Full Version: ignition miss ???
I had my car start to backfire and lose power almost cutting off but not . First thought opti cause same symptoms as when i lost a opti about 6 months ago except after backfire it died and wouldn't restart ! I nursed it home and my mechanic suggested removing coil and module clean thoroghly apply dielectric grease and replace . Fired it up ran GREAT !!! Next day after driving 15 minutes same thing ! So long story short it has a severe miss and backfire condition and the tach either stops moving or bounces around during the condition but only after warming up ! auto part store tested module said it's good but that was at room temp! I added a ground and spaced the coil and module bout 2 or 3 inches off the head to reduce heat but no luck ! any ideas ?
QUOTE(stv4icp @ Apr 15 2010, 09:06 PM) 
I had my car start to backfire and lose power almost cutting off but not . First thought opti cause same symptoms as when i lost a opti about 6 months ago except after backfire it died and wouldn't restart ! I nursed it home and my mechanic suggested removing coil and module clean thoroghly apply dielectric grease and replace . Fired it up ran GREAT !!! Next day after driving 15 minutes same thing ! So long story short it has a severe miss and backfire condition and the tach either stops moving or bounces around during the condition but only after warming up ! auto part store tested module said it's good but that was at room temp! I added a ground and spaced the coil and module bout 2 or 3 inches off the head to reduce heat but no luck ! any ideas ?
I know you don't want to hear it but it is DEf. your opti.
Don't feel bad I got 65 miles out of one
Recheck all of the wiring connections going to the Opti. I had some plug wires slip off of mine once.
Sorry to hear about the difficulties.
Problems like this are extremely difficult to fix or even diagnose--generally part substitution is the only fix. As the previous poster said, replacing the Opti is a good start--it's the internal module that goes bad on a new Opti and they can go out very fast, but it is rare. Also, since the 96 is vented, just leaving the car out in the cold can cause condensation inside, but that usually burns off as the Opti heats up and vacuum system sucks the moisture out.
When you mentioned the tach screwing up, the ignition module came to mind (Bingo!)--that is a typical symptom and you are right--testing a cold ign module won't tell you a thing about its true condition. But it can also be the PCM. More on this below.
Was the ignition module mounted using a dielectric grease? If not, then it is overheating. Even the coil should be mounted using the grease, including the plate that mounts to the head. Standoffs might help, but the module should still use grease for cooling and the coil/ignition module use the mass of the aluminum head for cooling....
Have you checked the routing of the coil wire? GM is very specific about this, it must take a turn and run a certain way to avoid interference--you'll have to check the factory service manual for how it is routed. For that matter, is the coil wire any good? How about the ignition wires entering the Opti (including the coil wire)? Are they connected firmly?--takes two clicks--push hard and use a bit of dielectric grease to lubricate the boots.
Did you use OEM ignition wires? The aftermarket and so-called low resistance wires that "generate more voltage" are a crock! They actually cause the ign system to generate more amps and less voltage which burns out spark plugs faster and throws a load on the coil, which causes it to overheat. If the coil is weak, the aftermarket wires can cause it to NOT fire the plugs and backfires, etc. happen, because the spark is miss-timed and weak. GM specifies 4,000 ohms per foot.
For that matter, have you checked the coil output? Standard testers really don't work. A bad coil can start the car, but then give up when you try and accelerate the engine. It takes roughly 10,000 volts to initiate OEM plug firing, but then the coil quickly deteriorates to around 2,000 volts as the air gap at the plug is ionized and the magnetic fields start to collapse. It's that 10,000 volts that is crucial. A 40,000 volt coil can quickly deteriorate to 10,000 volts, or less, with just one primary coil short at the wrong place and they always short in the wrong place.
