Boost spikes

[MEXICANPT]

I'm getting boost spikes up to 21 psi (I know boost readings depend on where you hooked up your boost meter) when I initially slam the gas pedal and then it settles back to 15 psi.

My spring mod gave 2 psi, which I think it's not too bad.

Anyone know what could be causing these spikes?

[Grandgrandpa]

When you say spring mod, are you refering to the stiffer spring for the wastegate actuator? That would be my first guess for the uneven readings. Also, where did you get the stiffer spring?

[MEXICANPT]

Yes, that's what I'm talking about, I got it a local parts dealer, it's a carburator spring.

I just installed it today, and before that the spikes peaked at about 19 psi, which I think it's still high.

[Jason_L]

Are you running an MBC? If so, how is it connected? Where is the guage connected?

[MEXICANPT]

No MBC here.

[Dalite]

Most likely due to the PCM venting the excess boost from the system to prevent it from being damaged from the change to the wastegate.

Once it gets the boost back down to what the stock wastegate should be maintaining, it levels back off at normal pressures.

The question should be: How much performance are you losing overall by forcing the boost levels out of acceptable parameters with the wastegate spring mechanical mod.

The PCM could use the time spent in neutralizing the effects of your mods to provide more consistent performance, and yield higher overall output...

Tune the PCM; not the engine - Then they will come...........

[MEXICANPT]

Maybe so, but once the boost comes down after the spike it still holds 15-16 psi all the way through redline, and that's something it had never done before.

[Jason_L]

hmmm... interesting. The PCM probably was pogrammed with the knowledge the WGA has a 4 or 5 pound spring in it, and cycles the solenoid, etc based on this.. the spring mod probably threw that logic off a bit. Maybe afte rrunning it for a while, the PCM will correct itself to accomodate this.
I had the same huge spike when I did the spring mod with the WGA solenoid still in the loop. I now have the WGA solenoid bypassed completely, and run a MBC and the spring mod. No more crazy spikes, it's pretty much a steady 15 psi the entire time. Actually, I take that back.. I was still getting spikes well over 20 psi at first, but I changed the pressure source to the MBC from the turbo (where i originaly had it), to the throttle body (where the TIP line went).. now the spike is gone.
I'm not so big on pushing that 15psi the second i blip the throttle though, as the PCM is probably still running closed loop and keeping it running at a lean 14.7 until it goes WOT This is will be fixed as soon as i figure out how to get my throttle switch set up!

[ptgtcb]

Have you looked at the posts on srtforums.com? There are quite a few threads on all this and it is totally kicking my a$$.[:0]
scottmech has got his stuff together on this not to mention quite a few other guys. Just do a search and the info is there, at lot to weed through so I print what is relevant to me. Give it a try.
[^]