Horrible MPG and hesitation under acceleration?

Hello,

Have had issues that have come and gone with my 03 3.4L superchargedTacoma for almost two years now. 112k miles on motor. 108k on S/C. No strange noises coming from it. Bearings appear to be good. When running right it still makes 7psi. Addressed the issues in a couple of other threads but never found anything. It has a lag or hesitation under moderate acceleration but will clean up and pull after heavy throttle. Also noticed that at 2000-2200 rpm and try to accelerate that it will not really pull and boost will only go to 4lbs and slowly build to 6psi. Also struggles on hills or towing anything. So anything that adds a load kinda makes it pull less than normal. Feels like I am a gear or two high. Downshifting does not fix it. This has been sporadic. Sometimes it runs great but now, more often than not, it runs as described above.

I have replaced just about everything that you would think of. Fuel pump, fuel filter, injectors, plugs, wires, MAF, timing belt, throttle body, gutted cats, O2 sensors. Cleaned and sea foamed everything as well. Checked all my grounds. No vacuum leaks found with smoke test. No CEL.

Bought a wireless OBDII plug in and got the Dash Command App for my IPhone. Only thing strange I noticed the other day was that under normal acceleration the live MPG drops to 2-3mpg and my gallons per hr goes up to 7-8gph. As soon as I reach a speed and stop accelerating it goes back to normal (16.5mpg and 2-3gph). Also noticed that my highway MPG at 75mph is the same if not a little worse than my around town driving. I have a 2 inch lift, 32 " tires, ARB bumper, and no roof rack.

Anyone have any ideas why the live MP would drop so low? Originally thought I was leaning out and it was retarding the timing but seems like it may be the opposite. AFR stays around 14.7 until hard acceleration and then it drops to 12.5.

Thanks for any help!

 

Not much help for you on your actual problem, but live MPG should drop under acceleration (a function of how much gas/throttle you are currently using and how fast you are going). My ScanGauge always drops to between 2 and 5 mpg when I am accelerating.

 

Ya, it has always dropped but I figured that was too much. For the short period that it ran good while I was monitoring the data it only dropped to 8-9mpg. This is also just normal acceleration like you would accelerate away from a red light, not full throttle hard acceleration.

 

The MPG data information is something that is more specific to the scan app. Those numbers are not abnormal at all to be honest. I have seen worse live-data numbers.

As for your problem, it is an interesting one. Going through the list of components replaced, you have gone through most every one! Since the supercharger boost is a direct reflection of the engine RPM (belt driven) then I think looking at your engine data parameters in the 2000-2200 RPM range will be what is needed. Check all data when at a steady cruise, then watch for abnormal changes as your acceleration at that point changes to a moderate throttle. When you replaced all of your components, did you use any used parts, or any parts that were of an off brand? (I find that Denso or Bosch work the best on the Toyota)

 

Oh ok. That was the only thing I found that I thought was abnormal. Thanks to both of you for that info.

I will try that. All of that parts were quality (don't remember the name brands). Some have been replaced twice now!

 

Any one have an idea?