topspin

Will a bad crank sensor stop the ignition coil from firing on a 96 LT-1 ?

Casethecorvetteman

I believe so. Its an optical sensor. If its failed it shouldve set a DTC.

Tom Piper

It is my impression that the '96 crank sensor is only for cylinder missfire detection.
If I am correct, it has nothing to do with ignition control.
The optical sensors in the Opti-Spark control the ignition.

Tom Piper

BAM92

It will stop you dead in your tracks. Been there on my 96 LT1 Trans Am.

Mo_Bandy

It references between the cam and crank for OBDII misfire ...

The opti sends the signal to the coil...

I have run with the crank sensor disconnected...

Mo

96GS#007

On the '96, the crank sensor is for OBD II compliance only. It's used to detect misfiire. I ran mine with a bad one for a couple weeks until I had a chance to replace it.

One minor correction to Mo...It looks at the acceleration and deceleration of the crankshaft to determine misfire, it doesn't bother with the cam at all. That's why the reluctor ring is on the front of the '96 crank

BAM92

Hmm, that it was the dealer told me back when it died and had it towed to them under warranty. Never looked into it further. Shows you can't trust the dealer.

Mo_Bandy

You're right Jim... thanks for the correction I was thinking of something else ... I'm an old froggie LOL

Cheers!

Mo

Desert1957

I had a 93 LT1 that would run great when cold and in "Open Loop" soon as the engine went closed loop it hardly ran sputterring and backfiring , the fix was a bad "Crankshaft Position Sensor"

Was a Warranty problem Vette had 4000 miles on it , took the Dealer 2 weeks to fix it. here is a list of what they replaced over the 2 week period. remmember WARRANTY repair

Spark Plugs
Spark Plug Wires
Complete "Opti-Sspark Distributor"
ECM (3 times)
Fuel Filter
Fuel Pump
Injectors

and the final fix was "Crankshaft position Sensor"

Desert

Casethecorvetteman

3 frigen times?? What a bunch of useless barstards eh? I bet youre glad you found out how incompetent they are while it was still under warranty and at their expense!!!!

Tom Piper

I think there are some mis-communications here.

On a C4, only a '96 has what I am calling a "Crankshaft Position Sensor."
As far as I know, the manual calls it a "Crankshaft Position Sensor."
It's only purpose on a '96 is for cylinder missfire detection.
No C4 before a '96 has this sensor.
It is located on the bottom of the timing cover and the only timing cover that has the place for it is on a '96 timing cover.
It has nothing to do with the Opti-Spark.
Since the originator of this thread specifically stated a '96, I am assuming it is this '96 only sensor.

The Opti-Spark has low and high-res pulses.
These pulses are detected by the ECM/PCM for what some call cam and crankshaft postion to control spark and injection timing.
All LT1 and LT4 engines have these pulses generated in the Opti-Spark.
On a stock engine, if the low-res from the Opti-Spark is completely missing, the engine will not run.
On a stock engine, if the low-res pulse is OK and the high-res pulse is missing, the engine will run at reduced performance.
I'm told that an engine with the Delteq requres both low and high res pulse to run at all -- and logic tells me the LTCC is probably the same.

Tom Piper

96GS#007

Tom is correct on all counts.

Desert1957

I did have this problem I listed in an early posting here , The Dealer did replace what they called a "Crankshaft Postion Sensor" on my 93 and it did effect the way the engine ran during closed loop , here is the gm part# 10457661

I did a seach on GMparts for less web link and Parts America , they all list this part for a 1993 LT1



So I guess I am questioning your quote "No LT1 engine before 96 has this sensor" help me to understand what I am missing , thanks Desert

Tom Piper

Since I have a '92 LT1, I don't have the Crankshaft Position Sensor that I am referring to.
So, I will have to let someone with a '96 confirm if that is a Crankshaft Postion Sensor.

What I can tell you is I converted my '92 non-vacuum vented Opti-Spark to a '95 style vented Opti-Spark.
And, part of that conversion was I had to change to the '95 style timing cover.
Since my '92 is OBD-I instead of OBD-II, I had to make sure I got a '95 timing cover (without the place for the Crankshaft Position Sensor) instead of a '96 timing cover (with the place for the Crankshaft Postion Sensor) because there was no need for the Crankshaft Position Sensor with my OBD-I.

Read this link:
http://para.noid.org/~muttvette/opti.html

As you can see, the third timing cover down for a '96 and '97 (F-body) has the Crankshaft postion sensor.

If the sensor you mention is really a '96 style Crankshaft Postion Sensor and it is on your '93, I would like to know how it got there.

Tom Piper

96GS#007

Hope they paid for that and not you because it's clear the dealer is making sh*t up if that's what they put on the invoice. The pic is not a pic of a CPS. No LT1/4 before '96 had a CPS, period.

GM Parts Direct lists the part as:

GM PART # 10457661
CATEGORY: Chassis Wiring & Computer Controls
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $30.28
OUR PRICE: $15.75

DESCRIPTION: SENSOR AS

The key descriptors are "Chassis Wiring...." and "Sensor AS" and specifically the one letter they omitted in the latter..."B" as in ABS. It's a rear ABS sensor.

Desert1957

I'm not saying you guys are wrong. I was just relaying an experience I had with my 93 as stated in an earlier posting.

I do not have the 93 anymore or the Dealer Warranty Invoice for the repair.It went with the car.

Did do a parts search and found a listing for a "Crank Position Sensor" listed for a 1993 5.7 LT1 corvette on "PartsAmerica" it listed the following OE# on the page with a pic #10457661

http://www.partsamerica.com/ProductL...osition+Sensor

Here is the other link you think I'm Lying about from "GMparts4less"



I'm just trying to figure out who is right , not saying you guys are wrong

Desert

topspin

My car ran great for about 15 minutes then it would always shut down. I replaced the ignition module and the ignition coil and car did the same thing only after fooling with it now I noticed the Tach has no reading. This is why I thought maybe the Crank P Sensor could have something to do with this problem. Now I cannot even get the Ignition Coil to fire. My readings are good on the ignition module connector with volt meter except I checked the ground on the black/white wire with key in the On position and it still showed grounded and I beleive it is not suppose to be grounded when the key is on.

96GS#007

The LT5 in the ZR1 had a crankshaft position sensor. The LT1 (prior to '96 did not).

VenkmanP

There was no CPS from the factory on any LT1 prior to 96. Read any of the LT1 books or any of the myriad websites describing LT1 changes over the years.

Let's say for a second that your 93 did have a CPS. How is your information on how the CPS caused problems for you in closed loop (which in itself is ridiculous - CPS doesn't care about open vs. closed loop) relevant to the OP's question of whether a CPS on a 96 will prevent the coil from firing?


Since you don't own the car in question any more, and your posts are irrelevant to the OPs question, you seem to be just a :

Mo_Bandy

I'll say it again... I have a 96, I can unplug the CPS it will not keep the engine from running, it will set a code...
But it will run fine (unless you have the timing off a tooth).

It only is there for OBDII for detecting misfires....

If you updated to a later model timing cover they did not have the cps sensor unnless it was at least a 96. If this is the case where is the harness to you connected the CPS too?

I'm with Tom Piper and 96GS007 on this one...



MO