Bogging/powering off/misfire

EAHAYES

MEMBER
1996 BUICK ROADMASTER
5.7L
V8
2WD
AUTOMATIC
138,000 MILES

I recently bought the vehicle listed above (wagon) that had been sitting for a while. It drove nice for a little while but now it's starting to shake and misfire.I changed the spark plugs and checked the wires hoping that that would fix the problem. But it seems to have made it worse. Now it starts and idles like perfection. But you can hear a difference in my passenger tailpipe. It kinda chugs instead of a smooth constant sound. It also shakes but no it doesn't want to accelerate and powers down.I checked the oil and it was a little dark so I'm going to change that. And I checked the transmission fluid as well and it seems to have had been overfilled, but it was running fine before so I'm not sure if that's to blame.

Monday, April 13th, 2020 AT 2:26 PM

2 Replies

KASEKENNY

MECHANIC
18,907 POSTS

There are a number of things we need to start checking. First we need to know if there is a check engine light. If there is, then let's pull the codes.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Once we know what codes we have if any, then we can take next proper steps.

However, if there are no code then we need to start running through these guides to try and narrow down this issue. Unfortunately there are a lot of things that can cause this.

This guide runs through misfire rough running issues. Then the next few run through the specific issues you mentioned. Hopefully we can start to eliminate these things so that we can figure out possible causes.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

https://www.2carpros.com/articles/engine-has-low-power-output

https://www.2carpros.com/articles/vibration-noise

If nothing else, we need to perform a vacuum leak test. This could cause the issue and not set codes or lead to any other symptoms. So let's run through this info and report back if there was a leak. Thanks

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

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Monday, April 13th, 2020 AT 5:04 PM

ASEMASTER6371

MECHANIC
52,796 POSTS

Good evening,

This motor has the distributor on the front of the motor in the timing cover.

This was probably the worse idea an engineer ever had. The issues were the water pump. The pump leaks out the weep hole right on to the distributor and causes all kinds of running issues especially under load. They even put a drain hole in the distributor for when the pump leaks, the water will drain out of the distributor.

I know you checked the wires but I would replace them. That is another engineering goof up. They are extremely tight and routed next to heat.

My suggestion is to change the cap and rotor and look for rust in the distributor. If there is, replace it.

Change the wires as well.

Roy

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