idealconcepts

So I bought a 2003 Prerunner (double cab, Auto) in the end of October with about 87K miles. I'm the third owner and the second owner bought the vehicle at about 50K miles from the first owner. Second owner didn't do the 60K or 90K maintenance on the truck or replace the waterpump or timing belt, he basically just did the oil change every 3-5K miles. So I had the maintenance done (fluids/T-stat, etc) along with the water pump/timing belt, and all other belts. He also added a MOC kit, not sure what this is but figure I mention it. Truck shifts alot better and is smoother when driven.

My mechanic works for the dealer but does this stuff on the side for me so I trust him and he has worked on my other 89 Toyota Truck over the last 2-3 years.

Only thing he wasn't able to resolve, he stated the first owner was informed about this by another dealer, was the idling problem. When in drive at a stop it idles pretty rough and you can feel the vibration in the cab and see it in the mirrors, but this doesn't happen if you switch gears to N or P, the rough idling stops and feels normal. The idle actually goes up when in in N or P to the last line before 1 on the RPM gauge and when in drive at a stop it is in the middle line of the three lines between 0 and 1. This is all happening when the truck is warm and running under normal operating temperature

If I recall the conversation correctly my mechanic checked the computer readings and monitored the engine. He stated the MAF (can you tell me what this reffers too) was fluctuating slightly but was still in the normal operating tolerances. He cleaned the MAF but stated he didn't notice much of a change and also added I think a fuel cleaner to hopefully help with the rough idle. He also stated the AFR sensor could be a source but with either sensor he was very hesistant to replace anything just yet since the computer reports and when he monitored the engine the readings everything appeared normal.

My questions:
1. What is the correct RPM for idle on my truck? Is that the last line just before the 1 on the RPM gauge or is that the middle of the three lines of the gauge? As I stated above the rpm moves from the middle line in D at a stop (this is idling rough) to the line just before the 1 when in N or P at a stop and the idling is not rough.

2. Should my RPM be moving up if I switch from D to N or P? Or should the RPM remain the same if I am at a stop and switch to any of those gears?

3. Any suggestions or recommendations I can check, look, keep an eye on to maybe resolves this? If I can fix this issue myself I would like to.

I'm also doing some searches on YotaTech in hopes someone had a similar problem and was able to resolve is easily.

Thanks in advance for your help.

98tacomamudder

I have the same problem with my 1998 Tacoma 2.7L with 72k. I got it stuck in a deep water hole and it has not idled the same since. Sometimes if it sits for a day or so it will stall out after turning over the first time. Im not positive what it is but I was told it is probably my idle control sensor.

idealconcepts

Thanks for the reply. Did you ever get that part replaced? If you did, did it resolve the problem? Do you recall the cost of the part?

Thanks again.

SPL15

Is it constant vibration or more like an engine miss?

I have no experience with your engine, but lots with other engines. What I usually found was a problem with emissions system (duh... I guess). Small vacuum leaks, bad/stuck EGR, plugged vacuum lines, leaking EGR system, Dirty Throttle body & idle air components. etc.

Also ignition problems can cause this, weak spark from bad worn out coil packs, leaky wire set, bad spark plugs. Also depending on engine design, Crank Shaft Position Sensors can cause wierd issues like this.

The wierdest one was where the ground strap from the engine to frame was pretty poor. It would start alright, but caused enough ground potential difference it messed with Sensor readings. If your trucks ECM is at a slightly different ground potential than engine sensors it can throw off voltage ranges being read by the ECM. Rough Idle, poor gas mileage, wierd check engine codes, poor power, etc..

Also could be something as dumb as a bad motor/transmission mount. I had this with a Nissan Altima. Transmission mount and motor mounts were toast. Idled fine in park/neatral but any load from the transmission would cause the engine to vibrate the car due to the slight twist when loaded.

idealconcepts

Thanks SPL15. Yes it is a constant vibration not really an engine miss.

It sounds similar to your last sentence. I'm gonna see if my wife can sit in the car in drive with the her food on the brake, hood open, and see if the engine vibrates excessively or not. Hope fully it's something that simple.

Thanks for your reply, gives me a good place to start looking. If it's not one of the mounts I'll look at the other things you mentioned.

Thanks again.

swerks

I have same issue with my 86 4runner anything new here ??? this is very frustrating

idealconcepts

No nothing new, wife was pregnant and had the baby a few weeks ago so haven't had alot of time to take a look at the issue. I did observe the idle gets better when the AC is on. Yes it is very frustrating, when the trk is in motion it drives perfectly fine.

element

I had a similar problem. It turned out to be a vibration caused by the exhaust. I got under the truck with it in gear (my wife with her foot on the break) and pulled on the exhaust pipe while it was running. The vibration disappeared.

While doing research here for my issue I found that people were suggesting:
MAF
Motor/Trans mounds
U-joints (if serviceable)
Exhaust

HTH

idealconcepts

Thanks Element.

How did you end up permanently resolving the vibration caused by the exhaust pipe?

element

Sorry it has taken me so long to get back to you.

In my case, the exhaust was sending vibrations through the chassis because the spare tire wasn’t completely retracted. FWIW, mine vibrates at stop in drive without the spare on the truck (slightly different vibration).

I couldn’t find the post on this site that got me looking at the exhaust in the first place. To sum it up, a YT member had the same type of vibrations that were being caused by a loose bolt on the trailer hitch. He had recently traded hitches with the one that was on his wife’s truck and left one of the bolts loose.

idealconcepts

Not a problem, thanks for the info Element.