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Severe bog/timing retard probs at 3200

16K views 49 replies 13 participants last post by  jonsangel 
#1 ·
Hello All, Been lurking a while and can't seem to find a suitable solution to my latest issue by way of search, so here goes.... Forgive me for being long winded....

The vital stats of my truck are:
'01 Tacoma Ext Cab TRD 4x4 3.4L Manual
TRD S/C, URD 7th Injector, 2.2" pulley
Doug Thorley Headers/ Exhaust
De-Cat, URD O2 Sim
NGK AFX wideband O2
160,000......

I installed the TRD S/C about a year ago and, aside from running the truck with no fuel upgrades and the low rpm ping issue, had a good running truck...
My problem begins at the process of attempting to eliminate the low rpm/ high load ping issue. I ordered the URD 7th injector kit, Headers, Exhaust, and 2.2" Pulley this fall and installed the components as I had time, as the truck is driven on a regular basis.

First I installed the higher volume Walbro pump and drove the truck for a few weeks with no new problems. I then installed the Headers and exhaust (de-cat was done way before all of this) to get the shiny parts out of the view of my wife.... No noticeable problems that evening, but the next morning with the engine not fully warm I got on the highway to head to work. As I accelerated in third gear to 3200 rpm or so, the truck essentially would not allow me to rev any higher. The truck warmed up and the problem seemed to disappear.

Over the next couple of weeks, the truck began to do it more often, more so when the truck was cold, more so in the higher gears....


I finished the 7th injector install and installed the 2.2" pulley because I figured this problem may go away with a final tune and more fuel. It did not.... at least the high load ping was easy enough to tune away!

With the truck fully warm, it does not seem to "bog" unless I am in 3rd, 4th, or 5th at WOT and right around 3200. You can get through the hesitation and by about 3700 and the truck seems to run strong from there until redline.

What it is doing is pulling a lot of timing out right there ( I have graphed it out with a scantool, I do not have a screen shot to reference now...)

The AFR's dip way low through this area (sometime in the 9's) as well, but I am told this would be consistent with retarded timing and inefficient burn... From 3800 to redline the AFR's climb into the mid 11's.

I have installed a new upstream O2, cleaned the MAF sensor, checked timing belt tension and timing, crank timing, greased the driveshaft, washed the truck, etc...

I have not checked the knock sensor signal or fuel pressure (with the engine running strong up top, I don't see it being a fuel problem).

Any ideas about where to go next? I was thinking about getting some timing plots snapshotted, and maybe a video of the occurence just for clarification.
 
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#36 ·
WI Installed

I finished installing an Aquamist HFS-3 Kit over the Thanksgiving holiday weekend. I set the timing map on my URD 7th Injector AIC back to the factory set up (more advanced timing) and did some driving with a 51:49% Water/Meth mix. So far the results are good, EGTs are cooler and MOST of the knock is gone. I still have some tuning to do. I started on the conservative end of for WI flow (~300 cc/min) so I think will increase that incrementally up to ~400 cc/min. I also will need to adjust my AFR again now as well as pull some timing from the 3-3.5K RPM areas of my map to suppress some knocking there. At 3.5K RPM and above the truck pulls better than it ever has. Overall, initial results seem promising.

I'll post more updates after I get all the tuning complete.
 
#37 ·
Glad to hear you have positive results! I have since re-installed the 2.2 pulley, reloaded the stock timing map and made very small increases to the retard values in the 3k to 3.5k range (~.5 degrees additional). I also replaced my Denso copper plugs with the NGK Iridiums. The knocking has stopped for the most part. Once in a while for whatever reason, I'll still get it in the 3k - 3.5k range but very seldom. I'd like to figure out what's causing this to happen on an intermittent basis...
 
#39 ·
I wanted to bump this thread as I am having this problem as well. Reading through the thread it's difficult to see what the actual solution is. Was the solution just to change the timing? if im running rich that means the timing is too retarded but I have the stock map with a 2.2" pulley so that doesn't make sense

My setup:
2004 3.4L V6 Dbl Cab Tacoma
S/C, TRD 7th, 2.2 pulley
TRD headers
Cat-Delete
Stock TRD fuel Map

My Problem:
Truck bogs down around 3k rpm only under high load. I notice it most when it shifts up into 3rd. AFR will read in around 9.5. No audible knock.

I tried unplugging the 7th injector and that didn't really do anything.


PLEASE HELP!
 
#40 ·
HELP!!

Exactly the same problem..
0-3000rpm, all lovely
3000-3500 PURE EFFING HELL
3600+ pushes me back in my seat nicely

I have only found this thread with people displaying the same issue!! But no clear solution!?


