2000 Trans Am - Maf Unplugged runs strong - Maf plugged in Misses and no power. Help!

[Applied Concept LLC]

Hello All, I am new to the HP Tuners world and am watching videos and trying to learn as much as I can, but I need some help and guidance so I can get started troubleshooting.

I bought a 2000 Trans Am - MAF unplugged runs strong, no misfire or breaking up under load. - With MAF plugged in misses BAD and no power under load. Breaks up really bad at anything over 20-30% throttle. Idles ok.

New MAF Sensor. Fuel Pressure 56psi.

Could you guys take a look and see if something is way off on this tune file?

Car:

2000 Trans Am LS1 Automatic
TSP Torquer V2 Cam and Springs
Long Tube Headers - No Cats
SLP Lid
3200 Stall Convertor
Stock Injectors

Car was tuned by unknown person, I bought it this way. Seller said car was running great, then just stated falling on its face and misfiring. Not sure if that is true....

Tune and log attached, although Im sure I might not have enough parameters in the log so could use suggestions.

If its the tune causing the problem, I would like to start from a stock file and go through all the steps to do the tune myself.

[blindsquirrel]

Why has only the injector flow rate been changed, with the rest of the injector data same as stock? What type fuel pressure regulator is on this car?

Probably not a good idea to try to diagnose a MAF issue with it in forced open loop like that. But, fix the injector data thing first.

[Applied Concept LLC]

Why has only the injector flow rate been changed, with the rest of the injector data same as stock? What type fuel pressure regulator is on this car?

Probably not a good idea to try to diagnose a MAF issue with it in forced open loop like that. But, fix the injector data thing first.

Thanks for taking a look. The tune file is just how it arrived to me. I havnt made any adjustments yet. But judging by how it drives it needs a lot of help!

Stock injectors in the car, stock pressure regulator.

Should I pull the stock injector info from a stock tune file and add in?

Basically its undriveable with MAF plugged in. When you unplug the MAF it drives decent, but not perfect by any means.

Seems like its a cobbled together or incomplete tune.

[gtstorey]

Have you confirmed part number of the injectors? If the flow rate has been changed it likely had different injectors at one time, installed by someone that didn’t know what they were doing.

[Applied Concept LLC]

Have you confirmed part number of the injectors? If the flow rate has been changed it likely had different injectors at one time, installed by someone that didn?t know what they were doing.

That is a good point. They look like stockers to me, but I did not yet confirm part numbers. Will take a look further.

Any ideas on why it falls on its face, misses, and breaks up with MAF plugged in and runs decent with MAF unplugged?

[SiriusC1024]

Because MAF is tuned poorly. You have a vacuum-referenced regulator? Shouldn't if it's factory.

[gtstorey]

Running on speed density only with maf unplugged. Assuming your new maf isn’t bad, either you have issue with the wiring, a very bad vacuum leak somewhere, or someone screwed with the maf settings in the tune. Who nows what someone could have screwed up in 23 years.

I’m not sure where the maf sensor is on that car, but the the SLP lid might be screwing with it some.

[SiriusC1024]

This is one of the dumbest/most dangerous tunes I've ever seen btw. Desensitized knock sensors, reduced KR, no spark truncation for shifts, running OL, LS1 to 6900 rpm, 4L60E beyond 6000rpm. Just look at the MAF. Vacuum-referenced IFR with non-referenced everything else. Reduced injection timing values, yet a larger duration cam. I could go on. What chimp tuned this?

Start over with factory settings and tune it from scratch. You'll most likely get best results running Speed Density. If you insist on MAF start with the factory curve and multiply by 1.2.

[Applied Concept LLC]

This is one of the dumbest/most dangerous tunes I've ever seen btw. Desensitized knock sensors, reduced KR, no spark truncation for shifts, running OL, LS1 to 6900 rpm, 4L60E beyond 6000rpm. Just look at the MAF. Vacuum-referenced IFR with non-referenced everything else. Reduced injection timing values, yet a larger duration cam. I could go on. What chimp tuned this?

Start over with factory settings and tune it from scratch. You'll most likely get best results running Speed Density. If you insist on MAF start with the factory curve and multiply by 1.2.

Thank you for looking at it and for your feedback!

This is what I was thinking. A totally hacked tune. It basically wont accelerate at all when over 30% throttle with MAF plugged in.

Car came to me with this tune in it, and owner sold it because it ran like crap.

Im new to HP Tuners tuning, but not High Horsepower cars. Im willing to put in the work to get it right.

I was thinking that starting over from scratch may be easier than fixing whats in this file.

[SiriusC1024]

Hopefully you got a deal then.

Think about getting bigger injectors.
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