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1985 Fleetwood Brogham RWD
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74 Posts
Discussion Starter #1
My 1985 FWB with the 4.1 Ht4100 sputters and pops, especially under exceleration. As I have said before, I know jack shit about this engine. Does any one know what would could be causing this?:confused:
 

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1993 Eldo 4.9 66K miles
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368 Posts
Your symptoms are typical of an engine in need of a tune-up to include plugs, wires, cap, rotor, etc. It may well be something else, but I'd start the diagnostic process there.
 

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'87 SDV
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1,296 Posts
Always start by checking trouble codes. Symptoms like that could cost you a lot of time and money chasing ghosts. Your Cadillac will tell you where it hurts, most of the time.
 

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'87 SDV
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1,296 Posts
e29=shorted 4th gear circuit
e52=PCM memory reset (probably from replacing or disconnecting the battery)

Neither one would cause your popping troubles. Does it run bad all the time, or just when it warms up? Is this a RWD full size or FWD c-body?
 

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1985 Fleetwood Brogham RWD
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74 Posts
Discussion Starter #6
The sputtering/popping will happen any time I accelerate, weather I just started her up or I have been driving for a while. It seems to be especially bad if im in 3rd or fourth gear and start to accelrate.
 

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76 Eldo (54k), 76 Eldo (52k), 78 Eldo (9k), 85 Deville (43k)
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668 Posts
Check your timing. You could also have a collapsed valve lifter or flat cam.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
More than likely a flat cam, but verify fuel pressure is at spec. Low pressure can cause it to run too lean at higher RPM's. then backfire thru the intake.
 

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1985 Fleetwood Brogham RWD
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74 Posts
Discussion Starter #10
Well I dont think it would be the cam, because it just all of a sudden started happening one day. I would be more suspicouise of the fuel system except it feels like it happening in only one of the cylinders. It feels like one of the cylinders on the driver side just isnt fireing wright.

She needs a tune up any ways so Im gonna go ahead and replace the rotor, cap, incap-resistor, wires and plugs.
Does any one knoe if this is an HEI setup?
 

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76 Eldo (54k), 76 Eldo (52k), 78 Eldo (9k), 85 Deville (43k)
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668 Posts
Yes, it's an HEI setup. You have to transfer the coil from the old cap to the new one.
 

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1991 Deville / 1989 BMW 635csi
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896 Posts
I had the exact same problem on my 85 FWD fleetwood trned out to be a cupped lifter in #7 cylinder (cam ate lifter), i wasted my time and money witht he whoel igniton system, fuel press was fine. And yes mine happened out of the blue. I replaced the lfiters, ran good, btu i never checked pick up tube wether it was clogged or not, and my bearings discintigrated. Replaced motor and sold the car. car had 99,000 MILES on it, 159,000 KM's.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
Yes this is an HEI. With no codes related, start with plug wires and plugs. Make sure all wires are routed correctly by the book. If routed incorrectly this engine will cross fire causing a miss. You only have 2 injectors on this engine so an injector is unlikely. If after the wires and plugs it still pops, then pull the valve covers to verify all rockers are fully pushing open the valves. Popping thru the intake on hard throttle is a sign of a flat cam or collasped lifter.
 
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