C4 Woes : Updated

"CaptDale - is secretly British" (captdale) 09/22/2019 at 18:05 • Filed to: Corvette, C4 Update, Optispark

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I was up until 2 am last night finishing putting the car back together. All suspension back on and torqued down, lowering kit fully installed, 4 braided brake lines installed, brakes bled, new serp belt installed cause I had to cut my old one off (got stuck on something and couldn’t remove it), new coolant temp sensor installed (broke the electrical portion in the original one), new and correct plugs (at some point wrong plugs with .01 smaller gap were installed), new plug and coil wire, and re installed the driver seat after removing it to see if my aftermarket seats for the Healey would fit in.

After all that the fucking car won’t start. Cranks and cranks and cranks. I hear the fuel pump and smell unburt fuel, so not the issue. I checks all the wire routing and rechecked the coil wire, those all seem fine. Check all the fueses, those are fine. All the air sensors are plugged in and t body is working, so air doesn’t seem to be the issue.

I don’t know what I did, but I certainly feel punished by the universe. Thank you GM for making a ridiculously hard to work on 350.

Update:

I am out of town this weekend so no proper diaging able to do other than research. The LT1 and LT4 do not have crank position sensors because the Optispark relays both cam and crank position to the ECM.

How does it work? The optical section consists of a disk with 360 slots in it, representing 360 degrees of crank rotation. A small laser/eye unit throws a beam through the disks and reads the pulses created as the slots pass through the beam. In this way, the PCM knows the precise location of the crank at all times. Spark pulses are timed through the cap/rotor side and injector pulses are also timed from this. When its working right, the optispark is an extremely accurate timing mechanism.

Now mine has already been upgraded to the MSD unit that seems to be a popular choice. There are a few other that even eliminate the whole thing and us LS coils and another style of pick up.

So my guess is either the whole MSD Optispart died (which can cause my same failure) or there is some bad connection somewhere. I will go back over everything and pull a plug to see if there is indeed spark going to the plugs. Just when I was really excited to be driving the car with good working suspension. *sigh* I guess it is good what ever failed, failed in my driveway?

Thanks for all the ideas of things to look for. I shall update as things continue.

jimz > CaptDale - is secretly British 09/20/2019 at 14:54

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this doesn’t have that Optispark distributor, does it?

Nothing > CaptDale - is secretly British 09/20/2019 at 14:56

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Plug wires back on in the correct firing order? Timing off?  You’re getting fuel but no spark.

jimz > CaptDale - is secretly British 09/20/2019 at 15:01

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oh, and since you said you were tugging at the belt to try to remove it, check and see if you didn’t do something like disconnect or break a cam/crank position sensor.   I don’t know where they are on the LT1, though.

Future next gen S2000 owner > Nothing 09/20/2019 at 15:02

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EFI so now distributor, right? 

Future next gen S2000 owner > CaptDale - is secretly British 09/20/2019 at 15:02

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Are you getting spark?

BrianGriffin thinks “reliable” is just a state of mind > CaptDale - is secretly British 09/20/2019 at 15:04

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Simple things first: you sure the battery is providing enough current to turn over the engine? There might be enough for the fuel pump to prime but not to start. 

RamblinRover Luxury-Yacht > CaptDale - is secretly British 09/20/2019 at 15:08

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|hard to work on 350

MKULTRA1982(ConCrustyBrick) > CaptDale - is secretly British 09/20/2019 at 15:13

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Start  simple: negative battery terminal?

Brickman > CaptDale - is secretly British 09/20/2019 at 15:21

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It’s hard to work on the Corvette if it’s staring at you from undet the hood

Demon-Xanth knows how to operate a street. > CaptDale - is secretly British 09/20/2019 at 15:23

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Optispark?

benn454 > Brickman 09/20/2019 at 15:26

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 It's just watching you to make sure you don't screw anything up. Like that one customer in the window. You know the one.

Schaef_Camaero Z/28 > CaptDale - is secretly British 09/20/2019 at 15:51

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So it seems likely it’s an ignition issue. I would start by removing & reattaching each plug wire to make sure they’re fully seated on the plug. Shbox.com is also a great resource. It’s F-body centric, but much of the engine stuff should apply to Corvettes. You can check the opti to make sure it’s sending the signal to the coil.

