Intermittent Problem Supercharged 2003 4.7L

Hi everyone,

I purchased a 2003 Tundra Limited (4.7L V8) which came with a factory installed supercharger. Truck is in good shape and has ~ 176k miles on it, is due for the timing belt change in ~ 20k miles.

I've been having problems with the truck running like garbage intermittently/randomly.

Over the course of about a year, several times, while otherwise driving normally, the truck will just out of the blue have a slight flutter (loss of power even under gentle accel) and then start running horribly, wanting to die. I was able to keep it running one time by repeatedly pumping the gas pedal and was able to make it home about 10 miles. Another time, my wife was driving, it did the same thing, she pulled over and let it sit for a couple hours, after which it started and seemed to run fine. Another time more recently, it did this right on initial startup in the driveway, in Park obviously, and wouldn't run at all unless I kept the RPM > 2000 or so at least. I managed to get it to a local shop, they were unsuccessfull in reading any codes in order to find a smoking gun as it were.

Over the past year I replaced the fuel filter, the MAF, sparkplugs, cleaned throttle body, also replaced the battery (Optima red top) and also replaced the entire exhaust including both upstream and downstream oxygen sensors. I thought the exhaust system was "it", the source of the problem, based on temperature readings with an IR gun one of the catalytic converters was plugged (both sides at about the same temp), many times it seems like when the truck was running bad, it was like someone did the old bannana up the tail pipe trick.

But, even after changing out the exhaust, just a few days ago, after running fine for about 4 months, it happened again, the truck just randomly started running like crap, where I had to keep it > 2000 RPM to keep it running in Parl, once the engine warmed up, I was able to get into gear and did the old pump the pedal trick to get it to the shop, and actually while driving it to the shop, about a 5 minute drive, it went away, and truck started running fine again!?

But for the latest round at the shop, the fuel pump was replaced but the shop also unplugged one of the 9/10 injectors and the truck seems to be running fine, no codes so far, so far so good. I read on another post that a fellow had bad idle problems which he solved by unplugging the extra injectors (his theory was the TRD ECU turning on the extra injectors even when they're not needed), he then changed over to Unichip.

Has anyone encountered this sort of thing before? If it's the TRD ECU I'm not sure how that could ever be fixed? I don't know if replacement injectors are available for the extra 9/10 injectors?

I don't really care about the SC if it's going to be a pain or a liability, just would like a reliable truck. I will be doing a bit of towing so I thought the SC might help but I could live without it if it's the source of the issues somehow.

Thanks in advance for the help.

 

I was gonna a say fuel pump, and then saw you replaced that. I would highly suggest looking at getting it properly tuned, there are several vendors on the forum that can help with that.

Also it was *dealer installed, not factory. The TRD Supercharger weren't offered on factory trim, only dealer accessory

 

Is the new fuel pump a good match for the supercharger?

 

You replaced the plugs....did you replace the coil packs as well?

 

Maybe fire it up and spray some starting fluid around the engine bay to check for vacuum leaks. If you get a sudden increase in revs while spraying a certain area, narrow it down and fix it.

 

Hi everyone, thanks for the help, oh yes, dealer installed, you're right, sorry about that.

The new fuel pump (OEM replacement, not a high performance one, and the motor only, not the entire assembly) was installed just a few days ago, and it's been running fine since then, with one of the 9/10 injectors unplugged as well, but it also ran fine for ~ 4 months after changing the exhaust and O2 sensors. Only time will tell if the fuel pump was the issue I guess, I'm half expecting this problem to happen again, ideally I would find out "for sure" what the issue is I guess so I can be confident in driving the truck.

No, only the plugs were changed, not the packs. I was considering changing the coil packs since I think I can do that myself, and maybe the fuel pump resistor and the fuel pump relay, but throwing money at the truck in a "trial and error" experiment sort of way is not great, obviously.

I wasn't sure about the 9/10 injectors, if there's a replacement part, I may have found something on URD website that claims to fit, but again, is a shot in the dark. Apparently can read codes off the TRD ECU itself, but have to access an unused cable with a test light and count the flashes (OBD-1 style).

 

Test fuel pressure regulator

 

I'm thinking fuel delivery. Or potentially MAF. i.e. something that's reponsible for fuel or air delivery and/or measuring it.

 

Thanks for the help, I'm not sure if the fuel pressure regulator has ever been checked, a while ago I let the local Toyota dealer drive it around for about a week (don't ask how much that cost!) and they could never see an issue with the fuel pressure, the local independent shop I just took it too, who changed the fuel pump said that the pressure with the old fuel pump was fine but that it wasn't supplying enough volume of fuel?

 

Makes sense. Might need to buy a higher flowing fuel pump. I know Dirt Deeds Industries sells one for our trucks. URD may as well.



When you replaced the spark plugs, did you get iridium plugs?
The supercharger requires iridium plugs.

