4.0 1gre no power

Hey ya'll. back again for more punishment.

So i had some electrical issues that were giving me a no start situation. thanks to a ton of help from the Gurus here i finally got that solved. ended up replacing interior fuse box due to intermittent faulty connections on ignition circuit.

was having issues with drivability and assumed it was due to clogged injectors. well got them back from FI shop after having them professionally cleaned and they said they were in great shape. So I think my problem lies else where. At idle it runs great, but when i actually drive it, it feels like its running out of gas. and started throwing code for bank too lean. Im getting my piggyback ecu sent back from URD after getting a new board put in it. so ill put it all back together and double check its doing the same thing. will be getting a Fuel pressure gauge to check at the fuel rails to make sure im getting the correct pressure from URD fuel pump when its running. but just kinda confused on why it runs fine but once you put a load on it the power drops to nothing.

 

here is a engine pic for reference

 

Have had a compression check done?

 

Like my avatar says.

 

Need to start by looking at fuel trim readings at idle and under load

 

its a brand new build. built in a race shop, arp heads studs and cometic head gaskets due to a pinched vacuum line to the wast gate it lifted the heads, since then i had complete motor built and gone through at machine shop.

 

fuel trim like off my scan tool? since i have a urd fuel pump and injectors i talked to gadget and i should be getting 43psi constantly. but have to verify that with pressure gauge. trim should be something i can see on a scan tool though correct?

 

Yes on the scan tool. But definitely do your fuel pressure checks first

 

ok cool. i have no idea what any of the information on the scan tool means but i can at least get it i think
im definitely more of a mechanical type of guy, the tuning stuff and electrical is rough on me but i get through it

 

Fuel trims are the computers way of calculating whether it needs to add fuel or take it away. By watching the trims you can tell if the computer is struggling to balance the fuel mixture.

That lean code is basically the computer trying to tell you it can't balance the mixture and it needs help. We know it lacks power under load so we're already pointing in the right direction. It's either running lean because of a calculation issue like mass air flow sensor or oxygen sensor.. or a mechanical issue like fuel pressure or fuel delivery (injectors, clogged filter, etc)

 

ya that's what is puzzling. i just had injectors professionally cleaned. and i just put the engine back together and fired it up. its is ramping up and down almost bouncing. but i dont have my piggyback ecm with a tune back from gadget yet. and ordered a pressure tester for the fuel rail. so this weekend i should have at least a scope of what my fuel pressures are and that is more info then i had before so its a starting point

i know fuel injectors are clear. and fuel filter has been removed and bypassed other then the built in tank screen one. when i read fuel trims what should i look for or would it be better to just take a picture and show yall

 

You may want to vheck for a vacuum leak or air being introduced somehow

 

I've thought of this, but don't have any idea where to start on tracking a vacuum leak down.

 

For a vacuum leak start with checking each vacuum line/connection visually and if you can't find anything then move onto DIY testing if you're comfortable with it. Can use anything like starting fluid, carb/brake cleaner, propane, etc. just a little bit around all the vacuum line connections and gaskets. DIY at your own risk as always, use common sense and don't spray stuff right on a hot exhaust manifold and start a fire.

If there is a vacuum leak it will pull it in and burn it like extra fuel and rev up momentarily. Is your idle steady enough to hear a difference if it jumped up? It may help to watch a youtube video and/or look up a vacuum line routing diagram for the specific engine if you're not familiar with where you should be looking.

 

Be careful running it with those lean codes or you will be back in the machine shop for a rather large bill. Check your fuel pressure and fuel trims as mentioned above.

 

Not without my piggy back ECM. It's currently reving itself over and over agian

 

so got my fuel pressure gauge in and im sitting perfectly steady at 43.5 psi just like gadget said but its ramping from 500 rpm to 2100 rpm. waiting on ucon piggy back ecm to get in then i can hook up my scanner to get fuel trims. is there anything in particular i should be looking for?

i feel that with it ramping up and down and the fuel pressure staying steady, plus known good injectors. there couldn't be anything other then a fuel pressure regulator issue? or would that not cause that. TBH that's definitely not something i know how to test though

 

Surging idle of that much sounds like its more likely to be a vacuum leak or sensor issue from my past experiences on various cars.

 

ya i believe it is a vacuum issue. i got my piggyback ecm back installed in the truck and started just dabbing starting fluid around the intake and it started surging when i sprayed around the intake on the drivers side. i need to replace the vacuum line running to whatever sensor that is but when i moved it out of the way and sprayed the intake itself around the same area it revved up still. but i dont know what is under there to cause a vacuum leak on that side, cant seem to see anything around there other then the first line coming off the front of the intake manifold

 

So found a nub coming off intake manifold. No hose to connect too. So I capped it and truck stopped reving. I fixed vacuum leaks I think so progress.