No Codes but will surge a little on steady hwy speeds or up hills Please Help!!!

[TFaoro]

Maybe it's affecting the apps sensor somehow. You need to get the truck back to 100% stock! No EB no Quad nothing that can effect. If you still have surge I would say cam positioning sensor or VP. (That is if you are 100% sure on the apps being good)

[Dieselfuture]

Maybe it's affecting the apps sensor somehow. You need to get the truck back to 100% stock! No EB no Quad nothing that can effect. If you still have surge I would say cam positioning sensor or VP. (That is if you are 100% sure on the apps being good)

Got new cam sensor in last year, I'll try again unhooking everything and see what happens, thanks for advice.

[Mopar1973Man]

Possible air leak? Thinking out loud...

[Dieselfuture]

Possible air leak? Thinking out loud...

I thought about it too, but I can hold 30 psi steady on hill and boost gauge is smooth and not jerky, same with fuel pressure. Stays right at 18-19 with load on engine and 30 psi. I never pressure tested air system but I did check all clamps and boots.

[Mopar1973Man]

Possible air leak? Thinking out loud...

 

 

I thought about it too, but I can hold 30 psi steady on hill and boost gauge is smooth and not jerky, same with fuel pressure. Stays right at 18-19 with load on engine and 30 psi. I never pressure tested air system but I did check all clamps and boots.

 

Fuel system not air system. I've seen a few older Ford 7.3L now that have the ability to hold prime just fine be pull a continuous air stream into the injection pump causing it to run rough and skip. Depending on load and fuel flows.

[Dieselfuture]

Fuel system not air system. I've seen a few older Ford 7.3L now that have the ability to hold prime just fine be pull a continuous air stream into the injection pump causing it to run rough and skip. Depending on load and fuel flows.

I did this trick with clear hose on windshield and pulled a trailer and no air was in it, not even tiny bobbles. I puy it in just after my tee for fuel gauge, about foot away from vp. Maybe I didn't do that test right.

[Ilikeoldfords]

As long as you had the clear hose in line before the VP and the fuel had to flow through it to get to the VP, then the test was done right. I am sure you probably thought about this, but what about a bad tank of fuel? Could have gotten some water in it or something.

[Dieselfuture]

As long as you had the clear hose in line before the VP and the fuel had to flow through it to get to the VP, then the test was done right. I am sure you probably thought about this, but what about a bad tank of fuel? Could have gotten some water in it or something.

Yes that's how I had that hose, was long enough to stretch under wiper on windshield. Good point on contaminated fuel, but every time I chek fuel/water separator no moisture at all comes out. I drain some in clean glass jar. What's wired is as soon as I changed injectors problem went away with same tank of fuel, and after about 3 thousand miles it came back out of nowhere. I haven't called DAP yet but I'm thinking about it.

P.S. I just got this old bit up 12 valve and been driving it daily, getting attached to it now. Also on last tank I got 21 mpg and it's got small tires and 4.10s. Thinking getting an older suburban in good body shape and putting this 12valve and nv4500 in it. My biggest problem is time, don't have a lot of it now being married and having kids.

Edited January 25, 2015 by Dieselfuture

[Mopar1973Man]

On the contaminated fuel thing... I would open the filter housing and look down at the bottom with a flash light. I've seen a few trucks locally with enough dirt in the bottom to cover the bottom of the filter housing. Just because your changing filter make sure the bottom is cleaned out too. If you have to pull the housing to do it. One local boy had changed his filter and didn't clean the dirt out and complained of low power and hard starting after being out in the hills bouncing around.

[Dieselfuture]

On the contaminated fuel thing... I would open the filter housing and look down at the bottom with a flash light. I've seen a few trucks locally with enough dirt in the bottom to cover the bottom of the filter housing. Just because your changing filter make sure the bottom is cleaned out too. If you have to pull the housing to do it. One local boy had changed his filter and didn't clean the dirt out and complained of low power and hard starting after being out in the hills bouncing around.

Sorry I didn't mention that I don't have factory housing, I took it off. All I got is ad150, and when my problem went away for almost a year I never changed filters before or after, and my pressure is still 19 under load.i don't drive much a year and don't change filters every year, I don't think they break down. I know a guy that got expedition for about 6 years now and he never changed oil or filter, somehow it still runs. He puts maybe 5k a year on it. I'm sure it will blow up eventually.

[Dieselfuture]

Ok after all this time I decide to check ac noise again and this time I'm reading .00 at idle .2 at 1200 .5 at 2000 and so on. Took it to parts store test passed but I already new that was not the case after reading other posts, so I found local guy that fixes alternators and starters he checked it and his little analog gauge was showing almost bad for diodes. He said, yeah need new rectifier, so he ordered one $40 out the door, was supposed to be here today but now it will be Monday. I got bosch and not denso, and according to him bosh will be discontinued soon, so maybe I should buy 2 of them. I sure hope that this stupid intermittent issue I had with this truck for like 3-4 years now will soon be over. I will update results as soon as I get it fixed.

