2008 4runner Serious Cold Start Issues

I think I have good news this morning, it is 10 degrees out right now so I went and got into my car and let the ODB2 sync and the garage temp was 30 degrees and the Air Intake Temp with the engine NOT running was reporting 31-32 degrees, for me it doesn't get any better than that, so I think it is fair to say that my problem is NOT the Air Intake Thermometer. At least that answered something that I know it is not now

So once I got that info I tried to start the car and on the first key turn it probably tried about 3x Ra-Ra-Ra before it slowly started up and running. Before it was taking around 20x before the computer stops it and I had to try it multiple times.

So this result is fantastic and makes me feel a little positive about what I am doing. The only real critical changes I made yesterday was cleaning the throttle body and the MAF. The MAF had some dirt on it but the throttle body was caked with carbon build up, it really was pretty bad. Using carb cleaner and a very small brush cleaned it right up. I also added fuel injector cleaner to the tank of gas last night but only drove 4 miles, so I dont think I can chalk up a win for that yet, it needs more time to clean the injectors. So right now I am sticking to the MAF and Throttle Body cleaning as the "fix".

Now realistically I think it is too early to claim victory and I am not fully convinced this was the issue. To see if the throttle body and MAF cleanup was the fix I need to not do anything else to the car and see how she acts today and tomorrow and see if the problem starts to get progressively worse again. If so I will start looking at the fuel system again and get that fixed.

I will absolutely keep this thread up to date as the week goes on, I am not a total pessimist, but I don't think this is over...:ranger:
 
In the 4 years I owned mine it has done what you describe, turns over but engine never fires off. I know mine did it once maybe twice. I remember the first time because I thought something broke as I just bought it, thinking just great. My issue just kept turning over, I had to turn my key back in the off position and then try to start it again and no problem. Whats makes my issue different is it wasn't cold outside, maybe 40/50 something degrees at coldest.
 
TN_4runner said:
In the 4 years I owned mine it has done what you describe, turns over but engine never fires off. I know mine did it once maybe twice. I remember the first time because I thought something broke as I just bought it, thinking just great. My issue just kept turning over, I had to turn my key back in the off position and then try to start it again and no problem. Whats makes my issue different is it wasn't cold outside, maybe 40/50 something degrees at coldest.
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How many miles on it?

Could you do me a favor and look for carbon build up on the throttle body and the rest of the intake? This helped my problem immensely I think the carbon build up was limiting the movement on my throttle body contributing to my problems.

Also I put in injector cleaner and seafoam (2 separate partial tanks) and that seemed to help out as well, this in effect cleans out the fuel system, the regulator if sticking, the injectors if clogged, and the fuel filter if dirty.

I am still going to pour a 1/2 bottle of Seafoam into the engine and a 1/2 into the vacuum brake line to help clean out the engine.

Could you try the throttle body or seafoam and see if that helps? I really want to figure this thing out.

Tomorrow we are supposed to get freezing rain so I will check and see how cold it is in the morning and get a temp read from the IAT sensor and the car before I start it but I expect them to match as they have been.
 
You may have an issue with water in your gas. Living in northern Canada some gas stations had water contamination in the bottom of the tanks, usually not an issue in southern climates. At -20c/-5F I added gas line anti-freeze on fill ups. Nothing worse than stranded at -40 in the back country
 
I have done all of this and still have the same issues below 15f...no water in the fuel, clean Intake, clean sensors, new plugs. Never had a check engine light on once in 185000 miles...injector service preformed recently....I own a full service repair shop and have done everything under the sun except monitor all my data at very cold start with scope...anyone figured this out yet?


Veritas said:
How many miles on it?

Could you do me a favor and look for carbon build up on the throttle body and the rest of the intake? This helped my problem immensely I think the carbon build up was limiting the movement on my throttle body contributing to my problems.

Also I put in injector cleaner and seafoam (2 separate partial tanks) and that seemed to help out as well, this in effect cleans out the fuel system, the regulator if sticking, the injectors if clogged, and the fuel filter if dirty.

I am still going to pour a 1/2 bottle of Seafoam into the engine and a 1/2 into the vacuum brake line to help clean out the engine.

Could you try the throttle body or seafoam and see if that helps? I really want to figure this thing out.

Tomorrow we are supposed to get freezing rain so I will check and see how cold it is in the morning and get a temp read from the IAT sensor and the car before I start it but I expect them to match as they have been.
Click to expand...
 
to the OP, do you still have these issues? i'm at 100000 miles too for 10 years now and never had a starting problem ever since. (only had a problem when i forgot my keys in the truck turned on while i was fixing it. :) )

here are a few things to check that might be causing it not to start.
1. fuel pressure (related to fuel pump)
2. crank position sensor might be bad
3. fuel pump might not be working when it's too cold


keep us posted! i'm interested to know since I know i might experience the same problem. thank you.
 
LobstaMobsta said:
I have done all of this and still have the same issues below 15f...no water in the fuel, clean Intake, clean sensors, new plugs. Never had a check engine light on once in 185000 miles...injector service preformed recently....I own a full service repair shop and have done everything under the sun except monitor all my data at very cold start with scope...anyone figured this out yet?
Click to expand...

