Stumbling Problem in Great Detail
11-23-2003, 11:06 AM
#31
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I actually have another tune stocked away on my computer, just no chips to burn it with. My freakig Epromer5 decided to quit/fry my extra 29C256 chips on me.
funny thing is, on my first tune, the car was almost perfect, just a little lean up top. this came from my mechanic, as I was out of town when he got it running. The problems appeared after the first time on the dyno. the car blew out the opti seal. Off came the opti and everything and the opti and crank seals were both replaced. At that point Tune #2 was put in and the problem presented itself. Tune #2 was the same as #1 with a little more fuel added up top per Alvin's saying. That's why I'm convinced that it's a mechanical thing. I have put thought to trying someone else, but I want to be absolutely sure that it's the tune before I do that.
Madwolf, if you're reading this, are you located in the PA area???
funny thing is, on my first tune, the car was almost perfect, just a little lean up top. this came from my mechanic, as I was out of town when he got it running. The problems appeared after the first time on the dyno. the car blew out the opti seal. Off came the opti and everything and the opti and crank seals were both replaced. At that point Tune #2 was put in and the problem presented itself. Tune #2 was the same as #1 with a little more fuel added up top per Alvin's saying. That's why I'm convinced that it's a mechanical thing. I have put thought to trying someone else, but I want to be absolutely sure that it's the tune before I do that.
Madwolf, if you're reading this, are you located in the PA area???
11-23-2003, 08:20 PM
#33
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New development
Well, after giving the old lights out test another shot, it became aparrent tonight that I DO have a slight arcing problem.
My ENTIRE coil bracket is arcing DURING the stumble. The whole friggin thing. I saw light coming from four points on the bracket. How do I go about fixing that?!?! I don't think it's the plug wires routed underneath the coil bracket, that would have to be one heck of a glow from those.
Anyone ever experience this before??? How did you fix it?
My ENTIRE coil bracket is arcing DURING the stumble. The whole friggin thing. I saw light coming from four points on the bracket. How do I go about fixing that?!?! I don't think it's the plug wires routed underneath the coil bracket, that would have to be one heck of a glow from those.
Anyone ever experience this before??? How did you fix it?
11-30-2003, 11:30 AM
#34
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Well, looks like this one might have gotten the better of me. In the rush to fix the problem, I "inspected" my plug wires, to the extent of looking at them as close as possible while still in the car. Upon removal today, I found one tiny burn mark, but three seperate wires were heat cracked. Is this the problem??? We shall see.....
12-03-2003, 01:42 PM
#35
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I have tried, and failed.
Well, after new plugs and wires, THE MOTHERF(*#^%^ STUMBLE IS STILL THERE!!!! 
I can't find anything wrong with the damn thing, but it still hesitates and stumbles when the throttle is moved in anything other than a slow speed.
I put the scanner on it after a drive around the block, and my right O2 millivolts were steady in the 900's while the left was bouncing around from low to high, like it should.
I can't take it anymore. anyone want to videotape me igniting my car??
I can't find anything wrong with the damn thing, but it still hesitates and stumbles when the throttle is moved in anything other than a slow speed. I put the scanner on it after a drive around the block, and my right O2 millivolts were steady in the 900's while the left was bouncing around from low to high, like it should.
I can't take it anymore. anyone want to videotape me igniting my car??
12-03-2003, 05:12 PM
#37
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I'm having the exact same problem, even the 02 situation is the same for me. Do you have any tuning software? I changed the WOT table to zero percent across the board, and the stumble goes away.
This means it is a bad 02, MAF, MAp, or egr...
I haven't replaced anything on my car, yet but 02's are going ot be first this weekend. my problem started when I installed my direct port nitrous kit a week or two ago, but I ahven't used it yet.
I got some oil on the o2s during install and that caused this problem I'm thinking.
If you have tuning software, try eliminating the maf and running speed density. With no 02 feedback, change the tps for WOT to 0 percent and the stumble will disappear if it is not mechanical.
This means it is a bad 02, MAF, MAp, or egr...
I haven't replaced anything on my car, yet but 02's are going ot be first this weekend. my problem started when I installed my direct port nitrous kit a week or two ago, but I ahven't used it yet.
I got some oil on the o2s during install and that caused this problem I'm thinking.
If you have tuning software, try eliminating the maf and running speed density. With no 02 feedback, change the tps for WOT to 0 percent and the stumble will disappear if it is not mechanical.
12-03-2003, 05:20 PM
#38
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Originally posted by kindaslo
If you have tuning software, try eliminating the maf and running speed density. With no 02 feedback, change the tps for WOT to 0 percent and the stumble will disappear if it is not mechanical.
If you have tuning software, try eliminating the maf and running speed density. With no 02 feedback, change the tps for WOT to 0 percent and the stumble will disappear if it is not mechanical.
