Ridge06

Been a mechanic for years, military, still learning most of this stuff for my TBIs. I know a fair amount, enough to keep them, this is my first built one. My understanding of the fuel and air and all the numbers is a bit slacking. That's why I'm here.

345-350hp 1991 k1500 currently stock 3.42 (will be 3.73 posi once engine is set)
350 block stock pistons double roller timing set
-headers dual to Thrush welded
-186 heads
-edelbrock 2102 cam
-edelbrock 3704 Intake
-stock throttle body with adjustable FPR, unsure of injector lb. (RIN1001/1020 and 1032) red tips with faded yellow center, whatever that means. (Picture)
-open air element setup
-transmission is 5speed manual
-stock fuel pump until I find a suitable DIRECT replacement for it
**** I also have a Harris Performance chip installed built for a 91 suburban with flat top pistons a bigger cam and ported stock tbi heads and intake***

Currently it starts up great, idles where it should cold and idles as it should until warmed. Throttle is good to 3500rpms, no issues. Once I drive, my issues are:
1. When coming to stops or holding clutch in (coasting) the idle gets too low, more so the longer I drive it, and has even died on me.
2. When I'm cruising around 20mph or 30 or 40 (have not taken on the highway yet) and I want to take off in the same gear it slightly wants to cut back or bog and also pops the smallest amount.

My FP is at about 11 right now which is low, I should be closer to 14 or 15 but I'm currently waiting on the pod gasket since I broke it. Once fixed i can see where my adjustment went to. If I am cruising at 20-25mph and stick it in 4th and go WOT it seems like the fuel pump is keeping up about 98% give or take.
Basically just looking for some input on similar builds and input on the pictures if I'm able to show them after typing all this. I appreciate any help in advance.

update: uploading pictures works but is funky so bear with me. Also, I've edited the build list slightly.

Pro

My truck acted the exact same when it was TBI and had 11psi. Then i fixed the regulator and all went good. So maybe fix that and then report back

89-S-dime

iTrader: (3)

345-350hp ?

6998poncho

I'm wondering why you would try to floor it at 20-25 mph in 4th when you're way below the powerband of the engine. Not really a valid test IMO. I'd drop a gear or two and rev it out. Since you have mods beyond the stock parameters have you tried to drill out the plug on the throttle body and adjust the idle with the adjusting screw behind the plug? That might be an option to try.

ShiftyCapone

iTrader: (7)

Your problems are due to the chip. You need to datalog and custom burn a chip for the combo you have. Anything else is just chasing parts. These cars will not run well with TBI mods (either through parts or displacement) without custom tuning.

Ridge06

Update:
I adjusted my FPR 4.5 times which got me to 13.5psi. It seems to be a little better for it, but hard to tell. The only problem I'm having now is when I go for a drive and on the way home every stop I get to basically almost kills the engine because the rpms get way too low. I can sometimes downshift to slow myself down, and even use 1st only because I do it at very slow speeds but it keeps it from going too low of rpms if I can get on the gas again to go. So when I actually get home and have to turn into my slightly inclined driveway that's where it gets low enough to shut it off and it has twice now out of a small handful of times. Fuel pressure is staying at 13-13.5

Schurkey

What is the data stream showing?

What is the commanded idle RPM? What is the actual idle RPM? IAC active?

Coolant temp?

O2 sensor readings?

EGR working properly?




When was the last time this thing got a compression test, distributor cap 'n' rotor, plug wires and plugs?

Ridge06

So even though the chip is tuned for another very similar build, without having it tuned for mine specifically then that's where my problem could be?

Tuned Performance

iTrader: (92)

The only way to tell is datalog. I have seen a shady trick done in Harris tunes setting the min/max of the int and blm to 128 so it looks as if the tune is perfect.

Ridge06

well with it all being new, yes I do need a new distributor but it is working fine it's just used, I know all the sensors and other components are working properly yes. I'm not sure what you mean by "commanded idle rpm", could you elaborate more? The idle is about 600 give or take 50 when normally idling, and its smooth. The idle starts put around 1100 in cold start and slowly drops to that 600ish when fully warmed. I can sit in the truck and rev it with no problems, I can drive it with no problems up until I'm coming to a stop. Fuel pressure stays the same through and through even when its idled way down when coming to the stops. I feel like maybe my injectors maybe aren't the right ones or maybe my pump isnt the greatest or maybe the chip is further off than I thought or maybe my old distributor could be throwing it off just a little. I'm also thinking maybe my transmission is getting to be toast. I'm not familiar with the nv3500, I'm more of a 700r4 kinda guy, but with a new clutch it still may be too worn inside. I think maybe once I get the 3.73 locked axle under it and get the chip burning stuff from my buddy I'll have decided to put my rebuilt 700r4 under it and maybe everything will fall together at that point. I should be able to tune it myself via the chip if the burn isnt close enough to my build, and I absolutely believe the 3.73 will help a lot but if I cant get the tuning checked out then I could be chasing my tail.

Ridge06

Ok so I need to just get the datalogging stuff from my buddy and see what the chips at? So another thing to throw in is it smells a little rich when warming up and more rich when fully warmed, now wouldn't adding fuel pressure just make it run more rich or would the added fuel pressure tell the computer to lean it out due to the added fuel pressure? Or neither?

Tuned Performance

iTrader: (92)

The added fuel pressure would richer up the mixture.
Here is the $42 adx to datalog with tuner pro rt. The ecm will try to pull fuel in closed loop.
http://www.gearhead-efi.com/Fuel-Inj...Information-42

ShiftyCapone

iTrader: (7)

Yes. Mail order tunes are like mail order surgery. The Dr. needs to have the patient in hand.

Schurkey

Connect your scan tool.

What RPM is the computer trying to achieve (commanded RPM)? What is the actual RPM? A difference indicates a problem with the IAC, wire harness, or ECM, or indicates a mechanical problem such as a vacuum leak.
Don't forget about the other items:

Coolant temp?

O2 sensor readings?

EGR working properly?

When was the last time this thing got a compression test, distributor cap 'n' rotor, plug wires and plugs?