It's a 96! Your car has the OBDII PCM. Since your engine is having problems, you didn't mention that the SES light is on. Is it? Did the PCM throw some codes? If not, then the PCM is probably defective and must be replaced (the CPU within the PCM "IS" failing to communicate with the Buss). A simple test is to disconnect the battery, wait about 5 minutes for the block learns to clear, then reconnect it. This wipes out the Block Learn variables and starts the basic programming. If the engine runs better for about 15-20 miles or even more, then goes back to running badly, it's a really good bet that the PCM is defective.
Look for some really nasty vacuum leaks. The worst is the one that happens underneath the rubber elbow as it goes into the MAF. Also, intake manifold bolts can loosen and this causes lots of problems. Those two are the usual culprits. Check under the rubber elbow at the MAF and correct it, then torque the intake manifold bolts to 34 ft lbs.
Hope this helps.
Problems like this are extremely difficult to fix or even diagnose--generally part substitution is the only fix. As the previous poster said, replacing the Opti is a good start--it's the internal module that goes bad on a new Opti and they can go out very fast, but it is rare. Also, since the 96 is vented, just leaving the car out in the cold can cause condensation inside, but that usually burns off as the Opti heats up and vacuum system sucks the moisture out.
When you mentioned the tach screwing up, the ignition module came to mind (Bingo!)--that is a typical symptom and you are right--testing a cold ign module won't tell you a thing about its true condition. But it can also be the PCM. More on this below.
Was the ignition module mounted using a dielectric grease? If not, then it is overheating. Even the coil should be mounted using the grease, including the plate that mounts to the head. Standoffs might help, but the module should still use grease for cooling and the coil/ignition module use the mass of the aluminum head for cooling....
Have you checked the routing of the coil wire? GM is very specific about this, it must take a turn and run a certain way to avoid interference--you'll have to check the factory service manual for how it is routed. For that matter, is the coil wire any good? How about the ignition wires entering the Opti (including the coil wire)? Are they connected firmly?--takes two clicks--push hard and use a bit of dielectric grease to lubricate the boots.
Did you use OEM ignition wires? The aftermarket and so-called low resistance wires that "generate more voltage" are a crock! They actually cause the ign system to generate more amps and less voltage which burns out spark plugs faster and throws a load on the coil, which causes it to overheat. If the coil is weak, the aftermarket wires can cause it to NOT fire the plugs and backfires, etc. happen, because the spark is miss-timed and weak. GM specifies 4,000 ohms per foot.
For that matter, have you checked the coil output? Standard testers really don't work. A bad coil can start the car, but then give up when you try and accelerate the engine. It takes roughly 10,000 volts to initiate OEM plug firing, but then the coil quickly deteriorates to around 2,000 volts as the air gap at the plug is ionized and the magnetic fields start to collapse. It's that 10,000 volts that is crucial. A 40,000 volt coil can quickly deteriorate to 10,000 volts, or less, with just one primary coil short at the wrong place and they always short in the wrong place.
It's a 96! Your car has the OBDII PCM. Since your engine is having problems, you didn't mention that the SES light is on. Is it? Did the PCM throw some codes? If not, then the PCM is probably defective and must be replaced (the CPU within the PCM "IS" failing to communicate with the Buss). A simple test is to disconnect the battery, wait about 5 minutes for the block learns to clear, then reconnect it. This wipes out the Block Learn variables and starts the basic programming. If the engine runs better for about 15-20 miles or even more, then goes back to running badly, it's a really good bet that the PCM is defective.
Look for some really nasty vacuum leaks. The worst is the one that happens underneath the rubber elbow as it goes into the MAF. Also, intake manifold bolts can loosen and this causes lots of problems. Those two are the usual culprits. Check under the rubber elbow at the MAF and correct it, then torque the intake manifold bolts to 34 ft lbs.
Hope this helps.
Today i bought a new msd coil and ignition control module $140 !!! seemed to pick up ALOT of pep but after about 12 minutes same thing happened ! backfire and tach stopped working ! HELP !!!
The last thing you want to do is make changes with non-stock, aftermarket parts when something else is wrong.
