Surging at slow speeds!!!

[tomlexa1983]

Hey guys I need some help. I recently just bought a 1994 Toyota 4 Runner. It has a 3.0V-6 and a 5 speed and is 4x4. I love it except that when I am driving along and just trying to maintain speed, it surges and snaps on and off the throttle. I don't even move the pedal but it's either on or off, there is no in between like there should be. I adjusted the throttle cable because is was way loose and that helped a little bit but it still does it and it's driving me crazy!!! I don't know what else to do so PLEASE help me before I pull my hair out!!! Thanks guys -Tom-

 

[hickory]

surging

I had a 94 nissan pickup that did that for a while. It was the O2 sensor. I also had a short in the wires to the fuel pump another time. I've not had that problem with my T4R.

 

[Sidney]

My wild guess would be TPS=throttle position sensor area,so pull ECU (EFI computer codes) first, then measure resistance/voltages on TPS and compare with service manua,then clean throttle body if problem remains then re-adjust TPS using the free service manual download links I provided.

About half of the ECU codes stored on the first & second generation EFI Toyotas don't show a constant blinking check engine light therefore you must pull the ECU codes to see if a fault is registered.

To pull the ECU codes:

All 1980-1995 and including 1995 EFI equipped vehicle allow you to find engine and related faults by pulling the ECU (computer) codes without the need for a handheld OBDII diagnosis scanner, the sites listed below have the fault codes needed to pull the codes and the instructions on how to do it:

http://autorepair.about.com/library/ts/obd-i/bl-dtcs-36.htm
http://autorepair.about.com/library/ts/obd-i/bl-dtcs-53.htm
http://autorepair.about.com/library/ts/obd-i/bl-dtcs-71.htm
http://autorepair.about.com/library/ts/obd-i/bl-dtcs-90.htm
http://www.autozone.com/az/cds/en_us/0900823d/80/16/11/12/0900823d80161112/repairInfoPages.htm
http://www.off-road.com/toyota/tech/codes/index.html
http://www.4crawler.com/4x4/CheapTricks/index.shtml#TimingCheckConnector
http://www.4crawler.com/4x4/CheapTricks/Images/85diagnosticcodes.gif
http://lcengineering.com/TechNotes/TechNote12.htm
http://lcengineering.com/TechNotes/TechNote13.htm
http://www.geocities.com/MotorCity/Pit/9975/dataBySubject/Engine.html
http://www.mad-mechanic.com/toyota/toyotaobd.shtml#obtaincode
http://www.freewebs.com/th3duke/22RE-ECU.mht
http://www.troublecodes.net/Toyota
http://www.autoshop101.com/forms/h27.pdf
http://www.cygnusx1.net/Supra/TechTips/engine_error_codes.aspx
http://forum.ih8mud.com/79-95-toyota-truck-tech/201623-toyota-2lte-error-codes.html
http://www.showmesome.info/hilux/info/manuals/1KZ-TE/Page0096.htm
http://www.efisakh.narod.ru/at_toyota.htm (auto tranny codes)
http://www.usatransdoctor.com/foreigntoyota.htm
http://www.obd-codes.com/forums/viewforum.php?f=3

Pulling the ECU (EFI computer) codes is the first thing I do to diagnosis a problem thereafter I reset the ECU to see if the same problems show up and if so I then take voltage measurements at each ECU wire both with the engine running and not and compare with the factory service manual, I also close the ignition switch after a cold engine and also after a warm engine and compare the resistance values with the factory service manual.

This technique will completely isolate your problem without having to do trial and error and it is the technique I use when repairing tv's, vcr's, home/car audio.

Usually excessive short trip city miles combined with low octane gasoline causes excessive carbon build up in the throttle body which does not allow sufficient airflow and hence the butterfly flap/accelerator plate to close all the way.

To clean the throttle body remove the air intake hose, examine the intake and throttle body for excessive carbon build 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 then shut the engine off, hold a rag below the lip of the throttle body poor the stuff and use a tooth brush.

