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Just some guy
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Discussion Starter #1
So I've had a stumbling idle problem since I picked up my car. I replaced a BHG as soon as I got it, and after putting it together it had a stumble, to the point it shook the car a little. It was not noticable once the revs went up. I redid the head, good compression, so not a mechanical issue. Checked for leaks in the intake system, checked ignition, sensors, the whole gambit, no dice. Replaced parts with known good parts from my other mk3 and problem persisted. So I decided to live with it.

Now I'm replacing a slight BHG (water jacket copper was crushed). Anyways, I notice that the #5 cylinder port on the head is cleaner than the other, noticably cleaner. Intake runners on plenum/runners are all equally black (egr/pcv kaka). But the port on the head, after the fuel is introduced, is clean. not totally clean, but much cleaner than the rest. This leads me to believe that the injector on #5 had been leaking. Now the weird part is, I sent all 6 injectors off to RC to get cleaned/balanced, and they came back with a seal of approval. Could RC have missed the fact that one was leaking?

Any input would be appreciated.

Christian
 

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Always playing catch up
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1,632 Posts
hm.... wierd, but it could also be the injector is being set to wide open by the wiring. as for it being cleaner, did you read the plug when you pulled the #5 plug? it should be black IIRC.

how was your vac? i dunno thats a very wierd problem

<l><l>
 

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Just some guy
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1,681 Posts
Discussion Starter #3
vacuum at idle actually sucked, around 15-16 in/hg. When I pulled the manis, I checked the gaskets for leaks and surfaces for trueness, and everything looks good.
 

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Always playing catch up
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1,632 Posts
i would start there, as 20ish should be the target, might have a hairline crack in the IC pipes or something. most likely the cause of your problem

<l><l>
 

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Registered
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Check the thick rubber rings in the head which "hold"the injectors. Most likely they're hard and maybe one of them leaks. Had it once before. Car was driveable but sucked at idle.
 

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JZS161 Aristo TT
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881 Posts
C44 said:
Check the thick rubber rings in the head which "hold"the injectors. Most likely they're hard and maybe one of them leaks. Had it once before. Car was driveable but sucked at idle.
I had a craked pintle cap on used 550's flow checked ok service agent installed new filters but not the 20 cent plastic cap
 
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