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Old 09-11-2010, 03:38 PM   #1
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Default Injector question

My engine has developed a miss lately. It happens after "spirited" driving, when the engine is good and hot. And only at part throttle, with very light throttle application. Seems to be getting worse by the day. It happened maybe once or twice at idle, again when hot.

When the engine cools down, everything is OK till the above-mentioned conditions occur.

My question is, can an injector go bad in such a way that it only fails when hot, or after seeing higher duty cycles?
I mean, if it is a clog type problem, it would happen all the time, so I don't think cleaners/additives will be of help here.

Have you ever seen such a case when the injector fails under these conditions?

BTW, I have the original red (99-00) injectors, and just about 100k miles on the clock.
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Old 09-11-2010, 03:49 PM   #2
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I highly doubt its your injectors
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Old 09-11-2010, 03:55 PM   #3
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This problem started just as I was planning to switch to COPs.
So the plugs, wires and coils are gone, and replaced with Toyota coils and new plugs.

Also, I see 16:1 afr levels when this happens.

And, there would be a problem with two cylinders if it was an ECU related problem.

This is why I was thinking it must be an injector.
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Old 09-11-2010, 03:58 PM   #4
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Mine does that too man. If i beat on my car for a while then drive it easy i get weirdness. I have noticed when this happens i am usually at about -5 to 0 and my afr drops to like 16-17. I always thought it was in my tune or shitty injector wiring.
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Old 09-11-2010, 03:58 PM   #5
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16-17 is lean. Very lean.
When I lean out my car that much it does the same thing. When I get it back into mid to low 14's its fine again.

What engine management are you running?

I have a feeling this has more to do with the map and enrichment settings than messed up injectors.

just my .02
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Old 09-11-2010, 04:03 PM   #6
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I guess it goes lean when the injector craps out.

I have the PcPro cards. Had no problems for about a year and a half. Started happening recently.
The miss happens off boost, so the cards are not even in the picture.

Sometimes hot restarts are kinda rough, too.

If only I had a scope...
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Old 09-11-2010, 11:10 PM   #7
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Mine off boost too. I switched off ego correction and it seemed to solve the problem. But when it decided to sputter it always showed stupid AFR? I kinda thought the EGO correction was screwing up. I started just not using it.
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Old 09-13-2010, 07:26 PM   #8
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Problem solved.

Turns out it was a nozzle rather than an injector.

I have a direct port water injection setup as you may know.
And, of the four nozzles, THREE were clogged.
So, all that flow and pressure was behind one nozzle, which was nowhere near sufficient to discharge the water in time.
The nozzle kept on dribbling long after the engine was under boost, till the line pressure was relieved, hence the miss after a hard run.

I will order four nozzles, rotate them once a month, and have the set I pull off cleaned ultrasonically (which I can get done for free) before I reinstall them.

Car runs great now.
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Old 09-13-2010, 07:35 PM   #9
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Glad you figured it out.
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