BodybyFisher Posted October 3, 2011 Report Share Posted October 3, 2011 DTC P0351-P0358 Circuit Description The electronic ignition (EI) system uses an individual ignition coil for each cylinder. There are 2 separate ignition module assemblies located in the camshaft cover of each cylinder bank. Each ignition module assembly contains an ignition control module (ICM) and 4 ignition coils. Each ignition coil connects directly to a spark plug using a boot. This arrangement eliminates the need for secondary ignition wires. The ignition module assemblies receive power from a fused ignition feed. Both ignition module assemblies connect to chassis ground. A reference low and 4 ignition control (IC) circuits connect each ignition module assembly to the powertrain control module (PCM). The PCM uses the individual IC circuits to control coil sequencing and spark timing for each ignition coil. The IC circuits transmit timing pulses from the PCM to the ignition control module to trigger the ignition coil and fire the spark plug. The PCM monitors each IC circuit for improper voltage levels. If a short to ground occurs in the IC circuit, this diagnostic trouble code (DTC) will set. Conditions for Running the DTC The engine speed is more than 400 RPM. Conditions for Setting the DTC The PCM detects a short to the ground on the IC circuit for less than 1 second. Action Taken When the DTC Sets The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 3, 2011 Author Report Share Posted October 3, 2011 I did not find that ground under the EGR, I did find a metal conduit, that did not apprear to be totally seated. I seated it, but no difference. I will pull the injectors tomorrow and inspect them, first I will buy some o rings. I did play with the harness more and can't say for sure, that sets it off. I did take a ride and I do feel fairly certain that the misfire changes with ......every bump. I think something is loose and I don't see it anywhere. Also, Just sitting there without moving it cycles from rough to smooth and back. Perhaps the injector seating. I did spray stuff around the seat and did not see anything. Well, wouldn't it be funny if this was an issue of a nickel o ring! Thanks again! Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 3, 2011 Report Share Posted October 3, 2011 I think you are getting there, its good you are replacing the orings, put a little engine oil on the o rings when you reseat them but BE CAREFUL NOT to touch the ends of the injectors at all!!!! and NEVER try to clean them... Just be gentle when you get the fuel rail up, support it and turn the key ON (not RUN) and see if she drips Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 3, 2011 Report Share Posted October 3, 2011 Here is the procedure from the manual Fuel Rail Assembly Replacement Removal Procedure Tools Required J 34730-1A Fuel Pressure Gauge J 43013 Fuel Injector Remover Tool J 37088-A Tool Set , Fuel Line Quick-Connect Separator Notice Remove the fuel rail assembly carefully in order to prevent damage to the injector electrical connector terminals and the injector spray tips. Support the fuel rail after the fuel rail is removed in order to avoid damaging the fuel rail components. Cap the fittings and plug the holes when servicing the fuel system in order to prevent dirt and other contaminants from entering open pipes and passages. Relieve fuel system pressure. Disconnect the IAT sensor electrical connector Disconnect the MAF sensor electrical connector. Remove the air cleaner intake duct. Clean the fuel rail assembly and fuel pipe connections Remove the quick-connect fittings at the fuel rail. Remove the fuel pressure regulator vacuum hose Remove the PCV air tube Remove the fuel rail end-point bracket retainer nut Remove the fuel injector electrical connectors from the fuel injectors. Lay the harness aside. Remove the fuel rail attaching bolts. Raise the fuel injectors from the intake manifold gently a little at a time Lift the fuel rail and remove the fuel rail. Remove the injector lower O-ring seal from the spray tip end of each injector. Discard the O-ring seals If the upper and lower O-rings are different colors (black and brown), be sure to install the black O-ring in the upper position and the brown O-ring in the lower position on the fuel injector. The O-rings are the same size but are made of different materials Installation Notice Use care when servicing the fuel system components, especially the fuel injector electrical connectors, the fuel injector tips, and the injector O-rings. Plug the inlet and the outlet ports of the fuel rail in order to prevent contamination. Do not use compressed air to clean the fuel rail assembly as this may damage the fuel rail components. Do not immerse the fuel rail assembly in a solvent bath in order to prevent damage to the fuel rail assembly. Lubricate the new lower injector O-ring seals with clean engine oil. Install the new O-ring seals on the spray tip end of each injector. Install the fuel rail assembly on to the intake manifold until the fuel injectors are fully seatedInstall the fuel rail attaching bolts. Tighten the bolts to 10 N·m (89 lb in). Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 3, 2011 Author Report Share Posted October 3, 2011 Thanks very much again, I will take great care with this exercise and I am hopeful that this will be the solution. Makes sense to me especially on #4. I look forward to reporting tomorrow! Link to comment Share on other sites More sharing options...
