'92 Saturn DOHC - fuel injector test?

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Old 10-21-09, 07:17 PM
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'92 Saturn DOHC - fuel injector test?

Recently the #3 cylinder on my Saturn quit making compression. The other three make between 175 psi and 205 psi, but #3 makes none. A leakdown test reveals it's getting out the exhaust valve. The prior owner says he lost compression on #2 a while back because the injector failed CLOSED and burned an exhaust valve. I had the engine ready to pull the cylinder head when he told me this. But in getting it apart, I found that the canister purge vacuum hose had been disconnected, probably for quite some time. My questions: Is there a way I can test my injectors instead of replacing one (or more) as a precaution at $80 a throw? Is it possible this protracted vacuum leak has caused my loss of compression? And, might I be time and money ahead to just replace this head with a reman unit, if the leak might have damaged other valves? I hope some of these questions will be answered as soon as I pull the head, but some guidance from the field is always appreciated. Thanks in advance - Chris
 
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Old 10-27-09, 06:25 AM
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Okay, got the head off and, sure enough, there's a burned exhaust valve in the #3 chamber. The valve itself ought to be a pretty easy fix (I've got a machine shop picked out), but I'd like to find the cause and prevent future incidences of this problem.
I checked resistance through the injector coils; #1 was 4.4 ohms, #2 through #4 were 2.4. Factory manual calls for 1.0 to 2.0 An incomplete injector opening would cause a lean condition just like a vacuum leak would, right? And would either or both of these conditions cause a burned valve?
 
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Old 10-27-09, 06:35 AM
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Try to find a F/I service shop. I had one when i was a autotech and they would clean/test the injector for me.

The way i use to test was to move it to another Cyl and see if the problem followed it. But if the injector was locked up/closed then you should have got a miss/lean check engine light on.
 
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Old 10-27-09, 07:22 AM
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Once I replaced the burned-out Check Engine bulb, I retrieved codes 13, 26, 32, and 45. Don't remember the exact relationship, but one was for a quad driver problem, one for an EGR failure, one for O2 sensor showing rich (open loop when it should have been in closed?), and one for an open O2 sensor. Since the bulb had been out since I bought the car, I'm not aware of the history of the codes. But as far as this incident goes, there was no code for a lean condition stored.
 
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Old 10-27-09, 09:00 AM
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A bad EGR valve can cause a lean condition as well.

I would have the head brought back up to spec and replace the O2 sensor. Run the car and see if it runs well and/or gives off any other codes. You will not burn a valve off that quickly so this had to be a long problem that the last owner did nto fix and just kept driving.
Then fix the issue once the car is back together. Should be easy if a F/I is bad. car would run very badly.
 
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Old 10-28-09, 09:10 AM
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Though the people here seem extremely knowledeable, might want to ask over at SaturnFans Forums - Powered by vBulletin too.
 
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Old 10-28-09, 04:33 PM
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Since this EGR valve is controlled by a vacuum solenoid, problem could be in the solenoid, the valve, the wiring/circuit or any combination, yes? Could the large vacuum leak have left insufficient vacuum to operate the valve properly, also? Just trying to cover as many bases as possible as economically as possible! Hey, aaron7, I tried to get on SaturnFans.com. It let me register, I followed the link e-mailed to me, and my registration was complete. But it won't let me post new thread yet. Not giving up, though... Chris
 
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