hey guys i got a 3.4l v6 that has a hard time starting. when i bought the truck it didnt have any problems starting but needed rear wheel bearings so it sat for about a month while i redid the rear end.
After i got it all together the truck is really hard to start when cold. i replaced the fuel pump, fuel filter, plugs, and air filter. also cleaned the Idle air control valve.
It takes on average about 3 cranks holding the key on for about 3-4 seconds each time or maybe a little longer. i also have been keeping the gas pedal down about 1/4 of the way because it seems to start faster doing this. but then i get a real bad GAS odor from all the built up fuel.
If i dont keep the gas down it takes about twice as long to start and the engine idles so low the rpm guage just barley bounces off the bottom. and it seems to just gradually catch like its something in the ignition maybe not hitting all the cylinders? but as soon as i tap the gas it goes up to regular idle speed.

when i pull in and get gas it will start right up after being off for a few min.
But if i leave it for like 20 min even though the engine is still warm and the temp gauge is gone about half way down its still hard to start.

anyone have a problem like this before? or have an idea on what else i could try?

 

Well you got fuel, did you check to see if you have spark from the spark plugs (although they are new)?

Did you use the Denso / NGK dual grounded plugs (U-groove as Denso calls them)?

Do you have a CEL? If so, what are the codes?

Did you replace your spark plug wires?

How many miles do you have?

Do you have all the wires to the throttle body put back on?

If you did put OEM spark plugs in there, I would check the spark plug wires to see if they are bad, then do a compression test to see how much compression you have in each cylinder.

My GUESS is that you didn't put OEM spark plugs in, you have bad wires or your IAC is not working correctly.

 

i used botch double platnum plugs. i saw on the valve cover that they used the double kind so i used those. i didnt replace the wires. I did check for spark on all wires. NO CEL. 225k miles. and all wires are back on the throttle body.

 

The Bosch are your problem. They plain don't work in Yotas. Get those out of there. Use Denso or NGK ONLY. I have read of many people having issues with them in Yotas (specifically V6 model cars and trucks). For a VW or something European they work good, I will give them that but for Japanese, they suck balls. I will never use Bosch in a Japanese car, I feel weird putting German designed stuff into a Japanese car anyway. I bet if you replaced the Bosch with NGK or Denso your problem would go away. I would consider changing your wires if they have never been done with that mileage while you are at it too.

 

i had ngk's in there when the problem started. i switched the plugs out thinking that was the problem but it didnt change. so i put the ngks back in there and it's the same way.
Could it be that the injectors get stuck closed during start up? because if i dont step on the gas when turning it over to start it. when it finally starts it idles really low so low that it doesnt even want to run. i have to tap the gas real quick to get it to idle where it should when its cold.
It has NO problems when it's running at all. it runs great no misses or sputtering at all. which makes me really scratch my head

 

Where the NGKs bad when you took them out? I still would get the Bosch out of there. It is well documented and proven for many people that they just plum don't work in Yotas. You can go to toyotanation.com and read all the people in the Camry forum (with the 1MZ-FE 3.0 L V6) that have had issues with the Bosch. The 5VZ-FE and the 1MZ-FE I can imagine are similar engines. It is just really hard to imagine that all 6 of your injectors quit working all at the same time. A 6 cyl car / truck can still start on 3 cyls although it is not good for it. If it is not your spark plugs, then I would check your wires, and take apart your throttle body (take it off the truck) and give it a really good cleaning. Since you don't have a CEL, this might be your issue, but no way to know for sure. Nevertheless, I still wouldn't leave the Bosch plugs in there. I have helped rebuild 2 engines due to the electrode of the Bosch plugs breaking off inside the cylinder. I will never buy Bosch because of this. I would also clean your MAF too. Consider running BG44K or SeaFoam through a tank of gas to clean up the injectors.

