toyoman13

I'm having a problem with my 93 4runner v6 4x4. It started with a bad idle and has gotten worst. When I first start it in the morning it is fine but after I drive it awhile and turn it off is when it act up. If I just turn it off and run in the store real quick it is fine. But if I let it sit about an hour and start it I have to push the gas pedal to keep it running and it sputter and misses until i get above 2000 rpm and hold it a while. Then it will idle rough but not die. If i don't hit the gas pedal as soon as i start it will die and then can't get to start until I let it about 15 minutes then try to start it but I still have to press the gas pedal. I don't if it is important but when get it to idle if I press the brake pedal the idle will smooth out and go up to about 500 rpms. It likes to to idle at 250 rpm when it is idling rough. I have changed the spark plugs, wires, cap and rotor. I have also check the timing. I'm pretty good that taking stuff apart and putting it back together but I suck diagnostic. If someone could help it would be great. I have a downey ram air kit and cat back exhaust if makes a difference.

runrunner

I just had the same problem, i did mayor tune up with same results, the culprit was two injectors not receiving pulse, replace the pigtail / harness and now its working.. do you have a CE or any codes?

kev

check also for leaking fuel injectors/cold statr inj. Kev

Noltz

#1) Use vice grips and pinch off the vacuum line to the booster. If your engine is idling up when you PRESS the brakes, you have a booster problem.

#2) Please try unplugging both coolant temp sensors. The ECU may be getting false signals. If it gets NO signals, it goes to safe maps.

I highly doubt it's the ECU or wiring, or the problem would present while it warms up, not just when it's partially warm and cooling off.

toyoman13

How would you go about checking to see if the injectors were getting the correct pulse. I haven't had a check eng. light come on when it happen so I didn't think it would have any codes. I will try all those things and let you know how it goes thank you.

abecedarian

if injectors aren't firing, eventually the ECU should throw a code about having to compensate for a lean mixture.

try this- next time you think the engine's going to act up during a warm-start, just turn the key on and crank it a second, then do that again, then try to start it up. if it starts fine, your fuel filter might need replaced, or possibly there's an issue with the coolant temp sensor or fuel pressure regulator and potentially the cold start time switch.

Noltz

Ideally, an oscilloscope would be used to check the pattern, but you never see those in garages - and even fewer people know how to use them. Noid lights the standard test; They're little bulbs that attach in place of your injector. With the truck running (or at least turning over) you can watch the bulb flash, indicating the injector is getting both power and ground signals. Revving up the motor will cause the noid light to flash faster. And I'm not convinced a '95 will have the 'capacity' to detect a lean run condition. '96 was the introduction of OBD2 (On-Board Diagnostics V.2), and they do have the capability to detect misfires and lean run condition (right down to which cylinder!).

Do you have the option of hooking up a fuel pressure tester and driving for a few days? This would check abecedarian's suggestion of a partially clogged filter or failing pump. When the truck acts up, you can glance at the fuel pressure and see what the engine is getting.

toyoman13

Do you have the option of hooking up a fuel pressure tester and driving for a few days? This would check abecedarian's suggestion of a partially clogged filter or failing pump. When the truck acts up, you can glance at the fuel pressure and see what the engine is getting.[/QUOTE]


I can get a pressure tester from a friend. I have recently replace the fuel filter. About what should the fuel pressure be.

abecedarian

fuel pressure should be around 38-44 PSI.

Noltz

Run with the gauge for a while and get back to us. 35-45 is normal & your truck should be running good anywhere in there.

The other thought I had is a failing ignition system. Heat soak may be causing your coil to break down. Again, without a proper scope to scan it, sometimes these things are really hard to find. At the garage I keep a known-good coil for most common vehicles. I can then eliminate the coil right away (and I've caught a few bad ones really quickly too!)

toyoman13

I'm getting the pressure gauge this weekend from my friend so hopefully I will find out something. I will let you guys know.

toyoman13

Sorry it been awhile but I finely got my friend to bring over the pressure gauge and it didn't work. He got it from one of is friends and he works at ford dealer so it didn't work on the yota. I was wondering if it could be the fuel pressure regulator but that would be hard to know with out the pressure gauge.

toyoman13

Where would the water temp sensor be located.

Green93

The coolant temp sensor is located on the back of the engine by the firewall. Look from the top, behind the intake plenum and you will see a bunch of sensors.

I am having the same problem. Starts fine in the morning or if I turn it off to get gas or something. If I shut the engine off and it cools down for 30 mins or so it has to crank for awhile before firing up again. And I have to press the gas pedal. I'm running out of sensors to replace.

Jason

toyoman13

What have you all replace on your yota.

toyoman13

I ran it with out the coolant temperature senor plugged in and I didn't really notice a difference in the way it idles. I was wondering if an O2 sensor could cause the problem. I also notice that when hit the throttle really fast it idle really low and rough but if a touch the gas a little it will bring the idle back up and run a little smoother not much but a little.