I just bought a new coil just like i already had on my car there's few (stock) parts on my car ! it also has msd ignition box, 58mm throttle body,lt4 hot cam kit roller rockers,titanium valve springs,lt4 intake ,28.6lb injectors,k&n cold air intake,gutted cats , rear o2 simulators, flowmaster exhaust,high performance fuel pump,adjustable fuel pressure regulator,and the list goes on but thats a little about my ignition fuel and exhaust system ! thanks keep the suggestions coming !!!
Ahhhh...I see. The best thing to do is go back to basic parts. First, if you can substitute injectors, go back to the 24 lbs/hr. The ones you have are technically too large for the engine--they should have been nomore than 26 lbs/hr. The stock 24 lbs/hr can support up to at least 400 hp! Unless the heads are ported and polished, the engine probably isn't making more than 350-360 absolute tops! However, if the PCM has been programmed for the 28.6 lbs/hr injectors, there might be idle problems. Are the Roller Rockers 1.6 or 1.5?
58 mm throttle body is an absolute no-no on your engine, esp. if it has the automatic. The big throttlebody will screw up the shifts and tear up the transmission as the throttle blades are in the wrong position as reported by the TPS for each shift. Lingenfelter absolutely does not recommend the use of the 58 mm with anything other than their engine with a manual trans. Even with a manual trans, I would not recommend it--they use it, becuz they have flow charted the entire intake system and reprogrammed the block learns within the PCM. Unless you have access to this info, it can't be done (read that as having big bucks, lots of big bucks).
The MSD box itself could be defective. Can you unplug it and run just the coil? There have been a number of complaints about this system on this forum--usually involving the box being factory defective.
The MSD system really doesn't help your car. The OEM ignition system with its puny little coil is extremely good, in fact, good enough to pass the long term durability testing by GM and still maintain a 100,000 mile emission pass. That means it burns all the fuel. How can you improve on burning all the fuel? The MSD system is really a race only item...it is known for burning hard to burn fuel mixtures. The heads and fuel mixture on your engine does not have this problem.
58 mm throttle body is an absolute no-no on your engine, esp. if it has the automatic. The big throttlebody will screw up the shifts and tear up the transmission as the throttle blades are in the wrong position as reported by the TPS for each shift. Lingenfelter absolutely does not recommend the use of the 58 mm with anything other than their engine with a manual trans. Even with a manual trans, I would not recommend it--they use it, becuz they have flow charted the entire intake system and reprogrammed the block learns within the PCM. Unless you have access to this info, it can't be done (read that as having big bucks, lots of big bucks).
The MSD box itself could be defective. Can you unplug it and run just the coil? There have been a number of complaints about this system on this forum--usually involving the box being factory defective.
The MSD system really doesn't help your car. The OEM ignition system with its puny little coil is extremely good, in fact, good enough to pass the long term durability testing by GM and still maintain a 100,000 mile emission pass. That means it burns all the fuel. How can you improve on burning all the fuel? The MSD system is really a race only item...it is known for burning hard to burn fuel mixtures. The heads and fuel mixture on your engine does not have this problem.
QUOTE(Me Too @ Apr 17 2010, 08:36 AM)
Ahhhh...I see. The best thing to do is go back to basic parts. First, if you can substitute injectors, go back to the 24 lbs/hr. The ones you have are technically too large for the engine--they should have been nomore than 26 lbs/hr. The stock 24 lbs/hr can support up to at least 400 hp! Unless the heads are ported and polished, the engine probably isn't making more than 350-360 absolute tops! However, if the PCM has been programmed for the 28.6 lbs/hr injectors, there might be idle problems. Are the Roller Rockers 1.6 or 1.5?
