Still Trying.. (One Last Shot pt2)

[AutoVation]

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

I'm not sure if I replied to this previously but could it be a fuel rail pulsation issue? Maybe the rail damper is broken/defective?

 

[BoostedSUV]

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

I'm not sure if I replied to this previously but could it be a fuel rail pulsation issue? Maybe the rail damper is broken/defective?

Rail damper? I'm Not sure what you are reffering too. I have not tried to replace the fuel rail because I never looked at it as anything more than some tubing that flows fuel? There's a mechanical part of the rail? I did have it off and blew it out to be sure it wasn't clogged up. Also fuel pressure is steady, wouldn't that effect it?

 

[AutoVation]

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

Rail damper? I'm Not sure what you are reffering too. I have not tried to replace the fuel rail because I never looked at it as anything more than some tubing that flows fuel? There's a mechanical part of the rail? I did have it off and blew it out to be sure it wasn't clogged up. Also fuel pressure is steady, wouldn't that effect it?

Pressure is different than pulsation. Isn't there an external pressure damper on the fuel rail? Pulsation does only occur at certain RPM's, think of it as pressure waves in the fuel that can actually go against each other and starve the injectors at different RPM's. Isn't there an SAE paper floating around on the SyTy engine? It might have more details, I'm not sure.

 

[Don W.]

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

I gave up reading somewhere back around page 10 but I have a couple of ideas for you.

First:
I use the Moats EX remote to select tunes. I forget the EXACT problems I was having but it turned out to be related to interference being picked up buy the cable from the ECM to the Moats EX. A shielded cable fixed everything. My problems were similar to yours.

Second:
Pull the ECM and then disconnect all three multi-pin connectors. Now get a good light (actually a small flashlight with good bat's is best) and inspect each and every one of the the connectors. I'm talking the "female" connectors inside the plastic holders. What you're looking for is any connector that has slipped out of position. IOW it's not fully seated. You can tell because it will be up inside the connector instead of nearly flush like the others. Also look for connectors that are "sprung." IOW they've opened up a bit so they don't fit tight on the ECM pins. Also inspect each wire and give it a little tug to make sure it is making a good connection with its terminal.

Some contact cleaner and some compressed air to clean things wouldn't hurt while you're at it.

Slim chance of this being the problem because last I heard Slim left town but worth a look.:roll:

 

[BoostedSUV]

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

I gave up reading somewhere back around page 10 but I have a couple of ideas for you.

First:
I use the Moats EX remote to select tunes. I forget the EXACT problems I was having but it turned out to be related to interference being picked up buy the cable from the ECM to the Moats EX. A shielded cable fixed everything. My problems were similar to yours.

Second:
Pull the ECM and then disconnect all three multi-pin connectors. Now get a good light (actually a small flashlight with good bat's is best) and inspect each and every one of the the connectors. I'm talking the "female" connectors inside the plastic holders. What you're looking for is any connector that has slipped out of position. IOW it's not fully seated. You can tell because it will be up inside the connector instead of nearly flush like the others. Also look for connectors that are "sprung." IOW they've opened up a bit so they don't fit tight on the ECM pins. Also inspect each wire and give it a little tug to make sure it is making a good connection with its terminal.

Some contact cleaner and some compressed air to clean things wouldn't hurt while you're at it.

Slim chance of this being the problem because last I heard Slim left town but worth a look.:roll:

All of this was tried and done. I checked that each connector pin was tight and connected, I sprayed contact cleaner and I even replace the engine harness. I don't have a Moates adapter with a switcher so there's no cables involved, just an adapter board. The truck will act the same with out the Moates adapter running on the stock memcal... Great ideas but I've tried them already.

 

[BoostedSUV]

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

Pressure is different than pulsation. Isn't there an external pressure damper on the fuel rail? Pulsation does only occur at certain RPM's, think of it as pressure waves in the fuel that can actually go against each other and starve the injectors at different RPM's. Isn't there an SAE paper floating around on the SyTy engine? It might have more details, I'm not sure.

I understand what you're saying I wasn't aware of anything controlling pressure other than the regulator. Does anyone have any more insight on this one? If this is the case with our fuel rails it's something to look into for sure...

 

[vinnieTy]

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

Matt - listed on this thread is more great ideas then i could offer but i did bring this to you at renzfest but you said you changed them out. Im talking about the injectors. I had an explorer that would stumble at a certain RPM all the time and give me hard time starting on cold days. Gas additives helped a little but never good enough, until i sent the injectors out to get cleaned. At the same time i changed the gas filter. It made a big change with gas mileage, throttle response and of course the stumble was gone.

