Boost Spike, but how?
Boost Spike, but how?
As a few of you know i just finished installing my custom turbo setup and i seem to have a problem with the boost spiking way too high. The (Built in)wastegate was supposed to be set at 4 psi, a nice low safe number. At half throttle it spikes to 7 and settles at 5(just as it should do), but when i give it 3/4 throttle the boost spikes way up to 10-11 psi until it settles at around 7. I have a boost controller but i took it out and just put a vac line in the place of it to check if that was the problem and it still reacts the same way. I have yet to floor it because i dont know how high it will spike. Is there any way to check my wastegate to see if its set to a higher psi or something? Thanks for your help guys.
check all your vac lines, and if worst comes to worst, just pick up another wastegate at a junkyard or take it to a local tuning shop without boosting on the way there and let them look it over for ya. i wish i could help ya more being i sold it to ya but i didnt mess with anything or even start the car, so i guess your best bet would be to contact megadeth2018 on aol aim. thats the guy i bought it from, he had it running on his set-up so maybe he can help ya too.
btw: i STILL have no word on that egt guage.
btw: i STILL have no word on that egt guage.
Well it would probably still spike, but at least you'd know the where the boost was set. I think spikes are fairly routine, and it only seems like a big difference because you're running such low boost. 3 psi is definitely a spike, but it only looks like a big number because you're running 4psi. 
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i talked to my bro and he said that its probably just the wastegate going bad, so if i were u i would just pick up another wastegate, or go the expensive way and weld the internal gate shut and buy an external one thats adjustable.
he says thats what they do when they get old, and i couldnt tell ya how old it is, but i bet ya the wastegate is just bad.
he says thats what they do when they get old, and i couldnt tell ya how old it is, but i bet ya the wastegate is just bad.
thanks for all your help guys the problem has been figured out but not solved. The t25 that i have is off of a 2g eclipse and is set at 10psi or so so thats why its going that high because its set that high. Maxum thought that it was set at 4 for some reason oh well problem figured out. I figured this out by talking to the person that sold it to maxum, megadeath.
One other thing to be considered, is the source for the boost gauge. Where did you tap the vacuum line for the boost gauge? You don't want to tap the vac line going to the wastegate, you want a dedicated line for that. Your best bet is a line directly off of the IM. Just something else to check.
Never thought of that jay i just tapped the the bov line because it was the closest. I am just curious as to why thats not a good thing. Finally how should i make a dedicated line for this when there is only one line coming from the IM and that line has to go to my fmu and my bov?
Well, there should be a vac line coming off the turbo going to the wastegate. If not, then I'm at a loss because you're right, there isn't a good place to tap into at that point. You could try the brake booster line. The reason why I say it's good to have a dedicated line, is because it's THE most important vacuum line. If you have 5 things running off one vac line, then that just leaves more room for error in a device to suck away some boost pressure, and then you would be running higher boost.
Another thing, mechanical boost gauges (esp Autometer) are netorious for being erratic and not being calibrated exactly. An Evo guy RichJ on the DCEvo forum, said he has 3 boost monitoring devices and all three read differently
Another thing, mechanical boost gauges (esp Autometer) are netorious for being erratic and not being calibrated exactly. An Evo guy RichJ on the DCEvo forum, said he has 3 boost monitoring devices and all three read differently