Wow, this sounds amazingly like the issue we were having with the 3SFE Camry's that I ended up curing by replacing the ignition coil and putting diaelectric grease on the posts. I don't know if it applies here, but the symptoms are identical.

 

my truck does the same thing. it is like at 3k it has a power band and accels very fast kinda puting you back in your seat. i have done every thing you have done as well. i have been told that my problem is because i have 35 inch tires and because of the low torque in the engine once the truck gets rolling and the rpms kick up the horspower sets in and gets moving. but im not sure it did seem to happen once i put the larger tires on the truck. but if this has happened to any one else and they have fixed the problem i would sure like to no about it.

 

Same Problem

Nighttrain - I have a 94 Xtracab, V6, 4x4 5-speed, 297k, with the same problem you are describing - lags/hesitation/stumbles after the engine is warm. I am very interested in hearing what the answer to this one is. I've changed the plugs/wires/coil/dist cap and rotor, and put on all new vacuum lines as well, and cleaned the throttle body. Nothing seems to help - it still acts weird after the engine temp comes up.

I haven't done the PCV valve yet - from all I hear it's a real PITA to get to on these engines. I am wondering if its the 02 sensor, but I would like to hear if anyone has solved this type of problem before I get one.

Wiccanferret - thanks for the suggestion regarding the dielectric grease - I will try that today to see if it helps!

Regarding the power jump just past 3000 rpms - my truck has done that since I've owned it (almost 4 years). It had stock tires and wheels on it when I bought it, and since then I've put on a set of toyota alloy wheels (the 4 spoke type you see on 4-runners) and larger 31x10.50 tires. It still has that same power jump right past 3000 rpms. I always thought it was the way the ECU was programmed from the factory.

Anyway - I'll be interested in hearing what others have done with this problem!

Gil

 

Clean throttle body & replace oxygen sensor PERIOD.

Lots of city miles combined with low octane fuel & no Techtron fuel additive (cleaner) creates excessive throttle body carbon build up (gunk) so throttle body must be cleaned.

To clean the throttle body remove the air intake hose and examine the intake and throttle body for excessive carbon build up if found then buy a can of throttle body cleaner labeled "safe on oxygen sensors,TPS's and catalytic converters" do not use carb cleaner make sure your engine is fully warmed up prior to using as when the throttle body is hot it dissolves the carbon easily and quickly.

The labels usually specify to park the vehicle at ground level (0 degrees,no inclination) and have the engine running but I disagree I instead park the vehicle on a hill facing down and shut the engine off and hold a rag below the lip of the throttle body and poor the stuff and use a tooth brush. You can also use "Sea Foam" the best engine cleaner:

http://www.seafoamsales.com

available in Canada through UAP/NAPA Auto Parts Stores.

The oxygen sensor is replaced for free in the USA only when the vehicle reaches it's first 80 000 miles regardless of the age & number of owners as stated in the factory owner's manual in the maintenance section,some Toyota dealerships are reluctant to replace it for free if that happens contact the Toyota regional head office for your region where they will give your local dealership 48 hours to comply.
On average the oxygen sensors should be replaced every 6 years or 100 000 miles or so which ever comes first as stated in the owner's manual,warranty booklet and factory service manual.

Symptoms of a bad o2 sensor are poor gas mileage,hesistation in acceleration,worse emissions,and in severe cases after the stat opens the engine can no longer maintain stable 750 rpm (with manual 5 spd tranny) idle and the engine begins to stall.

The 02 sensor is designed to function once the vehicle has warmed up which is about after 10 minutes where the thermostat begins to open at 190 or 195 degrees Ferenheit depending on thermostat then the vehicles ECU system enters what they call a "closed loop system" then the exhaust manifold's temperature reaches 400 degree Ferenheit (I think)that's where the sensor starts to do it's job which is usually when the thermostat first opens up then the oxygen sensor senses the ratio of air to fuel and sends a signal back to the ECU then ECU compensates by increasing or decrease the open time for the fuel injectors to pump fuel.

So usually the problem of stalling shows up after about 10 minutes of driving or so.Many folks think that the o2 sensor is bad but an exhaust leak can cause excess oxygen to enter the exhaust system thereby fooling the sensor into thinking there is too much oxygen,there are other problems that could cause it to give false reading such as a vaccuum leak.