Jordan and the Slowrunner, Boomer Intensifies > CaptDale - is secretly British 09/20/2019 at 16:11

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I can’t help but to notice how much more room the C5 has under the hood.

ITA97, now with more Jag @ opposite-lock.com > jimz 09/20/2019 at 16:44

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It does.

DipodomysDeserti > CaptDale - is secretly British 09/20/2019 at 16:56

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You try pouring a Coors Light over it?

MM54 > CaptDale - is secretly British 09/20/2019 at 17:14

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Sounds like a spark issue (as everyone else is saying). Work backwards - is there spark at the plugs? At the distributor? Is the coil good? All the wiring right? etc.

Grindintosecond > CaptDale - is secretly British 09/20/2019 at 18:19

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If you got a haircut recently during se rvice, you may have run afoul of the mullet sensor. You may need to just crack open, not drink,  one single Bud light or Coors light to get ignition. That circumvents the sensor 

CaptDale - is secretly British > Demon-Xanth knows how to operate a street. 09/22/2019 at 18:05

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Kind of looking that way, though may be the MSD replacement set up may have an issue

CaptDale - is secretly British > benn454 09/22/2019 at 18:06

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Those are literally the worst customers

CaptDale - is secretly British > jimz 09/22/2019 at 18:07

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Apparently there isn’t one on the LT1/4

CaptDale - is secretly British > BrianGriffin thinks “reliable” is just a state of mind 09/22/2019 at 18:07

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Yes plenty of battery

CaptDale - is secretly British > Grindintosecond 09/22/2019 at 18:08

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But I had 3 C oors lights trying to fix the issue.... of suppress it, though that might require good ol’ southern moonshine XD

CaptDale - is secretly British > Jordan and the Slowrunner, Boomer Intensifies 09/22/2019 at 18:09

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Well more like accessible area. The clam shell makes a ton of space under there and once you remove the side wheel well liners there is a fair bit of access . That said deeper work requires moving a lot of things out of your way .

shop-teacher > CaptDale - is secretly British 09/22/2019 at 18:14

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Good luck!

dogisbadob > CaptDale - is secretly British 09/22/2019 at 18:15

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Is your water pump weeping?

CaptDale - is secretly British > dogisbadob 09/22/2019 at 18:20

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I don’t believe so

CaptDale - is secretly British > shop-teacher 09/22/2019 at 18:21

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Thanks. I need it XD

My bird IS the word > CaptDale - is secretly British 09/22/2019 at 18:50

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How does it work? The optical section consists of a disk with 360 slots in it, representing 360 degrees of crank rotation. A small laser/eye unit throws a beam through the disks and reads the pulses created as the slots pass through the beam. In this way, the PCM knows the precise location of the crank at all times. Spark pulses are timed through the cap/rotor side and injector pulses are also timed from this. When its working right, the optispark is an extremely accurate timing mechanism.

When this was done with a regular distibutor, the engine still knew exactly where the crank was lol

CaptDale - is secretly British > My bird IS the word 09/22/2019 at 18:53

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*shrug* GM=InNoVaTiOn 

Brickman > CaptDale - is secretly British 09/22/2019 at 19:02

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I never heard of the Optispark.  S o it’s like a CD.... Very 90's

CaptDale - is secretly British > Brickman 09/22/2019 at 19:08

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I’d say closer to laser disk, but yes XD

Highlander-Datsuns are Forever > CaptDale - is secretly British 09/22/2019 at 19:08

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I’m betting you knocked something loose when doing the plugs or belt. I went to drive my Datsun today and one rear wheel brake  cylinder had leaked all over the garage floor! So I removed it, cleaned it up as there was some oxidized inner wall in the cylinder and just took it for a spin. If I could fix everything with some steel wool that would be great.

CaptDale - is secretly British > Highlander-Datsuns are Forever 09/22/2019 at 22:44

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I hope so... Not much up there to knock loose as far as I can tell. But we will see

Urambo Tauro > Brickman 09/22/2019 at 23:20

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I’d heard of Optispark  woes, but didn’t know that this is what the actual mechanism looked like inside. Neat!

Grindintosecond > CaptDale - is secretly British 09/23/2019 at 01:08

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Bringing a sledgehammer to repair fine watches!