06-07-2005, 10:41 PM
Starting with this post, I’ll pay $100 to the first person who pinpoints and helps me resolve (with how-to directions) my no-start problem during the next two weeks, resulting in me getting my 1994 968 six-speed running again. After that, the offer is off and I’m making an appointment with the mechanic. The time stamp on your reply should break a tie if someone is able to help me figure out this puzzle. $100 would be a bargain compared to what I've spent already and may have to spend yet. More information on the problem and what I've done so far is listed below.
Since the t-belt/waterpump/rollers/seals changeout, I’ve tried a dozen things to get the car to start, but no luck. The starter turns the engine over fine, battery good, has 12v electricity to both sides of coil and injectors (but they don’t pulsate or fire), fuel pump works but only if you jumper it at DME relay, etc. but it’s apparently not getting the pulse that triggers the coil or injectors to fire. I’ve replaced with new parts the coil, coil wire, dist., rotor, plugs, cleaned wire grounds (about 8 of them, including the two on top of bell housing), battery terminals sanded and cleaned including small wires, I replaced the reference sensor with new part and calibrated distance to ring gear (about thickness of a dime), checked all fuses, tried 3 diff DME relays, switched and tried another DME controller, checked wires, receptacles, good compression, etc.
There are three things that I’m wondering if they could be the cause of the problem, but there are others I'm sure. What do you think?
1) On the flywheel, there are two sets of marks: “0 | |” marks at one spot then two arrows and three marks at another spot “> > | | |”. Using the small round inspection hole at bottom of front of bell housing, I centered the middle mark of the three horizontal marks (I didn’t use the “0 | |” ). This put the cam gear mark in alignment as well as the balance belt gears “0” marks and cylinder #1 at TDC. I then locked the flywheel in this spot to change belts/rollers. At the time I didn’t see (nor read about) the “0 | |” marks but they don’t seem to line up with the cam gear mark….so…am I OK on this or is timing way off because I might have set the flywheel at the wrong spot? If I did, the settings really didn’t change much if any from before the rebelt job to after…I’m almost certain of this since I locked everything down and marked with paint. I'd hate to move to the other "O ||" and bend my valves. ???
2) Another possibility, there was a pinched wire that I found that goes to the junction plugs just behind the cam gear housing. The Hall sensor junctions here too (BTW, I never messed with the Hall sensor or took the cam gear off). The reference sensor wire has two small wires inside a foil cover and that is covered with braided wire. At the relatively small pinch, I teased apart the plastic, foil, and braided wire and all looks fine. All three are still together although I’m not sure how to verify whether the small wires actually may have a break in them somewhere . They don’t appear to, but I could be wrong. I’m not sure how to check continuity on these wires since they split somewhere and may also go to the DME relay area. Also, resplicing of this wire looks to be difficult but I sure don’t want to replace the whole wiring harness. I need to learn how to troubleshoot this whole circuit I guess. I have voltage/ohm meter but can't use an occilloscope. Also, the trouble/fault codes don't work on my car and I hate to pull the dash and fix that until I get this fixed first.
3) If the ignition junction switch box (round white plastic piece with wires coming out of the back of the key switch) is similar to the 928, these go bad pretty often and, IF the DME gets power from this switch, perhaps that’s another place to look. However, jiggling the switch while cranking usually betrays the problem but it doesn't help my situation.
So…it appears to me that either the reference sensor is getting a confusing signal from the flywheel (see 1 above) and shutting down the triggering signal to coil/injectors…the DME is not getting power…or the sensor wire to the coil area may be broken. However, if the latter, how come the injectors aren’t clicking and putting out gas? (they’re not..it’s dry inside cylinders.) Or are they on the same circuit as the coil? As of today, I know the reference sensor is calibrated right. I've not yet jumpered the Alarm System to bypasss it. Would a malfunction there result in a no pulse situation? The directions I read for bypassing were for a 944...similar but not the same. On the 944 if the sensor is passing on "sensing" the tach needle jumps. Mine doesn't.
What else should I check? I posted a foto of the starter wires and I don’t think there’s a way to hook them up wrong since they really only fit on the posts one way. Maybe there's another wire or ground under there someplace that I need to check? Also, the rotor will only screw on only one way so I don't think that's off, the aluminum spacers are in place, etc.
I’m ready to try about anything at this point. I’ve spent a wad of $$ replacing parts and not any of the possibles I’ve checked seems to be the culprit. I know some of you are tired of hearing of this problem but I HAVE to be getting closer to a solution. Your suggestions are always welcomed. I’ve searched all the archives and have tried about everything…but as some of you have said…”it's probably something simple or something I did while making the belt change” The car did set a couple of months before I got the parts for the work. I know that diagnosing something via email is difficult since you can’t see and you don’t know if I’m a total klutz or not. I built a ’32 Plymouth street rod w/vette engine from the ground up (every frame-up part) and have rebuilt Chevy engines. I’m not great but I’m no novice, although when it comes to electrical stuff, I confess to being a little better than helpless and have to be carefully mentored. Or take it to a mechanic.