Sea Foam is available in Canada through UAP/NAPA and Car Quest:

http://www.seafoamsales.com

Free 1990-1995 Toyota 4-Runner Factory Service Manual:

http://forums.bauchan.org/portal/viewdownloads.php?rid=166
http://thepiratebay.org/tor/3536729/1990_to_1995_OEM_Toyota_4Runner_Service_and_Wiring_Manuals
http://torrentportal.com/details/73...ta+4Runner+Service+and+Wiring+Manuals.torrent

Free 1995 Toyota 4-Runner Factory Service Manual:

http://rapidshare.com/files/34006966/Toyota.4Runner.1990.1995.SIL.rar
http://www.the-roo.com/4runner (3VZE engine, 3 liter, V6)

For TPS adjustment:

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

Sidney

 

[fishrod]

Would issues with the TPS (Throttle Position Sensor) go away once the car had warmed up?

I am still having issues with my 94 4runner. It surges/chuggs a bit when its cold. Its fine once its been left to warm up for 5 mins or if I drive it nice and easy for the first few KM's. Its noticeably better if I leave from the comfort of my heated underground garage as opposed to work, where it can sit in -30C for 12 hours.

Im not real good with fixing cars so Im trying to find easy things I can check/replace before taking it in to a mechanic.

So far plugs, leads, air filter all been replaced.

I tried to look up on the Airflow Meter (no MAF in the 2nd gen) but Im not convinced it would be an issue with this as it seems to be fine after its warmed up a bit.

Guess it could be the O2 sensor as well? Might take a look at that.

 

[fourwd1]

I don't think temp would affect the TPS, but the ECM does use coolant temp for a number of things.

The first thing would be to be to check to see if the ECM has stored any error codes, and go from there.

 

[the_dingman]

Would issues with the TPS (Throttle Position Sensor) go away once the car had warmed up?

For a while after starting the engine will run off default settings, ignoring the sensors. This is why you'll hear the engine change sounds, and usually drop RPM after a few minutes. Toyota and Honda are the most noticeable with this.

 

[rjyhdc4]

have you checked the iacv?

 

[fishrod]

I don't think temp would affect the TPS, but the ECM does use coolant temp for a number of things.

The first thing would be to be to check to see if the ECM has stored any error codes, and go from there.

Hmm, yeah I had the codes pulled when I first bought the car (5 months ago) by Canadian Tire. They "recommended" (ie didnt say it would fix it) a full tuneup including plugs, leads and distributor as well as an injector clean. All for the bargain price of 900 bucks.

At the time I thought it was just the plugs anyway, so I had my mate just do the plugs, leads and distributor (for 200 bucks). It was a little better for a bit, but then went back to its old ways.

I have to say that its gotten a shietload better in the past 2 weeks since the temperatures up her now hover between 0 and 10C.

Im hoping its just a stupid sensor somewhere and its an easy fix that I can do. I hate paying joints to do something and it doesnt make a difference.

 

[fishrod]

For a while after starting the engine will run off default settings, ignoring the sensors. This is why you'll hear the engine change sounds, and usually drop RPM after a few minutes. Toyota and Honda are the most noticeable with this.

Yeah I know that sound. Most noticable is the fan under the hood going nuts. Its not to do with that really. That lasts about 30 seconds or so, the problem Im having can still be affecting me 5-8 mins after the car has been turned on (usually depending on how cold it is)

 

[fishrod]

have you checked the iacv?

As far as I can tell IACV issues are usually to do with Idling problems? (I had no idea what this was so I just googled it - haha)

There is nothing wrong with the Idle. If it starts up cold, it idles at about 1300-1500 rpm for about 2 mins, then slowly drops. Once warm it idles stationary at about 700-800rpm and it has never stalled on me.

Thoughts?

 

[fishrod]

My IACV research led me to the ERG Valve. Sounds like it could be the go, lots of other forums where users had similar issues. Its not exactly cheap to replace (~$120 - not 100% its the issue) but its easily accessible and I can check the filter to see if its a bit dirty.

4x4 season is just around the corner and I should probably get all the fluids checked and topped up so I might just write down a big list of things and get someone to check it out.

Ill let you know if the issue gets resolved!!