Ranger Posted October 4, 2011 Report Share Posted October 4, 2011 I conducted tests twice. Hose is not long enough to tape gage to windshield, but I drove in driveway with hood up. Rough Idle 38, smooth 36, pull hose on FPR and jumps to 41.....car starts with a touch of key....Today perhaps because engine is cool it would cycle from rough to smooth without touching it within a minute. It starts smooth, goes rough, smooth. Does this mean that pump is OK? I think your pump is fine. I just checked my fuel pressure the other day for someone and it is almost the same as yours. Link to comment Share on other sites More sharing options...
donljacobs Posted October 4, 2011 Author Report Share Posted October 4, 2011 I followed instructions carefully and when I had injectors out, I turned on key to look for leaks. One of them sprayed, but I am alone and could not tell if it is 2 or four. I resealed all the injectors, put it back together, started car same problem! I then drove to the parts shop and bought two injectors came home pulled apart again, hot, hot, and replaced injectors two and four, turned on key, no leaks, put back together .................same problem! Is there a chance that Auto Zone sold me a bad coil pack? In other words my current pack is bad..........and the new one I bought is bad??????? Is that two far out? Is there another direction to go? Is there someting else to try. The tab on the fuel rail that locks the injector on 2 is cracked; However it did snap in and when replaced and of course it is bolted down. The car is exactly the same as before I started. Again, I welcome new ideas, any ideas where to look. Oh, I also cut more wire back on the coil pack harness for good measure, soldered and coated in plastic. No difference. Thanks for sticking with me! Link to comment Share on other sites More sharing options...
Ranger Posted October 5, 2011 Report Share Posted October 5, 2011 I don't think that is too far out. Anything from Autozone is suspect. Their Don'tLast parts are not known for quality. Link to comment Share on other sites More sharing options...
airmike Posted October 5, 2011 Report Share Posted October 5, 2011 I don't think that is too far out. Anything from Autozone is suspect. Their Don'tLast parts are not known for quality. dj8815 That is why many times you read/hear "use known good part" . New doesn't mean working! Get a known good one and try it, then you will know for sure, even if you have to swap it from a different cylinder, at least your miss would move to a different cylinder and you would KNOW. Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 5, 2011 Report Share Posted October 5, 2011 airmike, 2000 is a little different, its a cassette not cop, you cant swap. This is a frustrating problem, You had this misfire before you changed the coil pack? Did you say you could not find the ICM ground? This engine was out, you need to look over grounds Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 5, 2011 Author Report Share Posted October 5, 2011 Yes, the cradle was dropped to do the HGs. Yes had misfire before new coil pack, same after, I took it out. The ICM is integral to the coil pack and no I could not find that ground. The misfire will occur at Idle, then without touching, go smooth. On take off, it stutters, misfire SES blinking,then it like catches on and runs smooth, untill idle again. Sometimes it will not stutter and take off smoothly. Someone said the ground was near the EGR, but I did not find it. It would be a great help if I knew where to look for grounds and how many. Meanwhile, I am going back to Autozone where I got the coil pack and see if they can check it and see if it is bad!!! I strongly suspect it is bad. Meanwhile, I am happy to do any other tests you may come up with. Again, I truly appreciate you sticking with me if not for only moral support. The is the most frustrating thing I have ever run into, Thanks! Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 5, 2011 Report Share Posted October 5, 2011 Yes, the cradle was dropped to do the HGs. Yes had misfire before new coil pack, same after, I took it out. The ICM is integral to the coil pack and no I could not find that ground. The misfire will occur at Idle, then without touching, go smooth. On take off, it stutters, misfire SES blinking,then it like catches on and runs smooth, untill idle again. Sometimes it will not stutter and take off smoothly. Someone said the ground was near the EGR, but I did not find it. It would be a great help if I knew where to look for grounds and how many. Meanwhile, I am going back to Autozone where I got the coil pack and see if they can check it and see if it is bad!!! I strongly suspect it is bad. Meanwhile, I am happy to do any other tests you may come up with. Again, I truly appreciate you sticking with me if not for only moral support. The is the most frustrating thing I have ever run into, Thanks! Ok, so the new coil pack cassette did not fix the misfire problem. If I recall, you had this misfire BEFORE you did the head gasket and blamed the misfire on the bad head gasket is that correct? If you look at the picture below, the ICM is grounded to G103, I have directed you to G103 and you don't seem to be able to locate it. You must make sure the ICM is grounded. The ICM connector "B" is the ground utilizing a BLK/WHT wire. What you should do is test that connector B is actually grounded by pulling the connector, and using an ohm meter in position B of the connector and touching the FRAME to ensure that B is grounded. You can check for 12V power on A and the ground on B, see the following pics and legend pic Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 5, 2011 Author Report Share Posted October 5, 2011 Thank you very much for the schematics. I did exchange the new coil pack for another new coil pack at Autozone today. Installed it, no difference! I am now going to attach a wire to the B (ground wire) on the new coil pack connector and then ground that to see if it makes a difference. I can't find the original ground, so I am making a new one, correct? I will also check for 12 V on a from the connector wire. I am assuming that taking a wire from the battery to the a A wire on the connector will prove that out? If that isn't it, I am thinking something in the PCM is intermittent? Is there anyway to check PCM without having to go to a dealer? Thanks again for sticking with me! Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 5, 2011 Report Share Posted October 5, 2011 I don't agree with that kind of 'testing', by replicating existing lines, I would prefer to use an ohm meter to test the ground and a volt meter to test the power. Watch the power when the engine becomes rough. This could be the PCM, do me a favor, take the air fiter box out and tap on the PCM with you knuckle like you know knocking on it and see if you can induce a misfire. As you know the PCM is located below the air box Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 5, 2011 Author Report Share Posted October 5, 2011 I took the Ground wire B from the connector and directly grounded to Frame, No difference! I took the Power wire A from the connector and directly attached to the battery, no difference. Is there anyway to check PCM without dealer? The only code showing right now is 0300, the misfire #4 is gone. Those were great tests and I am glad that we did them. Are there more tests that we can run, thanks! Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 5, 2011 Report Share Posted October 5, 2011 You said you thought it messed up over bumps I said to TAP on the PCM, if you can induce a stumble or rough idle or misfire, that is the problem, also check the PCM connectors and grounds near it Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 5, 2011 Author Report Share Posted October 5, 2011 Thanks for reminding me. I will tap and check around. I did push and wiggle the harness wires and nothing happend, but I will get my 24lb sledge and tap it, no, I mean my rubber mallet. Thanks again! Link to comment Share on other sites More sharing options...
