LT4 Engine Quits on Highway

[Coyote]

I was returning from a nice Easter weekend in Perdido Key Florida. I was behind a slow vehicle on HW-98. I downshifted to 3rd gear and was in the process of passing. I noticed that I was not accelerating and was actually slowing down. I clutched in and the engine went dead. I coasted to a stop and got off the highway. Tried to crank but engine would not catch. My first thought was the fuel pump. Checked the schrader valve on the rail and there was plenty of fuel and pressure.... hmmm, something similar happened to my Grand National back in the 90's and it turned out to be the MAF sensor. I unplugged the MAF sensor so it would run in "Open Loop" mode.... still nothing. Like I tried to teach my son, no matter how advanced the technology is, all an engine needs to run is Fuel, Air, and Spark. I ended up getting a ride home, borrowing a car trailer from a friend, and heading back 90 miles to pick up my sticken LT4! I brought it home and rolled it into the garage .... where it is sitting at this very moment. I did put my timing light on six of the plug wires and only have spark on #2. I haven't put much effort into it since Sunday other than reading the shop manual. I hate the thought of taking off the distributor because I have to drain the cooling system and pull the water pump to do it. Anybody out there experience a similar failure? It would be nice if it was the coil.

 

[Huskerman]

First thing the C4 guys are going to want know is what codes is it displaying. I hate it when a car strands me. Usually its a fuel pump issue or the opti maybe in your case. Good luck with it.

 

[Coyote]

No Code

First thing I checked when I got it home.... No Codes!!!! This is strange because it threw a code on the way over to Perdido Key. It had been throwing the code for the O2 sensor previously so I figured I was still having O2 sensor problems. There was a lot of oil in the exhaust manifolds from having the engine inverted on the stand so I figured I smoked up the sensor. I had taken it out and cleaned it with solvent and thought the problem was solved. It may very well be but for some reason, the codes it threw are not there anymore. I didn't disconnect the battery or anything else, they're just gone! Since I can't get the engine cranked, I can't tell if the Check Engine lite is still on.

 

[XLR8]

Hi Coyote!
I can't help with your issue but we have some very knowledgeable C4 folks here so I know you're in good hands. I just wanted to give a shout-out and welcome a fellow Mississippian to the I'm south of you on the coast.


Enjoy the forums... and your C4 when you get it turned around.

Jane Ann

 

[Coyote]

On the Coast

Hi Coyote!
I can't help with your issue but we have some very knowledgeable C4 folks here so I know you're in good hands. I just wanted to give a shout-out and welcome a fellow Mississippian to the I'm south of you on the coast.


Enjoy the forums... and your C4 when you get it turned around.

Jane Ann

Not sure you can be south of me! I'm 300' from the Gulf of Mexico in Pascagoula!!!

 

[XLR8]

Not sure you can be south of me! I'm 300' from the Gulf of Mexico in Pascagoula!!!

:L

When you mentioned FLA via HWY 98 I thought 'Hattiesburg'. My bad.

 

[Coyote]

Perdido

:L

When you mentioned FLA via HWY 98 I thought 'Hattiesburg'. My bad.

Nahhh, I was over in Perdido Key, FL taking the "back way" home to Pascagoula!

 

[Coyote]

LT4 Still Won't Crank!

Well, I think I am going to have to bite the bullet and drain the coolant, remove the water pump, and finally the distributor. I put a timing light on the coil wire and the coil seems to be working fine. When I crank the engine over I get steady pulses. I put it on the spark plug wires that I could reach and only got spark on #2. I couldn't reach #1 or #3. No other plugs are firing. I'm almost convinced its the distributor. I've never had one do this before and I can't imagine what can be wrong. I guess when I open it up the tale will be told.

 

[XLR8]

Sorry to hear you're having trouble... that LT4 is made to be enjoyed! It sounds like you have the issue well in hand tho, so I'll just wish you luck with it and say keep us informed with what you find.

Oh yeah... and Go 'Goula!

Jane Ann

 

[93Rubie]

The good news it that if you have spark from the coil but not at the plugs your coil, ICM, and Opti-Spark are working.
The distributor cap or coil wire maybe defective and the spark is not A: getting to the cap B: Cap and rotor are not distributing the spark to the cylinders. Possibly bad plug wires but I doubt it.

Rotors have been known to come off known and then. You won't be able to tell without pulling it out.
If this is the case, a cap and rotor kit maybe all you need. Up to you if you want to spend the extra coin to put in an all new Opti or not.
FYI, regardless, if you do replace the cap and rotor or Opti, Blue Locktite those bolts that hold the rotor on.

 

[Coyote]

Found Problem

The good news it that if you have spark from the coil but not at the plugs your coil, ICM, and Opti-Spark are working.
The distributor cap or coil wire maybe defective and the spark is not A: getting to the cap B: Cap and rotor are not distributing the spark to the cylinders. Possibly bad plug wires but I doubt it.

Rotors have been known to come off known and then. You won't be able to tell without pulling it out.
If this is the case, a cap and rotor kit maybe all you need. Up to you if you want to spend the extra coin to put in an all new Opti or not.
FYI, regardless, if you do replace the cap and rotor or Opti, Blue Locktite those bolts that hold the rotor on.

Man you hit that one out of the park and didn't know it!!! I finally rolled my sleeves up last night and pulled the distributor. I didn't have the special E4 female torx bit so I had to wait until today. Napa Auto Parts had one so I gave them my $4 and went my merry way. I got home to start the autopsy on the distributor and noticed that there was a rattle inside. I removed the 4 screws and low and behold! The screws securing the rotor had come completely out!!! Mystery solved! Thanks for your insight. I read your response after I found the problem but you were dead on!!!!

 

[93Rubie]

Now locktite those new bolts so it doesn't happen again.

If there appears to be no water intrusion or rust inside the Opti-Spark. I would just put a new cap and rotor on it.
That is me anyhow.

 

[Coyote]

Done and Over With!

Now locktite those new bolts so it doesn't happen again.

If there appears to be no water intrusion or rust inside the Opti-Spark. I would just put a new cap and rotor on it.
That is me anyhow.

The distributor looked fine except for the missing screws in the rotor! I cleaned everything up and reassembled. Used blue loctite on the screws. Everything went back fine. Fired her off and she cranked right up. Back in business.... now to fix the other nit-picky items!