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Post by philip1 on Dec 1, 2012 17:11:14 GMT -5
I have a Saab with CIS and a turbo. I have a persistent misfire on #2 cyl. I've changed the fuel distributor to a freshly rebuilt one and no change I'm not going to throw money at it without knowing where to place it. So..... HELP needed.
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Post by soloracer on Dec 1, 2012 23:16:08 GMT -5
If i knew anything about cars i would volunteer.
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Post by CoolGuy094 on Dec 2, 2012 0:09:52 GMT -5
Do you have a wideband? Is it running really rich when you start misfiring? Does cylinder 2 constantly miss or is it just under certain throttle conditions or at certain boost levels? Guessing you know its cylinder 2 because of a CEL code? What is the car and engine code? Also guessing this is not a factory turbo setup?
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Post by philip1 on Dec 2, 2012 6:16:01 GMT -5
It's a 1978 Saab 99 turbo all factory including the turbo, no cel (almost no computer) No wide band on this car. Misfire detected the old fashioned way, find the cyl that doesn't change when spark is removed. I have not even made any boost yet. I pulled the fuel line while running to find almost no pressure at the injector. The other three have plenty. But changing ports changed where the misfire is. This baffles me because the parts are all new, fuel distributor to injectors. Do I need a fuel pump? Do I need to start over? And how do I test fuel pressure on a system with banjo fittings and no rubber lines?
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Post by CoolGuy094 on Dec 2, 2012 15:42:50 GMT -5
Ugh, I was going to say clean the injectors by flowing carb cleaner through them and make sure they are all producing a good spray, then pull the plugs and see what they all look like. You say changing ports changed where the misfire was... if you swap the injector for cyl 2 to cyl 4 does the misfire move with the injector?
I have heard of people drilling and tapping fuel rails and installing pressure gauges... not sure how far you want to go with this. But I have also heard of the same people developing leaks at these drilled/tapped sites.
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Post by philip1 on Dec 2, 2012 16:07:42 GMT -5
No but if I move the hose it does.
I don't have a fuel rail
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Post by philip1 on Dec 2, 2012 16:18:19 GMT -5
This might help you visualize the system This is the fuel distributor  And these are the injectors with hoses attached  |
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Post by soloracer on Dec 2, 2012 20:03:14 GMT -5
trying to clear my scedule for sat.
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Post by CoolGuy094 on Dec 2, 2012 20:41:38 GMT -5
Sounds like its an issue with the specific port within the distributor. Something internal to the distributor is causing that port to flow too much fuel. I know nothing about old Saab's.
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Post by philip1 on Dec 2, 2012 21:05:38 GMT -5
Too little fuel is the issue.
Port no2 is the last one in the chain and without enough head pressure it's the first one to stop flowing. This system is weirdly simple using poppet valves at the distributor and the injectors. Basically if you don't have enough pressure they won't open.
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Post by cashflyer on Dec 4, 2012 14:35:14 GMT -5
This *may* be of help. jimsbasementworkshop.com/CIS/I think if you had a weak fuel pump, that you would have a problem on all cylinders. Start then quit, or stumble under acceleration, etc. - not just one bad cylinder. I would suspect a blocked line. Either blocked at/in the distribution block, or in the line itself. But that is just my desk-jockey guess. I know old lines get brittle. Can you pull the suspect line off the distributor and see how the fuel flow is straight from the source? You said you replaced the distributor... can you exchange it as a defective unit? And how do I test fuel pressure on a system with banjo fittings and no rubber lines? Something like ebay# 360152710099 would do it. |
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Post by philip1 on Dec 4, 2012 16:23:29 GMT -5
It does stumble but Shane said it fuel starves when under 1/4 tank it's sitting ay about 1/8th tank
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Post by stealthgtfour on Dec 5, 2012 15:25:17 GMT -5
this needs to be moved
+1 on clogged port or line
can you pull both ends of the hose off and blow air through it?
or move entire hose to another cyl.(both ends) if it fallows the hose then you found it
if not then its a dist issue.
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