Still trying to figure this one out....

[BacNBlak]

So with the mods in my sig, 51K miles, and about 15 passes on the ole girl I launched a rod. I have a feeling it was an underlying cause and not just the boost or tune. Tell me what you think....1st gear was all good. 2nd was good but around 4,000 RPM in 3rd the engine started to 'flutter' and the truck totally fell on its face. This happened before, several times actually, but it was just as I crossed the 1/4 mile line. This time it was about 3/4 track. I let off the throttle (93 mph) and it let go. I checked the plugs after previous runs and they looked good. When the engine let go, there were 3 melted plugs. So why is the engine good in 1st and 2nd but screws up at the top of 3rd, and thats on the track or the street. JMS, my tuner, assures me it isnt in the tune and that its conservative. Any ideas? Got a new Ford long block and trying not to repeat!

 

[Nvr_Spds]

It leaned out at the top of third. If the tune is conservative, then you may have an issue in fuel delivery. Clogged filter maybe? Or possibly a pump or injector issue?

It is my understanding that third gear is more of a load(More fuel demand), since you dont have the gearing advantage like you do in 1st and 2nd.

 

[BacNBlak]

could be. It was a new filter and for three cylinders to lean out, it sounds like a pump or tune to me

 

[Fade 2 Black]

It was the lack of a Maf upgrade most likely. Happens every time, sorry man.

 

[Mondo1]

Either of the 2 reponses above could be correct IMHO. You may have pegged the MAF and she leaned out big time or you have a fuel pump/line problem. I'm leaning toward the MAF, myself.

 

[svtdvm]

Did you not ever do any datalogging? You may have been lean from the get go, conservative tune or not.

 

[Ct.TOPGUN]

At 6#s over stock boost it is possible the Maf counts got too high and pegged. Fuel delivery at about that HP level gets a bit tight also. Some get away with it, and some need upgrades.
I would add a bigger Maf or extender, and go with 60# injectors with twin 255 pumps. Datalog it on the dyno, and also under load conditions.
Jim

 

[BacNBlak]

thanks for the advice. I called the bubs at JMS and they swear that I didnt need a MAf extender. I was gonna buy one and they still said I didnt need one...got me guessin. Could it be lack of the boost bypass mod?

 

[Lightningfr]

thanks for the advice. I called the bubs at JMS and they swear that I didnt need a MAf extender. I was gonna buy one and they still said I didnt need one...got me guessin. Could it be lack of the boost bypass mod?

no you pegged your maf

 

[Dusten]

thanks for the advice. I called the bubs at JMS and they swear that I didnt need a MAf extender. I was gonna buy one and they still said I didnt need one...got me guessin. Could it be lack of the boost bypass mod?

the boost bypass mod has nothing to do with your situation. If your tuner is telling you that you dont need one at 6lbs over stock, you dont need that tuner.

 

[samiam513]

the boost bypass mod has nothing to do with your situation. If your tuner is telling you that you dont need one at 6lbs over stock, you dont need that tuner.

:rofl: no joke.

That's like tech inspection telling a 9 second street car he can run with no cage, jacket, helmet, etc....

 

[Fade 2 Black]

Your tuner is stupid, whomever JMS is so tell them thanks for the advice.

When you get back up and running call and talk to Linn or Rick at Amazon so you can get a properly done tune this time. :thumbsup:

 

[runs2rch]

It was the lack of a Maf upgrade most likely. Happens every time, sorry man.

At his power level the maf was pegged?

 

[Dusten]

At his power level the maf was pegged?

I almost pegged mine with a 4lb lower. Each maf is a little different, and i highly recommend everyone should data log

 

[Sinister04L]

2nd was good but around 4,000 RPM in 3rd the engine started to 'flutter' and the truck totally fell on its face. This happened before, several times actually!

If this was happening, why did you keep pushing the truck without findout out what was wrong with it? I guess you were just begging to blow the motor. :shrug:

 

[RUNVS?]

Am I correct to assume your tuner put the truck under load on a dynamometer with an A/F readout when he built your tunes? Anything less than that is rolling the dice.

 

[BacNBlak]

Yea sinister, I know i was rolling the dice...I was trying different plug gaps...was told that could be a possible cause. I was running around .0035 gap. And yes it was put on a dyno for the tunes. To be honest, I was still (and still am) fairly new to the whole modular game. I guess I just put my trust in them and it bit me in the arse. Lesson learned the HARD way. Thanks for the advice. Any good tuners in the Virginia Beach area? Just moved here...