Squarebody1

I'm new to the group. I'm hoping for a little advice I have a 2000+ 5.3 truck engine and 4l60 transmission I'm putting in an 85 Chevrolet pickup. I had the engine running before I pulled it from the donor. I installed a btr stage 4 truck cam, valve springs, timing set, oil pump, and long tube headers. I'm running a flashed computer. I put a 3200 stall in trans. Dropping it all in this weekend. I have a set of 36# injectors but I'm not sure I'm going to need them. Anyone farmilliar with this setup? Am I going to need a tune immediately or will it run on stock tune? It will be open headers on initial start so I'm not planning to run it long. Thanks in advance

Floader

iTrader: (32)

It will run on the stock tune if you dont change the injectors. It probably wont run real well, but it should fire up and idle as long as the VATS is deleted.

Squarebody1

Thank you floader. The vats is deleted. I pulled the setup out of another older truck and it ran in it. I'm not all up on the computer thing , that's why I'm here. Why will it run rough? Is it because of the cam and different air flow? If I buy a handheld tuner , can I tune it myself?

LS1MCSS

iTrader: (18)

Take it to a good tuner. Hand held tuners are usually a joke.

Squarebody1

So I've got the motor and trans in. I'm finishing up the wiring this morning and plan to start it in a few hours.

Squarebody1

Chirp chirp

G Atsma

Because a cam changes the way the engine pulls air in, which would change fueling and spark advance parameters. A different cam needs a different tune. A stock tune will not like a bigger cam, making for rough running.

Squarebody1

Kinda what I was thinking. What about the O2? Not showing any codes on a handheld scanner. Could they have been deleted too?

G Atsma

You can't delete the forward O2 sensors, as they are vital to running the engine.

Squarebody1

It's running. No codes and no 02 sensors. Was told I didn't need them but will get some if I do

G Atsma

It's running in open loop, speed density. About as accurate as a carburetor.

Lsxford

iTrader: (6)

You need to find a tuner and consult them on whether to use o2s or not. If its tuned properly it will run great in open loop, alot of turbo cars are this way. Are you running a MAF sensor?


G Atsma Will it not use the MAF sensor for fueling even without O2s? Should be open loop MAF or is that a custom OS only?

G Atsma

The MAF tells it how much air is coming in. The O2's tell it how much of that air got used. Which of those two functions would you rather do without?

Lsxford

iTrader: (6)

i understand what each sensor does. IMO for a daily i would want all 3, but for a performance type vehicle like a weekend toy you can get by with none of the 3 and it will perform fine. there are pros and cons to all of them, CLMAF, CLSD, OLMAF, OLSD. i believe it comes down to 2 things, the person that will be driving the vehicle and the person that will be tuning the vehicle. OLSD may not be as accurate as CLMAF, but it can run efficiently with great drivability.


my own vehicle runs OLSD btw different strokes for different folks.