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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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#3 ·
After writing that entire post, I realized that I did not mention the fact that the engine does not have an audible ping anywhere in that rpm range, as opposed to the low rpm ping which you can't miss. I say this because if I were hearing a ping up there, I'd think the factory ecu was taking out timing for that reason, but for the ecu to pull almost all of the timing out, I'd expect to hear a lot of audible ping...

This problem occured before the URD unit was installed and is not always the same severity/ occurs worse at cooler engine temps so I feel it must be an input of the factory computer...

Does the factory ecu truly not use the knock sensors below 3000 as I have read elsewhere? If so, it seems that the ecu receives a knock signal as soon as the knock sensors are enabled. Wouldn't the ecu typically pull only a degree or two out at a time and continue to pull as ping exists? Would it be possible to unplug the knock sensors for a test run to determine whether it is truly the input from them causing the retard issue?
 
#4 ·
It almost seems like you are flooding the engine, since you say the AFR gets down to the 9's at the rpms you are having trouble at. Also it seems like the problem started when you put the big fuel pump on. I would track back your steps, and check all that first, starting with the fuel regulator..
 
#5 ·
Have a look at the fuel trims. Boost leak can cause excessively rich conditions. How much boost are you seeing around those RPMs? Other areas are the AFR sensor (that you replaced when?) and fuel injectors. Since you're seeing excessive fuel, I doubt the fuel pump is the issue.
 
#6 ·
I'll have to fire up the laptop to see the boost numbers at 3200, but as I remember I was seeing full boost (8.5 psi or so) by a little over 2000 on...

What exactly is boost leak? The AFR sensor (upstream O2?) was replaced last week, no change in performance from original O2....

What sort of diagnostic can be done to verify injector performance? Plug check?
 
#7 ·
A boost exists in the areas after the blower and before the motor, as you're aware. Leakage can occur at flanges, fittings, hoses, etc. The MAF sees a certain amount of air flowing through it, and if there's a boost leak, the motor sees less air than the ECU sees. The motor still gets what the ECU thinks is the appropriate amount of fuel, which results in a rich mixture. If there is a boost leak, I would expect the fuel trims to be in the negatives.

Maybe you should contact URD.
 
#8 ·
I am having the same issue

I know this is kind of an old thread pull, but thought it would be better to post here than starting a new thread.

First my stats:

5VZ-FE w/ Black S/C
URD 7th injector kit w/ ARR calibrator
90 LPH fuel pump
IK22 Spark plugs
URD 2.2" pulley
TRD 60 degree T-stat
Stock air box w/ deck plate
Airaid MIT
AFE Pro Dry filter
Completely stock exhaust from manifold back
285/70R17
Stock 4.10 gears

The Problem:

I am having pretty much the same problem as the OP:
-No HG/LR ping

-Power is fine below 3K RPM but once above 3K (knock sensors active) my timing drops down to ~9 and as low as 6 degrees of advance and AFRs read in the low mid 10s.

-At no time do I hear an audible ping, but I have a lot of cab noise from the S/C intake and mud tires so it could possibly go unnoticed.

-This happens mainly in 4th gear at WOT but it has happened at WOT in lower gears at higher engine loads when pulling slight hill. Scan gauge always seems to read 99% load when this happens, but it dosn't always happen when reading this amount of load.

-The problem is more prevalent before the engine is at opp temp and seemingly at lower ambient air temps.

-Fuel trims are an aggregate total of -2 at idle and stick pretty close to that throughout closed loop.

-EGTs are always higher when this problem happens as well i.e. cruising at ~80 MPH on the freeway for several min, then WOT, Max boost, with EGTs approaching mid 1400s, AFR mid low 10s and, timing retards ~9 degrees, and I cannot accelerate past ~3300-3500. If I decrease the throttle below WOT I can accelerate past the problem area then push pretty hard, but it is time to slow down at that point...

From URD:

I have spoke with URD about this a couple of times and one possible explanation I was given that seemed to closely fit my problem was regarding a compression ratio problem with some of the 5VZs. Here is what they have seen: At about 3200 RPM the engine would knock and the ECU would retard timing and dump fuel. A thicker head gasket was installed to reduce static compression enough to solve the problem in that situation. The only thing that doesn’t fit is there was an audible knock in that situation and I can hear none.

What I have tired:

1)Seafoam through intake to try and remove possible carbon deposits and eliminate hot spots.

2) After being told about the compression problem I removed the 2.2" pulley and installed the stock pulley to reduce effective compression. After running this way for a week I never noticed the problem, but after a while I started pushing the engine harder and finally on a particular freeway on-ramp (pretty heavy incline) that always seemed to induce the retard problem it happened again. I am still running the stock pulley because it seems to reduce but not eliminate the problem.