Just ideas.........Hope you get it fixed soon.

 

[BoostedSUV]

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

Matt - listed on this thread is more great ideas then i could offer but i did bring this to you at renzfest but you said you changed them out. Im talking about the injectors. I had an explorer that would stumble at a certain RPM all the time and give me hard time starting on cold days. Gas additives helped a little but never good enough, until i sent the injectors out to get cleaned. At the same time i changed the gas filter. It made a big change with gas mileage, throttle response and of course the stumble was gone.

Just ideas.........Hope you get it fixed soon.

Hey Vinny, once again it was nice meeting you at the wrench session... I had a great time regardless of my truck.

Anyways, in part one of this thread started back in june I was covinced injectors or fuel pump were my my problem even though I had my doubts. I went ahead and spent close to $600 at racetronix and got brand new flow matched injectors and a brand new walbro fuel pump. Needless to say that didn't solve my problem but they were a needed upgrade... The pump and injectors have less than 500 miles on them so I'm pretty certain they're not my issue. I even replaced the injector harness just to be sure... The fuel filter however I haven't changed in a while but it has only about 15k on it. I replaced it while chasing this issue 4 years ago... Wouldn't hurt to change it again but I'm almost positive that's not my problem either. I know it's something stupid I just need to pinpoint it. Thanks for the ideas!

 

[MikeRenz]

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

i know i asked you this weekend if you'd swapped out the fuel rail...i forget what you said though.

How about slapping a bigger alt on? You have more electronics in your truck than any 5 trucks combined. Maybe it's simply interference. You have that MSD mounted about 4 inches from your ecm. I think one thing to consider is unplugging all of your electronic crap, ease the load on your battery/alt...remove the msd out of the equation again....get it down to the bare essentials. Recheck the resistance of your plug wires.

I'd still like to see what your timing is doing during the hesitation.

or maybe blue loom instead of red loom?

 

[dgoodhue]

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

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:

I mention this before but I would check the battery grounds. I am not so sure I like the alternator bracket to the chassis (Is this the frame or body?) Temporarily try adding a ground from the battery directly to the frame (frame ground is for the fuel pump)

 

[SloGN]

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

ok guys


I had a very interestig thing happen on a local GN that i ave helped tune over the last few weeks. He was having a very similair issues with stumble and going lean and other crap.

His wideband should show very large changes, but the narrow band o2 would show very little change. But the injector duty cycle would go higher during this lean spike anf so would his correction%.

I finally found it when i noticed that he had his innovate WB controller mounted near the coil/module unit. I took some aluminium foil and wrap the controller all issues were gone.

So i agree with Renz on eliminating some of the electronics and just have was is neccesary to run the truck. so you can see if it's a EMI noise affecting it. Try wrapping the ecm in foil as a barrier to EMI interference,


Have you thought about putting the stock injectors, map sensor and chip back in to see if the truck will actually run fine on those pieces? If it will that means the problem is contained to those units.

 

[kentuc]

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

I don`t remember if the alternater was changed, but it is rpm related and a bad or leaking positive diode will send out an AC voltage.....

 

[BoostedSUV]

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

i know i asked you this weekend if you'd swapped out the fuel rail...i forget what you said though.

How about slapping a bigger alt on? You have more electronics in your truck than any 5 trucks combined. Maybe it's simply interference. You have that MSD mounted about 4 inches from your ecm. I think one thing to consider is unplugging all of your electronic crap, ease the load on your battery/alt...remove the msd out of the equation again....get it down to the bare essentials. Recheck the resistance of your plug wires.

I'd still like to see what your timing is doing during the hesitation.

or maybe blue loom instead of red loom?

very funny mike, blame the red wire loom! :lol:
Anyways the rail hasn't been replaced but I did have it off and blew through it and looked into it with a flash light and didn't see anything. As far as the electronics are concerned all of them were added after the problem started (remote starter, in dash DVD, elec fan, MSD etc) I did indeed disconnect all of them and run the truck on the bare minimals and it did not change anything. Also the MSD was just added a few months ago in order to produce a bigger spark and hopefully fix things... no dice! I can disconnect it and I have done so a few times with no changes. The taylor wires on the truck have however many miles it took from my house to Matt's shop and back plus maybe 20. I just changed them, the distributor, and fuel pump very few miles ago...

