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Discussion Starter · #1 ·
Good afternoon all,

I have an 87 Shelby Charger that has developed a most unusual issue. When it starts, it runs for a while with a very high idle, around 3-4000 rmp. After a few minutes, it starts sputtering for a bit, then dies and won't start again. If it sits undisturbed for an hour or so, it will start back up and do the whole thing over again.
Pulling the throttle lever seems to have little effect when it is sputtering, but flipping it rapidly when it is revving does cause it to momentarily drop the engine speed slightly.
I know just enough about this car to be dangerous, but have no idea what these symptoms are telling me...
 

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I had a simular issue, but do some trouble-shooting or get it checked out before you take my advice. I think it might be the Turbo or the Distributer. Both happened to me on seperate occasions, far appart, with simular symptoms as yours.
 

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Discussion Starter · #4 ·
My symptom has changed since I posted this thread. What once was "high revving, sputtering and dying" has changed, literally overnight, to "won't start". Now, when I crank the engine, I get a brief bit of intermittent ignition, it dies, I crank it again, a couple of cylinders fire, it dies, etc. I've got good spark from the coil (I replaced it), but when I check for spark at the plugs, I only get spark at the brief times when I can hear it fire and try to start. When it's cranking with no ignition, I get no spark.

It seems to me that this would indicated that I'm not getting enough spark to the cylinders to really start the engine, but I'm a bit confused here. I did go ahead and replace the cap and rotor, to no improvement. Any ideas?
 

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Discussion Starter · #6 ·
Actually, the last time it threw a Power Loss light, the code pointed to a failure of the HEP, which I then replaced and it solved that problem. Does the lack of a Power Loss light mean that there are no codes?
 

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the power loss lamp is used to display codes - without it you would need the tool to plug in to read codes from the computer
if the bulb works you should always get at the very least a 1 second bulb test and a 55 message - 55 = end of messages

if it revs like mad at start up I'd be wondering if one of the little hoses between the throttle body and turbo inlet or between the turbo and intake manifold has a hole in it or has sliped off at one end - in fact this is the first thing I'd be lookin for
 

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Right now your issue is related to lack of spark, the no start condition has to be resolved before you can move on.

Invest in an HEI spark tester and verify spark/no spark for sure.(minimum 25 KV)
If you have a HEP issue the fuel pump will also not be running but to be sure disconnect the pump at the tank so you do not foul the plugs and load the engine with fuel during diagnostics.

Here are the diagnostics for no start/no spark.
http://www.turbododge.com/forums/f4/f14/358231-no-start-no-spark-84-90-a.html

Great Neck/Adjustable ignition spark tester (25069) | Ignition Tester | AutoZone.com
 

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Discussion Starter · #9 ·
The latest-- I'm pretty sure it's not really an ignition problem. It seemed like the spark was intermittent, so I bought a better spark tester, and it looked the same-- when I see indication of spark on the tester, the engine ignites and tries to start, then the next few cranks show no spark and the engine doesn't start. Parts are fairly inexpensive, so I went ahead and replaced the coil, the cap, rotor, and the entire distributor (including the HEF sensor.) I also replaced the spark plugs since they were in pretty nasty shape from all of the cranking. They reeked of gasoline, so I believe the fuel pump is working. The ASD relay passed the described test, and seems to be clicking as expected.

Is there anything else a layman like me can try?
 

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You replaced parts but did not test circuits.
1-2 sparks counts as no spark.

While cranking the engine do you have battery voltage(12volts)at the + coil?
If not your issue is with the HEP circuit and the controller is not seeing a crank signal so the ASD will not be actuated.
 

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check the ground for the coilpack might have buildup and after reading parts put in i dont thing i saw wires,if i missed that sorry if not you should replace them after you replaced the distributer did you check timeing?
 

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the power loss lamp is used to display codes - without it you would need the tool to plug in to read codes from the computer
if the bulb works you should always get at the very least a 1 second bulb test and a 55 message - 55 = end of messages

if it revs like mad at start up I'd be wondering if one of the little hoses between the throttle body and turbo inlet or between the turbo and intake manifold has a hole in it or has sliped off at one end - in fact this is the first thing I'd be lookin for
the reving like mad could be that little map sensor line you might have more then 1 problem here could be related will wait to here next reply
 

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By your diagnostics we have a no spark condition...
I am assuming your intermittent spark was tested at the coil wire not a plug wire.
I also assume your plugs are not fuel fouled.

Is this correct?
 

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Discussion Starter · #15 ·
Yes, the no spark condition is at the coil as well as at the spark plugs. When it cranks and briefly starts, the spark tester shows spark. Then, when it dies and just cranks, it shows no spark. I replaced the spark plugs last week because they were terribly fouled from the fuel going into the cylinders.

I double-checked the voltage at the coil. On the + side it shows anywhere from 6- 12 volts when the engine is cranking, and goes up and down depending on if it the engine fires or not.
 

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If your plugs were fouled the fuel pump is running which means you cannot have an ASD or HEP issue.
Disconnect the fuel pump during diagnostics.
Be sure the oil is not fuel diluted, if it is change it so you do not wash down the cylinder walls.

Power to the + coil, fuel injectors and fuel pump must remain at constant battery voltage while cranking.
From what you are saying the engine cranks easily, then hard causing the voltage to drop.
That is either caused by a battery problem or a compression problem(Timing Belt Jumped)
 
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