3)I am concerned at this point that the engine may be knocking, but I may not be hearing it so I have started to treat the problem as such. I had to pull my electric fans for some work and decided to try to replace my NAPA #17 170 degree t-stat (this t-stat did pretty much nothing to reduce engine temps it still ran at about 186-188 degrees and I ran at 190 with the stock) with a TRD 160 degree while I was at it. That reduced my coolant temps to 168-173. This really hasn't had any effect on my issue from what I can tell.

Plan of Attack
1) The low AFRs kind of concern me as I know they are too rich. I am thinking that since I am in UT at about 4500' and the URD 7th kit is base tuned at sea level that I need to adjust my fuel map accordingly. I would think that a richer AFR would prevent knock if anything though. I am going to shoot for about 12:1 throughout my open loop, but I would think going leaner would only increase the likely hood of pinging.

2) I am also strongly considering a WI kit; probably an Aquamist 2D kit. Cooler EGTs and CDTs should help suppress any detonation present and the octane boosting characteristics of the Methanol should do the same.

3) I also added a bottle of octane boost to my most recent AMSOIL order (which came today) I am thinking about running that in my next tank of gas to see if that solves the problem. If it does I would think that would be a strong indication that I am actually having detonation problems. I have never used an octane booster before are problems that they can cause? I am just planning on running the one bottle to see what effect, if any, it has on this issue.

4) I am planning on regearing (probably to 4.56) this month. I am wondering if a reduced load on the engine would help fix this problem. It may only move the timing retard problem to a different section of the power band though, I am not sure.

If anyone has any experience with this issue or suggestions please chime in. I know my gauge readings are kind of vague let me know if additional info would be helpful. I am going to try to get my gauges hooked up aux inputs on the Splitsecond unit soon so I can have some rough data logs to look at with more accurate numbers and maybe pin point the problem area data better. It is hard to watch all the gauges and the road :)
 
#10 ·
2) I am also strongly considering a WI kit; probably an Aquamist 2D kit. Cooler EGTs and CDTs should help suppress any detonation present and the octane boosting characteristics of the Methanol should do the same.
Sorry I didn't have time to read all your posts, but let me just say I think this would be a good idea. It will also clean the carbon out too.

I will check my timing numbers to see what I have.
 
#9 ·
Octane Boost Results

So after my last fill up I ran my tank down to just under 15 gallons and added the bottle of Amsoil Octane Boost I ordered.

Stock Pulley
After adding the AOB I had a long drive home on the freeway which also involved a long climb up a fairly steep hill. I still had my stock pulley installed and usually WOT/Max boost up even a slight grade would induce the timing retard problem I was having. However, I was able to climb the hill at max boost for long stretches (other cars were in the way ;)) and my IGN Timing never dropped below 13 degrees and was usually around 15, but my EGTs did reach 1500 (at Cyl#1) and I normally try to keep them under 1450. EGTs seem to climb more rapidly with the octane boost I noticed. A major improvement in timing advance from 6 and 9 degrees. Also my AFRs are slightly higher, high 10s and low 11s at WOT.

2.2" URD Pulley
Yesterday evening I put my 2.2" pulley back on to see if the AOB would allow me to run at increased (~1-1.5 PSI) boost. I was able to make it on the freeway a couple of times after installing the pulley, and there was no change in timing advance between the stock and URD pulley. However, this morning on my way to work I took a longer stretch of freeway and noticed some hesitation while in second gear WOT on my way up and inclined on-ramp. When I looked down at my IGN timing it was at 6 degrees and dropped to 3 Degrees before I quickly got off the throttle. I eased into it again and again the hesitation, timing retard and I think I actually heard some knocking this time.

Results
So the AOB allowed me to run the stock pulley fine without any knock, or timing retard and slightly increased my AFRs, but also seems to have increased the rate at which my EGTs climb. AOB will still NOT allow me to run the 2.2" pulley without timing retard.

Moving Forward
Anyone have any suggestions on what I need to do to fix this problem? I don't really want to run octane boost all the time, doesn’t really seem like a solution. I may have some carbon deposits in my combustion chamber or on the pistons (possibly enough to increase static compression enough to cause a problem ??) and running the octane boost may be enough to help remove residual deposits. Not sure how likely this is though: I always use Chevron gas, run a fuel system cleaner (Amsoil PI) every 4K and recently seafomed the engine so I would think it would be pretty clean ... but maybe?? The WI with 50% meth may work but not sure how much it will increase my octane in boost, and if it will be sufficient to run my 2.2" pulley or not. I am sure it will tame my EGTs so maybe the combo of lower EGT and increased octane would do it. The steam cleaning effect would also do a good job of cleaning the combustion chambers.
 
#13 ·
Yes I went to 4.56 from the stock 4.10. It did help a little bit because it reduced the load on the engine at WOT, but I still have problems with knocking in some areas. I have been messing with the tuning lately and have my OL AFR dialed in pretty well; it stays between 11.5 and 12:0 consistantly now.

