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Injector Questions

 
Old 11-23-2011, 03:01 PM
  #1  
sundog
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OK, so at a track day at Laguna Seca yesterday, and on staging for the third run session of the day my car started running rough and belching a lot of white smoke. Got out, and it smelled like gas, not oil, a couple of the GGR guys said, stuck injector. So, I took it apart in the paddock, and disconnecting the plugs from each successive injector didn't fix it. The ScanTool registers a 52, Injector Failure #2 error.

So it looks like the injector is mechanically stuck on full flow. I'm a little concerned about just replacing a single injector though. but all six would be close to $1K!

Ideas, advice? They were all rebuilt/cleaned about 20K ago when I rebuilt the engine.
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Old 11-23-2011, 03:29 PM
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I guess first I would pull them all and check each one.

9 volt battery will work the injector and you can shoot it into a glass jar. Look for spray pattern, leaking, and drips after it's closed.

If the rest of them seem to be okay, it is probably okay to just that one.

If you have 2 or 3 more questionable ones probably makes sense to replace them all.

When I used to work on these cars for a living we would replace onesies all the time without any ill effects.
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Old 11-23-2011, 04:02 PM
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I had a hot start issue I traced to Injector #6. I tried cleaning the contacts but no luck so I had the all injectors cleaned and #6 rebuilt when the engine was out and it solved the problem. At that time new ones were about $1k but the rebuilt one has been fine with no issues.

Marc
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Old 11-23-2011, 04:05 PM
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I just sent mine out to witchhunter performance to be cleaned and tested. I imagine a broken injector is a broken injector, but for 20 dollars to clean test and flow, and replace o-rings etc, probably a good first shot to see if you really need to replace...
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Old 11-23-2011, 04:15 PM
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Originally Posted by Marc Shaw View Post
I had a hot start issue I traced to Injector #6. I tried cleaning the contacts but no luck so I had the all injectors cleaned and #6 rebuilt when the engine was out and it solved the problem. At that time new ones were about $1k but the rebuilt ones have been great with no issues.

Marc
Tell-tailed sign of a bad injector.
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Old 11-23-2011, 05:02 PM
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Originally Posted by Marc Shaw View Post
I had a hot start issue I traced to Injector #6. I tried cleaning the contacts but no luck so I had the all injectors cleaned and #6 rebuilt when the engine was out and it solved the problem. At that time new ones were about $1k but the rebuilt ones have been great with no issues.

Marc
Don't want to hi-jack the thread, but what kind of issue Marc?

Mine fires up fine and then dies... Not always, just sometimes. If I keep on the accelerator she is fine. If I drive her for a minute no stalling either. Heven't been able to trace it to the source.
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Old 11-23-2011, 05:58 PM
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Originally Posted by Navaros911 View Post
Don't want to hi-jack the thread, but what kind of issue Marc?

Mine fires up fine and then dies... Not always, just sometimes. If I keep on the accelerator she is fine. If I drive her for a minute no stalling either. Heven't been able to trace it to the source.

Hot or Cold start ups?

Idle Control Valve.
Fuel Check Valve.
Accumulator.
Low Fuel Pressure.

There is a bunch of things that it could be.

Generally speaking a leaking injector will upon a hot restart will crank and not want to fire up becuase it is basiclly flooded at that point.
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Old 11-23-2011, 07:58 PM
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Originally Posted by Navaros911 View Post
Don't want to hi-jack the thread, but what kind of issue Marc?

Mine fires up fine and then dies... Not always, just sometimes. If I keep on the accelerator she is fine. If I drive her for a minute no stalling either. Heven't been able to trace it to the source.
[HIJACK]

Exactly like Makmov said.

If I came off with the engine stinkin' hot, shut it off and let it cool, it restarted fine but if I tried to restart right away, it started but sounded very rough like it is not running on all cylinders (as it was not). The garage could not replicate it as they could not get the engine hot enough with street driving so I took my Hammer to the track to diagnose it.

Marc

[/hijack]
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Old 11-24-2011, 08:32 AM
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Shop- you can find injectors for around $500 if you look. There was a rebuild company mentioned that does good work as well.
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Old 11-24-2011, 01:08 PM
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+1 on having them serviced; it's quite common in various other automotive circles I've frequented (Flyin' Miata turbo cars, Subarus...) While you may find you *do* need to replace it/them, it's not a given.
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Old 12-10-2011, 09:51 PM
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Well, I replaced #2 injector today, and it did not fix the problem. I had the scan tool connected, and it still said failure on injector number 2, even though I replaced it with a new one. Then I took off the connector to number 1, and the error went away. Next I replaced number one, and the same error, number 2.

Since I was on that side, I switched the new one to number 3, and it no longer has the error.

Does anybody know what the error actually means? The resistance was within the limits of 16 Ohms as specified in Adrian's book. Is it possible that the cabling is bad, or the DME?
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Old 03-23-2012, 11:08 PM
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OK, so today at the track, I got in 4 great sessions. Before the third, the CEL came on, and the injector issues appeared again. I was able to restart car, and problem went away. Then before the 5th, I started up and the CEL won't go out. Tried unplugging all 3 injectors on the left bank, and no more white smoke. But the resistance of all injectors is fine, and all the cabling was showing same resistance and voltage output of ~13 V.

So is there a way that the DME could be sending a bad signal to an injector?

I'm really stuck here does anybody have any ideas?
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Old 03-23-2012, 11:22 PM
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Disclaimer: Mechanical engineer.

There's driver circuitry somewhere that controls the injectors, and given the speeds at which these need to cycle and the loads that they need to work against they're the electrical equivalent of little hard working machines. It's possible you could have an issue on the injector control side. Try another DME or one of the specialty ECU repair places.
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Old 03-24-2012, 04:02 AM
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and no more white smoke
that tells me you have a leaking injector.....

Sounds like you need to clean and flow test the injectors.

You have one spare injector that is known good unit?

Does it look like this? https://rennlist.com/forums/964-foru...corrosion.html
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Old 03-24-2012, 08:18 PM
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Originally Posted by sundog View Post
Tried unplugging all 3 injectors on the left bank, and no more white smoke.
I'm really stuck here does anybody have any ideas?
Take the 3 off the left side and put them on the right side ...
Does the problem switch sides ?
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