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Discussion Starter #1
Tundra brothers, Im turning to you for help. I hate double posting but I've searched and searched, tried everything i could think of (even going to the dealer) and Im not getting anywhere.
I have a 2001 Sequoia 4.7 4wd.. Here is my original post http://www.tundrasolutions.com/foru...p-lots-cranking-start-then-rough/#post1506858

basically, with 80k miles, new plugs, fuel filter, timing belt, clean TB, clean MAF, tested CamPS, fresh oil change, no rubbing of CrankPS line, solid fuel pressure, good fuel, injectors and temp sensor within spec, DENSO oxygen sensors Im getting a difficult start (2-5 2 second cranking sessions), and then a rough idle below 1,000pms.

Im so out of ideas now, I have a RossTech USB OBD2/CAN scanner tool so I can see the sensor output in real time.. everything from engine temp to O2 sensors, TPS output, MAF and load conditions look good... but no luck.

This problem has been lurking for several months now, it started before any of the work had been done, none of which really fixed it.

Could this be a stupid leaky injector or a vac issue?

Help and thank you in advance
 

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As simple as it may sound, maybe try disconnecting your negative battery cable to reset your comp, and cleaning out your engine with some sea foam or lucas upper cylinder lubricant. It cheap and it seems like you've tried everything else.

Usually lost of cranking means the engines not getting the gas it needs (clogged/bad fuel injectors or fuel line), it can't ignite the gas correctly (bad plugs, plug cables, compression), or the air/fuel ratio is off (which shouldn't be the problem since you cleaned the MAF.

How does it run at WOT and during normal driving? any pinging or hesitation in the engine? or is it just at start up

We had a 2001 seq also, and the thing always gave us goofy problems like yours. Ended up having to trade it in for a used 2006 model after all the frustration.
 

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Discussion Starter #3
Thank you for the response, I will try some seafoam in the tank and 91 octane, I'l do the seafoam through the booster vac line before i do the next oil change...good idea

At WOT and anything over 1k rpms its fine, runs like a champ, shifts tight..no complaints.

Certainly a goofy problem, I will try disconnecting the battery over night, its weird because I jsut drove it and it started on the first cranking every time, warm or cold, but still the idle issue and I'm sure the starting problem is not over...
 

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A bad maf sensor, and an intake leak are two definite places to look. I would not think a single injector would be the problem.
A fuel delivery problem would show up at higher rpm I would think. Bad ecm's are really rare so that is the last place I would
look. Try some starter fluid on a hard starting morning. It should help weed out coils, plugs. For an intake leak or lean condition introduce propane into the intake after the maf and see if it smoothes the idle out.
 

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Discussion Starter #6
Good idea with the propane!

P0300 code came back today, still showing the left bank, considering a swapped left bank coils to the right and vice versa, im ruling out coils.

I will check the tank for fuel and run seafoam..

I saw a thread where someone sealed their intake box with silicone and it fixed the idle.. I dont see how it could givent aht anything up until MAF is still unmetered air, so if there is a leak around the filter, you MAY be introducing 'dirty' air but it would still be metered... right?

Also, is there any kind of Idle Air controller or valve that mightneed to be cleaned or is that all just done through the TB opening? When i cleaned the TB, I didnt see any side passages on it?
 

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What's a PO300 code? You didn't mention any codes before did you? You can actually find an intake leak with propane.
Just wave it slowly around any suspected areas that may leak and the idle will smooth out when you find it. Ok, I just
clicked your original thread.
 

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here are the book listed problems for P0300, Random Misfires.
open or short in engine wire
connector connection
vacuum hose connection
ignition system
injector. ( your idea once I believe)
fuel pressure
mass air flow meter
engine coolant temp. sensor
compression pressure
valve clearance
valve timing
ECM
 

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Discussion Starter #9
the P0300 is Multiple cly misfires.. ffollowed by other P03 codes signifying which cylinders.
Being an 01 it still has the throttle by cable and a massive TB setup... I noticed a faint humming/churing sound coming from the driver's side of the unit the other day when it wouldnt start, also what is th tube that attaches to the top of the TB and goes to the drivers PCV used for?
Im starting to think that this large TB may need to be removed and cleaned... it looks like there are small passages on the rear?
 

