ravencr

I think I probably really did something stupid today. I'm going to cut right to the chase and I'm sure I'll get a lot of people laughing at me for this one, but I'm in dire need of some help with this.

Today, I completed the custom intake running the deckplate, elbow removal, and Supra MAF. I got everything back together, pulled the EFI fuse for 15 minutes, reinstalled it and started the 4Runner. It ran like s*it! Stalled, can't give it any gas, nothing! When I give it gas, it backfires or sounds like that through the intake tube. It finally decided to idle, but it's not idling smooth at all. I got a check engine light after a couple of time trying to get it started. Then I decided to disconnect the battery to make sure it reset, and then the check engine light went off, but it still idles rough, can't give it much gas at all, and if I do, it sounds like it's backfiring out the intake.

Now, here's the funny part! You're probably thinking that I already have my supercharger installed, larger injectors, Pigy-back computer, etc., but nope! Just the intake modifications as mentioned above. I assume this is my problem, right?

Please help me with this, because I can' drive anywhere with it like this.

Chris

Sludge

It sounds like to you may have a possible MAF problem. Im not 100% sure tho.

ravencr

MAF was just checked last week, so I know it's good! I actually got it running okay, but it's real weak in the higher RPM's. It must be leaning out real bad. Anyone else have any comments?

Chris

CTB

Just curious - what sort of advantage does the Supra MAF give you?

ravencr

Right now: TROUBLE! It provides a lot more air than the stock MAF sensor, but it seems that without the fuel mods, it is not a good idea. The fuel system just can't keep up. It pinged with 87 octane, and then I put 92 octane, which seems to be fine now. But I still don't have any power in the higher RPM's at all, which my guess is that there's not enough fuel, but I'm not sure yet.

Chris

ManyMods

Chris,
If I recall, you related your installation procedure for the MAF install and it sounded real scary ... cobbled together? I too think your problem lies with the MAF. You may also have leaks somewhere along the line. Too bad you didn't keep your OE intake and use a donor for this project. You know that mafs are easily damaged or contaminated. How do you know the maf was good to start with? I've had defective mafs. I feel your pain but am not smart enough to help you with what you have described.

Peter

ravencr

A week before buying the MAF sensor, the guy I bought it from put it back in his car, and tested it to make sure it worked fine. He said it worked perfectly, but who knows at this point. I really don't think it's that now that it runs fine, just real weak at the higher RPM's.

Chris

Dr. Zhivago

Personally, I don't see how that Supra MAF can be controlled by the Stock 3.4L ECU. It is MUCH larger and allows a LOT more air into the engine. Much more than the Stock ECU Programming was designed to deal with.

I think until you get a piggy-back module to retune the Supra MAF's output into a range the 3.4L ECU can deal with, your truck is not going to be driveable. Your other option is to put the FIPK back in place, with the stock MAF, provided you still have that.

Good Luck, Chris.

My .02
Dr. Z

ravencr

Nope, it's been sold, but I do have the stock MAF still. I guess I may have to break out the money for the piggy-back computer, which I'll need anyway. Any more recent news on the SMT-6, Dr. Z?

I still can't decide between it, the SAFC, and FTC1-E.

Chris

ravencr

I just unplugged the EFI fuse and battery to reset everything once again, and now it's idling weird again. I can't drive it with it idling like this, but I noticed that when I give it throttle it bogs down, but when I let off the throttle it actually revs up for just a second. Weird, but I'm sure someone knows what the heck is the problem, right?

Chris

Duffdog

hey raven

For what reason did you install the supra MAF? it should only be installed IF you need more air into the engine-- with a stock NA engine, that cant be the case--the stock MAF was computed to give maximum intake air velocity for that specific engine size fuel demands. It aint gonna do ˟˟˟˟˟ unless you have all the other crap too-- and i do believe the SAFC is the best way to control the injjectors after installing the larger MAF.

tim

ravencr

Thanks Duffdog!

I just got it to run better and more normal again by flooring it, which I guess opened up the fuel. I installed in, because I'm expecting to do all teh other stuff real soon, but I think it's running really lean now. Probably not good at all, right?

Chris

ravencr

Hey Tim,

Does the SAFC retard timing at all or just air fuel ratio? Is that all it does?

Chris

mhawker

Chris,

I'm with Dr. Z. I don't think you CAN run a Supra MAF without an SAFC or whatever.

Totally talking out of my a$$, but I think that is where your troubles lie.

Mike

ravencr

I'm beginning to think the same thing. It runs fine now, but I don't know why. I had to floor it before I could drive it. Weird, but it was almost like no fuel was getting to it or something. I don't know, but I'm trying now to determine which unit: SMT-6 or FTC1-E????

Chris

FattyCBR

The stock MAF and Supra MAF both potentially put out between 0-5 volts, but the same amount of air will not produce the same voltage between them. So here's an analogy say for example the stock MAF reads 5 volts at 100 cubic feet per minute (cfm) of air moving through it, but with the Supra MAF at 100 cfm it only reads 3 volts. So at start up and idle with the stock MAF you may be moving 20 cfm through it producing 1.5 volts, but if you were to put the supra MAF on there at idle you would still be using 20 cfm, but your voltage reading may be more like 1.0 volts and your engine doesn't add enough fuel and does not run correctly. The point being, do not use the Supra MAF until you have something to modify the signal it's sending the ecu because you may damage your engine.

ravencr

Good point! I'm going to install the 370cc injectors and Fuel Pump to see if that works without the Piggy-back. Gadget said that he knew of someone that claimed this combination could work, but nobody is for sure yet. I'm going to order the injectors tomorrow!

Chris

Duffdog

you mean to tell me you have a supercharger sitting around and it is not installed??? install the stupid thing when you change the injectors-- youll have to take the intake runners off anyways!! And the fuel pump does help with the 370cc injectors. If you do everything at the same time you will not run the risk of messing something up--keep in mind all of these mods are part of a system and do not neccesarily work independent of each other.

Someone asked about the SAFC-- it modifies the air signal into the ecu and tricks ithe ecu into thinking it is operating with its original components and the ecu changes the fuel. The ignition retard/advance is not controlled by the SAFC directly, but if you set it wrong, the engine will retard timing anyways.

Tim

ravencr

Yeah, I know! It's a wife problem. She doesn't know I have it, and I couldn't really afford it when I bought it, so I've been unable to install it. Ok, start laughing now! At any rate, I wish I had the money to get this all rolling, but I don't. It sucks that I have to get the piggy-back right now, otherwise it's not drivable.

Chris

ravencr

Well, through responses made by the geniuses on this board, I have been told that I definitely need a piggyback computer and larger injectors, so I guess I'm going to have to spend all the money right now.

Chris

This is the end of this thread, I guess, and I just wanted to thank everyone for all the help!