If you discover that the o2 sensor is bad and it is not under warranty then from my/others experience/research purchase an o2 sensor in the following order:

1)Toyota (NipponDenso now called Denso)
2)Denso aftermarket (Same as original but sold aftermarket)
3)NTK (oxygen sensor division of NGK)

Available at:

http://www.1sttoyotaparts.com/partscat.html (10% shipping by Fed Ex or free shipping with $100 & over speak to Roger at 1-888-271-3948)
http://www.Toyotaparts4U.com
http://www.toyotaofplano.com
http://www.densoaftermarket.com
http://www.ngksparkplugs.com
http://www.pythonparts.ca

Sidney® ™
Repairs TV's,VCR's,home/car audio out of my apartment
E-mail:sidneybek(at)yahoo.com
Dartmouth,Nova Scotia
Canada
1985 Toyota 4-Runner,solid front straight axle,factory cruise control,sunroof,22R-E,W56,RN60LV-MSEK,with 256 000 KM

http://web.archive.org/web/20040312...15/www.herald.ns.ca/cgi-bin/home/displayphoto?2002/12/22+126.raw+1019+Business+

http://web.archive.org/web/20040229...5/http://www.herald.ns.ca/cgi-bin/home/displaystory?2002/12/22+126.raw+Business

 

Well I continue to have this problem...bit of a rough idle, intermittent stumbling and hesitation at lower rpms, and still the power surge anywhere between 3-4k rpms. Truck is still very much drivable, but there is definitely something wrong, that is why I want to get this fixed and it is bothering the hell out of me.

I am going to check the air flow meter, coolant temperature sensor, fuel pump and delivery including injectors (filter was just changed). Other than that, I am not too sure what else this could be...what would the ignition and its components have to do with this, anybody know?

 

have u checked the timing?

 

O2 Sensor?

I ordered an O2 sensor earlier this week - came in today. I'll install it this weekend and let you all know if it helps.

I'd be interested to hear if anyone else has that power surge just above 3000 rpms - mine has done it since I've owned it and it never was really a problem since the truck ran fine until a few months ago when it started act up.

Anyway, I'll post after the O2 sensor install....

Gil

 

Fixed for now

Sorry for the delay in posting - things got busy round here!

OK - I put in the new O2 sensor and it made no appreciable difference. The truck still ran like crap, missing and bucking. At that point I decided to go back to basics and went and bought 6 new NGK plugs (nothing fancy, just the $2 plugs). I gapped them to the specs in the online manual, and installed them. The old plugs didnt look too bad - they were splitfires and had a clean burn on all of them, but I did notice the gap was at .060 or better on most of them, which seemed a bit big. The new ones are gapped at .031 (if I recall correctly, I'd have to check the manual again).

Anyway, I put in all new plugs, checked all the ignition wires for continuity and resistance (again per the online manual) - everything checked out OK. The wires, cap and coil are all relatively new.

After the plug change, I drove the truck and to my amazement it ran smooth with no miss, bucking or any of that crap. It's been more than a week now, with a trip to upstate New York from Baltimore and still no problems.

I don't know if it was a combination of the O2 and new plugs or what, but things are definately fixed (with my fingers crossed).

Thats my story!

Gil

 

Folks - I had the exact same problem as described in the first post in my 1994 Toyota Pickup Dlx with the 22RE Engine.

I pulled the distributor cap and found that it and the rotor button needed to be replaced. I did so but it did not solve the problem. I then pulled the spark plugs and found they need to be replaced as well (dire need of replacing actually). I replaced them with plain Jane NGK plugs with a .031 gap. While I was at it, I took Sidney's advice and cleaned the throttle body with the carquest generic brand of cleaner. Problem solved. Runs smooth with no hesitation or lag in power.

Like Gilbey, my truck had splitfires in it with a huge gap. I think SF may require a larger gap for a better burn. Still, these were in pretty shot condition and in dire need of replacing.

All total, I spent less than $40 to get it fixed. I held off on replacing the O2 sensor because I wanted to see if the above steps would fix it before dropping $100+ dollars on the new sensor. If it starts acting up again, I'll replace the sensor and see how that goes. So far, so good!

 

Same problem/opposite conditions

It's great to see folks fix problems encountered with their Toyotas. I know how frustrating it could be.

Perhaps someone can help me. I get the exact same symptoms in my truck, BUT when it is cold. Once the truck warms up, the problem goes away.

