Emission Control Problem?
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Senior User
Joined: Jan 2003
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From: Lower Rainland British Columbia, Canada
Emission Control Problem?
84 BII 2.8 Auto. Recently the trucks been running poorly at speed. Not always but every once in awhile, revs drop off and power disapears. I can kick it down to second but I'm still losing speed. Also the manifold vacumn goes all haywire when it should be almost 0 like when I've got it floored it's up in the 25lb range and when I lift off the throttle it tries to go to 0lbs and stall.
Anyone have an idea?
Anyone have an idea?
Senior User
Joined: Jan 2002
Posts: 140
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From: CT USA
Emission Control Problem?
I have see this up for a few days with no replies so i figured id throw in a starting point at least. The crazy vacuum gauge could mean you have valve problems. On the 2.8 the service manual says to adjust them every 30000 miles. Most 2.8s i have seen have never been adjusted being such a pain to do. I would start by giving hte valves a quick adjustment although it is likely the guides are warn and your heads could use some machineing. From my experience the 2.8 will run (not stall) even if the valves are not in good shape. I would check for vacuum leaks around the manifold, vacuum connections, carb base, etc. Spray some carb cleaner on all the joints while the engine is running. If suddenly it smooths out you have found a vacuum leak. Also check under that black plastic cover where all the vacuum lines go. Might be able to hear a hiss comming from one of those solinoids under load or something. Pull the codes as well. It might flag something to give you a starting point. Hope this helps a little.
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Senior User
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From: Lower Rainland British Columbia, Canada
Emission Control Problem?
Thanks Matt_W: Valves are in good shape, I adjusted them 15,000km ago;the only pain was the old cork gasket. The black plastic cover... I can here the solenoids going crazy when my problem is occuring. They sound like a bad plug wire on that side. I'll pull the codes later today or tomorrow. Thanks again.
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Joined: Jan 2003
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Emission Control Problem?
if your o2 sensor and cat are that bad,,are you able to run with straight pipes??its not always legal,,,,but that depends on where you live! to get rid of all those vacuum lines,why not change to the duraspark ignition? it makes tuning so much easier,and no vacuum leaks.
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Senior User
Joined: Jan 2003
Posts: 392
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From: Lower Rainland British Columbia, Canada
Emission Control Problem?
Not A Hope!!! I live in the most tree hugging, ECO Centric, Navel Gazing area of the free western world. Tightest emission standards that I know of. I grew up in Calif. so I know how bad it is there. Here you have to pay for a smog test on your brand new car before registering it. Thanks for the ideas though. If I had it my way I would have a 5.0L/C6 in it, but dream on.
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