lv74nova

Hello all,

I am new here and I am hoping someone can give me some insight on issues with my swap/running condition. I started my swap a couple years ago and have finally gotten everything in "fire up" mode.... I have a 99 Vortec out of a silverado pickup, sent wire harness and PCM out to have Vats removed, all emissions, rear O2 sensors, reprogram, the usual.
Using a "Tanks" fuel tank with in tank pump, stock truck intake with regulator.

I have the car so it will fire up and run, to a certain extent..... This is where the problem is....

When I initially fire it up I can get on the throttle and it will respond, only when it fires up at a higher rpm. If i let it come to an idle it will sometimes sit and idle rough, or maybe stall, but at that point I have no throttle response (drive by cable) then I shut it off and restart, try and hit the throttle pedal and sometimes it will kick up , sometimes its dead pedal. I have replaced the MAF, checked all my grounds, pulled all injectors and have them all spraying nice (after some cleaning, engine sat for 3 years) I have a TPS on its way thinking that is the issue.... I am plannimg on checking it with a meter today, also worried maybe I have a low fuel pressure issue so I will be going down to pick up a fuel pressure guage to check.

Any other ideas PLEASE let me know.... I am starting to pull my hair out with this.... Wondering why I just didn't build a small block for her now...

Also, would exhaust straight off headers bother the Fuel air mixture to computer, New forward O2 sensors are in place and plugged in but no exhaust on it as of yet.

Thanks in advance to all who may be able to help me out.

Steve

truckdoug

iTrader: (25)

yeah some exhaust will help. what kinda codes is the pcm throwing?

lv74nova

I will have to get with my son, he brought the scanner from work and was watching for codes, problem was I had three injectors that were plugged and not spraying at all at the time....

Got that issue taken care of and replaced MAF, got my alternator hooked up and a couple more grounds. Since then I have not put a code reader on it....

None of the things I have tried have helped the problem.

ls1nova71

iTrader: (4)

I would definitely put a fuel pressure gauge on it and see where its at. What are you using for a pump? Also you can check the TPS with the scanner to see if it's working. If not and your new one doesnt fix it, you should ohm the wires between the TPS plug and the PCM to make sure they're good.

lv74nova

This is the pump that came with my Tanks kit:

The GPA-4 Walbro In-tank fuel pump assembly is rated for 255 lph and up to 650 hp.

Maybe I forgot to tighten a clamp or something when installing the tank.....

I guess once I get a pressure guage on it I can go from there....

lv74nova

Ok, so i have 58-60# of fuel pressure, tps is working as it should after I put a multimeter on it.... I am stumped.....

Could it be the exhaust (or lack of exhaust on the car) is causing my issues?

Smells as if it is running rich, (sorry I don't have a scanner here today to check codes)
I can get the throttle to respond, then after awhile it seems to go into limp mode and nothing.

I also replaced the the engine coolant temperature sensor thinking that might be the issue....

I am waiting for my collectors to come so I can hook them up and my crossover pipe and mufflers... Maybe I will just have to wait and see what that does.

Pulling my hair out!!!!

ls1nova71

iTrader: (4)

Did you check the pressure when it was not running right? Could be a lot of things. May be loosing power to the pump at times?

lv74nova

I left the gauge hooked up on start up, and till it runs crappy and it still holds between 55 and 60 the entire time, never faulters..... I am stumped and ready to jerk it out and put in an old school built 383 with a carb and distributor..... lol!

ls1nova71

iTrader: (4)

You have probably already done it, but check all your grounds. Bad grounds can do some weird things.

lv74nova

I checked them but will do that again.... Here is what I have for grounds, please correct me if I need more, or if they are in the wrong places....

Braided ground that was on the rear of engine when I pulled it is hooked to my firewall

Added a ground from the Negative battery cable to the body

Ground from the alternator bolt location to the frame

Negative to battery is hooked to the engine block

and the negative from the wire harness is hooked to engine block on drivers side where it was from factory.....

lv74nova

I have a set of long tube headers I built/ modified from a set of small block headers, I welded O2 sensor bungs about 4" to 6" from the ends of the headers, could it be that its not reading correctly due to no exhaust....? Even then I would think it should run better than it does, I have seen people with no O2 sensors hooked up and still atleast can keep it running.... Also how long will it take the PCM to re learn wrap around the new program and engine mods? I know when my 04 Tahoe gets the battery unhooked for any reason its a bugger to drive till the PCM "relearns" everything..