2003 Toyota Hilux (Australia)
5vz-fe
TRD Supercharger
URD 7th injector Kit (with enrichment)
98RON Fuel
Headers
Highflow everything


My first thought was, could bad enough valve clearance make the knock sensor lose its shit? But I have a knocklite on my car and it only activates HARD in the 3000-3500rpm range..

So I can confirm that it IS the knock sensor losing its absolute shit.. but why? and why does it clear up so nicely?? surely if it was hot spots or compression it'd occur at the same boost level and load, not only 3-3.5K rpm.

WHY?>?

please, any assistance would be amazing. I'm starting to get hemeroids over this shit
 
#41 ·
I havent posted in here cause i still havent found the cause. After talking with someone we determined that the fuel pump i had might have been overrated for the fuel system which would blow out the fuel pressure regulator and when im on the gas the regulator cant release enough pressure and the truck bogs. So after that i replaced the pump with a properly rated walbro. That didnt solve the problem however. I think i need to replace the regulator too so thats the next step. That's interesting about the knock sensor though. Wouldnt the truck throw codes if it was knocking? I another cause i read about is the truck going into a "limp" mode which has to do with sensors too
 
#42 · (Edited)
Interesting about the pump

What caught my eye is the description by the first guy: It first happened early one morning

Exactly the same here. never had any issue. then one day.. on a downramp onto the freeway one cool morning, it first occured. Then slowly more and more regular until now 4th and 5th gear (manual) it "pulls timing" at high load ONLY between 3000 and 3700ish

It must be to do with the stock ECU.. but what?

Is it a condition learnt by the ECU that triggers it?

I have currently gone back to "stock" maps on the URD system and it still occurs, but less than before. I even tricked it into not happeneing today by easing the throttle on once already above 3000 rpm. To me it happens the worst when i am WOT coming from below 3000. Say i plant it a 2500rpm. It accels nicely.. then 3000 comes along and FLOP.. linger though the shit (9-10afr, still 7psi boost).. then pulls again above 3700 (back to 11-12afr, still 7psi)

Has anyone overcome this?

Does anyone have a setup WITHOUT the problem?? If so what truck do you have?
Im starting to think my ECU cant handle it and i need to change to a different model ie prado/tacoma/4runner (currently 2003 hilux)


OMG what if we are exceeding the flow of the Airflow meter. and the last dying stages of closed loop loses its shit before going back into open loop and behaving??
Edit: no way.. it still responds correctly at higher flows after 3700
 
#45 ·
For years before the charger mine always ran 10w-40.. used 5w-30 when it was supercharged.

I looked in a cylinder today with a boroscope and saw some uglyness. There is a shit tonn of carbon built up in the combustion chamber.

It made me think, why did this problem start to appear and get worse and worse. Could carbon buildup cause the problem? I use a pretty cheap oil at the moment so I'm going to do the best I can at seafoaming the carbon out and then switch to a good synthetic oil. So far after one rough seafoam the lagging section is a lot better. I plan to get rid of more carbon and hopefully the problem goes away more.

Might be onto something, will report back
 
#47 · (Edited)
Biggest improvement ever! Will report back more as time goes on

Edit: sorry I'll elaborate..

2nd seafoam: took all spark plugs out and foamed directly into each cylinder. Used about 3 times as much as directed so be cautious. Ran the engine over before putting plugs back in to spit out as much crap as possible and it was still a pig to start.. recommend WOT cranking when you try and start to help clear it out.

I think resetting the ecu is as important as the actual cleaning after making such a change to the engine. Mine takes >2 hours with battery off and ignition on to properly reset

Car idles dead smooth again, like I could balance a coin on it. And shit it feels so so much better to drive :D

Plus the section between 3200 and 3700 appears to be clear! I drove it for 40 minutes without it happening and I'm super excited :p hopefully it doesn't come back.

If this is the fix I will only use full synthetic oil and develop my own crankcase ventilation system that doesn't feed oil vapour into the intake so there is a lot less chance of this problem coming back.

Hopefully I'm not celebrating too soon!
 
#49 ·
I had a 2.0" pulley on my stock 2001 5spd 3.4l with no tuning and it made plenty of power above 2500 rpm. Below that if I went into boost it would bog due to the amount of water/methanol (-20f windshield washer fluid) I was hosing into it. So you can make knock go away with enough water/meth. I just drove it either light enough throttle to keep it below a couple pounds of boost or get the rpms up and hammer down with the full 12.5psi.

When I get time/money I'll fix the rear bearings in my supercharger and put it back on with a 2 stage water/meth injection system so I don't loose the low end due to too much water going in. The stub ends of the rotors got chewed up when the rear bearings failed, so I'll have to figure out what I can do to machine them down and use different bearings. Running the bearings directly on the shaft without a replaceable inner race was dumb on Eatons part.
 
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