The car sat for roughly 2 months. I started driving it again last week. After coming back out from shopping it was hard to start but eventually fired up and drove fine. The next day it quit altogether. It would sputter but not really start for any more than about 2 seconds. ECU showing code 21 and I am seeing weak spark on 3 out of 4 cylinders. The distributor and cap have been replaced and seemed to help it run a bit longer but still weak spark. I was suspecting bad wires at this point but since they are special order I wanted to be sure so I moved the plug wire from the cylinder with good spark across all cylinders. Suprisingly, the other three cylinders still showed weak spark. Could a bad coil cause weak spark on some cylinders but not all? or would this be more likely the CAS? I did check that the connector on the coil is getting 12V and the resistance to battery ground is roughly 34ohms (not sure if this is acceptable or not).
Looking for any help to diagnose the issue as I need this car for work. This forum's been fantastic with information to get me this far but I'm getting stumped using searches.
Modified by jval at 9:36 AM 12/30/2008
Modified by jval at 10:21 AM 12/31/2008
Won't Run - Weak Spark
Re: Won't Run - Weak Spark (jval)
Pulled coil out to verify. Primary is 1.1ohms, secondary is 12.3 kohms.
Anybody know if 12.3 is out of spec compared to the 10k it calls for?
I'm also assuming there's not supposed to be any continuity between connector ground and bolt holes for grounding to the head?
Anybody know if 12.3 is out of spec compared to the 10k it calls for?
I'm also assuming there's not supposed to be any continuity between connector ground and bolt holes for grounding to the head?
Re: Won't Run - Weak Spark (jval)
More updates:Checked coolant temp sensor resistance: 6.3kohms at ~25FDisconnected MAF: no differenceI did a second test on the coil using two different methods:1) unbolted it from the engine. Plugged a spark plug wire into it and inserted a plug. Connected to the electrical connector and turned ignition on to supply steady voltage. When I tapped the top of the valve cover there was no spark.2) Using aligator clips, I connected respective positive and negative side of coil to battery. Using the same plug and wire again tapped the valve cover. Again, no spark.
I'm thinking the coil is shot but looking for someone to confirm this test method.
Thanks.
I'm thinking the coil is shot but looking for someone to confirm this test method.
Thanks.
Re: Won't Run - Weak Spark (jval)
I'm really hoping someine can jump in with something I've missed.
Anyway, more updates:Checked compression: 150psi on all cylinders (dry test) I'm assuming this would also tell me that the cam timing is good as well, right?Installed a different coil: good spark on all cylinders (I could have been using bad area to ground plug before though)
When I removed the plugs they were soaked with gas. So either I'm not getting spark at the right time or there's too much fuel being added. I tried unplugging the fuel pump relay and it started for a few seconds before fuel ran out.
Next step is to start playing with ignition timing. I've avoided this until now as there's no way the distrubutor has moved. Bolts are all tight and symptoms started showing up randomly.
Anyway, more updates:Checked compression: 150psi on all cylinders (dry test) I'm assuming this would also tell me that the cam timing is good as well, right?Installed a different coil: good spark on all cylinders (I could have been using bad area to ground plug before though)
When I removed the plugs they were soaked with gas. So either I'm not getting spark at the right time or there's too much fuel being added. I tried unplugging the fuel pump relay and it started for a few seconds before fuel ran out.
Next step is to start playing with ignition timing. I've avoided this until now as there's no way the distrubutor has moved. Bolts are all tight and symptoms started showing up randomly.
Re: Won't Run - Weak Spark (jval)
No dice on the timing. One direction made no difference, the other it wouldn't fire at all.Next step, fuel pressure check.
Re: Won't Run - Weak Spark (jval)
I havn't been able to get my hands on a 1/4 to 1/8 NPT adapter yet for fuel pressure test but I did try a crude test to see if I could manually regulate the pressure with a pair of pliers on the rubber fuel hose (just after the filter). With the car sputterring away I slowly increased the pressure on the hose until it eventually died out.
On a good note, I was able to get it to run longer by randomly unplugging sensors to see if it would send the car into a limp mode and allow it to idle better. I found the IACV was somewhat successful in that the car would now run for almost a minute before it died.
Through much pain and torture, I was able to remove it from the car (much harder on the transverse mounted engines), cleaned it and reinstalled it today. On first startup it seemed like it was working as it revved up nice and smooth but promptly died again. After messing with the adjustment screw from full in to full out with it plugged in and unplugged, I'm back to where I started.
Back to being stumped! Any suggestions? I can get an audio clip if that would be any help.
On a good note, I was able to get it to run longer by randomly unplugging sensors to see if it would send the car into a limp mode and allow it to idle better. I found the IACV was somewhat successful in that the car would now run for almost a minute before it died.
Through much pain and torture, I was able to remove it from the car (much harder on the transverse mounted engines), cleaned it and reinstalled it today. On first startup it seemed like it was working as it revved up nice and smooth but promptly died again. After messing with the adjustment screw from full in to full out with it plugged in and unplugged, I'm back to where I started.
Back to being stumped! Any suggestions? I can get an audio clip if that would be any help.