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Rough "pulsing" idle


SLDPRN6

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So after almost 10 months I finally have the ranger back together. Problems I am having are getting it to idle down and stay running. No tach but would have to guess around 1100-1200 and trying to get it under 1k for idle rpm. The other issue is when not at WOT or even at half it "pulses" enough that in the first test drive it jerks the truck like a Newby to a clutched vehicle. Which this is also a manual truck. I have put all new guts in the carb as well yet still to no avail, along with adjusting idle air screws. Nothing gets rid of the pulse. I will try and upload a video or two of it so you can attempt to hear what it is doing.
 


franklin2

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What engine? If it's a 2.8 v6, has it been converted or still running the computer system?
 

SLDPRN6

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What engine? If it's a 2.8 v6, has it been converted or still running the computer system?
it is the 2.8, far as I know it is all OEM. I personally have not altered it.
 

tw205

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The accelerator lever on the carb rests on the idle control motor. The computer uses this motor to adjust the idle. Is the engine surging because the control motor is changing it or is the surge from the carb itself.
Was the carb disassembled and cleaned before you put new guts in it?
Has the idle mixture been set with a vacuum gauge?
Timing?
Is the TPS plugged in and testing good?
 

SLDPRN6

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The accelerator lever on the carb rests on the idle control motor. The computer uses this motor to adjust the idle. Is the engine surging because the control motor is changing it or is the surge from the carb itself.
Was the carb disassembled and cleaned before you put new guts in it?
Has the idle mixture been set with a vacuum gauge?
Timing?
Is the TPS plugged in and testing good?
It was pulsing from the carb its self, not from the high idle motor. Might have figured out the culprit, the EGR. Unplugged the vac line to it and it purrs like a kitten now, and can get the idle below 1k and it not die. Yes I tore the carb down to just a fancy bowl with holes in it and went over it 3 times before putting the new guts in it. As for idle mixture with vacuum no, and not sure what you mean or how by that?!? The idle mix screws were adjusted though. The timing was the problem before the carb on why it didnt want to start or run. This little hot wheels truck has fought me every step of the way for running and driving again lol.
 

franklin2

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The idle mixture screws are carefully adjusted for the highest and smoothest idle. You have to keep going back and forth between them a couple times to get it the best. Then you can reset the idle speed if it changed too much.

Some people like a visual aid when doing this. When you get the highest smoothest idle, you will have the highest vacuum reading on the gauge if it's plugged into the intake manifold. This helps some people set the idle mixture screws.
 

SLDPRN6

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Yea it took some time fiddling with them to get the idle down from what it was. Huh ya now that you explain it like that I remember seeing or hearing about that for adjusting a carb in general. My head has been in the compression ignition world for so long, the bits and pieces for spark ignition I knew have faded, could say I'm a bit out of practice lol.
 

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