Driving to work this morning while passing pushed er up to 3100,above 2700 I noticed a surging.Truck was fully warmed up have 17*pump in w/14.6kmod,27*outside tc locked (switch),new fuel filter,full oil,everthing else stock.I'm thinking weak fuel pump or could it be alittle lean do to cold air? All opinions welcome.
Oh yea thouhgt maybe weak lpop.

 

Could be defueling. Did it almost feel like a gasser hitting the limiter? Do you have a boost gauge?

Unlikely a weak LPOP cause that would cause low ICP resulting in a CEL. Try to make it do it again if you can.

 

No guages yet,working on that though.Truck would still accelerate but alittle slower,running @ 80 at that point.I could feel and hear it in the turbo though. I'm getting ready to head home should have plenty of opportunity to try it (70miles).

 

What would cause defueling with stock injectors and programming ?

 

TJ, I think you're right ,it does feel like hitting a limiter. Why the defueling ?

 

High boost. The MAP signal gets scrambled at higher boost pressures. Thats why I put a mini pressure regulator in the MAP line. Its possible that even with the stock injectors and your 10K mod (while I find it hard to believe) that its seeing high enough boost to confuse the sensor. maybe try running it with the MAP unplugged. or if you jsut want to try the regulator its around $25. look here for write up
http://good-times.webshots.com/album/558926270AQyXsy

read the descriptions of the pics

 

I wonder if the map is failing?I like you doubt that i'm seeing more than 12-15psi.

 

Try it once with the electrical connector unhook. it will set the CEL but may run fine. if its does run good then you need a MAP sensor

 

I'll try it tomorrow thanks TJ,I was affraid noone was going to give me any input..

 

I might be giving input I just hope its headed in the right direction!

 

I can't see it being much else if it's defueling but i think you are right after driving home.It would get to about 80 then start loosing power just enough to maintain the speed.I don't run that fast often just noticed it today.I'll check hose to map also been doing some work replacing hpop maybe damaged hose..???

 

Ok ran truck today with connector to MAP unplugged still defueling or surging.Seems to be worse in 3rd and 4th,didn't notice it much in 2nd when running above 2600rpm.I think i'm going to have to get a fuel pressure gauge on it in the future to see what is happening if anything with pressure during accurences(sp??).

 

an intersetng problem. pull the 14.7 out and try it, you could be runnig the pump down on pressure by the time you get into 3rd and 4th.

 

My truck did this surging. Did not know what it was, and not totally sure what it was but while running down the road 65 or so with the cruze on, it would surge. Not bad, but a buddy asked me what was wrong so he noticed it. I did change a few things, the fuel pump was leaking, changed it, and the CPS was giving sign of failure, so change it too. Both the leaking fuel and motor cutting out were cured. The surging also went away. Did it have anything to do with it????

my 2 cents

good luck

 

I'll pull14k out before I leave for work.I have a small fuel leak under the regulator not sure of source.I wonder if a seal dried up while down and apart awaiting parts.Been back together week and half.Replaced UVC harness,VC gasket,cps,fuel bowl standpipe and filter.Also replaced hpop at same time.Can't really say whether problem excisted before.During trip to Wis. in sept.I could get this but atribbuted it to superchips programing w/10kmod and old 15*pump.Since had to give programmer back to friend. 17*Hpop came off of '00 w/200000miles but assume it's ok. Runs fine until you get to 75.