58 mm throttle body is an absolute no-no on your engine, esp. if it has the automatic. The big throttlebody will screw up the shifts and tear up the transmission as the throttle blades are in the wrong position as reported by the TPS for each shift. Lingenfelter absolutely does not recommend the use of the 58 mm with anything other than their engine with a manual trans. Even with a manual trans, I would not recommend it--they use it, becuz they have flow charted the entire intake system and reprogrammed the block learns within the PCM. Unless you have access to this info, it can't be done (read that as having big bucks, lots of big bucks).
The MSD box itself could be defective. Can you unplug it and run just the coil? There have been a number of complaints about this system on this forum--usually involving the box being factory defective.
The MSD system really doesn't help your car. The OEM ignition system with its puny little coil is extremely good, in fact, good enough to pass the long term durability testing by GM and still maintain a 100,000 mile emission pass. That means it burns all the fuel. How can you improve on burning all the fuel? The MSD system is really a race only item...it is known for burning hard to burn fuel mixtures. The heads and fuel mixture on your engine does not have this problem.
58 mm throttle body is an absolute no-no on your engine, esp. if it has the automatic. The big throttlebody will screw up the shifts and tear up the transmission as the throttle blades are in the wrong position as reported by the TPS for each shift. Lingenfelter absolutely does not recommend the use of the 58 mm with anything other than their engine with a manual trans. Even with a manual trans, I would not recommend it--they use it, becuz they have flow charted the entire intake system and reprogrammed the block learns within the PCM. Unless you have access to this info, it can't be done (read that as having big bucks, lots of big bucks).
The MSD box itself could be defective. Can you unplug it and run just the coil? There have been a number of complaints about this system on this forum--usually involving the box being factory defective.
The MSD system really doesn't help your car. The OEM ignition system with its puny little coil is extremely good, in fact, good enough to pass the long term durability testing by GM and still maintain a 100,000 mile emission pass. That means it burns all the fuel. How can you improve on burning all the fuel? The MSD system is really a race only item...it is known for burning hard to burn fuel mixtures. The heads and fuel mixture on your engine does not have this problem.
the car had all these parts when i bought it ! I think the previous owner had it on the bottle (nos) but i have had the engine rebuilt since i got it ! the heads are ported and the rockers are 1.6 I agree the throttle body is way to big and the idle has always been rich ! it has a transgo hd2 shift kit and performs well ! how would i go about trying the car without the msd box ? the previous owner had big bucks ! it even has a carbon fiber drive shaft ($800 to $1000) thanks for the help!
I agree with everything Me Too had to say about your car. Be thankful that it was the previous owner that spent all that cash on it and not you! It sounds like he was not very knowledgeable about these cars and did not have a sensible modding plan. Best to decide how much extra HP you're going for, how you are going to use the car, (street or strip), and start with the basics (intake@ exhaust )and go from there. And most importantly keep it simple using stock parts when possible. Dave
Wow, that sounds like a nice engine---or, it could be a nice engine once running properly.
Mine had a switch to turn it off, don't know if the new ones have that feature or not. If no switch, it has to be removed and any wiring changes have to be restored back to stock to run just the coil and ignition module. You can run the MSD coil. No problems there, but it is overkill.
If the previous owner had NOS, that would explain the 28 lbs/hr injectors. It should have had 26 lbs/hr without NOS. The 58 mm TB is too large and it can cause problems with shifting. 52 mm is max. However, the large TB is not causing your problems. It would be more like ignition or a severe vacuum leak, bad plug wires, the MSD box, a malfunctioning fuel pressure regulator (you want to see 43.5 psi while cranking), or even a bad fuel pump. More than likely, and just a guess on my part is an ignition problem. By the way, the OEM 48mm TB will flow more than enough air for your engine, the 52 isn't even needed. There are reasons why owners use the 52 and that is to transfer some torque to the top end for a better charge across the finish line, but for around town, the 48 mm OEM is superior.