If it were my truck I would (in this order):
1) change spark plugs to NGK / Denso dual grounded electrode plugs OEM only
2) change spark plug wires (~$50 from stealer)
3) take the throttle body completely off the truck and clean it really good (including the little ports on top next to the butterfly inside the barrel)
4) Run a can of BG44K through a gas tank to clean the injectors out (seafoam would also work but it is not as good as BG).
5) Clean the MAF
6) See what happens.

 

If it were me I would replace the coolant sensor. If that didn't work I might start thinking about the ECU.

 

If it were me I would replace the coolant sensor. If that didn't work I would start thinking about the ECU.

 

I think Hokkaido is right. I have the same problem and I know that it's not the fuel pump. I know that the fuel rail is not getting pressurized with the key in the On position. This is the ECU's fault, it's not closing the circuit to turn the fuel pump on. Even if I do jumper the fuel pump relay and pressurize the system manually before cranking, it still takes too long to catch.

There could be 4 reasons for this:

1. The IAC isn't opening during cranking. This can be tested with a vacuum gauge. If the manifold isn't pulling any vacuum during cranking, we know that the IAC is opened and working as it should. I have yet to test for this. This can be a dirty IAC/weak motor or no voltage sent from the ECU.

2. The injectors are not opening immediately as they should. This would be caused by a delayed tach signal received by the ECU. This is either the crank position sensor's fault or the ECU's fault.

3. The injectors are not providing enough fuel to start. This is the coolant temp sensor's fault or the ECU's fault.

4. There is air in the injectors. The ECU is supposed to open the injectors for a few milliseconds when the fuel rail is primed. This clears the injectors. I think this is part of my problem but not the entire problem.

 

For sure I don't want to lead you astray to think that spark plugs are the cause of your problems. All I am trying to say is that the problems with Bosch spark plugs in Yotas is well documented and I will never use them. I completely agree with LifeOnABoard and Hokkaido that the coolant temp sensor may be the cause of your problems. I still would clean the IAC really well to make sure that this is not the culprit.

 

I agree about the plug wires...pretty simple fix and they probably need to be replaced anyway. I did mine a few months ago b/c I noticed a 'miss' during acceleration; when I pulled the plug wires one of them broke in two. I'd start with the plug wires then move on to the more complicated solutions.

 

Yes, definitely do the simple things first, especially if it's a periodic maintenance item. In my case I have installed new plugs, plug wires and fuel filter. I also cleaned the MAF. But the MAF isn't involved in the start process as far as I know. Intake temperature only modulates the timing by a few degrees. I now have a smoother idle but the extended cranking is still there. Also, this is not an isolated issue. There seems to be at least a handful of people here with this mysterious problem. The older engines seem to respond well to cleaning the IAC.

 

Yeah, could be the IAC (which can go bad without throwing a code -- mine did). If the IAC is suspect I recommend just replacing it; cleaning may work for a while but just delays the inevitable IMO. It only takes an hour or two.

Also this may be dumb/obvious but are you sure it's not the battery causing your starting issues? You could have it tested for free just to make sure.

 

I'm having what seems to be the same issue as the O.P. I've recently changed my plugs to the Bosch Platinum, New NGK wires, 6 refurbed Fuel Injectors, and 1 brand new coil pack. I had changed all the above to get rid of a CEL indicating Cylinder 1 Misfire....ended up being the Fuel Injector.

Now, I know that some folks hate the Bosch Plugs in our 3.4l engines...is it myth or reality??? Did it get disrproved??? What pisses me off is, when I went to the Parts store looking for my OEM Dual Electrode plugs, they didn't have them, and only listed the Bosch Platinum plugs. I wasn't keen on the tiny electrode from the Bosch...but was re-assured by the counter person that they would be more than good enough.

If I change them out....what do you think the odds are that the store will take them back??? HA HA HA!

 

I've run the bosch plugs in my 3.4 and they worked just perfect. No issues whatsoever...had them in for 50k or so.