Question about 1999 Toyota Tacoma PreRunner

1 Answer

Single female with intermitatant emission problems(please help)

For about the last year every three months or so my truck(automatic,3.4L 6 cylinder) will start and idle very rough.When I put it in drive it does not want to move.It will go fine in reverse,low and 2nd.After a few minutes it will start running fine and do so for several months. I have noticed if I put regurlar unleaded in it it will be worse.I have changed the transmission fluid and filter.It has been about 2 years since I changed the fuel filter.Also the gas milage has dropped from about 21 miles to the gal. to 17.The problem seems to happen when it is hot,like when I drive about 20 miles and then stop.Like I said it only does it every tree months or so.Hard to trouble shoot like this.
The check engine light does not come on.I have run diagnostics anyway in case the light was bad and it does not pick up any codes.
I have been trying to check the EGR valve and every diagram I find seems to put in a different location.

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Toyota Master
  • 5,568 Answers

I vented yesterday about GM so won't repeat it here.

You should be able to locate the EGR valve by checking anything attached to the exhaust manifold and following lines.

The EGR is typically equipped with a drum shaped housing with fittings on the top and bottom, sometimes (often) mounted on the exhaust manifold itself.
The drum houses the diaphragm that is controlled by vacuum and opens a small path between the exhaust manifold and the intake side to inject (supposedly) some unburned gases to burn again.

Since we are kind of anonymous here, I can admit to having cheated all of them since it mostly brings a little more mileage.
Stuffing a ball bearing in the vacuum hose and reattaching it to the EGR lets it appear to be functional.
While still in CA, we never had a vehicle fail emissions testing despite this 'cheat.'

If the EGR valve has failed and stuck open, then exhaust gases are entering even at an idle which can cause the symptoms you describe.
Engines running at mid-RPMs can tolerate the garbage being fed them without gagging, but not at an idle.

Good luck-

Posted on Aug 07, 2008


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya Mechanic can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US.
click here to Talk to a Mechanic (only for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Took my 2006 Navigator for an oil change, came out with timing chains and converters changed. Now it won't run right.. The motor shakes and shuts off randomly. Retimed perfectly now, and won't start! It...

Can't help you

What happened to the shop that did
the work,why can't they resolve

Those issues are from either not changing your
oil enough or failed VVT Cam Actuators,sometimes
the chain guides wear but not on a 2006,too new

Exhaust Converters fail from leaking injector, which
is a know problem on your motor from 2004,05 & 06,
& bad COP Ignition Coils, which causes cylinder misfires
& ruins the converters

All of the issues could have been prevented & all of the
coil are bad by 6 to 7 years & both upstream oxygen
sensors need to be replaced at 100,000 miles

Too bad your not my neighbor,you won't have one problem
The transmission will fail next, from not changing the fluid every
3 years

I happen to know the vehicle & ford/lincoln issues

Exhaust Converters last 14 years & still pass emissions
inspection if your proactive & road test & take a scanner
with you a 2 or three times a year & look at all data parameters
& keep an eye on things

Just to drive any vehicle with todays technology & never look
at data or do preventative maintenance or know what is needed
& stay up to date using the internet every month,your going to
have problems & serious ones at times

Aug 31, 2013 | 2006 Lincoln Navigator

1 Answer

2004 dodge sx automatic intermittent start problems

If it starts with booster cables, it points to bad electrical connection or discharged battery , clean battery posts and terminals . have battery tested with high discharge tester.

Nov 30, 2017 | Dodge Cars & Trucks

1 Answer

O2 sensor

It is a single wire coming out of the harness that goes across the cylinders 2,4 and 6, about center of the vehicle. You probably need to use a mirror to be able to see it since is hanging down behind the engine. I hope this helps.

Mar 06, 2012 | 1992 Pontiac Trans Sport

1 Answer

Electrical problems

Are these factory OEM replacements? I once put three cheap aftermarket Kragen batteries in my Corvette in 6 months, bought a Delco and problem solved, that was years ago. Sounds like your problem is that the car sits to much, if it sits more a few weeks either hook up a float battery charger or disconnect the negative cable to the batt.

