Weird starting (03 v8)

[Moist]

Every now and again when I start the 4runner, the revs will jump all the way up to 2000 before the engine shakes, it loses power, and dives below 400.
Sometimes it totally stalls out and then refuses to start for a few other attempts. (In that the starter doesn't do anything)
Otherwise it starts just fine. No loss of power driving, and a ticking coming from the engine (most likely serpentine belt).
Not sure what causes this, but it's happening more and more.

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[ArthurKotb]

My old 91 Camry had symptoms similar to this. Turned out to be the air idle control valve. There seems to be something similar on the V8 4Runner.
Fuel Injection Idle Air Control Valve
You might try taking it off and cleaning it to see if it improves performance. Also check for leaky vacuum hoses.
2003 Toyota 4Runner Fuel Injection Idle Air Control Valve. Bypass - 2227062050 - Genuine Toyota Part

Idle Air Bypass Solenoid - Repair or Replace
Has your 2003 Toyota 4Runner suddenly began idling either too high or too low? This condition is sometimes caused by a faulty idle air bypass valve. Consider having our certified technicians inspect yours to determine the best solution.

 

[ArthurKotb]

[snip...]
Otherwise it starts just fine. No loss of power driving, and a ticking coming from the engine (most likely serpentine belt).
Not sure what causes this, but it's happening more and more.

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The ticking could be the exhaust header or a tappet. The Gen4s have a known issue with the steel headers rusting and breaking. It's an expensive replacement of the headers. They are steel, not cast iron and cannot be repaired.

My 2004 (137K) has a very slight tick from time to time, especially after a long trip. My son's 2006 (159K) has developed a loud ticking but when the engine gets hot it pretty much goes away. When metal heats it expands and seals the crack... for a while.

 

[AuSeeker]

My old 91 Camry had symptoms similar to this. Turned out to be the air idle control valve. There seems to be something similar on the V8 4Runner.
Fuel Injection Idle Air Control Valve
You might try taking it off and cleaning it to see if it improves performance. Also check for leaky vacuum hoses.
2003 Toyota 4Runner Fuel Injection Idle Air Control Valve. Bypass - 2227062050 - Genuine Toyota Part

Idle Air Bypass Solenoid - Repair or Replace
Has your 2003 Toyota 4Runner suddenly began idling either too high or too low? This condition is sometimes caused by a faulty idle air bypass valve. Consider having our certified technicians inspect yours to determine the best solution.

If I'm not mistaken the IAC valve on 4th Gens is integrated into the throttle body and not a separate part as it was on 3rd Gens and prior models, so you would have to replace the throttle body if it is indeed the IAC causes the issue.

The part/IAC valve at the link posted is for 3rd Gens and some other Toyota models, but not a 4th Gen T4R, click on the "what this fits" link for fitment.

 

[Moist]

My old 91 Camry had symptoms similar to this. Turned out to be the air idle control valve. There seems to be something similar on the V8 4Runner.

Fuel Injection Idle Air Control Valve

You might try taking it off and cleaning it to see if it improves performance. Also check for leaky vacuum hoses.

2003 Toyota 4Runner Fuel Injection Idle Air Control Valve. Bypass - 2227062050 - Genuine Toyota Part



Idle Air Bypass Solenoid - Repair or Replace

Has your 2003 Toyota 4Runner suddenly began idling either too high or too low? This condition is sometimes caused by a faulty idle air bypass valve. Consider having our certified technicians inspect yours to determine the best solution.

Thank you for the response.
Would that valve change idle speed?
If so what would the regular idle be?
I'm idling anywhere from 1200 to 700. (Depends on the day I suppose)

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[AuSeeker]

Have you tried cleaning or replacing the MAF sensor?

 

[Moist]

Have you tried cleaning or replacing the MAF sensor?

No.


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[rdruss]

Go buy some throttle body cleaner and MAF sensor cleaner and do both and see what happens.

 

[ArthurKotb]

If I'm not mistaken the IAC valve on 4th Gens is integrated into the throttle body and not a separate part as it was on 3rd Gens and prior models, so you would have to replace the throttle body if it is indeed the IAC causes the issue.

The part/IAC valve at the link posted is for 3rd Gens and some other Toyota models, but not a 4th Gen T4R, click on the "what this fits" link for fitment.

Good catch! My bad. It asked me to select a year and it showed a separate part. i didn't notice the caution that it didn't fit. On top of that, there was the text referencing a 2003 and to check with your Toyota shop.

Thanks for catching that!

 

[ArthurKotb]

Thank you for the response.
Would that valve change idle speed?
If so what would the regular idle be?
I'm idling anywhere from 1200 to 700. (Depends on the day I suppose)

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Sincere apologies. I didn't read the text saying it didn't fit the 2003 (gen 4) models. Auseeker says he thinks it's integrated into the throttle body.

Try some throttle body cleaner on it to see if it improves performance. You might also call your dealership or independent garage to get a repair estimate.

Really sorry for the error

 

[Moist]

Sincere apologies. I didn't read the text saying it didn't fit the 2003 (gen 4) models. Auseeker says he thinks it's integrated into the throttle body.



Try some throttle body cleaner on it to see if it improves performance. You might also call your dealership or independent garage to get a repair estimate.



Really sorry for the error

Its alright, will pick up some cleaner when I'm free and see what it does.
Thank you all for the help so far!

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