Hesitation, running lean??

[MoreBoostPlease]

Alright guys, here's my problem. Bought an 03.5 MSP a few weeks ago. Now I come from the DSM family and have built a few motors for them, so I am pretty knowledgeable on turbo cars. I know u can make them faster with just a few minutes and some patience!

I went ahead and put a T on the vacuum line leading from the wastegate to the intake manifold, just to add a little more boost. Then I completely yanked it off, running I'm guessing bout 10-12 lbs of boost. Got check engine light, put the T back on, reset the computer, and that was that, no problems. Installed lean-rich and boost gauge 2 weeks later. Now, with that T on, only boosting an additional 2, maybe 3 lbs of boost on my gauge, I'm getting massive hesitation as soon as I hit 4200-4300 rpm. It lags, and the car seems as if it recovers, but its like hitting a brick wall briefly when i hit that rpm. Under 42-4300 rpm is fine, no problems at all. My lean-rich gauge reading is one bar off full rich, so I was confused as to why it was hesitating. Does the computer regulate these cars to only run stock boost? If so, is there a simple mod to fix or is a chip required? What can I look into to fix this issue? I'm an MSP newbie, so any advice would be greatly appreciated. Thx.

 

[Matthew]

you need to take it to the dealer to be flashed. search for "flash" and read for about 30 minutes and ask any more questions you may have afterwards.

welcome to the board!

 

[MoreBoostPlease]

matt thanks for the advice. I have already checked into it, it's been flashed once, I tried to get them to do it again, they said it would not have any effect. :/

 

[Striker187]

is the sticker on your car saying that it was done? check the door jam. are you sure it's just at that rpm? cause otherwise you may be hitting fuel cut/spark cut.

 

[Matthew]

what he said ^

otherwise...hmm...turn the boost down to 8-9psi and tell us what happens

 

[MoreBoostPlease]

Alright guys, turned the boost down only running 7-8 psi. Weather was a little cooler this morning, and it ran a little smoother, it didn't hit that brick wall as hard, but I still felt the hesitation. As far as the sticker showing the flash, I was unable to find one in the driver door jam, or under the hood, yet the dealer has told me it was done. Is there any way I can find this out for sure on my own, or do I have to trust the dealership? Please advise. Thanks guys.

 

[Matthew]

go to a different dealer. you should have some sort of sticker.

 

[jersey_emt]

It soudns like you're maxing out the MAF...if you boost too high, especially in cooler weather, too much air will be sucked in through the intake, and the ECU will cut the spark to prevent damage to the motor. Some people say it's a fuel cut, but that doesn't make any sense at all....the ECU sees too much air, thinks that there won't be enough fuel to maintain a safe A/F ratio, so it cuts fuel?? Some safety precaution THAT is....

I hit it at anything above 10psi in warm weather, and 9psi in colder weather. There's products available that will prevent this, and allow you to run higher boost.

 

[Matthew]

yea but he said he turned it down to 7-8

 

[Installshield 2]

The hesitation is most likely caused by the rich running...The brick wall you are talking about could possibly be the switch from closed loop, in which case it is trying to run as close to stoichiometric as possible (which is pretty lean for a loaded engine), to the dead rich maps used in open loop...You need to wait for perfworks to get the work done on a S-AFC-II from Apex'i...it should be finished soon, but other than that no fixes are available yet other than a full expensive stand alone...the flash helps a little, but mostly only when the stock boost is used...I would suggest dialing it back to around 6psi...and wait for the fuel controller...

it is hard to notice an engine that is running lean to a certain point, mostly becuase it feels very powerful for the most part...Rich mixtures cause the poor drivability and hesitation...When the ECU switches modes it is going from lean to rich basically, which will make that bad feel...