I’ve first posted this at 968Forums and 968.Net. Later on, I might post to Rennlist, etc.
What do you think? Thanks.
Harvey
Since the t-belt/waterpump/rollers/seals changeout, I’ve tried a dozen things to get the car to start, but no luck. The starter turns the engine over fine, battery good, has 12v electricity to both sides of coil and injectors (but they don’t pulsate or fire), fuel pump works but only if you jumper it at DME relay, etc. but it’s apparently not getting the pulse that triggers the coil or injectors to fire. I’ve replaced with new parts the coil, coil wire, dist., rotor, plugs, cleaned wire grounds (about 8 of them, including the two on top of bell housing), battery terminals sanded and cleaned including small wires, I replaced the reference sensor with new part and calibrated distance to ring gear (about thickness of a dime), checked all fuses, tried 3 diff DME relays, switched and tried another DME controller, checked wires, receptacles, good compression, etc.
There are three things that I’m wondering if they could be the cause of the problem, but there are others I'm sure. What do you think?
1) On the flywheel, there are two sets of marks: “0 | |” marks at one spot then two arrows and three marks at another spot “> > | | |”. Using the small round inspection hole at bottom of front of bell housing, I centered the middle mark of the three horizontal marks (I didn’t use the “0 | |” ). This put the cam gear mark in alignment as well as the balance belt gears “0” marks and cylinder #1 at TDC. I then locked the flywheel in this spot to change belts/rollers. At the time I didn’t see (nor read about) the “0 | |” marks but they don’t seem to line up with the cam gear mark….so…am I OK on this or is timing way off because I might have set the flywheel at the wrong spot? If I did, the settings really didn’t change much if any from before the rebelt job to after…I’m almost certain of this since I locked everything down and marked with paint. I'd hate to move to the other "O ||" and bend my valves. ???
2) Another possibility, there was a pinched wire that I found that goes to the junction plugs just behind the cam gear housing. The Hall sensor junctions here too (BTW, I never messed with the Hall sensor or took the cam gear off). The reference sensor wire has two small wires inside a foil cover and that is covered with braided wire. At the relatively small pinch, I teased apart the plastic, foil, and braided wire and all looks fine. All three are still together although I’m not sure how to verify whether the small wires actually may have a break in them somewhere . They don’t appear to, but I could be wrong. I’m not sure how to check continuity on these wires since they split somewhere and may also go to the DME relay area. Also, resplicing of this wire looks to be difficult but I sure don’t want to replace the whole wiring harness. I need to learn how to troubleshoot this whole circuit I guess. I have voltage/ohm meter but can't use an occilloscope. Also, the trouble/fault codes don't work on my car and I hate to pull the dash and fix that until I get this fixed first.
3) If the ignition junction switch box (round white plastic piece with wires coming out of the back of the key switch) is similar to the 928, these go bad pretty often and, IF the DME gets power from this switch, perhaps that’s another place to look. However, jiggling the switch while cranking usually betrays the problem but it doesn't help my situation.
So…it appears to me that either the reference sensor is getting a confusing signal from the flywheel (see 1 above) and shutting down the triggering signal to coil/injectors…the DME is not getting power…or the sensor wire to the coil area may be broken. However, if the latter, how come the injectors aren’t clicking and putting out gas? (they’re not..it’s dry inside cylinders.) Or are they on the same circuit as the coil? As of today, I know the reference sensor is calibrated right. I've not yet jumpered the Alarm System to bypasss it. Would a malfunction there result in a no pulse situation? The directions I read for bypassing were for a 944...similar but not the same. On the 944 if the sensor is passing on "sensing" the tach needle jumps. Mine doesn't.
What else should I check? I posted a foto of the starter wires and I don’t think there’s a way to hook them up wrong since they really only fit on the posts one way. Maybe there's another wire or ground under there someplace that I need to check? Also, the rotor will only screw on only one way so I don't think that's off, the aluminum spacers are in place, etc.
I’m ready to try about anything at this point. I’ve spent a wad of $$ replacing parts and not any of the possibles I’ve checked seems to be the culprit. I know some of you are tired of hearing of this problem but I HAVE to be getting closer to a solution. Your suggestions are always welcomed. I’ve searched all the archives and have tried about everything…but as some of you have said…”it's probably something simple or something I did while making the belt change” The car did set a couple of months before I got the parts for the work. I know that diagnosing something via email is difficult since you can’t see and you don’t know if I’m a total klutz or not. I built a ’32 Plymouth street rod w/vette engine from the ground up (every frame-up part) and have rebuilt Chevy engines. I’m not great but I’m no novice, although when it comes to electrical stuff, I confess to being a little better than helpless and have to be carefully mentored. Or take it to a mechanic.
I’ve first posted this at 968Forums and 968.Net. Later on, I might post to Rennlist, etc.
What do you think? Thanks.
Harvey