The timing is rock solid during the miss, that is one of the things I verified, and the truck even does it (worse) with the EST bypass wire unplugged..

I mention this before but I would check the battery grounds. I am not so sure I like the alternator bracket to the chassis (Is this the frame or body?) Temporarily try adding a ground from the battery directly to the frame (frame ground is for the fuel pump)

I just added a 2ga from the batt to the head, and a 4ga from the frame to the alt bracket. Voltage seems to be good everywhere... injectors, ecm, fuel pump all see 13.8 with the elec fan on.

ok guys


I had a very interestig thing happen on a local GN that i ave helped tune over the last few weeks. He was having a very similair issues with stumble and going lean and other crap.

His wideband should show very large changes, but the narrow band o2 would show very little change. But the injector duty cycle would go higher during this lean spike anf so would his correction%.

I finally found it when i noticed that he had his innovate WB controller mounted near the coil/module unit. I took some aluminium foil and wrap the controller all issues were gone.

So i agree with Renz on eliminating some of the electronics and just have was is neccesary to run the truck. so you can see if it's a EMI noise affecting it. Try wrapping the ecm in foil as a barrier to EMI interference,


Have you thought about putting the stock injectors, map sensor and chip back in to see if the truck will actually run fine on those pieces? If it will that means the problem is contained to those units.

Pat, the O2 is all over the place that's why I put the wideband in a few months ago as a "second opnion" both show lean when the truck breaks up...

I no longer have the stock injectors or map, but as you know I replaced injectors (from 50's to 63's), and I swapped in a different 3 bar map. I tried running the truck on the stock memcal as it sits (obviously wrong tune) but the truck still stumbles and breaks up but only worse because it runs pig rich..

I can try wrapping the ECM in foil... right now it is sitting on the floor out in the open and easy to get to.

 

[BoostedSUV]

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

I don`t remember if the alternater was changed, but it is rpm related and a bad or leaking positive diode will send out an AC voltage.....

i had the alt tested for AC ripple and I even disconnected it and ran the truck off the battery alone to be sure.

 

[gkrcr882]

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

After skimming about 10 pages, my head began to hurt, so here are my thoughts:

Have you tried a fuel volume test? Pressure is great, but if the pump simply isnt flowing enough fuel, you'll go lean

Have you checked for excessive AC voltage from the alternator? Alternator is a 3 phase AC generator, and if the diodes are going you'll get unrectified AC voltage going through the system.

Hot start issue sounds like fuel vaporizing in the rails, however, if you have to hold it at WOT (clear flood mode), that would not be the case. Clear flood mode shuts off the injectors when cranking at at 100%TPS. Doubtful, but possible an injector is leaking

Have you checked for RFI? Were there any shielded wires that you replaced and didnt notice an external grounded wrapping?

Pinpointing which cylinders drop out will help immensely, since only having 2 drop on you is 1/3 of your engine.




Edit: Doh, he beat me to a few points!

 

[turboj91]

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

I don't know if you have your O-scope back up and running to check the electrical end of things but I still want to know what is comming out of the tail pipe. What do you have for emissions testing in NJ? and how difficult is it to get someone to test it. You have covered almost every other base. I also want to know if you wear your helmet when you beat your head against the wall with this issue. We all also have to remember that changing to the larger injectors had an effect on the issue and it seems everything else that has been tried has had no effect. BTW, where are you picking up the fuel pressure from (shrader valve in the rail?).

 

[dgoodhue]

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

I just added a 2ga from the batt to the head, and a 4ga from the frame to the alt bracket. Voltage seems to be good everywhere... injectors, ecm, fuel pump all see 13.8 with the elec fan on.

Reading 13.8V doesn't mean you have a good ground. Electricity moves from the battery positive (power wires) to negative (ground) if the system isn't complete it will not work or it find funny way of making a ground. This path of electricity has to happen for every electric component.

I personally think you have chased a lot of crazy things in this thread chasing this problem. This would have been one of the top 10 things I would have looked at.

How is you electric fan ground? Did you remove the factory negative battery cable. Any chance the ECM ground going to the front intake bolt is damaged? Did you attach a ground to front core suppport (if remove factory cable) Could the head ground (Ground strap to Body) have been paint and not making a good connection (are you using star washers on the two head ground)

 

[BoostedSUV]

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

After skimming about 10 pages, my head began to hurt, so here are my thoughts:

Have you tried a fuel volume test? Pressure is great, but if the pump simply isnt flowing enough fuel, you'll go lean

Have you checked for excessive AC voltage from the alternator? Alternator is a 3 phase AC generator, and if the diodes are going you'll get unrectified AC voltage going through the system.