 

Hi, thanks for the help, yes I believe the new plugs were Iridium sparkplugs, with a pretty wide gap, can't recall for sure, 60 thou maybe? Hope I don't need to get yet another fuel pump although I did notice the larger injectors (330cc) and the larger fuel pump from Dirty Deeds. Maybe the fuel pump couldn't keep up with the extra volume required by the 9/10 injectors and eventually burned out? I assume the pump I got changed out was the original pump, although I don't know for sure. If so, hopefully I'm good for a while, especially since I have only one of two 9/10 injectors currently plugged in.

 

Oh, forgot to say, if anyone knows of a vendor, or vendors, that can check or alter the tune on the TRD ECU, I would be interested in finding out, just in case I have a problem with the TRD ECU itself.

Thanks.

 

I would email Gadget at URD and see if he can be of any help.

 

Thanks for all the help, I'll email Gadget at URD.

 

If you want to get rid of that supercharger due to reliability concerns I'll trade my VVTI intake manifold for it. Dirty Deeds shows they make more power than the non-VVTI intake.

But on a serious note, if you ever want to sell it there's still a lot of interest in them. Myself included.

 

Don't sell yourself short. Those S/C's go for an absolute premium

 

Thanks, I'm on the fence with it, it (the S/C) does seem to be a bit of a liability at the moment, will take some time (and homework) to get it working properly I think, so just turfing it could be an option too, I'll definitely put up a post and let the forum know.

 

I'm with @2mchfun on checking for vacuum/boost leaks. At idle spray brake parts cleaner or ether around the intake manifold/tract/vacuum hoses. If your engine speed changes you found a leak.

Check your vacuum hoses thoroughly. A crunchy or cracked hose at the connector can give you intermittent issues like you describe.

Boost leaks can cause a rich spot in the RPM range. Vacuum leaks can cause a lean spot. Either condition will cause poor engine response, stumbling, and stalling.

 

I’m prob the last guy to answer this question but I had a similar issue after changing my injectors. I had tightened them up with one injector slightly off center. Truck ran fine at first then got random loss of power weeks apart. Eventually it stalled on me taking off at a red light then ran fine and got me home.

Didn’t see you changing yours and don’t think you would’ve needed to remove yours for the work you listed but it’s similar to the issue I had with how random the loss of power was. Maybe the rubber gaskets on the injectors if yours are the originals as the ones on my 2003 were falling apart when I pulled them.

 

I'd also heard similar happen when someone is installing new injectors and left one of the o-rings from the old injector behind, essentially double-ringing the replacement injector.

 

Hi everyone, thanks for the help, yesterday I sprayed MAF cleaner around the intake manifold and injectors and any vacuum lines/fittings that I could, unfortunately there was no change in the idle speed when doing this. Also, the boost gauge shows a steady ~ 20 in Hg vacuum at idle.

I never have changed any injectors yet, but I'm thinking about it, so I'll keep a close watch on any missing (or extra) o-rings there, can't honestly say I got the MAF cleaner around all the injectors, so would have to re-do that test I think.

I just heard back from Gadget at URD, he's leaning towards an issue with the TRD ECU. I guess I can disconnect it and drive around that way as long as I keep the throttle below 30 percent, if the problem never comes back, I guess we would have our answer. If it is the TRD ECU, not sure if it can be re-programmed or replaced.

 

If you have an issue with the TRD piggy back ECU and can only use the factory ECU reach out to Quantum Auto.

https://quantum-auto.com/

They cracked the Toyota ECM and may have a tune that can handle the TRD supercharger.

 

Yup, here it is...

https://quantum-auto.com/ols/products/sc-430-supercharged-ecu-re-map-service

 

Hey, awesome, thanks for the help, I'll check that out, that might be the 100 percent solution for me, or the MAPECU that Gadget sells.

 

Make sure that MAP ECU is compatible with emissions, assuming you need to still have emissions tests where you are.

Some of those stand-alone ECMs remove emissions monitoring sensors or OBD2 capability.

 

What brand of MAF did you replace it with?

 

Have you ever used them or know someone that has? Curious about their credibility. Seems like a way easier option that VF

 

The new MAF I tried was a generic one, not Denso unfortunately, Intermotor maybe? This was early on in my Tundra education and I wasn't aware of Denso yet, the shop I had it at a long time ago ordered this generic one for me. This was the first thing we tried, about a year ago, but, since the truck had the same behaviour after changing out the MAF, I concluded that the original MAF was probably fine, and went back to the original one, which has "TOYOTA" on the top of it, which is what is on the truck right now. More recently, after we completely changed out the exhaust and all O2 sensors (Denso), I actually tried out the new MAF again, just for the heck of it, it ran pretty well actually, had more power it seemed, but was throwing check engine lights (running too rich), so I went back to the original Toyota MAF and haven't had any CEL's since then. Then the truck started running badly again, and so most recently have now changed the fuel pump and unplugged one of the 9/10 injectors. It's only been about a week, but the truck has been running fine, albeit a little bit down on power maybe.

 

Hitachi is the OEM on MAF.

 

Quantum was recommended by Dirty Deeds for a canned "chip" option. VF offers canned tunes but I don't know if they have an SC option or not.

Yotawerx may offer a VF based SC tune. But most of the SC tunes out there are for the 4.0 V6 or 5.7 V8. Our 4.7s don't get much attention besides the LXtreme guys and XAT Racing.