Feb 02, 2012 | Cars & Trucks

1 Answer

How to find codes for check engine light on

Check Engine Light Codes and Meanings
Long blinks Short blinks Problem
1 1 Camshaft position sensor
1 2 Mass air flow sensor
1 3 Engine coolant temperature sensor
1 4 Speed sensor
1 11 EVAP control system (flow)
1 14 Fuel injection system right bank (too rich)
1 15 Fuel injection system right bank (too lean)
2 1 Ignition circuit
2 3 Closed throttle position switch
2 5 Idle speed control
2 9 Fuel Injection system left bank (too rich)
2 10 Fuel Injection system left bank (too lean)
3 1 ECU
3 2 Exhaust gas recirculation system flow problem
3 3 Front left O2 sensor
3 4 Knock sensor
3 5 Exhaust gas recirculation temperature sensor
3 6 EGRC-BPT valve
3 7 Closed loop control
3 8 Closed loop control
4 1 Air intake temperature sensor
4 2 Fuel tank temperature sensor
4 3 Throttle position sensor
4 7 Crankshaft position sensor
5 3 Front right O2 sensor
5 4 Automatic transmission control unit
6 3 Cylinder #6 misfire
6 4 Cylinder #5 misfire
6 5 Cylinder #4 misfire
6 6 Cylinder #3 misfire
6 7 Cylinder #2 misfire
6 8 Cylinder #1 misfire
7 1 Multiple cylinder misfire
7 2 Three way catalytic converter (right side)
7 3 Three way catalytic converter (left side)
7 4 Evaporative emission control system pressure sensor
7 5 Evaporative emission control system
7 7 Rear O2 sensor
8 1 Vacuum cut valve bypass valve
8 2 Crank position sensor
8 3 Absolute pressure sensor
8 4 Automatic transmission control unit
8 6 Evaporative emission canister purge control solenoid valve
8 7 Evaporative emission Canister purge control solenoid valve circuit
9 1 Front Right O2 sensor
9 3 Evaporative emission Canister vent control valve
9 5 Crankshaft position sensor
9 8 Engine coolant temperature sensor
10 1 Front left O2 sensor
10 3 Park and Neutral position switch
10 5 EGRC solenoid valve
10 8 Evaporative emission canister purge volume control valve
11 1 Inhibitor switch
11 2 Revolution sensor
11 3 Improper shifting to first gear (Automatic transmission)
11 4 Improper shifting to second gear (Automatic transmission)
11 5 Improper shifting to third gear (Automatic transmission)
11 6 Improper shifting to fourth gear (Automatic transmission)
11 7 Solenoid valve lock up function
12 1 Shift solenoid B (Automatic transmission)
12 3 Overrun clutch solenoid valve (Automatic transmission)
12 4 Torque converter clutch solenoid valve (Automatic transmission)
12 5 Line pressure solenoid valve (Automatic transmission)
12 6 Throttle position sensor (Automatic transmission)
12 7 Engine speed signal
12 8 Fluid temperature sensor
13 2 MAP/BARO Switch Solenoid Valve
13 5 Fuel pump control module
13 8 Cooling fan

Dec 12, 2011 | 1995 Nissan Maxima

1 Answer

Is it dangerous to drive with a problem with the Catalytic Convertor 1996 Jeep Grand Cherokee 6 cylinder

no it is not dangerous, but it is illegal. the catalytic converter is an emission control device designed to regulate pollutants produced by the engine. if your coverter is plugged it can potentially cause damage to your engine because it does not allow exhaust to flow properly. this wont happen over weeks or months, but long term, such as years can cause damage.

Aug 21, 2011 | 1996 Jeep Grand Cherokee

1 Answer

What is the correct iginition timing and process for a 89 Honda Accrod LX Automatic, 4 cyclinder, that's Carburated??

Hello leahlogan201: My name is Roger and I will help you. There are three different settings for this year car. setting #1 - Manual transmission 49 states and high altitude 24 deg BTDC at 800 +/- 50 rpm. #2- California emissions 20 deg BTDC at 800 +/- 50 rpm. #3 Automatic transmission 15 deg BTDC at 750 +/- 50 rpm in D range.
Should you need further help please just ask. Please rate the answer. THank You for using Fix Ya. Roger Note: That BTDC stands for Before Top Dead Center

May 19, 2011 | Honda Accord Cars & Trucks

1 Answer

My 1995 mustang stalls after turning on A/C

Sounds like the air conditioning pump is seizing up. You should get it checked out.

Apr 25, 2009 | 1994 Ford Mustang

Not finding what you are looking for?
1999 Toyota Tacoma PreRunner Logo

164 people viewed this question

Ask a Question

Usually answered in minutes!

Top Toyota Experts


Level 3 Expert

77499 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22306 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8825 Answers

Are you a Toyota Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides