eman resu sdrawkcab Posted February 8, 2015 Report Share Posted February 8, 2015 Ok need some help and Ill try to be as detailed as i can. 3.1 with 113k miles, having idle misfires and misfires at any rpm. Give it more gas trys to cover it up but its there. Checked spark plugs they all looked perfect, i replaced them anyway. I also replaced the spark plug wires. when you let off the gas it bucks and surges hard. in drive at a stop it feels like it will die but doesnt just idles missing . Theres no water or antifreeze in the oil. Theres good fuel pressure. No signs of vacuum leaks. New fuel filter . New air cleaner. Heres the snag I have run down on my budget for this car and I have enough to get a new ignition module or coil packs but not both. I really dont want to just keep throwing parts at the car. I know check for codes , plugged the code reader in and its not throwing any codes at all. Which boggles the mind with such pronounced misfiring. No codes. So which direction should i go or am i missing something? please help this is our only vehicle and I hate driving it in such condition. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted February 8, 2015 Report Share Posted February 8, 2015 is there any point in operation where it clears up at least a little, like idling just after a cold start? are you capable of accessing actual scanner data(fuel trims, etc) or just codes? ohm-tested the injectors? ohm-tested the coilpacks? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted February 8, 2015 Report Share Posted February 8, 2015 oh yeah, how long has this been happening? has it gotten worse? Quote Link to comment Share on other sites More sharing options...
GrandRegal Posted February 8, 2015 Report Share Posted February 8, 2015 I used this method to diagnose the problem in my regal. The hei tester costs about $10-15 bucks but you can use it to test your wires aswell. Cheap and easy way to diagnose ignition problems in obd1 car which never throw misfire codes. Link: http://easyautodiagnostics.com/gm/3.8L/ignition-coil-pack-tests-4 Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted February 8, 2015 Report Share Posted February 8, 2015 http://easyautodiagnostics.com/gm/3.1L-3.4L/ignition-coil-pack-tests-1 http://easyautodiagnostics.com/gm/3.1L-3.4L/testing-the-ignition-module-and-crank-sensor-1 those are more specific to the 60V6 ignition system, which are somewhat different than the 3800s. Quote Link to comment Share on other sites More sharing options...
eman resu sdrawkcab Posted February 8, 2015 Author Report Share Posted February 8, 2015 when its cold started it fires up and isnt as noticeable when the high idle is on but as it warms it starts missing. I cant tell you how long its been this way, as i recently purchased the car. But since i have owned it it has gotten worse , it started out only being at idle, now its throughout the rpm range. I have no better diagnostic tools just a code reader that seems useless. I also have not tested the injectors , the plugs dont show a lean or rich condition . Sorry I dont have better info than this. Quote Link to comment Share on other sites More sharing options...
GrandRegal Posted February 8, 2015 Report Share Posted February 8, 2015 If you want to test if the ignition coil is giving any spark without buying the hei tester you can take the wire off the sparkplug in the motor and use an old plug as you would the hei tester. If there is no spark or the spark is yellowish the coil is bad and needs to be replaced. If all cylinders give adequate spark the problem is either the icm or fuel related. Make sure to ground the plug to your battery using jumper cables if you use this method though. Quote Link to comment Share on other sites More sharing options...
Nas Escobar Posted February 9, 2015 Report Share Posted February 9, 2015 Theres no water or antifreeze in the oil. Theres good fuel pressure. No signs of vacuum leaks. New fuel filter . New air cleaner. Heres the snag I have run down on my budget for this car and I have enough to get a new ignition module or coil packs but not both. I really dont want to just keep throwing parts at the car. I know check for codes , plugged the code reader in and its not throwing any codes at all. Which boggles the mind with such pronounced misfiring. No codes. So which direction should i go or am i missing something? please help this is our only vehicle and I hate driving it in such condition. Thanks in advance. You did a tune up, but no coil swap? I'm betting it's the coils. Bad coils gave me 10mpg and loss of power. And you are missing something... tunerpro. With tunerpro, you can see more than just codes. You can see if there's a knock and where is the knock detected. It would save you a lot of hassle. You need an ALDL cable and a laptop or tablet to run Tunerpro. Quote Link to comment Share on other sites More sharing options...
eman resu sdrawkcab Posted February 10, 2015 Author Report Share Posted February 10, 2015 I ordered a trio of coils and some dielectric grease, Ill throw those in and see if that's solves it. As far as using tunerpro....yeah Ide love to but it looks really complex with a stiff learning curve . And Im not sure my old laptop would even work with it. It running windows 7 but it doesn't run many games so its not upgraded. To my way of thinking its going to be either weak coils , a bad ignition module, or on to fuel and air so, MAF, all the way to injectors. Hoping coils fix's it to be honest. Side question , I hear my fuel pump as i turn my key on and i always wait till it stops before starting the car , but once it starts should I be able to hear it at all? Im not sure if i just didnt notice it before or if its gotton loader but i can here it running with vehicle on in park. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted February 10, 2015 Report Share Posted February 10, 2015 (edited) Side question , I hear my fuel pump as i turn my key on and i always wait till it stops before starting the car , but once it starts should I be able to hear it at all? Im not sure if i just didnt notice it before or if its gotton loader but i can here it running with vehicle on in park. Impossible to say--since this hinges on your hearing acuity, and we can't assess that. I have NEVER heard the fuel pumps in my '92 and '93 Luminas. If I had to base their performance on the noise they make...I'd be in deep sh!t. This is why I test in-tank fuel pumps based on pressure, volume, amperage draw and RPM of the electric motor. Edited February 10, 2015 by Schurkey Quote Link to comment Share on other sites More sharing options...
