One last shot... Breaking up!

[WyoSyclone]

Re: One last shot... Breaking up!

It's a brand new cable that I just put in. I have it bolted to the open thread boss to the pass side of thermostat housing.

Would be better if it was bolted to the back of one of the heads.... that aluminum intake with gaskets and such can make for a less than optimum ground.

 

[BoostedSUV]

Re: One last shot... Breaking up!

Would be better if it was bolted to the back of one of the heads.... that aluminum intake with gaskets and such can make for a less than optimum ground.

Never really thought about that... I relocated battery and the ground when I first put motor in the truck. (stupid RPM a2a) Figured that would be a good spot since the wire harness grounds 6 inches away.

 

[WyoSyclone]

Re: One last shot... Breaking up!

OK.... here's my last thought for the night....
You've proven the alternator is not the cause, nor is the ignition coil....

So, I come back to this....

Ohm's Law...
E=IxR
voltage = current x resistance

voltage can go up above 12 if we're passing a set amount of current through a higher resistance.

There are two things common in your testing that may provide a clue...
1. When you took the wires off the alternator, you bolted them together.... this left the battery STILL feeding the B+ junction block via the FUSIBLE LINKS.
2. When you moved your probes, the 19 volts remained. The other possible area of increased resistance is via the internal resistance of the battery, although I doubt this to be the case.

EDIT... I can't remember... did you ever disconnect the battery positive and take a resistance reading from the positive battery cable end, to the B+ junction block?

So, if you know all your grounds are good, I would replace the fusible links next... The only other area of concern is the MSD box, but you said the problem was there before you put it in.... those fusible links were there before you put it in too

On the bright side, we have eliminated a lot of things tonight!

 

[kentuc]

Re: One last shot... Breaking up!

Run a 10 ga wire from the battery terminal to the junction block. that will equalize the voltage.

 

[BoostedSUV]

Re: One last shot... Breaking up!

When I ohm tested from the ALT end of wire to the distribution block I got a 0.0 reading. Are those fusible links anything special? Can I eliminate them completely or do I need to find replacements?

The next thing I'm going to do is remove alt bracket and grind down the contact points to be sure I'm getting a clean ground between bracket and head/block. I'm also going to try and figure out where to Move the batt ground cable to the back of the head where it used to be, You know as well as I do what a pain it is to get back there! I'd really like to relocate my battery completely bc I hate where it is, but I don't know the best place to put it is and I will probably just be adding another headache....

 

[BoostedSUV]

Re: One last shot... Breaking up!

Run a 10 ga wire from the battery terminal to the junction block. that will equalize the voltage.

even if that works I want to know why I'm seeing what I'm seeing it's not normal and could be a route cause of what I have going on. The weird part is without the truck running I get a solid 12.2, same as the battery :dunno:

 

[kentuc]

Re: One last shot... Breaking up!

Ohm test the end of the battery cable to the junction. Then the end of the battery cable to the wires from the alternator.If it`s 0 then the +`s are ok. Then check the ground cable from the battery to the block and other grounds

 

[SY2455]

Re: One last shot... Breaking up!

I was using the MSD 6A so it was connected to the dist block.

The MSD control box has a dedicated Ground wire for the unit. Do you have this connected ?

 

[turboj91]

Re: One last shot... Breaking up!

I've been reading along with all the posts, the tests and the results. No doubt that the tests need to be done as an issue has been found that needs correcting but..... I am confused. How does any of this stuff make the engine go lean for 3 very specific rpms and why would changing the injectors make the problem move up the rpm scale by about 300 rpms each. Do we think the electrical interference is causing the injectors to shut down for a second. I am assuming that the lean condition is due to lack of fuel and not an interference of spark or timing jump ect... IIRC, the wideband does not show pig rich just prior to the problem rpm and then the engine goes lean to compensate for being so rich. It shows normal and then goes dead lean at the specific rpm. I have never read any of his DM files but a few others have and advised that nothing obvious jumps out as being improper. This is why I am confused. If I am understanding things correctly, it is a LEAN misfire (because the gauge says so) and not a misfire due to improper operation of the ignition system (ie; bad plug, flame blowout, crossed plugwire ect...). With all due respect, I am wondering where you guys are making the connection (no pun intended - haha) between the bad grounds, the 19 reading at the block ect... and how these things make the engine go lean.