I am hoping there is no issue with the PCM service I had done.... I was not very happy when I asked the guy I sent it to about a few wires that had lost their stickers telling where they needed hooked up... Got the run around and was very short with answers.... I assume if the Vats had not been taken out it wouldn't even run as long as it does.

pdsq98gt

The exhaust shouldn't stop it from starting. It doesn't use O2 sensors until it warms up. Sounds to me that either the injectors are still plugged or something isn't right in the tune. Is the cam and everything stock? Also make sure when scanning that you get crank rpm, no cam sensor codes, and map kpa is near 100 KOEO.

Old Geezer

iTrader: (3)

How did you "clean" the injs?
"Smells rich".. Ya, the O2's are sending a lean signal to the PCM, causing fuel to be added. Any leaks up stream where you "modified" them?
Coil harness on backwards?
Inj harness on backwards?
Suggest you get the scanner and use it til you find the problem[s].[weekend??]
Throwing parts at it, is only going to make your wallet lighter..But, U already know that, right?

lv74nova

I used a can of carb cleaner, rigged up a nozzle to fasten at the top of the injector. I put power to the injectors, 5 sprayed nice but they sprayed even better once I ran some cleaner thru them. 3 of them wouldn't spray at all..... I had to work with them, power to them, then off, then on, and so on till I got some spray, after a can of cleaner the other three were working like new. Motor sat for a few years, my guess is that the old fuel plugged them from sitting.

I am going to see if I can get my son to bring a scanner so we can get codes tonight. I will post what I find for codes tonight if that works out..


Thanks all for your help. And yes parts chasing gets expensive, although I atleast know they are new now and shouldn't have to worry down the road. I am into this TOY so far now whats a few more dollars.... LOL

lv74nova

Oh forgot, it is just a stock 5.3 from a 99 silverado. Only thing is the pcm was programmed to add a little H.P., running headers, cold air intake and that is it, no cam at this time.....

DW SD

Does that throttle have an IAC (idle air controller bypass) to adjust idle? Any chance that is stuck? I have the later DBW and I think it uses the throttle plate drive by motor itself for IAC.

I wonder if you are better off disconnecting the O2 sensors until you have the exhaust setup. The access to air probably will have it running very rich to compensate for air in the exhaust.

Are all of the exhaust ports getting warm? easy check to identify bad cylinders with an infrared gun.

truckdoug

iTrader: (25)

i dont think the O2's are in the picture until it's warmed up enough to go into closed loop, which doesnt sound like is happening. if it's a '99 it'll be DBC too.

Even a cheapie elm327 and the torque pro app will make your life easier in the long run. You can pull codes and see what the injectors are doing.

lv74nova

That is another question I had, What to buy for a program to diagnose codes and tweak my tunes.... Do I guy a program for my laptop or a simple tuner? I am new to this so bear with me.... lol

Havent gotten to pull codes from it yet, my son has been busy and now we are heading out of town for a few days so it will have to wait.

Any other ideas I can throw at it let me know.... I am going to check injector wires, and coil wires and make sure they are all where they are supposed to be...

Eckel974

stop killing yourself and go buy a cheap 70$ actron u-scan with real time data so you can see what is and isn't working or within spec. That is what you really need something to read data from computer. Good luck!

lv74nova

OK, here are the codes I have P0102B and P0200B.

It will Fire up, run so so if I give it throttle right after I start it and feather the throttle, If I let it go to an idle it won't take any throttle at all and barely idles.....

I checked the TPS and it registers nice and smooth all the way thru wide open throttle with a meter.

PLEASE any input is appreciated.....

I have 60lbs of fuel pressure. Could it be dirt in fuel line? Plugging the injectors?