Sputtering, backfiring, & stalling +12mpg. HELP!

I recently purchased a 2003 double cab Tacoma with the 3.4, TRD supercharger, URD controller, 7th injector kit, 2.2" pulley, brute air intake, larger exhaust, and who knows what else... At time of purchase, the truck had been throwing a trouble code P0340 'camshaft position sensor A circuit (bank 1 or single sensor)'. The previous owner replaced the sensor the day before I purchased the truck. He said he drove it for 100 miles or so with no issues but then on the highway, experienced sputtering, and backfiring for about one minute, before the truck began to run normally again. He also had issues with the catalytic converter so he reamed it out as there are no emissions required in our area. It also smelled very rich when we test drove it. He unplugged the seventh injector as he thought maybe it was over fueling and causing the sputtering. He said that the truck had sat for sometime at his cabin. It seemed to me like the battery had died and perhaps the computer was remapping since having the battery recharged. I also thought that perhaps due to sitting for an extended period that the gas had Gone bad or gelled possibly causing the issue. He cleared the code and the truck did not throw it again. In the past few weeks when driving in, the issue sporadically occurs where it will sputter, backfire and die. It is difficult to restart. It smells very rich, like it is flooding. The gas mileage has also dropped significantly. I'm getting 11ish mpg. I'm sure winter fuel mix has plays a small part in this. I truly have no business touching an engine. I bought a scan tool, and it is throwing the same cam position sensor code again. Not only am I not a mechanic, (i seriously don't know a thing) I tend to break everything I touch. I live in a rural town in Southeast Utah and in calling around to several different local shops, none of the mechanics want to touch the truck due to the supercharger and the various controllers installed. In addition to all of this, it seems like the motor is extremely anemic for all of the add-ons. I know these trucks are not race cars by any means, but I would expect to have a little more throttle response with the supercharged motor. I lose speed on my old Hills, even with moderate throttle pressure. Then again, I have never driven a supercharged Tacoma previous to owning this one, so I am unsure if my expectations are realistic. So here are my questions. Could it be that the timing belt needs replacing- like the timing is off? Could the fueling issues have anything to do with the catalytic converter being reamed out, or cause it to throw an incorrect code? I pulled off the air intake and cleaned out the throttlebody and maf sensor ( at least I think that's what it was… ). The Previous owner told me that The motor has been replaced with a used one and has 70000 to 80,000 miles on it. The truck has 212,000 miles on it. What could the issue(s) be & what should be my priority in addressing the problem? Also, should I not be driving the truck? It is my main source of transportation. I do not have a lot of money to throw at the problem, nor a mechanic that is willing to take on the challenge. I could drive 120 miles to Salt Lake if anyone knows a reputable mechanic and is willing to work with superchargers and tuners etc. I am sick to my stomach about this. Can anybody help me?

 

Are you running the highest octane gas that you can get outside of race gas?

 

paragraphs are your friend.....

whats keeping you from thinking a squirrel or rat got in the engine bay and started chomping on some wires?

if your truck is running fine after clearing your computer, but has problems after, it could mean there is something wrong with either your egr, o2, or evap systems. those systems don't engage until some miles after a reset when the monitors are completed/active.

for all we know the EGR wasn't installed properly and is letting air in instead of exhaust gasses, causing hotter situations in your cylinders and causing the fuel to self ignite way too early (you'd probably need over 105 octane to counter this issue). this can really screw up your timing and maybe even cause your ECU to think your cam sensor is all screwy

 

Thank you for the replays. I run 93 octane which is the highest octane I can find in my town. Should I be using an octane booster as well? I was kind of under the impression that they gave only minimal gains.

Oh man, wiring scares me...
How do I check the EGR, just take it to a shop?

 

You are right to be wary and cautious about working on this car. This is the reason people often advise against modifying engines/buying modded engines.

You should post all the codes that you get when running your hand scanner.

Since you have little idea which sensors are working/intact, I would look for that first.

 

I would have your timing checked. Timing chains can stretch and throw of the timing. As in the previous post all are also quite possibly the issue. If it was mine I would remove the urd controller, and the 7th injector. Have the Ecm flashed by Toyota for the supercharger. Also put the proper size pulley on. This should get you to a somewhat stock setup so they can properly diagnose what's wrong with the engine. Then once it is sound again start going back with the other mods.

 

These trucks dont have chains, they have timing belts.

Sounds like it could be the crank angle sensor. Mine went recently, basically felt lit it hit the rev limiter at 3500 rpm. $70 and its literally 1 bolt and plug, that you can get to without removing anything except maybe the skid plate. Testing procedures in any repair manual.

 

Could your air fuel mix be way off because of the pulley and controller with the 7th injector? I would take everything off but that supercharger and refresh the thing.

 

try and tackle one problem at a time, ripping everything off is not an option as that's also throwing money at and not solving.

as @Gwarden mentioned get the codes and look them up. having a reamed Cat doesn't help the O2 sensor report correctly which could cause other issues or other codes.

start small and work from there.

 

I disagree it needs to get to a known good state. Remove the variables. When you do this you get it to a "stock" state. You don't have different components fighting each other. Less extra wiring and connections. It's obvious that he can't just verify that everything is working, installed, and tuned correctly. That's the problem with getting someone else's head ache. The previous owner sold it for a reason.

 

he also does not have the "stock" intake or pieces that may go with it. which means spending money to find used or new.

having the supercharger by itself produces low boost. the bad gas could have fouled things up and caused more problems running through.

the fuel filter is an easy replace and may need to as well.

however, going off your statement it would be best for you to have someone qualified look at it. maybe just to get a better idea of what's wrong. we can offer you all kinds of advice but we're not there...

 

Well a Cai in my experience has never been too much a issue as long as it isn't allowing unmetered air into the engine. As for the bad gas I assumed he has already ran through that and probably a couple of tanks since especially at 12mpg. I would suspect that bad plugs would throw a CEL fore misfires. The more I think about it I think it's timing or maybe in need of a valve adjustment? Not really up on 3.4l. Can the valve lash be adjusted?

 

I think they can be adjusted but have not heard many stories about touching them

 

Tight valves can cause spitting and backfiring.

 

Bad plugs and coils

 

I've had an issue almost identical

 

Was the issue resolved?

 

I had a similar problem of sputtering and dying with a cam position sensor error code in my '96 2.7.

It turned out to be a bad wire/bad connection to the igniter.

 

If the fuel is igniting too early, higher octane is only going to make things worse.

In my experience, backfiring is usually due to unburnt gas detonating in the exhaust system as opposed to pre-detonation. Once again, I'm thinking it's an electrical issue - a sporadic no-spark that is leading to unburnt fuel building up (probably in that reamed-out cat housing) while the truck sputters and chugs, and then BAM! It sparks again and that unburnt fuel torches.

I've actually been in two different old carbureted fords when the mufflers exploded in flames from a similar thing. Nothing blew up on my Tacoma, but it sure chugged and felt like it was dying.

 

take it to a pro. I have heard everything under the hood could be the problem. Take it to a pro...