2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Fuel sys won't depressurize - sec. rail prob?

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Old 02-13-04 | 04:54 PM
  #26  
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Interestingly enough, myself and a friend, both with good condition engines and strong compression numbers experienced the same thing after having our injectors cleaned/balanced.

For myself it began flooding ever since. For my friend, he only has 36k miles on his engine and flooding began the day he put in the rebuilt injectors.
Old 02-13-04 | 05:27 PM
  #27  
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Originally posted by Ni5mo180SX
Interestingly enough, myself and a friend, both with good condition engines and strong compression numbers experienced the same thing after having our injectors cleaned/balanced.

For myself it began flooding ever since. For my friend, he only has 36k miles on his engine and flooding began the day he put in the rebuilt injectors.



Then perhaps the moral is if it ain't on fire, don't fix it.


That's interesting to hear. FWIW, maybe you ought to take at look at your ignition system...
Old 02-13-04 | 09:15 PM
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Originally posted by Amur_
- all 4 plugs were cleaned 24 hours ago. When he pulled them he said that the trailing ones looked fine, but the leading ones did not. He pointed to a small, clean 'ring' at the innermost edges of the electrodes (I can chop a pic if anyone's having trouble with that description) and said that the last time he saw that pattern on a plug the rotor was about to go...
The leadings burn a little "hotter" since the hold going into the combustion chamber is larger.  On spark plugs with a lot of miles on them, the leadings look "normal", but the trailings look "rich".  The trailings do not get that big of a flame triggered by the spark plugs due to the smaller orifice going into the combustion chamber.  This part sounds alright...

He also said the leading ones looked as though the motor was running rich. The thing was, the trailing plugs looked fine. So it looks like the leading plugs aren't doing their job. Not doing it well enough, anyway...
Verify the leadings are firing?  Kill the fuel pump and pull one leading spark plugs at a time.  Replace the spark plug boot and ground the threaded part of the spark plug to a known, good ground point - I use the front upper strut tower studs due to it's close proximity (remove the stock black rubber cover to expose them).  Crank the engine and verify the spark plugs are sparking - this will pretty much confirm if the leadings are firing or not.  Coils typically fail totally, so if it's firing a spark the leading coil should be okay.  Now, it's a matter if the spark is strong enough...  The spark should be a blueish-white.  Weak spark looks more blue and barely visible.  It's hard to explain in words the difference, but if you've done this a few times you'll understand. Try checking all 4 spark plugs to give you an idea.


- I did a resistance test on the L1 wire (all high tension leads are OEM, the leading ones are the 'long' pair.) The 87 FSM says 16k/m. I got 7.7k. Is a lower resistance a desirable thing, or is it time to go shopping?
Check all 4 leads - if they are all close, then it's not that bad.  The resistance sounds about right, if I recall what stock wires should spec at.  If you're wary, you can replace them, as NGK replacements are reasonable priced.  Really low resistance really doesn't matter (except for extreme resistance readings like over 10k-ohms), as this is a common misconception about "performance".  The highest resistance in the "system" is the air gap of the spark plug tip.  This air gap is on the order of MEGAohms, so why would a few k-ohms matter?

So it looks as though there's a chance that my flooding is due to poor ignition on the leading plugs rather than a dying motor. I can't tell ya what a relief that was to hear. I only hope that it proves to be true.
To add my data point to the whole pro fuel injector cleaning, I've had the same thing.  I had my original 4x550's professionally cleaned locally, and it made the flooding problems WORSE.  A friend's FC turbo had massive flooding problems, and getting them cleaned (by the same shop as mines) did not make the problem any better.  That car has been a royal pain, as it's barely making 10mpg and sedate driving, and the FPR has already been changed with a brand new one from Mazda.  There might be an interesting connection between flooding and pro injector cleaning...


-Ted
Old 02-13-04 | 09:40 PM
  #29  
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Originally posted by RETed
Verify the leadings are firing?[/i]

I'll check all 4 plugs, as described.



Check all 4 leads - if they are all close, then it's not that bad.

I'll check all of the wires, plus an additional spare 4 I've squirreled away.


To add my data point to the whole pro fuel injector cleaning, I've had the same thing. There might be an interesting connection between flooding and pro injector cleaning...

I'll be damned...


We also discovered last night that my right outer tie rod end is about to fall off the car. The new one isn't due in until Tuesday and I'm going to try to keep her off the road until then; I'll do everything at once and post back Tuesday night.
Old 02-18-04 | 12:42 AM
  #30  
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So the only thing I didn't get done tonight was the damn tie rod end. The puller that I thought was at the shop wasn't.


Anyway, on with story...


- all 4 of my 'long' plug wires come back at slightly under 8k ohms.


- I show 11.7 volts at the leading coil. This is both before and after hella-cleaning its base (I assume that it grounds itself to the body...)


- I pulled the leading plugs. They looked just like they did last week. Black, like they're running rich... Didn't pull the trailing plugs - I think it's safe to assume that they're brown, like last week.


- did the coil resistance test (s4 FSM 5-31). Got 0.6, well within spec.


- didn't get to look at the plugs actually firing (was working alone.) Maybe Wednesday...


[edit]
- put in a spare set of leading plugs in very good condition. If this 'rich' state doesn't appear on them, we'll know my old plugs were pooched. If these temps do come back black... maybe it's time for new plugs...


Some things I probably should have mentioned earlier...

I have an un-tuned S-AFC in the car. It's hooked up properly but it's still on the factory default settings. The S-AFC was in the car before the flooding problem started.

The washers on all 4 plugs have been removed. I have been doing this with all my plugs since I first read about the idea here on the forum about 2 years ago.


On the fuel injector cleaning comments - are there any other options for dealing with fuel injectors other than pro cleaning? I think it's time for a Google search after this goes up.

Last edited by Amur_; 02-18-04 at 12:54 AM.
Old 02-18-04 | 02:42 AM
  #31  
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There might be an interesting connection between flooding and pro injector cleaning...


-Ted [/B]
My thoughts as well. With as many people as this has happened to under similar circumstances, its starting to become a front runner in my mind.
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