery does not have a vent connection, check the wiring and electronics in the trunk for corrosion.
Maybe you just have a bad battery even though it is still young.

 

[Broseph]

11.5 is getting close to the danger zone for a damaged battery. Giving that you tried starting it so much we'll assume that the battery is fine and just drained now.

Since shooting starter fluid in it past the IACV got it started, you could look into replacing the fuel filter although it's usually a rough running issue if it's clogged. What's the mileage on the filter?

If not then maybe the IACV is stuck. You could test it by holding the pedal down 1/4 and see if it starts then, which is basically bypassing that valve with the throttle plate. And always check the MAF.

Other than that, somebody might be able to figure out a 4L jag swap with twin turbos to get you back on the road :shifty:

 

[Broseph]

Well, that's about what it should be. If your battery does not have a vent connection, check the wiring and electronics in the trunk for corrosion.
Maybe you just have a bad battery even though it is still young.

I know the battery voltage can do all kinds of goofy things with this car but since his is cranking with COP's firing, wouldn't the issue be elsewhere?

 

[joegr]

I know the battery voltage can do all kinds of goofy things with this car but since his is cranking with COP's firing, wouldn't the issue be elsewhere?

I don't think that is is clear cut enough to rule it out. Yes, of course it could be something else, like the IAC, but if it were, I would have expected the starting fluid to make things worse.

 

[Broseph]

Mainly the reason why I led with fuel filter first.

It's a long shot for sure since most people seem to have "running" issues and not starting problems when the air metering devices decide to crap out. Just something else to look into if the battery is fine.

The one thing that stands out is it started after he shot the fluid through the IACV so I assumed something involving fuel/air is the culprit.

 

[joegr]

I'd lead off with fuel filter /fuel pump too, except that he said "Fuel pressure gauge showed the usual jumping rapidly between 40 and 60 while cranking."

I suppose it could be a MAF problem. If the PCM didn't think any air was getting into the engine, it wouldn't inject any fuel.

 

[Broseph]

I suppose it could be a MAF problem. If the PCM didn't think any air was getting into the engine, it wouldn't inject any fuel.

MAF while starting? Does it feed input to the PCM if the engine isn't running?

Good debate. I think cammerfe should get something resolved from this which is what I hope when troubleshooting....it was never my forte so I try to dabble in it as much as possible now to get better at it.

Btw, appreciate the help with my running issues last week. MAF fixed it

 

[cammerfe]

Part of my attempted starting procedure has been to, within a few seconds and certainly after spraying the ether, hold the throttle open so as to try to achieve a fire-able fuel-air mix.

Both on the first occasion and earlier today i only got a single cylinder fire and nothing in the way of anything at all regular.

Because of the flopping tach and speedo needles I have little doubt that, at present, there simply isn't enough voltage to make things work. But what started the symptoms in the first place? The filter has not been replaced for more than 20K miles. But even if that were the culprit, I'd think that the application of the ether should have resulted in immediate starting and it didn't. It probably took a minute-and-a-half. And as soon as it did start it ran just fine with no suggestion of fuel starvation. I suppose that it's possible that I flooded it with the application of the ether?

Although I feel as if my life experience makes it possible for me to assemble an engine using hot-rod components, and to do the fabricating necessary to install a pair of turbos one more time, I need to do a lot of head scratching when it comes to the inter-relationship of the electronic components in place on this LS. I don't work on any other LS than my own and that means that, particularly in this Michigan weather we're now blessed with, I don't even open the hood once a week. My ego doesn't suffer when I ask for input from those who most likely know more than I do---and surely have more experience in the area than I do.

I very much appreciate your input.

KS

 

[joegr]

MAF while starting? Does it feed input to the PCM if the engine isn't running?...

Yes, I learned that one the hard way. A small bug on the sense wire of the MAF is enough to keep the engine from starting. (Although some ignition does occur.)

 

[Broseph]

I was wondering if you'd catch that message

To be honest cammerfe, I'm a little disheartened at the speed bump in the twin turbo jag motor. The hot start to the project, along with the potential was intoxicating to read and follow along, but I completely understand the electronic aspect which many have talked about being the major barrier - not to mention project cost in a sudden economic crisis. Personally, I can't wait for it to gain traction again and look forward to future updates.

But I digress. Battery could be the big bug, and as history has shown, it can do crazy things. Not to mention you should be set to get a free replacement since even the junkiest of batteries have more than a year warranty.

Still the original start problem is perplexing. You can look at the MAF and clean it but I just don't think that would cause a no start.

You had spark and fuel pressure but no start - if it's not air flow than this will be much harder to diagnose

 

[Broseph]

Yes, I learned that one the hard way. A small bug on the sense wire of the MAF is enough to keep the engine from starting. (Although some ignition does occur.)

Well then, maybe it is that simple.

 

[cammerfe]

The weather has been !@#$#@! here in the Metro Detroit area and I've simply let the car set for the last several days. Probably try to do something with it early in the next week. My thanks to those who offered suggestions so far!

KS

 

[Broseph]

Cammerfe, any chance you happened to grab a wrench and find out what the issue was? It should have been at least 5 degrees up there this past week.

Kidding aside, just want to see what this issue is for future reference for others.

 

[cammerfe]

My schedule and the !@#$#@! weather have had me mostly inside with the car in a mound of snow in the parking lot. I'll post as soon as I have a disposition!

KS