I usually let my truck warm up for about 4 or 5 minutes before I start driving.
Even after 5 minutes of warm up, when I step on the gas, I get hesistation and at times the truck dies. The problem seems to go away when the temperature gauge needle is at about half way on the scale.

I recently replace the spark plugs, dist cap, rotor, wires, fuel filter, air filter, checked the timing, checked for vacuum leaks. Every thing is either new or been inspected without finding a problem. Last night the check engine light came on throwing a 71 code (EGR related). I am wondering if the EGR could be causing this problem.

Any help would be appreciated.

 

If the code showed an EGR problem, that's where I would start. A clogged or fouled EGR would cause problems with a cold idle. It actually can cause idle problems at any temp, but they are much more noticeable when the engine is cold. Pull it and clean it and see where that gets you. While you're doing that you may want to clean the throttle body (see earlier in this post). A dirty throttle body usually will cause hesitation at warm temperatures, but buildup on the EGR usually means buildup on other places.

Some other things to consider would be intake air temperature sensor, coolant temp sensor, or the idle air control. Since it threw the EGR code at you, I'm willing to be that's where your problem is.

 

The EGR is only supposed to operate above a certain coolant temperature. Perhaps the sensor or the valve itself needs to be replaced?

 

Hence my mentioning the fault may lie with the coolant temp sensor if cleaning the EGR doesn't fix the idle problem.

The EGR is only supposed to work above a certain temperature, allowing exhausted gas to be recycled into the combustion process. This actually cools the combustion temperature inside the cylinder, making the process more efficient and reducing the amount NOx emitted. The problem though is that buildup on the valve can cause it to become stuck open essentially causing a vacuum leak. This leads to to insufficient combustion, rough idling, hesitation, and even stalling.

It can also become stuck closed, also leading to problems. Because of the lack of NOx in the mixture, the combustion temperature becomes higher and can lead to the fuel mixture igniting prematurely (before fully compressed). The affects the timing of the combustion process. If this has happened, you may hear a slight knocking or recognize a surging idle (different from a hesitation idle) in some models.

Given your description and the engine code, my best is the EGR valve has buildup and is stuck open. I'd start by pulling it and giving it a good cleaning. This is the cheapest and easiest first step. If that doesn't fix it, start with the coolant temp sensor, then the air temp sensor and finally the idle air control sensor. The service manuals linked in at the top of the pickup forum can give you directions on checking each of these sensors.

 

Egr

I checked the EGR for proper operation according to the service manual. Everything appears to be working fine. There was no build up at all.

I also checked the EGR vaccuum modulator. This one had some build up and the filter was quite dirty. I cleaned it and checked for vacumm leaks again, but everything looks fine.

I bet it will be the coolant temperature sensor since it takes a while before the actual temperature needle moves. As soon as the temperature needle moves to about 1/4 of the scale, the problem goes away.

I will remove the coolant temperature sensor tonight and replace it tomorrow.
Update to come tomorrow

 

As the EGR was clean, you're best best is the engine coolant temperature sensor. If that doesn't work, let me know and I'll dig a bit and see what else it could be.

I want to say that a coolant temp sensor should have triggered a different code on the CPU, but I can't guarantee that. It's possible the EGR has failed all together. Maybe not as it appeared to be working. But on occasion, an EGR can appear to be working when running the test, but still have failed. My only reasoning is that it tripped the 71 code. If the engine coolant temperature sensor was bad it should have tripped code 4.

I'd still start with the coolant temp sensor as I imagine it's a lot cheaper than the EGR. Hope it helps.

 

no change

Well, I replaced the coolant temp sensor and the truck still hesitates when cold.

Maybe this is related, but I am not sure. I received the renewal notice from the Department of Motor and Vehicles. I took the truck to get tested and if failed. The guy said it is considered a "gross poluter". He tried to help me and noticed the EGR valve was working fine, but the vacuum supply is not there.

I explained the motor was taken out recently and he thinks whoever put the motor back in the truck misconnected the vacuum lines from the VSVs to the EGR and other vacuum inlets.

My truck has 4 very similar VSVs. I just don't know which one is the one that should supply the vacuum to the EGR. Standing next to wheel on the passenger side I see 4 VSVs or look like VSVs.

Does any one know which of these is the one that connects to the EGR valve?

Thanks