sc4runner23

I just got a magnaflow cat back exhaust installed on my 99 supercharged 4runner and when ever i step on it and get the rpm's up to 4 grand its starts back firing and the rpm's start to slip.
I don't know if its the exhaust or the supercharger because it has a 170,000 miles on it.
I need help figuring out if anyone thinks its the exhaust or the sc.

rimpainter.com

So just to clarify...you got exhaust installed and literally right after you left the shop this problem surfaced?

sc4runner23

Yes that night i got it. I wanted to check what it sounded like around 60 and it just kept back firing. It sounded like a tommy gun.

4runnerteen

Ok. So left shop, hit highway, backfire. If im not correct. No in-between time. Well if thats the case then something is not installed properly on the exhaust. I would take it back to the shop and see if they can do another look over on it.

Unless someone else has a better idea?

rimpainter.com

^ Agreed. The shop screwed something up. Here are my thoughts:

1. Did they disconnect the neg battery terminal? If not you can send a nice jolt of juice to the ECU and fry it. That's worst case scenario.
2. Front 02 sensor was messed up
3. Rear 02 sensor was messed up
4. Something is hindering the exhaust flow; Magnaflow mufflers are directional I believe (there should be an arrow on it) which means the muffler could be facing the wrong way.

Check into those things (not necessarily in the order listed).

sc4runner23

So i went to the place where i got the exhaust and they said that it couldn't be the exhaust because there are no sensors after the cat so it wouldn't be that. He said it could be leaking maybe at the headers or something which would cause it to run lean. Could something leaking cause this problem.

okie81

And it never did this before the exhaust work? A leaking manifold or header will usually show itself in a different manner than a backfire.

I don't know the reprocussions of mounting a muffler in the opposite direction of flow; maybe someone will chime in with symptoms of such an incident.

As mentioned above, check out your O2 sensor. If the wiring got burned/melted/disconnected when they did the exhaust, you could be getting some wild results.

sc4runner23

Thats exactly why i think it could just be tuned ty. My belt is slipping on the supper charger but i know that couldn't be the problem.

sc4runner23

tuned bad*

sc4runner23

its not as much as a backfire as a cutting out noise.

4 r u n n e r

Can you say........REEEEEEFFFUUNNNNDDDDDD!

Oh kinda sorta off topic but would your SC fit a 98 4runner?

rimpainter.com

I don't know about you, but I have an 02 sensor after the cat. I think it's known as "Bank 2" and doesn't do a whole lot other than keep track of how the cat is doing. But still...

tacoma27

I use to have this problem back when I use to drive a volvo 850 turbo...after install a 3" down pipe and a 2.5" cat back...this exact same thing happen(only when I punch on it and running close to max boost)...I did some search on volvo forum and people there told me to gap down the spark plugs...problem solved...since the engine boost faster now, gaping down the plugs will help burn fuel faster...good luck

rimpainter.com

Gapping down your plugs prevents a "blow out the candle" scenario, meaning, decreased chances of detonation/misfiring/over-fueling. SC'r boost isn't exhaust-dependent like a turbo, so I highly doubt decreased backpressure is the cause. Good thoughts though.

I would like an update on this thread. What happened?