OBS idling problem?

[DieselEater]

OK, so ill try and make this short. i bought a 97 with a bad engine and installed a 40k mile engine. after about 3 days of driving it around i noticed after jumping off the freeway and coming to a stop light, the truck would start to shake then the shake would increase until the light turned green, as soon as i take off the truck runs smooth, no bucking/hesitation and no loss of power, this would intermittently happen at everyother stop light. now also when starting the truck after its allready at operating tempature it kinda diesels in other words it idles up and down about 5 times until the idle sits normal. i have tried everything, using all of the old sensors from the old motor, ICP CPS HPOP IPR etc.... no codes or code light ever comes on. i have 8 new injectors with new cups and orings, two brand new fuel pumps and new mech fuel pump, new UVCH. ran a compression test and leak down test thinking i had a valve that wasn't sitting correctly, all checks out good. cranking fuel pressure is at 20 psi and sits at about 60 at idle even when the truck is shaking, now correct me if im wrong but i was told that low fuel pressure at idle can cause an uncomfortable idle? i had a friend from ford look at the truck and hook up a scanner when the truck was shaking, injector rate was normal and all sensors were showing correct voltages. i am completly at a loss and any help from you guys would be great, just tell me what to try and im on it, thanks.

[CHUCK]

bump up for ya.

[bondsman]

Exhaust back pressure tube clogged or clogging? Clean the fuel pressure regulator screen...

Just some ideas to throw out there for ya...

[DieselEater]

Originally Posted by bondsman

Exhaust back pressure tube clogged or clogging? Clean the fuel pressure regulator screen...

Just some ideas to throw out there for ya...

I used a wire flint on a drill and cleaned it out before i replaced the engine, it is possible a chunk could have made its way in there again, ill pull it off again and check it, screen is clean just did it about a week ago. keep'em coming ill eventually figure this thing out.

[bondsman]

SURGE AT IDLE
1. ICP circuit problem, disconnect the ICP sensor, if the surge goes away then you possibly have a bad ICP sensor.
2. AA code injectors installed into a engine that require AB code injectors will cause a surge (California emissions engines in 96 and 97 require AB injectors)

Pulled that off another website....

[bondsman]

If it is a stick, it could be the dual mass flywheel going...

[96F350KID]

Mine does the smae thing only thing is the idle will jump +/- 100 rpm i belive it has something to do with the FPR spring and the fact the fuel pressure jumps with it. In other words +/- 10-20 psi lope in fuel pressure. ONLY when warmed up

[waljon]

Is this an automatic? if so it could be the sensor on the transmission next time it starts to do funny up and down idle after it has been started shut it off put the trans in neutral then start it up again if it stops then that is your problem.

If this is a 5 speed than like stated above could be a duel mass flywheel Issue.

[DieselEater]

Originally Posted by bondsman

SURGE AT IDLE
1. ICP circuit problem, disconnect the ICP sensor, if the surge goes away then you possibly have a bad ICP sensor.
2. AA code injectors installed into a engine that require AB code injectors will cause a surge (California emissions engines in 96 and 97 require AB injectors)

Pulled that off another website....

ICP circuit is good!

[DieselEater]

Originally Posted by 96F350KID

Mine does the smae thing only thing is the idle will jump +/- 100 rpm i belive it has something to do with the FPR spring and the fact the fuel pressure jumps with it. In other words +/- 10-20 psi lope in fuel pressure. ONLY when warmed up

That is exactly what mine is doing except i think it jumps to 1k rpm, i will pull the FPR again and check it out.