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Unread 06-26-2012, 03:34 PM   #16
SchizophrenicMC
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1997 ZJ 
 
Join Date: May 2012
Location: Arlington, Texas
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Ironically enough, I just fixed my Saturn's Cylinder-1 Misfire. But Saturns have a common problem with their intake manifold gaskets cracking at cylinder 1, so they get all 16:1 with their air-fuel and it doesn't work.

Anyway, your plugs, wires, distributor, and coil are all fine, so you can basically rule out electrical problems. (The ECU wouldn't likely store codes like that if it was faulty. Mine didn't.) Check for compression. If compression is good, check your fuel system. If fuel pressure is good and consistent, and your injector works properly, you can rule out fuel system. If it's neither compression, nor fuel, re-evaluate your electrical system. I suggest going in this order because it's cheap and not as complicated as searching for electrical gremlins that may not exist.

Just putting it out there: Could something be blocking airflow to cylinder 1? I can't imagine anything that would be, at least without being obvious, but it's a possibility I suppose?

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Unread 06-26-2012, 08:56 PM   #17
Billyjoebob007
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1997 ZJ 
 
Join Date: Dec 2008
Location: Denver
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Quote:
Originally Posted by GunnyA View Post
Silly question what kind of plugs are you using? I had the same issue with my 98zj after changing all kinds of valves and sensors I was one step away from changing the ECU. I was scanning the threads and ran across some bosch spark plug bashing. I had new bosch plugs in there so I never thought they would be the problem. They were gapped correctly and looked fine. I decided to change them out for a cheap pair of champions. Go figure it cleared it right up. Could have saved me a couple of hundred dollars in parts I didn't need.
Humm, i have a set of E3 Spark Plugs installed. I didnt change them out when i did the tune up. If i recall, i may have swapped around the no.1 and no.3 plugs around to see if that changed anything and it didnt. At least i think i may have but dont fully recall
I have another set of autolites around, i could swap out the no.1 and see what that does.
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Unread 06-26-2012, 09:00 PM   #18
Billyjoebob007
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1997 ZJ 
 
Join Date: Dec 2008
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Quote:
Originally Posted by SchizophrenicMC View Post
Ironically enough, I just fixed my Saturn's Cylinder-1 Misfire. But Saturns have a common problem with their intake manifold gaskets cracking at cylinder 1, so they get all 16:1 with their air-fuel and it doesn't work.

Anyway, your plugs, wires, distributor, and coil are all fine, so you can basically rule out electrical problems. (The ECU wouldn't likely store codes like that if it was faulty. Mine didn't.) Check for compression. If compression is good, check your fuel system. If fuel pressure is good and consistent, and your injector works properly, you can rule out fuel system. If it's neither compression, nor fuel, re-evaluate your electrical system. I suggest going in this order because it's cheap and not as complicated as searching for electrical gremlins that may not exist.

Just putting it out there: Could something be blocking airflow to cylinder 1? I can't imagine anything that would be, at least without being obvious, but it's a possibility I suppose?
I havent had time to do that compression check yet, i have mis placed me check guage somewheres
I will have to ask our shop mechanic for his, to do it. Is 16:1 range where the compression should be at ?
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Unread 06-26-2012, 11:26 PM   #19
SchizophrenicMC
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Quote:
Originally Posted by Billyjoebob007 View Post
I havent had time to do that compression check yet, i have mis placed me check guage somewheres
I will have to ask our shop mechanic for his, to do it. Is 16:1 range where the compression should be at ?
No, 16:1 is low diesel. What I was noting was the air-fuel ratio in the Saturn with a bad intake manifold gasket. When performing normally an engine should have a stoichiometric ratio between air and fuel. This is roughly 14:1. That is, for every unit of fuel, there are 14 units of air. If you have more air coming in due to a leak (for example, the roughly 16:1 ratio in the leaking Saturn), it reduces the ability of the fuel to combust properly (the ECU can't meter fuel out properly) and it causes a misfire. Like I said, it's a Saturn problem, I doubt it's happening to you.

But the principle of an engine misfiring when it's out of stoich is universal.
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Unread 06-26-2012, 11:49 PM   #20
jnicewan
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Go ahead and try another plug in cyl #1, thats cheap and easy, and you are getting cyl #1 correct (frt cylinder drivers side)? I hate to ask that but some people (including me) get confused at times especially when working on a lot of different makes.

Testing compression is more about comparing it to a few different cylinders than specific pressure unless its real low. Its a good practice to check them all, but I would at least compare the suspect cylinder to a couple other ones. You should want to see at least 90-100PSI.

It was already mentioned above about a gasket leak or vacuum leak, this could be a possibility too. Others that have V8's might chime in about the plenum gasket too, Im not sure of what is common to see when a plenum gasket leaks, but maybe its leaking around cylinder 1 area? You might also spray some carb cleaner on the intake where it meets the cylinder head specifically around cylinder 1 area for a possible intake gasket leak.
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Unread 09-21-2013, 12:30 PM   #21
Billyjoebob007
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The problem ended up being a bad fuel injector.
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