Rpm without engine running
08-26-2008, 04:45 PM
#1
Teching In
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Rpm without engine running I have plum run out of ideas, and I am likely going to end up selling this car if things don't go better here sooner or later.
Background info....
97 T/A
94 Engine and PCM
CC 306
PCMforless tune
New opti
new ign module
new plugs
new wires
new coil
new coolant temp sensor
basic bolt ons other than cam (headers, cold air etc..)
The issue....
Ever since I have gotten done with the cam swap I have had problems that most would relate to opti issues. Per numerous people, I replaced the opti, and since I was there, I went ahead and did the whole ign system (125k on it, might as well). Still the car will cruise down the road, and suddenly start to feel like it is pulling timing like crazy. I assumed this to be a knock sensor problem, so I did the knock sensor bypass trick with the resistor, nothing changed. Everytime I get into the throttle the car runs pretty lean (wideband readings in the 14.5 to 14.0 range) and just does not make the power a CC306 car should make. The other day when I got in the car to go out for a drive, I turned the key on, engine not running waiting on fuel pumps to prime, and noted that my tach was sitting at 2k, and sat there while I was cranking the engine, only to drop to 1200 once it started to idle. At this point I start thinking engine ground issue, and go ahead and add a couple of engine grounds, one to the chassis, one to the battery, no avail. I got this engine set up and in the car back in March, and have been attempting to dianose this problem since, and I'm at whits end, ready to sell. Does anyone have any insight into what may be giving me such grief!?!
Background info....
97 T/A
94 Engine and PCM
CC 306
PCMforless tune
New opti
new ign module
new plugs
new wires
new coil
new coolant temp sensor
basic bolt ons other than cam (headers, cold air etc..)
The issue....
Ever since I have gotten done with the cam swap I have had problems that most would relate to opti issues. Per numerous people, I replaced the opti, and since I was there, I went ahead and did the whole ign system (125k on it, might as well). Still the car will cruise down the road, and suddenly start to feel like it is pulling timing like crazy. I assumed this to be a knock sensor problem, so I did the knock sensor bypass trick with the resistor, nothing changed. Everytime I get into the throttle the car runs pretty lean (wideband readings in the 14.5 to 14.0 range) and just does not make the power a CC306 car should make. The other day when I got in the car to go out for a drive, I turned the key on, engine not running waiting on fuel pumps to prime, and noted that my tach was sitting at 2k, and sat there while I was cranking the engine, only to drop to 1200 once it started to idle. At this point I start thinking engine ground issue, and go ahead and add a couple of engine grounds, one to the chassis, one to the battery, no avail. I got this engine set up and in the car back in March, and have been attempting to dianose this problem since, and I'm at whits end, ready to sell. Does anyone have any insight into what may be giving me such grief!?!
08-26-2008, 06:25 PM
#2
On The Tree
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Assuming you have a '94 harness. Have you checked these PCM ground wires. Three in the coil stud terminal and one on the block near the knock sensor. ref shoebox ' http://shbox.com/1/harness.htm ' The PCM reads the opti low resolution signal and generates the RPM to the tach. the false tach reading could be a bad opti harness or connection from PCM to opti. The PCM signal to the tach is shown here ' http://shbox.com/1/1995_pcm4.jpg ' pin a13. Are you throwing any codes, SES lite, fans running ? Would be nice to have a trace when it acts up.
08-27-2008, 09:02 AM
#3
Teching In
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I have no SES light, fans only run when car is at fan on temp. I will check some of those grounds tonight and see what I find. I am sure they are hooked up, but I likely as not should question their ground resistance.
I also note on the second schematic you posted, there is a traction control spark retard signal that comes from the ebtcm.... I have deleted ABS, which removed the EBTCM. When you do ABS delete, is there something in the computer that needs to be shut off, or told to go away when this is done? I suppose that a timing retard issue could be related to that.
I also note on the second schematic you posted, there is a traction control spark retard signal that comes from the ebtcm.... I have deleted ABS, which removed the EBTCM. When you do ABS delete, is there something in the computer that needs to be shut off, or told to go away when this is done? I suppose that a timing retard issue could be related to that.
