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Discussion Starter #1
Hey guys, I need your help. My son bought a 2003 IS300, drove great but had some leaking from crank seals and valve covers. Timing belt, pump, seals and so on were replaced, everything. Valve covers, ngk plugs and wires except for the ignition coils, they tested fine. I also replaced the ignition coil connectors since they broke upon removal.

Once we put everything in place, we fired up the engine and its running like crap. No power and its idling rough. I scanned the codes and got p300, 301&306.

I swapped ignition coils to see if the problem would follow but nope. I checked the newly replaced coil connector but it looked fine. Plugs are gaped correctly and wires are new.

Any ideas? My son needs a car for work and is eyeing my supra, that cant happen! :)
 

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Hey guys, I need your help. My son bought a 2003 IS300, drove great but had some leaking from crank seals and valve covers. Timing belt, pump, seals and so on were replaced, everything. Valve covers, ngk plugs and wires except for the ignition coils, they tested fine. I also replaced the ignition coil connectors since they broke upon removal.

Once we put everything in place, we fired up the engine and its running like crap. No power and its idling rough. I scanned the codes and got p300, 301&306.

I swapped ignition coils to see if the problem would follow but nope. I checked the newly replaced coil connector but it looked fine. Plugs are gaped correctly and wires are new.

Any ideas? My son needs a car for work and is eyeing my supra, that cant happen! :)
If everything at the coil is working. I would look at the ignitor connector and wiring. Other would be a ignitor problem. But that is a remote possibility.
 

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Discussion Starter #3
If everything at the coil is working. I would look at the ignitor connector and wiring. Other would be a ignitor problem. But that is a remote possibility.
Yeah ill redo the connector. Would vacuum leaks cause this type of codes as well? I was thinking since we removed the entire intake manifold, some of those dry hoses may be leaking now. Ill need to get some carb cleaner and spray around the whole intake and hoses.
 

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Yeah ill redo the connector. Would vacuum leaks cause this type of codes as well? I was thinking since we removed the entire intake manifold, some of those dry hoses may be leaking now. Ill need to get some carb cleaner and spray around the whole intake and hoses.
Vacuum leaks could. But you would have more codes. If the connections and all are good. Have you checked te compression? Also check the injectors.
 

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The only thing other than the connectors, which gave me issues when I did the maintenance, would be the timing belt. If it was installed incorrectly, it could be the source of the issue.

I'm not sure how you would go about checking timing though in case it is the problem.
 

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Discussion Starter #7
The only thing other than the connectors, which gave me issues when I did the maintenance, would be the timing belt. If it was installed incorrectly, it could be the source of the issue.

I'm not sure how you would go about checking timing though in case it is the problem.
Yes another good point, im actually going to have the timing checked this afternoon.
 

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Anyone use the NGK BKR6IX-11 Iridium plugs? I pulled the newly installed ones and they were gaped at .34. I didnt bother checking the gap since everyone had said Iridium plugs come pre gaped. Should i be gaping them to .44?
 

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Discussion Starter #9 (Edited)
I came across this information on a different post from a member and i believe this is my problem, I need to gap my plugs to .44 being that im stock. That may be the problem for the misfiring.

Member - DJSPOCK3030
"I happened to stumble upon this while researching some of the ol' famous cel codes like Trac Light flashing and P0300, P0301, P0302 etc etc. Researching posts all the way back to 2003 the most common issue for the cyl misfire codes was #1 spark plugs etc #2 random other shiz #fuel pump. I would seem 9 x out of 10 plug's or settings with the spark plugs, faulty plugs, or coil packs were always the issue. Found this gem of advice on the ngk site while researching cooler plugs:

3. Gapping

Since the gap size has a direct affect on the spark plug's tip temperature
and on the voltage necessary to ionize (light) the air/fuel mixture, careful attention is required. While it is a popular misconception that plugs are pre-gapped from the factory, the fact remains that the gap must be adjusted for the vehicle that the spark plug is intended for. Those with modified engines must remember that a modified engine with higher compression or forced induction will typically require a smaller gap settings (to ensure ignitability
in these denser air/fuel mixtures). As a rule, the more power you are making, the smaller the gap you will need.

A spark plug's voltage requirement is directly proportionate to the gap size. The larger the gap, the more voltage is needed to bridge the gap. Most experienced tuners know that opening gaps up to present a larger spark to the air/fuel mixture maximizes burn efficiency. It is for this reason that most racers add high power ignition systems. The added power allows them to open the gap yet still provide a strong spark.

With this mind, many think the larger the gap the better. In fact, some aftermarket ignition systems boast that their systems can tolerate gaps that are extreme. Be wary of such claims. In most cases, the largest gap you can run may still be smaller than you think.

I know stock guys are or should be at .044 on the plug gap. As of right now I am at .26 @ 8 psi. I would like to see what others are at post here:

NGK Recommendation Stock .044
Lexus Recommendation Stock .039-.043

Forced Induction Recommendations

NGK Recommendation: "A spark plug part number might fit hundreds of different engines from many different manufacturers. Although the NGK factory will set the gap to a pre-selected setting, this may not be the right gap for your particular engine. The incorrect plug gap for your engine can contribute to a high rate of misfires, loss of power, plug fouling, poor fuel economy, and accelerated plug wear. It is always best to check the gap against the manufacturer's specifications. If adjusting the gap on fine wire or precious metal plugs such as platinum or iridium be very careful not to apply any pressure or prying force to the fine wire center electrode or insulator as they can be damaged. The gap should be adjusted by only moving the ground electrode.

Another consideration that should be taken into account is the extent of any modifications that you may have made to the engine. As an example, when you raise compression or add forced induction (a turbo system, nitrous or supercharger kit) you must reduce the gap (about .004" for every 50 hp you add). However, when you add a high power ignition system (such as those offered by MSD, Crane, Nology) you can open the gap from .002-.005".
 

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Anyone use the NGK BKR6IX-11 Iridium plugs? I pulled the newly installed ones and they were gaped at .34. I didnt bother checking the gap since everyone had said Iridium plugs come pre gaped. Should i be gaping them to .44?
I just run OEM spec, although people go NGK because its a well known brand.

OEM is: Denso (3353) SK16R-P11 Iridium Spark Plug

As for gap distance, 0.044 thousandths is what N/A should run, your little find on boost seems about right.
 
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