Have you removed the negative battery lead, left it off for a couple minutes to force the PCM to cancel the Block Learns? This is an important check. If the engine runs better after this, then starts to run worse after about 20 miles (could be as much as 200 miles, but is usually around 20 miles), that would show you that the PCM is bad.
Also, don't underestimate the power of a massive vacuum leak. Anything around the heads/intake manifold or the rubber elbow where it comes into the throttle body can really mess up the running. Throttle bodies are a hiding place for leaks, everything from the cute little plate on top to the TB coolant chamber underneath. Don't forget to check the TPS and the IAT on the TB. Are they any good? Is the TB torqued with 10 ft lbs to the intake manifold.
Mine had a switch to turn it off, don't know if the new ones have that feature or not. If no switch, it has to be removed and any wiring changes have to be restored back to stock to run just the coil and ignition module. You can run the MSD coil. No problems there, but it is overkill.
If the previous owner had NOS, that would explain the 28 lbs/hr injectors. It should have had 26 lbs/hr without NOS. The 58 mm TB is too large and it can cause problems with shifting. 52 mm is max. However, the large TB is not causing your problems. It would be more like ignition or a severe vacuum leak, bad plug wires, the MSD box, a malfunctioning fuel pressure regulator (you want to see 43.5 psi while cranking), or even a bad fuel pump. More than likely, and just a guess on my part is an ignition problem. By the way, the OEM 48mm TB will flow more than enough air for your engine, the 52 isn't even needed. There are reasons why owners use the 52 and that is to transfer some torque to the top end for a better charge across the finish line, but for around town, the 48 mm OEM is superior.
Have you removed the negative battery lead, left it off for a couple minutes to force the PCM to cancel the Block Learns? This is an important check. If the engine runs better after this, then starts to run worse after about 20 miles (could be as much as 200 miles, but is usually around 20 miles), that would show you that the PCM is bad.
Also, don't underestimate the power of a massive vacuum leak. Anything around the heads/intake manifold or the rubber elbow where it comes into the throttle body can really mess up the running. Throttle bodies are a hiding place for leaks, everything from the cute little plate on top to the TB coolant chamber underneath. Don't forget to check the TPS and the IAT on the TB. Are they any good? Is the TB torqued with 10 ft lbs to the intake manifold.
I appreciate all the input i've gotten but the size of my throttle body injectors and the fact that the car has a MSD coil and ignition box are not relevant to the troubles i'm having ! I agree that theses are not (IDEAL) parts for cruising the streets but i bought the car with all of them and have gotten dependable service out of the car for nearly 3 years .i do put limited miles on the car 10.000 a year or less . i've checked for vacuum leaks and tested all the sensors up top and front of engine everything except 2 o2 sensors they are next i have o2 simulators in the rear of car . i have a P0372 code and since my coil, plugs ,wires ,and ignition module are all good i'm leaning toward a bad optispark but don't wanna jump to conclusions and waste $ ! On the other hand i don't mind spending the $ and turning the wrenches if that is the problem !!! I have read ALOT of cases online of the exact problems im having but never heard the cure yet and was hoping someone in my neighborhood (formula forums) may have had the problem and the cure ! Keep the ideas coming and i will post the cure for fellow neighbors once i find it ! THANKS AGAIN !!! STEVE
Great! Glad to hear you've got it fixed. 
Maybe you mis read my last post ! I haven't gotten the problem fixed yet but i'm leaning toward the optispark ! I will let everyone know what the problem was when i find it ! thanks
Nope, didn't misread your last post. You are leaning towards the Optispark, which is something that I and others mentioned in previous posts, so you think you've got the problem solved. It is a known problem and can fail right out of the box--it's the Mitsubishi designed module that goes, it can also be rust within the Optispark. Have you looked at the crank sensor? I think the 96s have them.
Have a good one.