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Discussion Starter #10
here are the book listed problems for P0300, Random Misfires.
open or short in engine wire
connector connection
vacuum hose connection
ignition system
injector. ( your idea once I believe)
fuel pressure
mass air flow meter
engine coolant temp. sensor
compression pressure
valve clearance
valve timing
ECM
thanks for looking it up. I've been dogging through the FSM trying to pinpoint the issue as well. But once, again, this board has proven more useful in dealing with the issue.

It looks like the starting issue is common and most likely unrelated to the idle stumble. I will run seafoam or BG44K if i can find some with a 91 octane fill up when we leave for the trip, highway driving should be a good way to clean the injectors.

When I get back I'l order the TB gasket, take apart the TB and see if there are any hidden passages that may need cleaning...
 

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Discussion Starter #13
Im not sure this is correct, but according to the FSM:
"Idle Speed Control
Previously, IAC valve was used to perform idle speed control such as fast idle during cold operating conditions and idle-up. In conjunction with the adoption of the ETCS-i, idle speed control is now performed by the throttle control motor, which controls the throttle valve opening."

So no IAC in the 4.7?
 

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Discussion Starter #14
Final Post - Conclusion

The Sequoia has been running and starting like normal all day today, despite the P0300 code coming back intermittently

We will be hitting the road soon, fingers crossed the truck makes it without issue.. Im taking the scanner to monitor the engine while driving, see if I get any goofy readings.

Thank you to everyone that has contributed, your suggestions and troubleshooting efforts have been tremendous.

I will post updates when I get back, hopefully the seafom and battery disconnect help. Based on everything till now, research on the board and your suggestions and in light of the lack of a IAC valve, I believe the starting issue is related to the Throttle Body, and will be removing and dismantling it next week. If the TB motor doesnt work (which would correspond to the noise I heard that one time), it wont allow the the TB to open and the engine will not get any air, it may sputter a bit first but the starve and fuel will flood the cylinders. The cable by throttle combined with a motor controlled/clutched TB is a horrible idea, expensive to make as it uses both fly by wire technology required for VSC Trac and cable... I guess there is a reason they did fly by wire on the newer models.
With the scanner I can view the TPS output, if it doesnt start thats the first thing im checking...

Thanks again, have a great weekend!
 

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I'm wondering if the crankshaft position sensor is causing the rough idle.
 

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Discussion Starter #16
Just got back, no major problems, the CEL came back a few times with P0300 citing multiple misfires 3,5,7 (not 1?)

Ran like a champ on the highway, filled it with 93 octane and a can of Seafoam, but it made no difference with the idle. and still a delayed start up every 3rd time.

I doubt it could be the crankshaft sensor if its always the same bank that is effected and it runs fine after 1k rpm. Im not ruling it out entirely but just temporarily.
While driving I was able to monitor the engine in real time, all four O2 sensors read identically across both banks. TDC timing adjustment was responsive, MAF was accurate, TB position was responsive and accurate..
One question, how does the ECU compute a misfire?

Next step in trouble shooting will be switching the injectors from one bank to the other.
 

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When you say fuel pressure is solid did you put gauges on the rails to determine that? Did you also check the fuel pressure regulator to insure that it isn't bleeding pressure while the engine/fuel pump are off?
 

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Discussion Starter #20
I measured it at the driver's rail, pressure remains until about 10 minutes after the engine was turned off.
I did not check the FPR, figuring the high rpms are fine and I was under the impression a faulty FPR results in a high RPM idle. How do I test the FPRs?

thanks
 
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