Maybe a bad wastegate?

[conno707]

I just swaped my sr, and it drove and boosted perfectly. But i was cruising down a road and i herd a backfire come from the exhaust. Now i can't rev over 3500 when it was a load on it. Revs fine when neutral, I didn't have the vacuum of the wastegate going to anything when it was revving fine. I've looked for boost leaks, and went over all the vacuum line. I can't find anything. Also one other thing is my 3 week old spark plugs are black on the tips. Could that be a bad o2 sensor?

I can't think of anything else, and i've tried searching.

[PyR0NiAk]

A bad maf would cause it to go into limp mode(2-3krpm limit) and dump extra fuel(black on tips of spark plugs)... Try swapping it out with a known good maf and see what happens.. also, try checking for codes.. fault-codes-t494878.html

[patrickm1587]

I didn't have the vacuum of the wastegate going to anything when it was revving fine..

You didn't have a wastegate hooked up at all when you were driving the car around?

[conno707]

I have a brand new MAFS, i also unhooked it and it doesn't let me rev over 3k when neutral, with it hooked up it it will let me rev fine when in neutral.
When im driving in first it backfires/missfires alot around 3k, in second its at about 2700, depends on what gear im in.
And yes i didn't have it hooked up, im wait on a new hotpipe. i also know it was stupid of me to do that.

[PyR0NiAk]

I'm pretty sure you most likely ruined your turbo, but I can't see why that would cause it to not rev...

[conno707]

I can hear spooling and the gauge says it builds up boost

[patrickm1587]

You seriously drove your car Without the wastegate hooked up? What on earth were you thinking? You do realize that without the wastegate hooked up the turbo can build as much boost as it wants to, right? Tell me you didn't take the car out and dog it while you didn't have the wastegate hooked up?

[conno707]

i kept out of boost as much as i could, because i didn't have it hooked up. I drove it like this for maybe 40 miles. At the most it was revved up to 4k

[PyR0NiAk]

Alright, let's ignore the turbo for now... Check for codes...

[timmysvert]

bump ....
my sr was doing the same thing the other night on my way home from work. my wastegate is connected. i only get the code 55 out of the ecm. i checked everything over the morning after didnt find anything.so i took the car for a quick drive and it was fine????? my only other guess is maybe the fuel filter picked something up and was plugging it ???? any other ideas ????

[conno707]

i made a boost leak checker ended up to be three decent sized leaks.

[timmysvert]

i already made a boost leak tester and used it and didnt find any leaks. its frustrating one minute it has no power the next morning its fine.

[timmysvert]

found it it was a combination of the fuel filter starting to plug and the parts store sold me a filter for a 90 300zx n/a not the tt

[PyR0NiAk]

That's not going to matter... the only advantage is with the bigger one you have a, theoretically, longer life span.