 

[BoostedSUV]

Re: One last shot... Breaking up!

The MSD control box has a dedicated Ground wire for the unit. Do you have this connected ?

I have it grounded to the firewall where the blower motor and motor relay ground to.

 

[BoostedSUV]

Re: One last shot... Breaking up!

Personally I think it's electrical as well but I have no explaination... haha It's almost as if I have a bad signal feeding through my wires and it's causing crazy things to happen. With a test light (and DM) the injectors never stop pulsing, also while scoping the dizzy (moving timing light from wire to wire) the flashing is continuous and in a normal pattern at all 6 cylinders. I don't get any spark drop out through the wires at least.

What goes on at the plug, and/or at the injector beyond the pulse I can not see. Fuel pressure does not drop as if the truck is loosing the fuel supply. All i can see is a lean reading on the O2 and WBO2, and hear a "miss" "stumble" etc in the exhaust...

Perhaps the block is not grounded properly, spark plugs need a good ground in order to fire... VOM doesn't show this at all, but who knoes at this point?

 

[turboj91]

Re: One last shot... Breaking up!

This is where the "art" of theory comes into play with diagnosis. It is an art which I take very seriously (my mom always said I think too much). If we knew what was happening to make it go lean, the problem would have been fixed already. I would love to watch every aspect of every function of every component in real time. Like having every piece of a puzzle in front of you. It's not long before you put it all together.

Going back to something basic, the problem started after an engine rebuild and install. Something happened at the time of removal or reinstall. If we only knew what we would all be watching the dancing girls that are 5 minutes from your house.

How many of us can you pick up from the airport at the same time. I say we all gang up on the truck, fix it and then take your dragster up and down the street. Yahoooooooooo

 

[turboj91]

Re: One last shot... Breaking up!

I am tired and have a headache that would drop a horse.
Where is the Dr. House of the automotive world. We need to work just like his team. He writes all the possibilities on the board them eliminates some based on known conditions, tests for others and continues with elimination. Then somewhere a light goes off in his head because of something totally unrelated and he figures is out. I want to be Dr. House and have the light go off in my head when some dancing girl (5 min from your home) is doing something (to me) totally unrelated to going lean.

Also, if I was the Dr. House, I could reach into my pocket and give myself some drugs to knock me out and get rid of this headache.

 

[SloGN]

Re: One last shot... Breaking up!

I was using the MSD 6A so it was connected to the dist block.

you state here that the MSD box is getting it's power from the junction block correct?


If so it may be possible that the msd box is causing the A/C ripple effect and making you see the insane voltages that you have been seeing. that could be a source of the leak and wyo mention about the coil.


How long has the msd box been on the truck?

 

[BoostedSUV]

Re: One last shot... Breaking up!

you state here that the MSD box is getting it's power from the junction block correct?


If so it may be possible that the msd box is causing the A/C ripple effect and making you see the insane voltages that you have been seeing. that could be a source of the leak and wyo mention about the coil.


How long has the msd box been on the truck?

3 weeks maybe? I litteraly just bought it from JHacking and put it in the truck. I can disconnect it and bypass it in about 3 minutes. I'm 99 percent sure I had the same thing at the junction block prior to the install. I will go back and check... I also put my stock coil back in last night and that didnt change anything.

 

[BoostedSUV]

Re: One last shot... Breaking up!

J if only it were that easy... I would be on the phone with my good travel agent friend booking flights. The beer and dancing girls would be at my house when everyone arrived! Lol I'm doubtfull the issue would be discovered quickly as I have been trying for 4 months now... I'm running out of patience, Advil, and "steam" as I can't even sleep at night because I haven't figured out how to turn my brain off at night. I've been driving my girlfriend nuts because this truck has me talking to myself in my sleep! Thankfully she has been letting me use her car since june or I would have probably lost my job by now... I leave for Florida the weekend after Halloween for a 2 week racing trip and my goal was really to have the truck in working order before I leave. At this point I'm doubt full that will happen. My new more realistic goal is having it figured out by the end of the year... That's 6 months from when I started! In that amount of time I could have undergone a complete overhaul instead of having a rusty TY that doesn't run. I've got a chance to buy a rust free shell and have the truck I've always wanted but I keep putting it off because why go through that trouble to just potentially move my problem into another shell that looks great but doesn't run for sh*t....?

