obdII question
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
It's highly unlikely he has such a swap, but I don't see any other theories in this thread for why the sys light cleared when he fixed the rear O2S.
Thread Starter
Heel & Toe
Joined: Jun 2007
Posts: 19
Likes: 0
I check all the plug wires last night as well as all electrical connections that i could, also checked to see if there were any burnt wires anywhere. Everything looked okay.
The problem started as a slight miss at idle and a little miss under a load. I took the car out last night and it barely want to run now. I put some more dry gas and some octane boost in it to try to rule out bad gas. Then i was going to take it out on the highway but getting to the highway wasn't an option when i was going down a 40 mph road and put it in 4th gear it wouldn't move. It was bucking on acceleration as well as at constant throtle.
Does anyone think that the opti is taking a crap?? It seems like a ignition miss to me. I'm going to do a compression test this weekend but i can't see it being something wrong with the motor to go from a slight miss to not wanting to run the next day.
Thanks, Shawn
The problem started as a slight miss at idle and a little miss under a load. I took the car out last night and it barely want to run now. I put some more dry gas and some octane boost in it to try to rule out bad gas. Then i was going to take it out on the highway but getting to the highway wasn't an option when i was going down a 40 mph road and put it in 4th gear it wouldn't move. It was bucking on acceleration as well as at constant throtle.
Does anyone think that the opti is taking a crap?? It seems like a ignition miss to me. I'm going to do a compression test this weekend but i can't see it being something wrong with the motor to go from a slight miss to not wanting to run the next day.
Thanks, Shawn
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Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
No, ive seen a fair few bad cap/rotor bad but i havent seen a bad optispark yet. They can go a few ways, but its better to check the cheaper stuff first before lashing out for a new distributor. If you were getting a problem in the optical circuit it will normally set DTCs to say whats not right. That doesnt mean it always will, but if its not setting any DTCs then you cant just assume its the distributor, cause if its something else, youve thrown an expensive part at it you didnt need.
Thread Starter
Heel & Toe
Joined: Jun 2007
Posts: 19
Likes: 0
Where i stand now.
I pulled all the plugs and they all looked good except for #7. it loked like it was not firing as good as the rest of them. It was a little wet with fuel and it looked like it ws intermitinley firing.
I also did a compression test on all the cyl. they were all at 175 psi except for #5 it was at 160 psi.
I also ckecked for spark and they all looked prty brite except for the #7 cyl. It was sparking but just not as strong as the rest. When i had the test light on any of the wires you could see the miss and sometimes there would be a pause in the light.
A buddy of mine had a new coil so we tried it to rule it out. because when i pulled the wire of of it the terminal was all white and the inside of thhe wire had some corrosion in it. New wire new coil and still doing it.
I think it is starting to point to the cap side of the opti.
Any body have any other Ideas.
I also pulled two more codes.
Module 1- ( H41 )
Module 9- ( H72 )
Thanks, Shawn
I pulled all the plugs and they all looked good except for #7. it loked like it was not firing as good as the rest of them. It was a little wet with fuel and it looked like it ws intermitinley firing.
I also did a compression test on all the cyl. they were all at 175 psi except for #5 it was at 160 psi.
I also ckecked for spark and they all looked prty brite except for the #7 cyl. It was sparking but just not as strong as the rest. When i had the test light on any of the wires you could see the miss and sometimes there would be a pause in the light.
A buddy of mine had a new coil so we tried it to rule it out. because when i pulled the wire of of it the terminal was all white and the inside of thhe wire had some corrosion in it. New wire new coil and still doing it.
I think it is starting to point to the cap side of the opti.
Any body have any other Ideas.
I also pulled two more codes.
Module 1- ( H41 )
Module 9- ( H72 )
Thanks, Shawn
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
So #7 isnt firing properly and # 5 is 15 psi down on the other 7 cylinders?
Have you checked where the leads connect to the distributor to be sure #7 is tightly connected and clean?
Did you check to see if you can find out a reason why #5 was down 15psi on the other cylinders?
DTC 41 in module 1 is PCM serial data comunications circuit, loss of communications. Book 1, pages 8D-54 and 8D-55 of the GM service manual.
Have you checked where the leads connect to the distributor to be sure #7 is tightly connected and clean?
Did you check to see if you can find out a reason why #5 was down 15psi on the other cylinders?
DTC 41 in module 1 is PCM serial data comunications circuit, loss of communications. Book 1, pages 8D-54 and 8D-55 of the GM service manual.
Thread Starter
Heel & Toe
Joined: Jun 2007
Posts: 19
Likes: 0
I checked all the wires and they are fine. I didn't check to see why #7 is 15 psi less than the others. I don' t think that is too bad. I put my friends ignition module on it and it is still doing it. I am leaning towards the dis cap. I'm going to tear it down and replace it.
Thanks for all the help, Shawn
Thanks for all the help, Shawn
Thread Starter
Heel & Toe
Joined: Jun 2007
Posts: 19
Likes: 0
I decided to put a new cap and rotor on it since that was the only reason that i could see to be causing the original miss. The end result was that the cap was shot. I don't know how any of them were firing. I put it all back together and the car was still running like it was down a cyl., so i decided to take the new plugs out again and look them over. They looked fine to me and #7 was now firing. So i guess the new cap fixed that. Just for the hell of it while i had the new plugs out i decided to put the old ones back in. Well there it was, the parts store gave me a bad plug, so needless to say, with the new cap and the old plugs she is running Awesome. I don't know of a way to check the plugs before you put them in, if anyone does please let me know.
Just a note, I can't believe how bad the inside of the cap was on that car. I guess a regular cap would look bad to if it had 43000 moles on it. But you would think these should last being that they are a pain to get to.
I want to thank everyone for their help.
Thank, Shawn
Just a note, I can't believe how bad the inside of the cap was on that car. I guess a regular cap would look bad to if it had 43000 moles on it. But you would think these should last being that they are a pain to get to.
I want to thank everyone for their help.
Thank, Shawn
