Bad wastegate???
 

Ok so a while ago I started having a problem when getting on the car in boost, not just wot but when I would get over like 5psi(using 7.25 spring) the car would feel like its misfiring sort of. Im using a tial 38mm wastegate with an extension pipe so its a divorced setup. I thought it was turbo related since it started when I put a different turbo on, so even tried another turbo which I had planned to but still happens. I tried a new gasket where the extension bolts to the manifold and even used copper rtv, and it still did it; didnt replace the gasket between wg and extension pipe cause I never realy needed to unbolt them.

Whats funny is once I forgot to retighten the wg extension to the manifold and it stopped the misfiring/backfiring feeling at wot, just sounded like ass cause there was a leak. Kinda sounded like a turbo honda with open dp haha plus boost was a little lower and kinda fell off. Does this sound like something wrong with the wastegate or any other ideas?

Thanks -----s.

try a different wastegate... if that doesn't change it then take a look at your tune, since you changed snails.

Does it have the fire ring installed?

Yes the fire ring is installed. Could any parts of the wg going bad cause this, diaphragm or something? My friend has a godspeed or whatever its called wg, maybe Ill give that a shot and see what happens.

I would also like to get a smaller size wastegate for different mounting purposes, anyone know if the turbonetics evolution is smaller in height/width than a standard tial 38mm? I love the new tial 38mm vband thats like a little over 3.5" tall, but dont like the price tag and v-band lol.

Diaphrams go bad or get pinched. Had one on a tial gate pinched from the factory

Does this sound like a problem that could be causing this? Ive heard of diaphragm problems and causing spikes but nothing like this.

Wastegates don't just go bad. Sounds like an ignition problem. What are your plugs gapped to?

Well I understand that. My plugs are gapped at .030 or .027, cant remember. Ive dealt with the gap problem a while ago and took care of it, I have an external coil swap from the coil on plug setup which is why its much lower.

If its ignition related, why would it not be a problem when theres a leak pre wastegate?

Higher cylinder pressures require smaller plug gaps and more power from the coil to fire. When you add boost pressure you have to make the plug gap smaller. You should have your plugs set to .025".

The reason the problem went away when the wastegate was leaking is cause the boost pressure wasn't as high so it didnt take as much power to spark.

I never raised the boost when changing turbo's. And when the wg leaked there was only about 1 to maybe 2 psi loss. Ill pull the plugs and check them, Im running tr6's. And since Ive been boosted(even when sc'd) I always started with a higher gap and gapped them down from there to reduce spark blowout.

I never said you raised the boost. Spark gap opens over time. 1 or 2 psi is enough of a drop to cover up a few thousandths extra plug gap.

Also, when you say "it started when I installed a different turbo" what do you mean? Is it the same turbo you had, just a different one or a whole different type of turbo? You can't change a turbo and not change the tune unless you put the exact same turbo back on.

I went from a turbonetics t3 super 60 to a garrett t3 super 60 lol. Same housing a/r's, both standard bearing and shaft. I thought it was because I had reused a wastegate gasket a few times when I had the turbo off for other reasons so replaced it and it was still happening.

wg at 5psi cannot cause a misfire with a 7.5 spring... sounds like a tune problem to me... re-check your ignition and afr...

sounds like an ignition problem. sprakplugs or wires.

check your afr. i could also be an injector which is failing and causing this.

Not an injector or tune since Ive changed both of them since the problem has started. Now, I do have some problems in my tune which are getting resolved soon but thats a dif story since the problem has started before I even swapped pcm's..my tuning isnt as simple as for honda's lol.

Ordered new plugs. Go to autozone and what not and ask for ngk tr6's and they ask for ------- make and model. So I got the make and model, they come up for an 06 zo6 7.0 haha. If something is wrong with the wg though, it will give me an exuse to get that new tiny tial vband 38mm :)

hmmm... still cant see how it could be the wastegate, but do let us know what happens

Will do. Im waiting for my new tuned pcm to get here, then pop in a fresh set of plugs and do a heated o2 sensor and see how it runs. The tune is my original boost tune, just changed some other tables like trans settings,inj constant,idle,speed limiter etc. No pe or ve tables were touched.

I also ordered a turbo rebuild kit for my old turbonetics t3 super 60, and getting a nicely professionaly prepped shaft and .63ar turbine housing for it; tired of the damn 2-bolt grand national compressor on my turbo, plus my turbonetics has waay less miles. Also ordered some 2.5" piping and bungs to make a new dp to flip my turbo around for easier fitment issues, and the bung placement now puts the the o2 farther from the turbo than I like. Also gotta refab a wastegate elbow and mod my charge pipes cause flipping the turbo. Working on an automatic ld9 cavalier is a bitch when it comes to space back there lol. Gona be a fun project!