Andycbr

Hello all,

I am new to this forum and tried to do a search but I have not found what I am looking for. If anyone could point me in the right direction I would really appreciate it. For some reason my 4Runner feels like it is pulsing or like something is slipping when I round a corner to the right especially if I am at low rpms and in second gear. Truck is a five speed.

Thanks for any links to the discussion of this problem.

Andy

midiwall

Welcome to the forum!

Can you tell us if you've done any other mods? For example, have you done "the fuel mods" (larger injectors, larger capacity fuel pump, piggy-back fuel controller); Toyota's 7th injector; or even the "Free FMU" mod?

"Gadget" is a guy aroujnd here (and other Toyota forums) that's done a lot of work investigating issues with the S/C on our engines. His site is a great place to start for information:
http://www.gadgetonline.com/

In particular, you'll want to look at these pages:
http://www.gadgetonline.com/Super.htm
http://www.gadgetonline.com/fuel.htm


Your symptom is "common" and is generally referred to as "surging". People usually attribute it to fuel delivery issues. One quick thing to try (if you haven't done it already) is what Gadget labeled the "Free FMU" mod. Toyota liked it enough to included it in a later revision of the installation directions. Details of it are on his fuel page (link above).


Tell us more about what you've got on the truck, and someone around here can help you out.

Andycbr

Midiwall,

Thanks for the response. I really haven't done anything but install the super charger. It seems as though my truck has lost a lot of power. Don't know if its from age or not. 124k on the clock now. The charger is also making a a noise at low rpm. I have the oil change kit which I plan to do soon.

midiwall

With 124k on the truck, is all that mileage on the S/C as well?

If so then an oil-change int he S/C is a good place to start. Checking in with Magnuson about a rebuild might be in order as well.

Andycbr

Thanks for the reply. The jerking is now getting worse. I don't know why but I get this feeling the Cat is on its way out. Egg smell very often now.

Jeff B. in Michigan

Hi Andy,

I have a 1998 SC SR5 5 speed with 128K miles and it does the same thing. In addition to the surging, every so often the engine will kill at a stop. This occurs after I have been driving on the highway for a few miles.

I am running a wide band O2 sensor and can see the air to fuel going from Stoich to lean … then it kills.

I have tried cleaning the throttle body (three times), replacing the front O2 sensor and messing with my Split Second box… nothing to date has worked.

FYI.. I have had the problem occur at the drag strip but when I mash the pedal to the floor I can still run in the high 14's with perfect air to fuel ratio

Let me know if you ever figure out what the problem is… I will do the same for you.

http://n8rws.com

midiwall

I think I know at least a couple of things that are contributing to the problem... It's a "deadly" combination of stuff in your sig:

With that pulley, you're going to be cramming air into the engine way beyond what the stock injectors and fuel pump can handle.

Have your ever looked at your LTFT with an OBD II tool? I'd bet that you'll find spots in the fuel map that match up with where you see things go lean. For the normal running around town (i.e., not WOT) you should be able to counteract this with the SplitSecond.

Also, in the stock ignition tables, there's a HUGE "blind spot" around (edit: 2500rpm) where the timing will advance... you can't get away with that on an S/C'd engine and it MUST be set back. I'm running a LOT of retard (-7) through a 3x3 block around (edit: 2500rpm) and 60-80% of my other input (MAF).

When you say "messing with the SplitSecond", do you mean that you're going at it blind and not really understanding what you're changing? If so, that's the other contributing factor to your trouble.

When you say "perfect air to fuel ratio" at WOT, what number are you actually getting? With an S/C, you should be running richer than you would NA at WOT.


I think the main thing that you're seeing is that the engine is being starved for fuel. Your wide band is telling you what's up - you need to pay attention to it.

So, a couple of things...

• Get a good OBD II system, one that goes beyond looking at engine check lights and will let you see things like Long Term/Short Term Fuel Trim. These are all excellent:
  http://obddiagnostics.com/
  http://www.auterraweb.com/
  http://www.obd-2.com/
  
  
• Get to know the SplitSecond and understand how to get it to work for you.
  
  
• With that pulley, you're going to have to get more fuel into the engine. That means the Walbro and injectors.

Good luck!

Jeff B. in Michigan

Hi Mark,

I wonder what you mean "deadly" combination? My air to fuel is exactly what it should be. I am running 12.5 to 1 AFR almost flat through the entire 1/4 mile run. Most tuners will agree this is the proper setting for max performance and safety. You can see the factual data on my WebPages, specifically this link: http://n8rws.com/TRD12.htm shows actual wide band AFR data through the entire 1/4 mile run along with the values I use in the fuel map. As you can see, the AFR is fine (notice with the BAP at "50" I can get it to run too rich @ 10.8 to 1).

I am experiencing two problems:

1) The truck surges when in second gear low RPM very slight load.
2) Occasionally, the truck will "run out of gas" on idle. This is a rare occurrence but is annoying. I can see it happening on the wide band O2 meter, essentially the truck runs out of gas. If I tap on the gas pedal it immediately corrects itself (the AFR goes to Stoich and it idles fine).

Andy and I seem to have the same problem (surging) and our mileage is around the same. I do not believe it has anything to do with the injector size, I wonder if some sensor or perhaps that servomotor in the throttle body is going bad.

Thanks again for the information

midiwall

Hi Jeff;

By "deadly" I was referring to what I was thinking was cause the symptoms. The problem being "deadly" in that it's causing the engine to cut out.


I agree that it sounds like you've got the AFR dialed in for WOT, but there's definitely evidence of fuel delivery issues elsewhere. The surging and the AFM are showing that.

It could be the TPS or the servo motor, or it could be settings in the SplitSecond maps. What if you really crank out the fuel around idle?

Have you checked power to the SplitSecond? If it's on a switched lead it could be picking up noise and burping. I had very similar issues with my SMT when I first installed it. Moving to a dedicated constant-power run helped loads.

It may also be the fuel pump... Not that you need the Walbro, but again, something is starving you for fuel at random times.

Actually.. that's a side point... Can you make the stall happen or is it really random, but confined to a certain area of the maps?

Have you done the deckplate mod, or something else to get more air into the intake? Obviously S/C is gonna suck a ton more than NA, but you may be stiffling it none-the-less.


Random thoughts...

Jeff B. in Michigan

Mark,

I did try to cut & add fuel at the low RPM but it did not work, now it is set to the "stock" value of 10 at idle RPM .

The problem does seem to be very random as far as day to day but I have noticed that on the random "day" that it occurs, it happens at the same stopping point. For example, on "the day" it will happen every time I come to a stop before turning the side street I live on.

I was starting to think about the feed power, it is currently going through a switch. I also wonder if it is picking up some interference from the box it is mounted on top of. (I mounted the FTC in the console just in front of the shifter. It is sitting on top of some other black box).

I think I am going to try to change the FTC power to another source. I installed a relay, which is engaged when I turn the key on and then provides a "heavy" source of 12V to the wide band O2 meter. I may try to tap into this source for the FTC.

Thanks again for the information