Refusing to go over 65mph - Page 3 - JeepForum.com

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post #31 of 41 Old 07-29-2013, 12:33 PM
vadslram
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Are you sure?
I just did a search for the part at two parts places and quadratec and none had a knock sensor for a 4.2.
I'll check my shop manual when I get home. But I highly doubt that the 89 or 90 computer was sophisticated enough to retard the spark because of knock.

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post #32 of 41 Old 07-29-2013, 01:28 PM
dancytron
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http://home.sprynet.com/~dale02/knock.htm

That's one of the big changes when you do the Nutter. Stock with the computer, the timing is set really high and it relies on the knock sensor to tell the computer to retard the timing when it knocks.
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post #33 of 41 Old 07-29-2013, 03:33 PM
vadslram
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Well I stand corrected. It is pin out #51. I guess I just assumed it was a temp sensor...I guess I need to get a pipe plug because that's one more thing coming out from under my hood.

Best thing my PO did was give me the shop manuals!!
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post #34 of 41 Old 07-30-2013, 08:54 PM Thread Starter
whiskeywiz
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that's not a Haynes manual. Looks nice. What is it?

Well I got a carb rebuild kit for a 77 Plymouth Volare which is what came with a Holley 2280, (which is as I said what somehow made itself onto my rig). Got home with the kit got to the first gasket and realized I had the wrong kit. Took it back to Autozone, got refund. Called Napa. After cross referencing a couple shop manuals, the guy said that the kit is obsolete. Well isn't that just wonderful.

So while putting my antique carb back together I noticed a stopper thingy next to a spring loaded plunger thingy. The stopper was in a stuck position. I freed it up with some carb cleaner and compressed air. Put er back together and its running like a raped ape again. Now if you recall, (I think it was this thread) it ran like that after I shot some carb cleaner down the barrel, but then after a day it went back to falling on its face when I gave it too much gas. As if I knocked some crud loose and it got re-stuck.

Did freeing up the stopper thingy solve my issue for good? (for a while anyway, until I get rid of that carb?)...
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post #35 of 41 Old 07-31-2013, 06:29 AM
vadslram
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It isn't a Haynes. It's the DC Jeep Shop manual,a 2 volume set one for engine and body the other is all electrical.

The stopper thingy sounds like the power valve. The plunger thingy is most definitely the accelerater pump.

You can google "holley power valve how it works" but here is a quick clip on it's operation

Quote:
A Power Valve is little more than a vacuum operated on/off switch for fuel. It operates using a vacuum diaghram and a spring, which determines when the valve opens. I believe this is best explained using an example. Let's use an engine that makes 13" manifold vacuum at idle, a typical lightly modified performer. Knowing that value, we know that a 6.5" rated power valve would be used (typical power valve selection is 1/2 the amount of vacuum at idle, in our case 13/2=6.5). So, during idle and light cruising (above 6.5" vacuum) the power valve will be in the closed position ("off"), but during moderate to full throttle operation the vacuum will drop to below 6.5" and will cause the valve to be open ("on"). The power valve itself doesn't control the amount of fuel delivered, that's the PVCR's job.
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post #36 of 41 Old 07-31-2013, 07:14 AM Thread Starter
whiskeywiz
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The part i am speaking of is number 25 in the diagram in the link below. Cannot find one with explanation yet, (on my phone at work).

http://www.carburetorfactory.com/images/expvw16.jpg
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post #37 of 41 Old 07-31-2013, 11:12 AM
vadslram
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Well #30 is the accelerator pump and from what I could find #25 is the power enrichment valve.
I came across a couple of 2280 rebuild videos on youtube, but youtube is blocked where I am now so I couldn't look.
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post #38 of 41 Old 07-31-2013, 11:38 AM
vadslram
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Here is a link showing how to adjust that power valve
http://www.autozone.com/autozone/rep...00c1528007fc69
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post #39 of 41 Old 07-31-2013, 09:01 PM
vcallen7
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I can get my YJ to sometimes do 70... downhill with a tail wind. I thought that was just the way it was. Guess I was wrong.
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post #40 of 41 Old 07-31-2013, 09:19 PM Thread Starter
whiskeywiz
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got er to cruise on the highway good. No bucking at 65mph. Spidey senses tingly though. Stopper thingy could bust loose at any moment. Just get me and the wife to the Hip show and back on Fri...
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post #41 of 41 Old 07-31-2013, 09:23 PM Thread Starter
whiskeywiz
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putting that carb on antiques roadshow after replacement arrives
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