Boost launch nose dive.

[Treymen]

Just did some mods to the truck over the weekend. Not going to say what it was yet. I dont want everyone to be biased and say thats the problem.

While driving today I decided to boost launch at a light. Theres not alot of stoplights around here that don't have ticket cameras on them, so I dont do it much. The last time I did it, it performed flawlessly at a 5# launch all the way up to about 70mph and ten I had to let out of it for the next light.

Today, I was back at the same light, pulled a 3# launch. First thing I noticed is it didn't have anywhere near the pull as last time. At about 25-3-mph, the nose took a dive and all the torque went byebye. The wastegate opened and my boost left. I only had about 5 gallons of fuel, so I went and filled her up with 100 oct in Auburn. Tried another launch and it did it again.

I cant really tell if it does it at speed. I nailed it on the highway at 60mph and there didnt seem to be any issues, but I couldnt stand on for very long because of traffic.

Any ideas what the problem may be. Fuel pressure is good throughout....Thanks

 

[qbnkiller]

Re: Boost launch nose dive.

did you overboost? If so, it will go into fuel cut and do just that...

 

[dgoodhue]

Re: Boost launch nose dive.

With my Syclone's stock turbo 3 psi is a lot different than 5 psi in terms of off the line accelleration. You nee to keep close a half of tank of gas to do a boost launch.

 

[Treymen]

Re: Boost launch nose dive.

No overboost. Never got above 8-10psi.
The launches are fine. It's the nosedive and cutting out in the middle of it that concerns me.

 

[CavScout]

Re: Boost launch nose dive.

Starving the fuel pump. Like the man above said, 1/2 tank or better.

Ready? GO!

 

[WyoSyclone]

Re: Boost launch nose dive.

Make sure a motor mount hasn't gone south, letting the engine torque over, possibly stretching wiring, fuel lines ??

 

[Treymen]

Re: Boost launch nose dive.

Any chance this could be a vacuum issue? I had the lines done last friday at a shop that owed me for some work I did. They told me they couldn't find 4mm hose and used 3.5 instead. They told me this after I called them and told them the problem. They suggested it is overboost as well, but I'm sure I didnt see the autometer boost guage go over 10psi.

Does this sound like a vacuum problem to anyone?

I'm really concerned about this. Been trying to get it ready for paint, but all the gremlins keep coming up. Now the season is too cold to spray in my garage anyway.

 

[KDBL1TY]

Re: Boost launch nose dive.

Seems like an overboost then fuel cut by ecm. Pull your codes.

 

[Treymen]

Re: Boost launch nose dive.

Ok guys thanks. Going back tomorrow. I don't have my Ostrich set up yet, so they are going to do it for me.

 

[ZavzTy547]

Re: Boost launch nose dive.

Ok guys thanks. Going back tomorrow. I don't have my Ostrich set up yet, so they are going to do it for me.

Do you still have the stock fuel pump? That's usually the first thing to go bad, when you start modding the truck.

 

[Treymen]

Re: Boost launch nose dive.

Walbro been on for a while now

 

[bundie]

Re: Boost launch nose dive.

is it like driving into a wall?

if so overboost. maybe the ecm reads a boost spike...

 

[ghettosled]

Re: Boost launch nose dive.

datamaster = $199. Answer to your problem.

Fuel starvation, overboost, or severe detonation.

 

[ziembic]

Re: Boost launch nose dive.

How about you tell us the mods you made that led to this?