The only thing I havent done yet is had a chance to check the Fuel Pump, Fuel Regulator, or Fuel Pressure. Did you check any of those?
 
radlynx said:
to the OP, do you still have these issues? i'm at 100000 miles too for 10 years now and never had a starting problem ever since. (only had a problem when i forgot my keys in the truck turned on while i was fixing it. :) )

here are a few things to check that might be causing it not to start.
1. fuel pressure (related to fuel pump)
2. crank position sensor might be bad
3. fuel pump might not be working when it's too cold


keep us posted! i'm interested to know since I know i might experience the same problem. thank you.
Click to expand...

Things have gotten much better but I stiill have a lag on startup, hasnt been too cold lately though.

Anybody have any ideas on checking the regulator, pump or pressure, seems like the only way to test them is to replace them...
 
I haven't tested fuel pressure on cold start like that, i guess i could try double priming the pump before crank but i am really leaning towards a combination of timing/detonation in low temps….it does seem to slightly flood and run rich for a moment when it does start. Man it sounds awful though, coughs chokes and bucks when it does this! can not be great for my rods :( Where would i even test for fuel pressure other than disconnecting the feed line at the back of the engine and hooking up my gauge then drive home and let it sit until morning with the gauge sneaking out through the hood or something. Frustrating not having any good help lol
 
LobstaMobsta said:
I haven't tested fuel pressure on cold start like that, i guess i could try double priming the pump before crank but i am really leaning towards a combination of timing/detonation in low temps….it does seem to slightly flood and run rich for a moment when it does start. Man it sounds awful though, coughs chokes and bucks when it does this! can not be great for my rods :( Where would i even test for fuel pressure other than disconnecting the feed line at the back of the engine and hooking up my gauge then drive home and let it sit until morning with the gauge sneaking out through the hood or something. Frustrating not having any good help lol
Click to expand...

Definitely keep us up to date it seems like nobody has the answer to this problem and like you said the lack of error codes is very frustrating. I might try and check fuel pressure here soon, I still think its a pressure issue, but don't know where or how to easily test it without buying specialized tools.

When mine starts it also has a real rich gas smell, its like the injectors are pouring gas into the cylinders instead of atomizing it properly.

Let me know if you find anything else :tea:
 
Veritas said:
Definitely keep us up to date it seems like nobody has the answer to this problem and like you said the lack of error codes is very frustrating. I might try and check fuel pressure here soon, I still think its a pressure issue, but don't know where or how to easily test it without buying specialized tools.

When mine starts it also has a real rich gas smell, its like the injectors are pouring gas into the cylinders instead of atomizing it properly.

Let me know if you find anything else :tea:
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Have you looked on some of the Tacoma forums ( such as tacomaworld)? I've found a lot of solutions there that weren't on 4Runner specific forums.
 
Dunngeon said:
Have you looked on some of the Tacoma forums ( such as tacomaworld)? I've found a lot of solutions there that weren't on 4Runner specific forums.
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Haven't looked on any of those sites yet, this is the v8 were talking about here so tacomas won't quite cut it lol
 
Veritas said:
Definitely keep us up to date it seems like nobody has the answer to this problem and like you said the lack of error codes is very frustrating. I might try and check fuel pressure here soon, I still think its a pressure issue, but don't know where or how to easily test it without buying specialized tools.

When mine starts it also has a real rich gas smell, its like the injectors are pouring gas into the cylinders instead of atomizing it properly.

Let me know if you find anything else :tea:
Click to expand...

Yeah I have the adapters to test the fuel pressure but honestly its a pain to hook it up and i really think its basically the way the ecm is programmed that they just didn't get the timing right for extreme cold starts, acts like post detonation
 
Dunngeon said:
Have you looked on some of the Tacoma forums ( such as tacomaworld)? I've found a lot of solutions there that weren't on 4Runner specific forums.
Click to expand...

I haven't done that, I will try to though as that is a good suggestion I have the v6. Thanks for the suggestion.
 
LobstaMobsta said:
Yeah I have the adapters to test the fuel pressure but honestly its a pain to hook it up and i really think its basically the way the ecm is programmed that they just didn't get the timing right for extreme cold starts, acts like post detonation
Click to expand...

Thats where I am at too it is a total PITA on a toyota to test fuel pressure, plus I dont own the custom tools for it.

The only reason I dont think it is ECM related or detonation/timing is because this is the first winter that this has ever happened to me, I have been in these temps for years with my runner and have been in MUCH colder temps then here lately and had 0 issues. I dont see how the ECM could be to blame as the programming is not altered, it has to be something mechanical in nature, it could be electronic, but I dont think ECM, more like wiring at that point.
 
I'm subscribing to this also. I have the exact problem going on. It started last winter when it did it a couple of times. Then it got warm and went away. Then last week I let it sit in the garage for 2 days. It was around 0 degrees outside. I went to start it and it just turned over but never fired. Did it two auto cycles then it finally started but it didn't like it. Every start throughout the day after that was fine. It is a cold start issue. I cleaned the throttle body and Maf yesterday but they were clean as I cleaned them like 20K miles ago. I also disconnected the battery and reconnected and let the engine re-learn the idle. Then this morning my wife tried to start it and it did the same thing. Two full auto-start (just flicking the key and letting the starter run on it's own) cycles before it finally started. We went and filled it up with 91 octane and I put some seafoam in it and got it on the highway for a while to run fuel through the system. Hope this helps cause I am at a loss. Temp when we tried to start it today was 40 degrees in the garage so it isn't so much a temperature issue as a fuel pressure issue I think. I'm wondering if maybe the pump is losing it's "prime" when it sits overnight?
 
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