96 burb 7.4 misfire after 5.0 injectors

[mehcs]

Hello Folks,
As the title say I have a 96 burn with 7.4 vortec. I pretty replaced the lower intake gaskets and while at it I replaced the fuel injectors with 50 Motorsports and new fuel pressure regulator.

Prior to this the truck ran fine other than hot start and bit of a chug if I pushed the throttle hard from dead stop.

When I got to the fuel rail I found the lines from the fuel pressure regulator was not connected to the manifold. Wondering if that contributed to the chug.

Anyhow, those are my problems anymore as once all put together the truck runs like crap. Misfires and rough idle. Also wants to die when I give it the slightest throttle.

The truck is relatively new to me so I do not know all service history but it surely ran better than this and I don’t want to start throwing parts at it.

I marked the distributor and cam retard is at -2.8 not sure at 1200rpm cuz the motor won’t get there…

Not sure if the pics are helpful….

I appreciate any advice.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[mehcs]

forgive my spelling errors.

 

[mehcs]

After rereading similar posts on the forum it seems there could be multiple reasons for this issue. I'm going off the basis that the truck ran fine prior to the injector change so was ruling out everything other than the new injectors and/or the fuel pressure regulator.

Planned on getting a fuel pressure gauge to check pressure.

Any guidance would be appreciated.

I was under the impression the 50 injectors were plug and play.

 

[RichLo]

Which injectors did you get? 5-0 website offers a few variations for these trucks

 

[Sean Buick 76]

Have you tried going back to the original fuel injectors? Whos tuning the computer?

 

[mehcs]

Which injectors did you get? 5-0 website offers a few variations for these trucks

These are the ones I purchased. I was under the impression they were direct replacement of the old and no tune required. Does that sound right?

You must be registered for see images attach

 

[mehcs]

Have you tried going back to the original fuel injectors? Whos tuning the computer?

That would be a great idea..... If i still had them. I'm basically an idiot and threw them in the garbage. I looked them up and seemed to be original and from reading on this forum, also junk and the 5O bosch are what to replace with.

 

[mehcs]

This all started with a leak on the lower intake and hesitation when throttling from dead stop. So decided while I'm down there to change the injectors and the FPR.

Now I have hard start.. Barely stay running with fluctuating idle. I'm pretty sure I set the dizzy right. Pulled #1 plug and felt for air and set directly on the line of harmonic balancer.

Kinda kicking myself as I had a for the most part decently running truck to a mess. I'm not a mechanic my any means but give me some instructions, youtube and a manual and I usually figure out. Not this time.

New to scanners as well. Pulled more pids for fuel trims, timing etc. My trims are way off from what I'm reading but don't know where to start.

Again, any help would be appreciative. Also interested to know if tune was required with new injectors.


C'mon GMT400.com help me out. Lot a smart folks on here.

 

[BeXtreme]

Those are the right injectors and shouldn't need any tuning. What are you using to get those scanner readings? I'm very confused by what it thinks Bank 3 and Bank 4 are? AFR's seem correct for the engine warming up. This looks a lot like either you instigated some vacuum leaks or you have messed something up on the ignition side. Did you put new plugs/wires/cap/rotor on as well? You might try spraying some carb cleaner around the base of the intake and around the base of the injectors as well. Did you grease the injector O-rings before installing them in the intake manifold and fuel rail?

 

[mehcs]

Those are the right injectors and shouldn't need any tuning. What are you using to get those scanner readings? I'm very confused by what it thinks Bank 3 and Bank 4 are? AFR's seem correct for the engine warming up. This looks a lot like either you instigated some vacuum leaks or you have messed something up on the ignition side. Did you put new plugs/wires/cap/rotor on as well? You might try spraying some carb cleaner around the base of the intake and around the base of the injectors as well. Did you grease the injector O-rings before installing them in the intake manifold and fuel rail?

Hi BeXtreme,
I'm using the Dash command app with Veepeak OBD2 scanner. The banks 3 and 4 threw me off too. may try to reset the pids but I'm assuming the values are meant for 1&2.
so the vacuum side is interesting and am thinking the same. Kind of.. This may throw for a loop but I'm going off the fact that what I'm about to explain were already missing from the truck and ran fine in that state. I actually posted this prior to making any of these changes but I'm missing this test port. The line from the canister was hanging. Also missing one on top of the plenum.. This is a CA emission truck.


PLEASE NOTE THAT i CONNECTED BOTH OF THESE ITEMS WITH VACUUM HOSE WHEN i REASSEMBLED BUT TOOK BACK OFF TO HAVE TRUCK IN THE SAME STATE PRIOR TO TEARING APART AND HAVING ISSUES.

You must be registered for see images attach

This is the other item. The actual hose is missing the right angle boot is there and yes today i noticed it sucking air. There's a broken plastic line that comes our from the passenger side of the firewall that I'm guessing it came from.

You must be registered for see images attach