Edited January 25, 2015 by Dieselfuture

[Dieselfuture]

Does anyone know where I can get rectifier( diode pack ) for my alternator, it's Bosch 0-124-525-005 local guy was supposed to get it and not sure if he will, just curious if you guys new a place. Thanks.

Ok I just found this place in case someone out there needs one http://store.alternatorparts.com/ibr256---bridge-rectifier.aspxthis is 117-132amps and this http://store.alternatorparts.com/ibr225--.aspx 132-136 amps

Maybe there are other places cheaper let me know.

Edited December 14, 2014 by Dieselfuture

[Dieselfuture]

Not sure if anyone is still reading this, just rebuilt my alternator and it wasn't that hard just had to take it one step at a time. Got new bearings, brushes, and racktifire. All went smove but a stud on rectifier was too short and thin. Used old one. Got windings pinched and soldered, tested for ac noise and was surprised to find .02 at idle and .05 revved up to about 2500. I know that Mike say no more than .02 but this is all new parts. Before it would clime to a least .5 I checked old diodes and got .536 from the ones in metal and plastic and low 500s from the metal strip ones not sure which ones are bad if any. My guess the ones with low 500s are bad someone school me. Also the more i check it less voltage drop I get, first time was .556then .536 and now .528, but between two strips there is a consistent gap of .30 or so, maybe battery in meter is slowly dying. I might go to RadioShack and see if they have diodes so I can repair this racktifire and keep I as spear, or figure out if I just had bad connection and solder these better together as factory has some sort of cheap spot welds on these, some of them came apart easy and some not. I did not drive truck long enought to see if it still surges, but my tach seems to be more steady. There are two pictures of rectifier one from website has a longer stud the one I got from local guy I had to put my old stud in, but they were both with 60amp diodes. 

Edited January 25, 2015 by Dieselfuture

[MnTom]

You should be OK with the .05vac. The limit is double that .10vac.

[Dieselfuture]

You should be OK with the .05vac. The limit is double that .10vac.

Thanks for making me feel better Tom, I thought Mike was saying anything over .02 is not great. But I guess it did go from .5 to .05 so that tells me I did something right. I'll post real results later when I get to tow again.

[Dieselfuture]

Ok I just found something else, sometimes my air dog starts to pulsate from normal 19 psi to 22 or so and makes noise like sucking air, and when that happens if I check for ac current I get spikes to about .5 and when there is no spiking my ac is around .02-.03 and if revved up it's at .06 max, but with air dog it spikes above limit for ac/v also might be greeds that cycle about same time and causing air dog to spike. Can air dog make ac noise? I'm guessing it can since it's electric motor. Any ideas. I don't want to fry another diode pack.

[MnTom]

If you are seeing over .1vAC then you have a diode that is failing. Chances are the LP motor will change pitch with the AC voltage sice it is designed to run on DC voltage. It sounds like the grid heaters are cycling normally and they will draw the charging voltage down causing the sound to change.

[Dieselfuture]

If you are seeing over .1vAC then you have a diode that is failing. Chances are the LP motor will change pitch with the AC voltage sice it is designed to run on DC voltage. It sounds like the grid heaters are cycling normally and they will draw the charging voltage down causing the sound to change.

I'm only seeing over .1 when air dog starts to act up. If pressure stays same then I don't see any ac over .06

[MnTom]

But, does the Air Dog act up at a time when the grid heaters are not cycling?

[Dieselfuture]

But, does the Air Dog act up at a time when the grid heaters are not cycling?

I believe so, I drove it to work again today and as soon as I got to work checked ac volts before I shut it off and was at .03 idle and .06 revved up. Then I took it for a quick spin and got on it a few times and sure enough air dog was acting up in pressure spikes of 3 psi. Put meter on alternator and had a steady reading of .125 for about 30 sec and who knows how long it's been at that as I had to hook up meter maybe few minutes, then I revved it up a few times and it seemed to drop a little. But to come back to .03 I had to shut the truck off and start it again and ofcose greeds were sycling and ac was affected a little, but then I drove it again at steady speed and air dog steadied out and ac came back to normal. I know this is not easy to explain but guy I work with really knows electronics and he also thought that somehow fuel pump was affecting ac noise. But he didn't have much time to piss with it. So I guess if brushes are old in air dog can that cause ac noise to back feed to alternator? One electrician told me about my alternator diodes were probably good and ac noise was caused by worn out brushes, because he checked my old diodes and didn't see anything wrong with them, but also said that that's half the test as they need to be under load to check for sure. Seems like I keep fixing things half asss, even though I'm trying to do it right the first time. But in the end by rebuilding my alternator so far I had no surging at all even on higher levels of qwadzilla, where before I didn't even use it for power as it would make surge more pronounse.