Nas Escobar Posted February 11, 2015 Report Share Posted February 11, 2015 I ordered a trio of coils and some dielectric grease, Ill throw those in and see if that's solves it.As far as using tunerpro....yeah Ide love to but it looks really complex with a stiff learning curve . And Im not sure my old laptop would even work with it. It running windows 7 but it doesn't run many games so its not upgraded. To my way of thinking its going to be either weak coils , a bad ignition module, or on to fuel and air so, MAF, all the way to injectors. Hoping coils fix's it to be honest. Side question , I hear my fuel pump as i turn my key on and i always wait till it stops before starting the car , but once it starts should I be able to hear it at all? Im not sure if i just didnt notice it before or if its gotton loader but i can here it running with vehicle on in park. If you're just using it to read the computer, the learning curve isn't that big. Robert Saar can help you with it. He's the tech guru of this forum. I run TP on a W8 tablet with a shit CPU. I'm pretty sure your basic W7 laptop can run it. Injectors would throw codes, more specifically rich/lean and knock codes. However, not a real guarantee. As far as the fuel pump goes, usually you can't hear it becasue of the carpet and other ambient noise. I can hear mine when running, but I'm gutted inside. Quote Link to comment Share on other sites More sharing options...
Hairdo12 Posted February 14, 2015 Report Share Posted February 14, 2015 (edited) If the plugs are brand new, pull them out and inspect them. A brand new plug that isn't firing will look like it just has a light oil film on it. It will be clearly distinctive looking compared to a plug that is firing and can't be missed. Checking for a bad coil is easy: one at a time pull off the 1,3,5 spark plug wires at idle... If the idle changes coil works... No change, coils bad. computer scanning is worthless on an odb1 car for finding a mis fire. Odb1 offers literally zero information to diagnose the problem. My old lumina had a dead coil, ran on only 4 of 6 cylinders, ran like shit, dumped tons of unburied fuel into exhaust, caused the cat to glow red and the computer thought everything was just fine. Edited February 14, 2015 by Hairdo12 Quote Link to comment Share on other sites More sharing options...
Nas Escobar Posted February 14, 2015 Report Share Posted February 14, 2015 (edited) Checking for a bad coil is easy: one at a time pull off the 1,3,5 spark plug wires at idle... If the idle changes coil works... No change, coils bad. I want to add to this that if you pull the wire from the coil, you should see a rapid spark at the tip of the coil. It should be strong enough to shock you as well (or at least I got shocked when I pulled the cable from the coil). I'm pretty sure you could do the old method of sticking a screwdriver in the boot of the cable on the spark plug side as well to observe computer scanning is worthless on an odb1 car for finding a mis fire. Odb1 offers literally zero information to diagnose the problem. My old lumina had a dead coil, ran on only 4 of 6 cylinders, ran like shit, dumped tons of unburied fuel into exhaust, caused the cat to glow red and the computer thought everything was just fine. Depends on the situation. Tunerpro did pick up a misfire on my 94 LQ1, pulled the plugs and noticed that the specific cylinder didn't have as much deposits as the other ones, swapped out the coil for it and I fixed my issue. Another dead giveaway for me was the BLM rating as well as the knock sensor. Then again 94 and 95 had funky systems where the codes were in OBD2 format but the plug was not. Regardless of the fact, it doesn't hurt to try. Edited February 14, 2015 by Nas Escobar Quote Link to comment Share on other sites More sharing options...
Schurkey Posted February 14, 2015 Report Share Posted February 14, 2015 (edited) computer scanning is worthless on an odb1 car for finding a mis fire. Odb1 offers literally zero information to diagnose the problem. My old lumina had a dead coil, ran on only 4 of 6 cylinders, ran like shit, dumped tons of unburied fuel into exhaust, caused the cat to glow red and the computer thought everything was just fine. What scan tool were you using? Two misfiring cylinders should have had the O2 sensor reading wildly lean because the oxygen from those two cylinders isn't combining with the raw fuel that's being dumped into the catalyst until after it blows past the O2 sensor. The fuel trim should have been commanded rich. There'd be few O2 crosscounts. Two dead cylinders should have the idle air control way open to maintain idle speed. All of this screams "misfire". How can this NOT show up on a scan tool? Edited February 14, 2015 by Schurkey Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted February 14, 2015 Report Share Posted February 14, 2015 Did you try to swap the coil position on the ICM to see if the misfire traveled to other cylinders? Quote Link to comment Share on other sites More sharing options...
eman resu sdrawkcab Posted February 14, 2015 Author Report Share Posted February 14, 2015 Ok coils just arrived today. Questions #1 Do I use dielectric grease on the pins as well as the towers? #2 This looks like its going to be a difficult job, I can see minimal room up top to get the top screw/bolts ...but the bottoms look next to impossible . Can they be gotton from under the vehicle or is it all from the top with bottom screw/bolts/ being blind? #3 Is there a write up on this process on this site that my noob search skills missed? TIA Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted February 14, 2015 Report Share Posted February 14, 2015 to get the lower coil bolts, I've had to go from the bottom. you'll want to be cautious of the starter wires while you're down there, or just disconnect the positive cable from the battery. Quote Link to comment Share on other sites More sharing options...
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