donljacobs Posted October 5, 2011 Author Report Share Posted October 5, 2011 There are two boxes in the air box up front which one is PCM? Also, what is difference between a 9 vin and a y vin and does that matter in PCMs? My first DTS was a 9 vin and this one is a y. I had no major issues with the 9 and too many with the y. Thanks again? Link to comment Share on other sites More sharing options...
Ranger Posted October 6, 2011 Report Share Posted October 6, 2011 I am almost positive there is a difference between the VIN Y & 9 PCM. airmike, 2000 is a little different, its a cassette not cop, you cant swap. Mike, It's till COP ignition. A separate coil for each plug embedded in the cassette, but I think I understand what you are saying, the individual coils themselves cannot be swapped. Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 6, 2011 Report Share Posted October 6, 2011 I am almost positive there is a difference between the VIN Y & 9 PCM. airmike, 2000 is a little different, its a cassette not cop, you cant swap. Mike, It's till COP ignition. A separate coil for each plug embedded in the cassette, but I think I understand what you are saying, the individual coils themselves cannot be swapped. Yes, that is what I meant, I think airmike was suggesting that a coil could be swapped to another cylinder and thereby move the misfire, I have done that myself but as you noted it can't be done with the coil cassette Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 6, 2011 Author Report Share Posted October 6, 2011 I got to the PCM and I tapped it with a screw driver, picked it up, shook it, turned it all kinds of way, pulled and pushed on connecters, nothing, but I went back to the FPR and I disconnected hose and I was told if fuel came out that was bad, but no fuel came out, but no change in intermittent misfire. I pulled to whole hose off to inspect it and the car actually ran a bit better. I tried this several times and it appears to run about 100 rpms better with hose off?????? Does this mean anything? Put the hose back on and it drops slightly in RPMs? Has anyone experience with this. I rechecked my codes and only one there is 0300. I sure hope this means something??? thanks again. Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 6, 2011 Report Share Posted October 6, 2011 That is odd. Typically, when you remove the vacuum hose from the FPR, the pressure will jump up, that is normal That your RPM jumps up to me, is indicative of low fuel pressure. Try this, next time your engine is missing, try pulling the FPR vacuum hose and see if the roughness or miss stops Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
donljacobs Posted October 6, 2011 Author Report Share Posted October 6, 2011 Well, that is what I did. When I pull the hose off while running, the rpms go up about 100 and it is smoother, but still a miss, when I plug the hose back in the rpms go down and it appears rougher. I am trying to locate somewhere in Detroit that can check this computer. I find ones that you pull and send it to them, but I have to have the car. There was an ICC Group A code which I believe was from testing the front coil bank, I cleared it and it has not come back. only code is 0300 and fuel sender unit. Thanks again for sticking with me! Link to comment Share on other sites More sharing options...
Ranger Posted October 7, 2011 Report Share Posted October 7, 2011 Pulling the vacuum hose is creating a vacuum leak. Same as pressing on the throttle. An RPM increase is exactly what I would expect. Link to comment Share on other sites More sharing options...
donljacobs Posted October 7, 2011 Author Report Share Posted October 7, 2011 Are there any other suggestions that I might try here? I will redo the test on the front bank using volts and ohms. Is there anything I can do to check this computer? I feel I am at my ropes end here. For sure I am dying a nickle at a time, new front coil bank, over $200, new harness for it $96, 2 injectors and o ring kits $180, etc. I fear that I now might have to go to a dealer, that is real fear. I will ask them up front what they would charge just to check the computer, but my life's experience has taught me to distrust dealers, too sad. Thanks again for sticking with me and all of your great expertise..........! Link to comment Share on other sites More sharing options...
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