Beer is within walking distance, dancing girls are a 5 minute drive, hotels are 3 miles away, my Dad's motorhome sleeps 6, and pretty much any food/restaurant you can think of is a short drive away... :lol: did I mention the dancing girls are 5 minutes away? When is the wrench session going to happen? I know it would never happen because who the hell would want to come to NJ? And who the hell would have the time... I sure as hell don't and the truck in my driveway! However, I do live in a quiet neighborhood and I would love to do boost launches and dragster burnouts up and down the street in celebration! I have friends that are township cops so I'm sure the "disturbing the peace" fine wouldn't be too bad . Hahahaha now if only I had that heated garage Rob requested! :tup:

 

[Quickstop [UK]]

Re: One last shot... Breaking up!

I've never been to NJ. Got a hot sister?

 

[WyoSyclone]

Re: One last shot... Breaking up!

I've been reading along with all the posts, the tests and the results. No doubt that the tests need to be done as an issue has been found that needs correcting but..... I am confused. How does any of this stuff make the engine go lean for 3 very specific rpms and why would changing the injectors make the problem move up the rpm scale by about 300 rpms each. Do we think the electrical interference is causing the injectors to shut down for a second. I am assuming that the lean condition is due to lack of fuel and not an interference of spark or timing jump ect... IIRC, the wideband does not show pig rich just prior to the problem rpm and then the engine goes lean to compensate for being so rich. It shows normal and then goes dead lean at the specific rpm. I have never read any of his DM files but a few others have and advised that nothing obvious jumps out as being improper. This is why I am confused. If I am understanding things correctly, it is a LEAN misfire (because the gauge says so) and not a misfire due to improper operation of the ignition system (ie; bad plug, flame blowout, crossed plugwire ect...). With all due respect, I am wondering where you guys are making the connection (no pun intended - haha) between the bad grounds, the 19 reading at the block ect... and how these things make the engine go lean.

Good question.... my train of thought on this one is....
It takes a certain amount of energy to fire the injectors - determined by voltage and current on the supply, and by the impedance of the injector. The impedance of the new injectors is just different enough to cause the problem to have moved up in the RPM range because the energy to open them has changed. Matt said that when he lowered the fuel pressure the problem got better... could this be because the amount of energy needed to fire the injectors drops with lower fuel pressure? They're not having to use as much energy to fire when the fuel pressure is lower.

Since the engine is a device that produces tons of vibrations, along with certain harmonic frequencies, it could be that a bad connection is being affected by these harmonic frequencies, causing a drop in current and corressponding rise in voltage (19 volts). Matt says the problem isn't very bad when the engine is cold.... ground problems get worse with rising temperatures.

Since this problem only happens at certain RPMs I think the tests have to be done by testing for voltage drop while the engine is running.

If it's a problem on the ground side of a circuit, it should be found by taking a length of wire and temporarily making an additional ground for each component along the path.

If it's on the power supply side, Matt could start the truck, having someone hold the throttle at the point where the engine starts to break up, then take a multimeter and start at the alternator and probe for DC volts from the output of the alternator to each downstream point along the power cable. Somewhere along that path he should get a reading of about 5 volts(19 - 14).... somewhere between these two points would be the source of the problem.

I hope this makes sense!

 

[Quickstop [UK]]

Re: One last shot... Breaking up!

I would get an oscilloscope onto the injectors. I really want one bad after the signal I saw on my truck one time. I think in this instance it would be revealing.

That would show the voltage on them as the rpm increases. You could tie it into your ignition as well.

That would really show you what you were getting rather than a VM.

 

[WyoSyclone]

Re: One last shot... Breaking up!

3 weeks maybe? I litteraly just bought it from JHacking and put it in the truck. I can disconnect it and bypass it in about 3 minutes. I'm 99 percent sure I had the same thing at the junction block prior to the install. I will go back and check... I also put my stock coil back in last night and that didnt change anything.

Is the red loop wire beneath the black cap on the 6A cut?