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4.9 wacko! electrcial? fuel?


tommyjack

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Have a 93 4.9 in a 92 STS (orginally a 4.9) that has rough idle, so so milegae, intermitent miss at highway speeds (when his happens the tach jumps up wildly several hundred RPMs. At wide open throttel it goes to about 4300 then shuts down like turning off the switch. Plug wires also arc slightly no matter if I replace them or reroute them. Has a auto zone replacement distributor when motor was replaced 16000 miles ago. Replaced cap, rotor, and wires twice, coil and plugs once. Any ideas?

Thanks,

TJ

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Have a 93 4.9 in a 92 STS (orginally a 4.9) that has rough idle, so so milegae, intermitent miss at highway speeds (when his happens the tach jumps up wildly several hundred RPMs. At wide open throttel it goes to about 4300 then shuts down like turning off the switch. Plug wires also arc slightly no matter if I replace them or reroute them. Has a auto zone replacement distributor when motor was replaced 16000 miles ago. Replaced cap, rotor, and wires twice, coil and plugs once. Any ideas?

Thanks,

TJ

Well, having just had my catalytic converter changed for my 92 seville, also with the 4.9 engine, I can say that a clear exhaust system is a MUST for these cars. Since replacing the catalytic converter the car runs great. No more hesitations or "rumbling" from the engine and she flies like a bat out of hell.

Have you checked your exhaust system to see if it's blocked or partially blocked? This causes a lot of problems with engines.

If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans.

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Have a 93 4.9 in a 92 STS (orginally a 4.9) that has rough idle, so so milegae, intermitent miss at highway speeds (when his happens the tach jumps up wildly several hundred RPMs. At wide open throttel it goes to about 4300 then shuts down like turning off the switch. Plug wires also arc slightly no matter if I replace them or reroute them. Has a auto zone replacement distributor when motor was replaced 16000 miles ago. Replaced cap, rotor, and wires twice, coil and plugs once. Any ideas?

Thanks,

TJ

All I know is that the 4.9 is a GREAT engine, GREAT. Its a workhorse. I would go through the engine with a fine tooth comb, checking cleaning and regapping the plugs, replacing the wires with OEM wires if they are arching AT ALL, checking the cap for carbon tracking and cracks, and checking the engine grounds. Check posts by MATT, when he replaced his engine he had similar complaints, and I believe it ended up being a bad ground, given that you had your engine replaced 16K ago maybe you have similar ground issues.

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Thanks! Where are the grounds locted?

Here is a schematic for the 92 I just happened to have it. HOWEVER, do do a search of MATT, he has a 92 also, and found that when they replaced his engine they left a ground off altogether, I think at the starter... Let us know how this turns out, Mike

post-3-1123375953_thumb.jpg

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Thanks! Where are the grounds locted?

One of the grounds is on the engine block next to the starter. You better move it to the starter's bracket which goes to the engine, or even better put a new solid ground from the battery to one of mounting bolts of the starter. I did it recently and without that jumper even new starter did not work properly. I'll take some pictures tomorrow to show the place.

The saddest thing in life is wasted talent

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Thanks! Where are the grounds locted?

One of the grounds is on the engine block next to the starter. You better move it to the starter's bracket which goes to the engine, or even better put a new solid ground from the battery to one of mounting bolts of the starter. I did it recently and without that jumper even new starter did not work properly. I'll take some pictures tomorrow to show the place.

Adallak is speaking of G104 in the above schematic

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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tommy,

As you can see I have attached a four gauge jumper right to one of mounting bolts of the starter (arrow). The bolt is accessible from the top. My battery has both side and top posts so that was not a problem to make reliable connection to the battery.

There was a SB addressing driveability issues caused by a bad ground. They advised replasing the ground stud, washers, etc. on the engine by the starter or moving the ground to the bracket wich grounds the starter frame to the engine. You can try that, but there is not much room up there.

post-3-1123429367_thumb.jpg

The saddest thing in life is wasted talent

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The previous owner of my 92 Seville had to have all the engine mounts replaced due to faulty start conditions. Everything seems ok, so far.

If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans.

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The previous owner of my 92 Seville had to have all the engine mounts replaced due to faulty start conditions.  Everything seems ok, so far.

the mounts or the grounds?

BTW, there is plenty of room between th engine and the fans/radiator to root the grounds to the battery.

The saddest thing in life is wasted talent

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  • 3 weeks later...

I changed out the distributor the other day and the car now will rev freely past 4000 rpm without shuting down. But I still have a miss. Now at least I have a code that is EO46-Right to Left Bank Fueling Difference. What does this mean and how can I fix it?

Thanks,

TJ

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Hi Marika

Did you get an OEM or an aftermarket catalytic converter? I have like a baffle noise at slower speeds, and I am not sure if it is the muffler or the converter. The car runs very good.

Regards

Runar

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Hi Marika

Did you get an OEM or an aftermarket catalytic converter? I have like a baffle noise at slower speeds, and I am not sure if it is the muffler or the converter. The car runs very good.

Regards

Runar

I got an aftermarket Cat. converter. Seems to be fine so far.

If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans.

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