MIke D Posted April 23, 2008 Author Report Share Posted April 23, 2008 Make sure all wire are snapped into the plugs, it can be tricky getting them snapped on Just re-read your post. Do you mean the 4 plugs next to the coils? The two on either end. I do have one that wont "snap" into place but it wont wiggle or fall out either. Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
Ranger Posted April 23, 2008 Report Share Posted April 23, 2008 Definately check that Mike if your 99 has one, my year does not have that plenum. I wonder what year they started using it? Here is a photo of the Plenum in question 2000 Mike. Link to comment Share on other sites More sharing options...
MIke D Posted April 23, 2008 Author Report Share Posted April 23, 2008 Definately check that Mike if your 99 has one, my year does not have that plenum. I wonder what year they started using it? Here is a photo of the Plenum in question 2000 Mike. It does not have one... Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 23, 2008 Report Share Posted April 23, 2008 Definately check that Mike if your 99 has one, my year does not have that plenum. I wonder what year they started using it? Here is a photo of the Plenum in question 2000 Mike. Thanks Ranger, that is what I thought, I didn't think Mike D's 99 had it.. As Mike noted the TB is bolted directly to the intake on my 96 as on his 99. 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 April 23, 2008 Report Share Posted April 23, 2008 Make sure all wire are snapped into the plugs, it can be tricky getting them snapped on Just re-read your post. Do you mean the 4 plugs next to the coils? The two on either end. I do have one that wont "snap" into place but it wont wiggle or fall out either. Mike I was talking about the ignition wires, they need to be fully snapped on the plugs. This is ODD, because at some point, you had it running good, then all of a sudden it ran badly again and you found a bad coil that made NO difference when you replaced it. Try running your engine in pitch dark, with the vanity / sound cover off the engine, be careful not to get hurt by moving parts, look closely for arching, then spritz the wires with a water squirt bottle and see if you induce any arching. Also, when you look at the plugs look for cracks. Check all vacuum hoses for good connection Have you had your intake off? Have you had your fuel rail out? Have you had you TB off? Are you getting a check engine or flashing check engine indicating a P0300? 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...
jking220 Posted April 24, 2008 Report Share Posted April 24, 2008 Were you gentle with the wires when you took them off and put them back on? (like bending them sharply) I had an 89 T-bird that developed a bad miss... I think I damaged a wire when I had them off... Put new wires on it and it ran like a top after that. Just an idea. Jonah Link to comment Share on other sites More sharing options...
MIke D Posted April 24, 2008 Author Report Share Posted April 24, 2008 Make sure all wire are snapped into the plugs, it can be tricky getting them snapped on Just re-read your post. Do you mean the 4 plugs next to the coils? The two on either end. I do have one that wont "snap" into place but it wont wiggle or fall out either. Mike I was talking about the ignition wires, they need to be fully snapped on the plugs. This is ODD, because at some point, you had it running good, then all of a sudden it ran badly again and you found a bad coil that made NO difference when you replaced it. Try running your engine in pitch dark, with the vanity / sound cover off the engine, be careful not to get hurt by moving parts, look closely for arching, then spritz the wires with a water squirt bottle and see if you induce any arching. Also, when you look at the plugs look for cracks. Check all vacuum hoses for good connection Have you had your intake off? Have you had your fuel rail out? Have you had you TB off? Are you getting a check engine or flashing check engine indicating a P0300? I did have the intake off 6 months ago for a starter going bad. It ran fine for 2-3 months after that. When I took it off the fuel rail and TB went with the intake as one piece. I have not had the po300 code since I swapped the first coil. It never registered with the second one going bad. The plug wires are tight both at the plugs and on the coils. I will try the water at night.... Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
MIke D Posted April 24, 2008 Author Report Share Posted April 24, 2008 Were you gentle with the wires when you took them off and put them back on? (like bending them sharply) I had an 89 T-bird that developed a bad miss... I think I damaged a wire when I had them off... Put new wires on it and it ran like a top after that. Just an idea. I will measure the resistance. I did have to "pull" them off but I thought I was gentle enough... Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 24, 2008 Report Share Posted April 24, 2008 The reason I saw did you have the intake off is because, if it is leaking vacuum you will get a problem, did you replace the intake gaskets at that time? When you put the intake back did you torque the bolts back to spec? 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...
