Still Trying.. (One Last Shot pt2)

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

Quickstop, the motor has been out 4 times but each time it has undergone an overhaul. Other than the rotating assembly, the bearings, rings, gaskets etc were all replaced. I really doubt that it's a mechanical issue on the engine side of things but it could be something weird going on? Either way, if the engine comes out it is not going back in. I've spent enough money trying to get this rust bucket to run right....

I've contemplated a kinked fuel line or something but even then the problem is too consistant and too specific. I'm still leaning toward electrical but what and how? I'm trying to borrow an O-scope but I don't even know how to use one! Lol I'm sure I can figure it out...

Come spring time here if I can't get this thing figured out there will probably be a Ty part out. 5 years trying to chase down an issue for truck that isn't worth much because of rust is getting to be ridiculous... I would really like to figure it out so I can at least enjoy the money I spent a little bit but its not looking too promising. :tdown:

 

[bezerk]

Re: Still Trying.. (One Last Shot pt2)

i call dibs on the steeringwheel

 

[bezerk]

Re: Still Trying.. (One Last Shot pt2)

could be a valve acting weird?? maybe with a probe gun check each cilinder on the manifold if it has the same temp?

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

I do have a temp gun and I've been meaning to check each cylinder to see if I have one or more lean cylinders or if it's across the board.

I doubt it's an issue with the heads/valves because I had this same problem with stock heads and it didn't go away when I put the vortecs on it. The only thing common since the first rebuild is the cam, pistons, rods, crank, balancer, block, and upper plenum.

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

Nolan sent me a new tune to try tonight and he took a little fuel out of the map... The miss got less noticable but it is still there at the same spots. Nick (NJ93TY) came for a ride with me tonight while I had DM hooked up. Maybe he will chime in with what he sees/feels.

Watching DM as the truck hits the "bad spots" the truck goes lean, gets a miss and the RPM will get "hung up" and not increase right away even though I continue depressing the throttle. TPS percentage increases slowly but RPM will not follow as it should... Once it gets passed the trouble spot the RPMs will jump 4-500 RPM and it will smooth out until the next bad spot.

 

[Quickstop [UK]]

Re: Still Trying.. (One Last Shot pt2)

Get the probe gun on it - I mentoned it before (cylinder specific) and rene said so as well - go with what he say :rotf:

Sounds like you're almost done with it - can't say I blame you. Have you checked the hydraulic lifters? I had a collapsed one and at a certain RPM it was rubbish but once I got through that band it was better.

I only found it after I took the engine apart though..

The probe gun will tell you a lot.

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

Ken (warmpancakes) also suggested a temp gun on the exhaust manifolds. Maybe I can pinpoint it to one cylinder, or maybe it's every cylinder leaning out. The weather forecasters all calling for 1-2 feet of snow in my area this weekend so I'm going to have to wait until next week to get anything done :tdown:

I'm also borrowing an o-scope so I will have time to read up on how to use one :rotf:

 

[qbnkiller]

Re: Still Trying.. (One Last Shot pt2)

if you dont have a temp gun, use a squirt/spray bottle, get the exhaust nice and hot, and spray the manifold on each exhaust runner to see which one doesnt steam up as fast as the others.

 

[dgoodhue]

Re: Still Trying.. (One Last Shot pt2)

No it started almost 4 years ago when I installed a fresh motor, 50#r's, AFPR, RPM A2A, battery relocate, and ultimate chip. I rebuilt trans about 2 years and not many miles ago

Where did you relocate your battery to? How it is grounded? I wonder if your have ground issues with the battery location or it's affecting you fuel pump operation in an odd way.

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

Where did you relocate your battery to? How it is grounded? I wonder if your have ground issues with the battery location or it's affecting you fuel pump operation in an odd way.

I moved it to the driver's side of the truck near the oil filter and in front of the ABS unit where the factory airbox was located. It was supposed to be a temporary thing but I never moved it. In any event I used the original power feed and re-routed it to the starter and I used a 2ga ground to the front of the driver side head (it was originally to the intake by thermostat housing but I moved it). There's also a 4ga from the alt bracket to the chassis, and I replaced the ground strap from the back of the head to the firewall. I'm also using the racetronix hot wire kit which was added in after the problem started. The weird thing is the fuel pressure looks perfect throughout the range :dunno:


We got 20" of snow on saturday, and we're expected to get another 18" of snow tonight into tomorrow so I haven't been able to get the temp gun to it yet....

 

[MikeRenz]

Re: Still Trying.. (One Last Shot pt2)

did you mod your ecm for low imp injectors? Are your injectors high or low imp? If you did mod the ecm did you reuse those little collars on the leads of the injector drivers?

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

did you mod your ecm for low imp injectors? Are your injectors high or low imp? If you did mod the ecm did you reuse those little collars on the leads of the injector drivers?

Mike I took out high imp 50's and put in high imp 60/65's to replace them. As far as I understand things there is no ECM modding required. I wish my problem was as simple as that.