Have a good one.
do you have any oil leaks on the front of the block? there are like 5 seals within thw water pump, cam shaft, distributor, etc. When I was having all of my ignition problems on my 97 trans am, I pulled 2 old opti sparks (long story, waste of $500) and sent my MSD one off to get rebuilt as it was under warranty. With one of the AC Delce opti sparks, I put it on, and it would run fine for about a day. Then I would get the missfire and lag in power. I pulled it all apart again and this time, took the optispark apart.
Odd enough, I found oil in the actual electronics chamber. I don't know if you have pulled yours apart, but there is an electrical eye and a disc with different slots, I'm guessing it is firing order. In the slots in the disc, I found oil, I would say 3 or 4 solid drops, accumulating around it. And with a Q-tip, i cleaned the electrical eye.
Putting it all back together, it ran fine again, for about a day. I spray painted almost everything red on the front of the block, it helps when looking for oil leaks. Turns out, I had a leak in one of the water pumps seals, and the cam shaft/distributor seal. Replacing those and putting my MSD distributor back on, the car runs like a champ.
Just my similar story, but hope some knowledge helps!
Sean
Odd enough, I found oil in the actual electronics chamber. I don't know if you have pulled yours apart, but there is an electrical eye and a disc with different slots, I'm guessing it is firing order. In the slots in the disc, I found oil, I would say 3 or 4 solid drops, accumulating around it. And with a Q-tip, i cleaned the electrical eye.
Putting it all back together, it ran fine again, for about a day. I spray painted almost everything red on the front of the block, it helps when looking for oil leaks. Turns out, I had a leak in one of the water pumps seals, and the cam shaft/distributor seal. Replacing those and putting my MSD distributor back on, the car runs like a champ.
Just my similar story, but hope some knowledge helps!
Sean
Bandit,
This is so--o-o-o-o-o-o-oo true! After replacing my Optispark and nearly completely overhauling the engine at the same time (once I got going taking things off, just couldn't stop--intake, heads, A/C, oil pan, starter, exhaust system--it was just the bare block that was left in the car).... Anyway, once completed, was on a trip about a week later and the A/C compressor literally blew up! All that was left was the compressor crankshaft rolling around inside of the housing. Compressor oil went everywhere. Didn't think about what the oil could do. You guessed it, it soaked into the Optispark and one week after finishing the rebuild, the Optispark was replaced. Took it apart and the entire inside was filled with A/C compressor oil. What a mess, engine ran like crap.
After that, killed one with a leaky waterpump seal--the seal went crooked before the mounting bolt was pushed in so I missed the seal without knowing it. Can't tell you how many of those stupid things I went thru, becuz of a leak here and another leak there. LOL
This is so--o-o-o-o-o-o-oo true! After replacing my Optispark and nearly completely overhauling the engine at the same time (once I got going taking things off, just couldn't stop--intake, heads, A/C, oil pan, starter, exhaust system--it was just the bare block that was left in the car).... Anyway, once completed, was on a trip about a week later and the A/C compressor literally blew up! All that was left was the compressor crankshaft rolling around inside of the housing. Compressor oil went everywhere. Didn't think about what the oil could do. You guessed it, it soaked into the Optispark and one week after finishing the rebuild, the Optispark was replaced. Took it apart and the entire inside was filled with A/C compressor oil. What a mess, engine ran like crap.
After that, killed one with a leaky waterpump seal--the seal went crooked before the mounting bolt was pushed in so I missed the seal without knowing it. Can't tell you how many of those stupid things I went thru, becuz of a leak here and another leak there. LOL
They are the LT1's Achilles' Heel....
Sorry i haven't been back with a update been busy riding the roads ! but yeah put in a new opti and she's running like a champ ! A few days afterwards i was underneath looking thingsover and saw i drop of coolant at the water pump weep hole ! I rushed and got a new pump before contaminating the new opti !!! Still running like a champ ! picked up alot of pep too ! my tires are hating life! and i can't get the grin off my face ! thanks for all the help guys !!! later , STEVE
Glad to hear you got that bird running again man
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