Lseconoline

I have a gen 4 LS5.3 and a 4l65e trans in a 63 econoline truck. pSI LS wiring harness. I had it tuned by a local tuner ( who is excellent) after build. Truck ran good but after winter storage it starts hard and goes into limp mode( I’m assuming). It runs really ruff and no throttle response after about half hour of driving but can always limp it home. If I un hook and re hook the MAF it will settle down and run again. I have replaced the MAF with a new one and no difference. My tuner guy is ridiculously busy and can’t look at it for at least a month. I would like to have as close to stock as possible tune in this truck. Don’t need performance extras and don’t care about fuel economy. Just want it to run awesomely. Any recommendations as to what to do. I would like to drive this truck because the season is really short up here in Canada. Has any body had an success with the folks that email you a tune? Should I purchase a tuner?
im an old school V8 guy this LS stuff is all new to me.

Thank you for any info.

Al

gametech

iTrader: (1)

You are barking up the wrong tree. Winter does not erase your tune. If it was tuned and running good, and now it is not, you have a mechanical issue to fix. You need to start at the basics and look for chewed wires, cracked vacuum hoses, etc.

Lseconoline

Appreciate that. It’s all new install. But I’ll start searching. Thanks for the response.

Kawabuggy

iTrader: (1)

How about start with the most basic thing you can do... Have you scanned it to read the codes and data? That's Step. #1.... Nothing comes before that...

Lseconoline

Thanks for that.
No I haven’t. There is only one tuner guy in our area. He’s too busy to look at it. GM garage told me the fact that it’s not stock they can’t (maybe won’t) read it. I was thinking about buying tuner software ( any recommendations) and figuring it out. No point in owning a custom I can’t fix if there is no help around.
Sure appreciate your input.

gametech

iTrader: (1)

If the psi harness has an obd plug on it (I am not familiar with them), you could probably get any local parts store to scan for codes. Or buy a cheap code reader for yourself.

Kawabuggy

iTrader: (1)

You have to be careful with the "cheap" code readers though. Often they will exclude important codes and data and not give you a complete picture. Every day I have customers tell me "I have this bluetooth reader that allows my phone to scan and there are no codes". They then show up and I plug in my Snap On Solus and it lights up like a Christmas tree..... Find a friend, or shop, with a REAL scanner, and get the data pulled. It sucks that most shops want to charge for this service. My shop will scan anyone's vehicle for FREE at any time during business hours. We do this to kind of put customers onto a good path as there are so many HORRIFIC repair shops that do not know how to diagnose a problem, are just parts replacers, and will simply keep taking the customers money for improperly diagnosing the vehicle until the customer leaves to find a new shop and the process starts over again. I've met only a handful of truly talented general mechanics and I refer a lot of business to them.. The # of poor mechanics-like drops of water in the ocean.

Lseconoline

Talked to a friend last night that said he had a code reader. Will try it tonight.
thanks for the input. I’ll post what I find. Might help someone else with the same problem?

mrvedit

I would start with the fuel system. Perhaps your gas tank got contaminated or the fuel pump decided to go into semi-retirement.
Perhaps you local auto parts store or friend has a fuel pressure gauge; if its stock, it has a pressure check port on the fuel rail on the engine. LS engines take 58 psi.

gagliano7

Had something similar happen to my dad's 03 silverado 4.8. Found a mouse made a nest in the pipe closing of almost all air flow.