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

I drove the truck to work today in a blizzard because I figured AWD is the best shot I have...

Anyways, I'm still having the hard starting issue when the truck warms up. That has to be related... DM shows 6000 rpm up and down while it's cranking and not running. The RPM graph looks like a bunch of M's. When it does this INJ DC jumps the 96% and it floods the truck. The tach doesn't move but I'm seeing it at the ECM via DM, I'm really thinking there's some sort of tach signal interference... but how? What is in the truck other than the coil and Ign module that sends or deciphers a tach signal? Can I cut the white wire off at the coil and connect it the tach output of the MSD and change the source of the Tach signal???


the truck breaks up/runs rough/leans out religiously at 1400ish, 2200, 2800... everytime, and only at those points. In between it's nice and smooth :dunno:

 

[Quickstop [UK]]

Re: Still Trying.. (One Last Shot pt2)

Have you got the knock sensor on there? is it trying to retard your timing or anything funky like that?

Doesn't the oil pressure switch prevent the tach signal or something to stop it starting?

I reckon you should use the MSD output and see what you get.

have you put a temp probe on the cylinders? It's a 1 minute job - get a friend to hold the rpm where it is steady - 1700 or so. Make recordings.

Then select a band - 2200 and check the temps of each cylinder. I know it's cold but man up

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

I'm not seeing anything wacky from the knock sensor... I even replaced it with no results. The oil pressure switch is also new and appears to be functioning properly as well.

My temp gun is in my racecar trailer and that got snowed in a friends shop an hour away. As soon as I have it in my possession again I will go out in the cold and see what I get. I'm also borrowing an O-scope from a friend of a friend. I just have to figure out how to use it. I have a feeling that will tell me a lot.

 

[Quickstop [UK]]

Re: Still Trying.. (One Last Shot pt2)

Can the friend of a friend not tell you? What model is it?

There are two settings on the oscope - voltage and timebase. There will be a switch to select the signal from either an RF lead or a probe.

You need to set the timebase so you can see the waveform of the signal - it will be repeating every 2nd rev of the engine and the duration of the spark will be in the order of a few microseconds. You need to set the probe so that it is in contact with the sparkplug or a piece of metal in that ignition circuit. You may need to make a little cut in the leads (not ideal) or connect the probe to the cap...hmm...thinking about this, this might be a little tricky. Are there any test ign leads you can get that have a contact point?

The second setting will be the voltage, so you can see the waveform of the o scope. The spark will be a pretty high voltage but the o scope should be able to cope.

Ideally you will have done the temp probe thing so we know if this is cylinder specific or if it is across the ign system.

If you take a picture of it and post it up I can tell you what you need to adjust on it... or attempt to. It's been a while but yeah, I think this will tell you a lot.

You can also check on what the injectors are doing - maybe they are getting a crazy signal from somewhere.

Can you try your MSD idea in the meantime? Have you got the wiring diagrams?

 

[TYTILIDIE]

Re: Still Trying.. (One Last Shot pt2)

If I were you, I would move your ground on the alternator bracket to the head. Even if that's not the issue they say always have grounds to the cast iron and not the aluminum. I would also consider grounding the battery straight to the frame and then ground the head to the frame:2cents:

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

If I were you, I would move your ground on the alternator bracket to the head. Even if that's not the issue they say always have grounds to the cast iron and not the aluminum. I would also consider grounding the battery straight to the frame and then ground the head to the frame:2cents:

Mike I have the battery ground to the alt bracket bolt that goes right to the front of the head. I also ground down both sides to assure it's metal to metal contact. It was grounded to the intake manifold but it was suggested to move it to head so I did. I just added a 4ga ground from the alt bolt that goes throught the bracket and grounded the other end to the top of the shock tower....

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

Quickstop.. As far as the oscope, I'm having a friend I work with get it from his friend so I won't be in touch with him to get a quick lesson. I will try to get the brand/model and do some research. I have a feeling I'm going to see some sort of "issue" either on the injector side, or ignition side of things. Something is interfering at specific RPMs. I just wonder what the common ground is at those RPM points.

I'm going to get my temp gun and try that. I do have wire diagrams so I'm going to see where is the best place to provide a tach signal directly from the MSD is. Would I need a tach adapter? Should I provide MSD tach signal to the gauges, to the ECM, or both? I know the tach signal comes from to different sources for each. I believe it's coil for the gauge, and ign module for the ECM...

 

[BoostedSUV]

Re: Still Trying.. (One Last Shot pt2)

I was going over the wire diagrams for the RPM signal (white wire) and the Tach is fed directly from the coil via the larger white wire, and the ECM is fed from the Ign. module. Seeing as i changed dizzy/ign module, engine harness and the coil I'm not sure what could really screw up an RPM signal. I also resistance tested the jumper from the coil to the ign. module and that seems to be find as well. Being as it's so RPM specific it's hard to believe it's not something electrical going on.... I'm waiting on the oscope, it's a Velleman hps10 if anyone has any insight on that particular model.