MIke D Posted April 24, 2008 Author Report Share Posted April 24, 2008 The reason I saw did you have the intake off is because, if it is leaking vacuum you will get a problem, did you replace the intake gaskets at that time? When you put the intake back did you torque the bolts back to spec? even though The FSM said you could reuse the intake gaskets, I still thing we got new ones. And yes we did torque them to spec... Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 24, 2008 Report Share Posted April 24, 2008 The reason I saw did you have the intake off is because, if it is leaking vacuum you will get a problem, did you replace the intake gaskets at that time? When you put the intake back did you torque the bolts back to spec? even though The FSM said you could reuse the intake gaskets, I still thing we got new ones. And yes we did torque them to spec... Good Mike Check to make sure that your injectors in your fuel rail are fully pushing into their locations in the intake. There is a way to check to see if you have a vacuum leak, I can't remember what you spray, maybe starting fluid, you might check each injectors seal by spraying starting fluid at each place where they enter the intake manifold to see if the engine responds from that. But as another member stated check your wires with an ohm meter and pull each plug and look for cracks in the porcelain. These plugs crack very easy. 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...
MIke D Posted April 24, 2008 Author Report Share Posted April 24, 2008 ok.. I will wait till the car cools down. I already burned my finger yesrterday on something reall really hot... Ha, who would have thought... I also just got 2 backfires into the intake manifold today. This is the first time in a long time that's happened... Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
caddypete Posted April 24, 2008 Report Share Posted April 24, 2008 Not Familiar with your model year intake, mine is different because of the boot between throttle body and intake. But you said you had starter work done, and then started having problems. You say you get backfires in the intake. When I replaced my boot and took the intake off, when I reassmbeled it I still had the miss and backfires in the intake which I didn't notice before, I realized the hose that runs to the PVC valve had come off where it connects on the inside of the intake. This would cause major problems because you are letting in unmetered air, it is worth giving that a look. A easy way to check is pull the hose off the PVC valve and put your finger over it to see if there is vacuum, if not that hose is off or leaking. Link to comment Share on other sites More sharing options...
MIke D Posted April 25, 2008 Author Report Share Posted April 25, 2008 Not Familiar with your model year intake, mine is different because of the boot between throttle body and intake. But you said you had starter work done, and then started having problems. You say you get backfires in the intake. When I replaced my boot and took the intake off, when I reassmbeled it I still had the miss and backfires in the intake which I didn't notice before, I realized the hose that runs to the PVC valve had come off where it connects on the inside of the intake. This would cause major problems because you are letting in unmetered air, it is worth giving that a look. A easy way to check is pull the hose off the PVC valve and put your finger over it to see if there is vacuum, if not that hose is off or leaking. It was 3-4 months after I pulled the intake off that this started. It started right after a real heavy rain. nothing was wet under the hood because it was just sitting in a parking lot. It then reappeared after a big thunderstorm. Once again nothing under the hood was wet. I really checked that time.... After typing thiat i think i will try a can of dry gas..... I did pull the PVC off before to check and it held lots of vacuum. I even cleaned the mass air sensor, air filter. I also checked the black plastic intake assembly (up stream of the throttle boday...) all are sealed and tight. Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
Texas Jim Posted April 25, 2008 Report Share Posted April 25, 2008 It was 3-4 months after I pulled the intake off that this started. It started right after a real heavy rain. It then reappeared after a big thunderstorm. Once again nothing under the hood was wet. I really checked that time.... Like BBF said.... Check the plug wires resistance and for a cracked plug. It sure sounds like one of those two things to me. I had a miss on one of my cars. It would miss in the morning...till the underhood engine heat dried out the wires. Then it ran fine ... till the next morning. New set of wires cured the problem. Link to comment Share on other sites More sharing options...
MIke D Posted April 25, 2008 Author Report Share Posted April 25, 2008 It was 3-4 months after I pulled the intake off that this started. It started right after a real heavy rain. It then reappeared after a big thunderstorm. Once again nothing under the hood was wet. I really checked that time.... Like BBF said.... Check the plug wires resistance and for a cracked plug. It sure sounds like one of those two things to me. I had a miss on one of my cars. It would miss in the morning...till the underhood engine heat dried out the wires. Then it ran fine ... till the next morning. New set of wires cured the problem. I found a really dark place last night and sprayed the wires down with a wter bottle. I found many areas where the aura was showing but not any place where they would spark. My dad is going to send back my old wires to see if there was a bad set of insulation on them. I will also check the resistance. Now I know with lenght comes more resistance so how will i know what they should be? I don't have my FSM yet. But I did get a used set off ebay for $40..... Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
JimD Posted April 25, 2008 Report Share Posted April 25, 2008 .... Now I know with lenght comes more resistance so how will i know what they should be? Something approximating 2.7K Ohms per foot. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 25, 2008 Report Share Posted April 25, 2008 Check the resistance and record your findings. You are looking for a wire that is way out of range from the others, it should be obvious. I am not sure what the OEM wire resistance is per foot, but you can probably do a math calculation to determine that when you have all of your measurements. Take the resistance you find for a wire and divide it by the wires length in feet (two feet 4 inches would be 2.33 feet, you will get an estimated resistance per foot). A bad wire should stick out from the rest. Did I ask you if you used dielectric grease on your spark plug boots? DON'T, if you did use it wipe it off the boots and plugs. And don't forget to pull each plug and look carefully for cracks, we have seen many plugs crack. 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...
MIke D Posted April 28, 2008 Author Report Share Posted April 28, 2008 Check the resistance and record your findings. You are looking for a wire that is way out of range from the others, it should be obvious. I am not sure what the OEM wire resistance is per foot, but you can probably do a math calculation to determine that when you have all of your measurements. Take the resistance you find for a wire and divide it by the wires length in feet (two feet 4 inches would be 2.33 feet, you will get an estimated resistance per foot). A bad wire should stick out from the rest. Did I ask you if you used dielectric grease on your spark plug boots? DON'T, if you did use it wipe it off the boots and plugs. And don't forget to pull each plug and look carefully for cracks, we have seen many plugs crack. We did talk about the grease. it is not on there.. I had 2 friends in town this weekend. I will measure tomorrow in between the rain drops and let everyone know. Thanks.. MD Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
MIke D Posted April 28, 2008 Author Report Share Posted April 28, 2008 I did not measure the length of the wires yet. I just did the resistance. I have an old set of good wires being delivered later today, i will measure them then. so far #1 was 1.6k #3 was 2.2k #5 was 2.1k #7 was 2.8k #2 was 5.4k #4 was 4.7k #6 was 4.2k #8 was 5.2k It started raining pretty good here so I did not have the time to pull plugs and check for cracks. When I get the new wires i"ll also check plugs then. I just hope it lets up or I will building an arc to get to work.... Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
MIke D Posted April 29, 2008 Author Report Share Posted April 29, 2008 Just changed back to my old wires (which have a much higher resistance) and the skip is still there. Checked all the connections and hoses and everything is tight. plugs look good. no cracks.... Fuel injectors are seated properly and the wires leading to it are good. Fuels rail is not leaking. I think my next move is to put a fuel pressure gauge on it and see if I have a bad pump or something.. what do you think. Still not able to do a compression check. Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 29, 2008 Report Share Posted April 29, 2008 Did you look at each plug? 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...
MIke D Posted April 29, 2008 Author Report Share Posted April 29, 2008 Did you look at each plug? yes. no cracks and the plug's head looked "good" not wet or cruddy! Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 29, 2008 Report Share Posted April 29, 2008 OK, plugs good, wires checked out OK, you replaced two coils, you looked at vacuum hoses and when you pulled your intake you replaced your intake manifold gaskets and torqued it to spec. Do you recall what spec was?, was it INCH POUNDS?, do you have an INCH POUND torque wrench and did you follow the tightening sequence if there was one specified? Just making sure. Assuming that all of the above is OK, this is either an injector problem, a vacuum leak (not likely) or a compression problem (still to be determined if problem persists). Do you hear any ticking or mechanical tap? See if you can buy a vacuum gage and read the vacuum at idle and see if you have any needle fluctuations. In your post #37 here, you said you got a couple of back fires and implied that you got back fires before. Lift your fuel rail, hold it up or prop it up, so you can see the tips, turn on or have someone turn the key to ON not START and see if any are dripping. Leave the key on for a bit and watch for drips. Maybe you have an injector that is dripping and not spraying but its not bad enough to set off a fuel trim problem yet. Any dripping, you need to replace the injector, I have a feeling that you have an injector leaking/dripping, due to the backfire into the intake. Check all grounds around the ignition module to make sure they are clean and tight and connected. Look at the manual for 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...
MIke D Posted April 30, 2008 Author Report Share Posted April 30, 2008 OK, plugs good, wires checked out OK, you replaced two coils, you looked at vacuum hoses and when you pulled your intake you replaced your intake manifold gaskets and torqued it to spec. Do you recall what spec was?, was it INCH POUNDS?, do you have an INCH POUND torque wrench and did you follow the tightening sequence if there was one specified? Just making sure. it was an inch pound torgue bar and we started in the middle and worked outward in a clockwise manor. I will pull the fuel rail next and see. I decided i will go up and see the folks for mothers day so I will have a compression gauge then and will check it out. Thanks again guys. MD Cop didn't see it, I didn't do it! 93 STS 225,000 Miles 99 STS 111,000 Miles Link to comment Share on other sites More sharing options...
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