Hot start issue sounds like fuel vaporizing in the rails, however, if you have to hold it at WOT (clear flood mode), that would not be the case. Clear flood mode shuts off the injectors when cranking at at 100%TPS. Doubtful, but possible an injector is leaking

Have you checked for RFI? Were there any shielded wires that you replaced and didnt notice an external grounded wrapping?

Pinpointing which cylinders drop out will help immensely, since only having 2 drop on you is 1/3 of your engine.




Edit: Doh, he beat me to a few points!

The first thread was 44 pages so be happy I condensed it :lol:
I have not done a fuel volume test but WOT under the boost I have 68psi and the truck does not lean out therefore I don't think volume is the issue. I have scoped the dizzy with a timing light and I am not getting spark drop out. I also temp checked the manifolds while someone held thew rpms at the break up point and I am not getting any hot or cold cylinders. All 6 are within a few degrees, it seem likes it's mixing up cylinders or whatever is happing is happening across the board. It's not cylinder specific. I eliminated the ALT from the equation so it's not AC ripple unless it can feed it through the ground
side with just the belt turning it and no wires connected...

I don't know if you have your O-scope back up and running to check the electrical end of things but I still want to know what is comming out of the tail pipe. What do you have for emissions testing in NJ? and how difficult is it to get someone to test it. You have covered almost every other base. I also want to know if you wear your helmet when you beat your head against the wall with this issue. We all also have to remember that changing to the larger injectors had an effect on the issue and it seems everything else that has been tried has had no effect. BTW, where are you picking up the fuel pressure from (shrader valve in the rail?).

Jim the fP sender is on an adapter off the shrader valve and I have messed with the o-scope (I broke it and need to send it back) I arced the coil wire off the o-scope probe (oops) so I need to have it warrantied... I haven't been too an emission test in years (shhh don't tell anyone) but I am due next month. I may take it and let it fail just to get a reading. The test they do is at 2500 rpm in park so it would be right on the money for what we need to see

Reading 13.8V doesn't mean you have a good ground. Electricity moves from the battery positive (power wires) to negative (ground) if the system isn't complete it will not work or it find funny way of making a ground. This path of electricity has to happen for every electric component.

I personally think you have chased a lot of crazy things in this thread chasing this problem. This would have been one of the top 10 things I would have looked at.

How is you electric fan ground? Did you remove the factory negative battery cable. Any chance the ECM ground going to the front intake bolt is damaged? Did you attach a ground to front core suppport (if remove factory cable) Could the head ground (Ground strap to Body) have been paint and not making a good connection (are you using star washers on the two head ground)

The elec fan is grounded to rad support, as is a 10ga off of the battery ground. I replaced the ground strap and clened the head and firewall to bare metal. I cleaned the grounds on the intake bolt and re-harnessed the truck. I also verified with a mulimeter that I have sufficient grounds to the ECM. Ground would be #1 suspect but I have chased them all down and haven't come up with anything :dunno:

 

[Quickstop [UK]]

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

Maybe the emsissions guy will know the problem

I'm in the USA in a couple of weeks so will hopefully be able to come up and have a look at your truck, at least bring some beers with me if nothing else

We need to see your injector duty cycle/ign cycle on the o-scope.

As mentioned above, the injector change was the only thing that has changed this, by lifting the RPM breakup bands by a few RPM.

Sounds like maybe the impedance of the injectors changed and therefore the RPM at which the problem occured - parasitic inductance/capacitance somewhere in there.

We HAVE to get this problem solved!

 

[BoostedSUV]

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

Maybe the emsissions guy will know the problem

I'm in the USA in a couple of weeks so will hopefully be able to come up and have a look at your truck, at least bring some beers with me if nothing else

We need to see your injector duty cycle/ign cycle on the o-scope.

As mentioned above, the injector change was the only thing that has changed this, by lifting the RPM breakup bands by a few RPM.

Sounds like maybe the impedance of the injectors changed and therefore the RPM at which the problem occured - parasitic inductance/capacitance somewhere in there.

We HAVE to get this problem solved!

You are more than welcomed to come up and have a shot at this POS :tup:

I will provide beer, food, place to sleep whatever you need.... If anyone else want to take me up on this offer feel free to join! We can have a wrench session in my driveway! :lol: