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Discussion Starter #1 (Edited)
96 fleetwood been perfect until today, started it but wont run, continued to start it but only sputters after long start. No check engine light on or key fault light on either? Could that be a tell sign of something bad if dont start? What are things i should check first? Before i assume opti or fuel pump? Im thinking first check fuel pressure, spark at the plug and coil right? How do i check for spark at the coil and plug? And how could i check if the icm working? Any help and tips would be much appreciated.trying to do as much as i can by myself in the driveway.
 

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Take a screwdriver, put 1 end in the ignition terminal end & place the other side near metal, maybe 1/2 - 1" away.
Crank it & look for a blue consistantly repeating spark. There are many variations. Such as using an old sparkplug with a large gap. Youtube probibly shows how to do this.

I like to test at 1 or 2 spark plugs 1st because it checks more of the ignition system vs just the coil wire.
I check for spark at the coil wire if there's no spark at the plug.

If it's related to the weather I would wonder if it could be water in the fuel system frozen.

Another thing to try is cranking with full throttle.
That put's it in clear flood mode & cuts off the fuel.
Then try to start normal.
 

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Same for the coil wire.
Depending how far the terminal is in the boot, sometimes it will spark when you put the boot next to metal.
Don't like doing that because it creates carbon tracking, which flows voltage, reducing the effectiveness of the insulator.

A spark plug has a small gap.
But for testing you need a much larger distance.
Because it's harder for the spark to jump under the compression stroke.
 

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Discussion Starter #5
Cool great mite do this today since i dont got my fuel pressure tester yet, so pull the plug off the coil or leave the plug in the coil and test end if the plug wire?
 

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Skip the coil wire for now.
Test at a few plug wires.
That determins the next step.

By it sputtering it means you are getting spark.
But it could be weak, cross firing, or shorting out.
 

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Discussion Starter #7
Ok will do ill keep you posted for sure but does the check engine light come on for a bad icm, coil or even opti spark?
 

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If it's running poorly almost anything could set the SES light.
SES was at orignally to let you know a problem with the engine management system alerting you it needs repair but many times still running in a limp mode.

With OBD2 & 4 O2 sensors in 96 it also incorperated more smog monitering.

Common things that will set a SES light and cause it to barley run are sensor inputs.
Coolent temp, air temp, mas airflow, manifold pressure, throttle position, etc.

A bad sensor reading tends to set the SES light off right away.
When the emmisions are too rich or lean the car needs to warm up, & sometimes be driven a bit to set those codes.

If the SES light is on with the engine running the 1st step in dignosis is alway check what the codes are.

There's a way to get the engine codes from the tempiture controls by pushing the right combination of buttons & reading the numbers.

They have lower priced scan tools that can read data. Don't have experiance with those.
But looking at the sensor readings is normally done along with reading the codes.
You can sometimes find something blatlent wrong like an engine ice cold reading a coolant temp of 276F on a scanner.

I don't know of any car computer that checks the ignition coil only.
Cars have gotton to where they detect cylinder misses.
Think it started on the 96 Fleetwood.
Which a coil, spark plug, ign wire, cap, rotor, engine mechanical problem, or even fuel problem could set.

The thing to keep in mind is almost any engine code shows a problem area, not nessisarly a bad componant.
You have to determine is that componant functiong right, is it a connection / wiering problem, something else causing the componant to be out of spec, or just a bad computer.
Such as a plugged air or fuel filter could set an 02 code.
There is no air filter of fuel filter code.
Yet they could set an 02 code.
Replacing the 02 wouldn't fix the problem.
 

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Discussion Starter #9
Oh ok i see, i had actually got a scan tool i plugged under the dash but didnt pull any codes but did a diagnostic test threw the hvac it pulled some codes but dont know what any of them mean?
 

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I've replaced a fuel pump in every LT1 car I've owned. Also... I've thought that it was not out of gas when it actually was. These cars have notoriously inaccurate gas gauges. If it's under 1/4 on the gauge, put a jug of gas in it.

Borrow a fuel pressure tester first before testing spark. So easy to check on the LT1.
 

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Discussion Starter #14
UPDATE i checked for spark at 3 spark plug wires with a screwdriver 2 on the driver and 1 on the passenger side i did not get any kind of spark to the exhuast heat shield or even my metal front cylinder shaft nothing
 

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Check the coil wire & coil tower for spark.
to check the coil tower hold a screwdriver or prybar with 1 side grounded and the other 1/2"-1" from the tower termanal.
Keep your hand out of the way.

That's a ton of codes.
Is it OBD 1 old style rectangle plug or newer style angle sided OBD 2 plug?
They look more like OBD 1 codes & a mix of all different system codes.
OBD 1 codes were 2 numbers starting with 11.
Codes 3, 5, & 10 may be for the HVAC.
OBD 2 codes were a letter & 4 numbers like P0300.
But again pulling codes from the dash is not the way it was done in the shops.
The trouble with doing it that way is it's easy to get lost in the menus of forget a rule like -1 means 2, or deal with the the desplay does not contain enough digits.

In 95 the 1 in fron means the code is saved, history, no longer detecting the problem.
 

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The HVAC codes are status, not necessarily problems. Here is a link to interpret them.
buickforums com/forums/threads/trouble-codes-accessed-in-the-climate-control-other-neat-info.10691/ (had to add spaces to be able to post it)

I agree on high probability of a bad fuel pump (but there should be a spark). (Replaced so many of them, I have lost count.) Get down near the fuel tank or remove the fuel filler cap and listen while someone else turns the key on (but not start it). The fuel pump should come on for 2 seconds and you can usually hear it.

On my Roadmasters (and Caprices), there is a fuel pump relay bypass connector near the fuse box. It's just a single terminal flat connector with a red(?) wire. You can jumper it to the positive battery terminal to turn on the fuel pump. If you don't hear it, then it's probably bad. Always change the in-tank harness with the pump.

I don't have any other tricks to test ignition than those already given. Failed parts could be ignition module, ignition coil, optispark (distributor), or all of the above (had that happen on two different cars). Clean the grounds on or near he thermostat housing and make sure the ground strap on the driver side from the engine to the firewall is in intact.

Good luck.
 

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Just skimming through this, but I don't see anywhere that you mention mileage. Just a heads up, the optispark on an LT1 dies like clockwork at 90-110k miles. If yours is within that range and has the original still, change it. Had a Roadmaster with the same engine, pretty much the same symptoms.
 

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I disagree with the Opti dying like clockwork. Lots of people blame them for problems that are usually something else.
 
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