Strange power loss with Supercharged 3.4l, any ideas?

Hello,

I have a 2003 4x4 Tacoma with a supercharged 3.4L that has started to lack power recently. It has 88,000 miles on the ODO and 83,000ish on the TRD supercharger (no rebuilt nose cone).

I started noticing it on a trip out west last month when I changed my plugs. I bought Denso IK 22's only to find out the original owner had put in IK 20's. I switched them out anyway and drove trails for several day. When I got back on the highway I noticed I had to use a lot more throttle and all 5lbs (indicated on guage) of boost to climb hills that I used to not have to. It also had nothing when I floored it. It was not dead but definitely lacking power. It felt like I was towing a heavy trailer.

I re-gapped the plugs to .035 without any change. I put the old plugs back in when I got home and instantly got my power back. It would chirp the tires in 2nd and pull hills easily at 0-1 lbs of boost. A couple of days later I noticed it was back to lacking power. I had changed nothing.

This morning I bought new wires and new IK 20 plugs, gapped them to .043 and installed. Problem fixed. Running great. Drove several miles down to Lowe's and turned the truck off. When I got back in truck and left it was doing it again. It felt like an old 2 stroke when the plug was about fouled. No check engine light showing. The truck is not un-driveable but feels like a N/A tacoma and doesn't sound very healthy when it is constantly on full boost.

The IK 20's were a tad dark but not oily or white. The old IK 22's were a great tan/brown. I haven't pulled the new ones.

Anyone have any ideas what may be going on? I am completely baffled by this. I am pretty sure it is not a spark plug/ wire problem any more but don't know what else it could be.

 

Just a guess...manifold intake blocked or bad fuel?

 

Fuel is from several different gas stations across the country and it never made a difference. Changing the plugs did something to wake it up temporarily.

Manifold blocked idk.

Come to think of it. Is the throttle butterfly supposed to open all the way when you turn it manually or does vacuum pull it open the rest of the way? I noticed the other day that the butterfly only opened about halfway when I turned it all way to the throttle stop. Engine was off and butterfly moved freely. Never really noticed if this was normal or not???

Thanks for the help.

 

I believe the throttle assembly is forced about half way when not requiring the turbo to kick in, but after the turbo is engaged it should force it open relative to the oxygen required. Since you've changed out the plugs a few times, I suspect the turbo charger isn't getting enough oxygen forced into the fuel mixture hence the reason you're losing power. It still sounds like either the intake manifold is blocked by something or the assembly itself just isn't opening up enough for efficient oxygen flow. Or your fuel pump isn't keeping up by delivering fuel when the turbo kicks in.

Get on NRP and call the Car Talk guys http://www.cartalk.com/ or give your dealer a call.

12Tac

 

Gotcha! Not that it matters much in reference to your reply but I have a TRD supercharger, not a turbocharger. I still don't understand why the engine will get more power when I change the plugs but lose it afterwards. I figure if something in the mechanicals was messed up then it would do it constantly. 3 times I have changed the plugs and it has got the power back, 3 times it has went away after a while (several hours or several days.)

I will try cartalk.

Anyone else have any ideas?

 

It turned out to be my coil side plug boots. They are $17 bucks a pop and I cheaped out and didn't get them when I got new plugs and wires. I figure I cracked one when I was pulling them out under the intake tube. This cause it to arc at full load and hence the black, wet plugs! Runs great now. If anyone ever has this problem make sure to buy the rip off priced coil under boots along with new wires.

Joe

 

BTW, I found out that on the newer fly-by-wire Tacoma's (02+?) that the throttle plate does not open fully when turned manually while the engine is off. It will fully open with the engine running. That feature allows you to limp home with quarter throttle supposedly if you have a problem. I thought at first this might be my problem but found out it wasn't (see above).

 

I'm actually having the same issue and now I'm curious if this will fix my problem as well. I just ordered a new K&N filter since my current one has 55k miles on it and is nearly plugged up, but was clean when I first installed the SC 26k miles ago. I'm going to try this tomorrow and see if it fixes the issue. Was getting ready to downsize my tires to 33's if replacing my air filter didn't help so this would at least give me a much cheaper option if it works. Did you go back with the IK 20 or 22? what gap did you use?

 

3 years and 4 days! Been a while since I had messed with this.

I would say the air filter would be a good place to look "26k miles since cleaned" and "nearly clogged up" are not good terms to describe an air filter. Since you are using oil clean your MAF too.

Can't remember what plugs I ended with and the gap. Google will answer the gap question. I sold that truck without ever finding the issue.

 

Ha, I didn't even think to look at the date posted was just excited to find someone having the same issue. so the issue came back even after replacing the coil boots? I just replaced the wires on the truck since I didn't change them when I did the SC install and new spark plugs. my K& N has like 55k miles on it, just 26k with the supercharger on. I always clean it every other oil change, but the mesh the filter is made of is breaking down since these filters are only good for 50k miles according to the manufacturer and mines been through hell with dirt roads and mudding over the years.

 

I would get rid of the K&N and go back to paper. Clean you Mass Air Flow sensor really well with electronics cleaning since the oil is prone to throwing them off. That would be my first guess.

Ya, coil boots were not it. I think it was some other electrical issue as the problem would come and go.