I am still struggling with the timing though. It is a tough to get the right balance between enough retard to suppress all the knock, but not retard it too much in order to keep the EGTs at a sane level. I am convinced that moving forward with the Aquimist kit and a 50/50 H20/Meth mixture will solve my problems because of the increased octane, cooling and cleaning properties it will offer.

With it installed I am hoping I will be able to reduce my timing retard due the cooler CDT and increased fuel octane. The combination of WI intercooler effect and advanced timing should reduce my EGTs and hopefully everything together will get rid of my knock once and for all. Should get a bit more HP as well. After it is installed I may go ahead and pay for a professional tune also...
 
#16 ·
Im also in the power loss problem club.

2003 Tacoma doubble cab 4x4 auto
second gen s/c
urd 7th injector
2.2 urd s/c pulley
TRD headers
magnaflow exhaust
stock intake

3200-3500 rpm at freeway speeds WOT the timming at short term fuel drop close to 0.

tried octane buster
then went back to stock pulley, no change.
next is 100 octane fuel because CA fuel sucks.
after that im considering trying the thicker head gasket or crate motor.
 
#24 ·
From my conversations with Gadget it is my understanding that the static compression on these engines can sometimes be higher than it is supposed to. Not a big deal N/A, but when you introduce boost that can cause the engine to knock similar to what we are experiencing. He told me that thicker head gaskets solved the problem for one customer in the past.

If you have a dyno shop with a tech you really trust you can see if he can work out the knock with a good tune. After I get my WI installed that is what I am going to try.
 
#27 ·
Do Not Remove Knock Sensors

You must leave the stock knock sensors in place. The ECU is constantly adjusting timing according to the engine knock threshold which constantly changes with operating conditions. The knock sensors and ECU are doing exactly what they are supposed to be doing, and you shouldn't try to interfere with that in any way. If you remove the knock sensors, or impair their ability to detect engine knock and report it to the ECU you are setting your engine up for a catastrophic failure. The problem is the operating conditions that are causing the engine knock; not the knock sensor's or ECU's detection of the knock.
 
#28 ·
The Idea came from a toyota dealership. So I brought up the idea with my mechanic and said it was worth trying. I have heard of people pulling knock sensors out of mustangs and other vehicles for the same reason. I thought the knock sensor just pulled timming an fuel when it detected a knock/ping. I know the ECU is constantly adjusting timing and fuel depentdant on many factors, but is it really dependant on the knock sensor? Anybody else have any thoughts on the topic?
 
#30 ·
I'm in the same boat.

2000 Tacoma w/ URD 7th
On the west coast at S.L.
Stock exhaust
IK22 plugs

After recently installing the 2.2 pulley I started having this issue too. I experimented with the timing map and ended up pulling up to 8 and 9 degrees in the 3000 to 3500 rpm range between 7.5 and 8.5 psi. That appears to have helped the situation but now I have a huge power surge while acclerating past 3500 rpm with the abrupt change in the map. When I smooth the timing numbers out, the truck loses a lot of its get up and go. I didn't notice this problem with the stock pulley so I'm thinking of going back.
Bummer..
 
#33 ·
I don't have an egt gauge, but my AFR stopped going way rich and settled in at 11.5 with the additional retard.

I never had this with the stock pulley. I hope going back doesn't give me the same problem. With the exception of taking off the heads to install thicker gaskets, maybe WI is the fix?
 
#34 ·
I have the same issues with my 2.2" pulley. When I dialed in that much retard (~8 degrees) I started to see my EGTs (TC in manifold at cylinder #1) climb extremely fast though. At WOT I could reach 1450+ easy! It would keep climbing if I didn't get out of the throttle. Right now I am still running with the high timing retard values, as I am taking the high EGTs over knock as the lesser of 2 evils; however, I have to keep a real close eye on the EGTs and take it easy. Just something you may want to think about since you are blind to your EGT with out a gauge.

I did try dropping back to stock pulley, and the reduction in effective compression did help with the knocking, which prevents the ECU from dumping timing, which prevents the increased EGTs. However, the problem was still present with the stock pulley.

WI/Meth is the route I have been planning on going. Hopefully cooler charge temps, and the increased octane of meth will allow me to advance my timing. All of which will hopefully recuce EGT and eliminate knock. The carbon removal properties should help too. I have been busy with work lately and the truck has just been sitting for a while though. I already have some of the WI components installed and I am hoping to give URD a call this week and order up an Aquimist kit. I am just trying to work out exactly how I want to set up the entire system. Right now I am trying to decide between a 2D kit (with some added fail-safe modifications) or maybe a 2C kit installed with a DDS3. We will see; right now I am not sure how important the ability to monitor the actual flow rate of the WI system is to tuning the kit to work with your fuel system.
 
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