2nd Generation Specific 1986-1992 Discussion

Crank Angle Sensor Question

Old 03-20-2004, 06:36 PM
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In the process of troubleshooting a lack of acceleration problem on a 91n/a engine installed in an 87 with the S4 sensors & manifolds, I checked the ignition timing. If I set the leading timing 5atdc like it should be and then accelerate the engine, while keeping the timing light on, the timing will stay on the 5 degree mark until the engine reaches about 1400 rpm. At this point, the timing advances, and keeps advancing farther the more the engine accelerates. Should the timing stay at the 5 degree mark for this long?? Just wondering...

Thanks!
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Old 03-20-2004, 06:39 PM
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thats about right. at 1500rpms it starts advancing
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Old 03-20-2004, 07:49 PM
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So that is normal.. doh.. thought I found it. My car still has a hesitation from 3500 to 4000 that isn't like the quick 3800 hesitation most cars get. (atleast I dont think so!) Anyways, when I advance my timing a little, say to 0 degrees, the hesitation almost completely disappears. If I retard the timing to about 10 degrees, it is much more prevelant. Also, my car idles like $hit with the timing advanced, but with it retarded, completely smooth. Does the CAS have anything to do with the secondaries coming online? I know that the trailing coil signal is what the ecu uses to drive the injectors, so could this even be related?? btw, my car has a large street port, and the car will not accelerate very well until after this hesitation. After the secondaries are going, i.e. 4000+, the car accelerates like no tomorrow. It doesn't seem to matter if the secondary port sleeves are opened or closed, or if the VDI is in either position. (I tried) I'm confused...

My car is tired of being smoked by riced out civics!!!
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Old 03-20-2004, 08:00 PM
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the ecu uses the cas to drive the injectors, the trailing coil drives the tach
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Old 03-21-2004, 07:33 AM
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Guess my info was wrong then. So if the ECU uses the CAS to drive the injectors, then this could be the culprit.. is that right?? like I said, the hesitation that happens at 3.5 and continues up to 4000 seems to be like a secondary hanging closed until the duty cycle comes up enough to open it. All of my injectors check out fine. What is really wierd is that the car will pull fine AFTER this hesitation, but before it, it doesnt. It is like a turbo car where boost would come online after this hesitation. In 1st, it takes about 2.5 seconds to pull up to 8000. about 2 seconds of this is spent below 4000 rpm including this hesitation. Is this normal??
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Old 03-21-2004, 10:09 AM
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its normal for all cars
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Old 03-21-2004, 12:07 PM
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Originally Posted by threcixty' date='Mar 21 2004, 05:33 AM
Guess my info was wrong then. So if the ECU uses the CAS to drive the injectors, then this could be the culprit.. is that right?? like I said, the hesitation that happens at 3.5 and continues up to 4000 seems to be like a secondary hanging closed until the duty cycle comes up enough to open it. All of my injectors check out fine. What is really wierd is that the car will pull fine AFTER this hesitation, but before it, it doesnt. It is like a turbo car where boost would come online after this hesitation. In 1st, it takes about 2.5 seconds to pull up to 8000. about 2 seconds of this is spent below 4000 rpm including this hesitation. Is this normal??
the cas has one moving part, all it does is send the rpm and crank position to the ecu. if the car runs it cant be the cas.
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Old 03-21-2004, 05:01 PM
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[/QUOTE]the cas has one moving part, all it does is send the rpm and crank position to the ecu. if the car runs it cant be the cas.



Good point. Why is my car slow??!? I would think that an S4 with a ported S5 motor should be atleast as fast as a stock GSL-SE.. no??

Thanks for the help!!

Jim
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Old 03-21-2004, 05:33 PM
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That hesitation is a lean spot, seems kinda like its maxing the primaries. With an A/F ratio meter you can see it hapening. I modded the AFM in my S4 N/A to kinda trick the ecu to think there is more air flowing. It alieviated the problem. Or you can get an S-AFC and iron it out that way.
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Old 03-21-2004, 05:47 PM
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the cas has one moving part, all it does is send the rpm and crank position to the ecu. if the car runs it cant be the cas.



Good point. Why is my car slow??!? I would think that an S4 with a ported S5 motor should be atleast as fast as a stock GSL-SE.. no??

Thanks for the help!!

Jim [/quote]

it really depends on your setup, a stock gsl-se works pretty good
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