I am speed density. 93 Trans Am. Interesting solution you brought up though. Easy way to rule it out. I do have Tunercat, but unfortunately, my chip burner is shot so I'm high and dry right now.
I'm trying to get my O2's swapped and am going to see if the problem switches sides. If it does, O2, plain and simple. If it doesn't, then crap. Probably a fuel or tune problem at that point.
12-03-2003, 07:18 PM
#40
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Well, swapped the O2's, and they both look good on the scanner now. 
BUT!!! The left and right integrator values were both driving down low, the left to about 20 and the right down to 1.
whatever those are.
Problem still there.
BUT!!! The left and right integrator values were both driving down low, the left to about 20 and the right down to 1.
whatever those are.
Problem still there.
12-04-2003, 12:02 PM
#42
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I am not saying an opti is your problem, but a week ago I was in your shoes. Rich at idle, stumble and hesitation getting on the gas. I had installed a GM opti 3 weeks before that problem surfaced, so I ruled out the opti and began troubleshooting. Last week my three week old opti died (code 36). After getting another one and installing it, problem solved. It is not common, but opti sparks can be bad from GM. Just something to think about.
12-04-2003, 03:37 PM
#43
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Originally posted by ZZtop
I am not saying an opti is your problem, but a week ago I was in your shoes. Rich at idle, stumble and hesitation getting on the gas. I had installed a GM opti 3 weeks before that problem surfaced, so I ruled out the opti and began troubleshooting. Last week my three week old opti died (code 36). After getting another one and installing it, problem solved. It is not common, but opti sparks can be bad from GM. Just something to think about.
I am not saying an opti is your problem, but a week ago I was in your shoes. Rich at idle, stumble and hesitation getting on the gas. I had installed a GM opti 3 weeks before that problem surfaced, so I ruled out the opti and began troubleshooting. Last week my three week old opti died (code 36). After getting another one and installing it, problem solved. It is not common, but opti sparks can be bad from GM. Just something to think about.
12-05-2003, 03:11 AM
#44
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that is a common problem, but.. my car doesn't have it anymore...
I take paypal, checks, etc... hahaha, just kidding.
here's the test: roll in the throttle, and it accelerates smooth; puch the gas and it stumbles, but not always.
here's why: the computer bounces the mix between rich and lean using the O2 for feedback. the software has a table of throttle vs rpm to determine if and when enter power enrichment (makes the car run more rich during heavy acceleration, that minimizes the risk of pinging around the peak torque area, etc). if you are in a lean part of the cycle and go in power enrichment, the software makes the car run too rich until you release the gas.
here's the fix:in the software, when it goes in power enrichment, there is a test to determine if it is in the lean part of the cycle, it needs to be removed from the code and then the stumble will be gone.
at least that's how the 95 obd1 system works, not sure about the others.
I take paypal, checks, etc... hahaha, just kidding.
here's the test: roll in the throttle, and it accelerates smooth; puch the gas and it stumbles, but not always.
here's why: the computer bounces the mix between rich and lean using the O2 for feedback. the software has a table of throttle vs rpm to determine if and when enter power enrichment (makes the car run more rich during heavy acceleration, that minimizes the risk of pinging around the peak torque area, etc). if you are in a lean part of the cycle and go in power enrichment, the software makes the car run too rich until you release the gas.
here's the fix:in the software, when it goes in power enrichment, there is a test to determine if it is in the lean part of the cycle, it needs to be removed from the code and then the stumble will be gone.
at least that's how the 95 obd1 system works, not sure about the others.
12-05-2003, 11:59 AM
#45
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Originally posted by tom3
that is a common problem, but.. my car doesn't have it anymore...
I take paypal, checks, etc... hahaha, just kidding.
here's the test: roll in the throttle, and it accelerates smooth; puch the gas and it stumbles, but not always.
here's why: the computer bounces the mix between rich and lean using the O2 for feedback. the software has a table of throttle vs rpm to determine if and when enter power enrichment (makes the car run more rich during heavy acceleration, that minimizes the risk of pinging around the peak torque area, etc). if you are in a lean part of the cycle and go in power enrichment, the software makes the car run too rich until you release the gas.
here's the fix:in the software, when it goes in power enrichment, there is a test to determine if it is in the lean part of the cycle, it needs to be removed from the code and then the stumble will be gone.
at least that's how the 95 obd1 system works, not sure about the others.
that is a common problem, but.. my car doesn't have it anymore...
I take paypal, checks, etc... hahaha, just kidding.
here's the test: roll in the throttle, and it accelerates smooth; puch the gas and it stumbles, but not always.
here's why: the computer bounces the mix between rich and lean using the O2 for feedback. the software has a table of throttle vs rpm to determine if and when enter power enrichment (makes the car run more rich during heavy acceleration, that minimizes the risk of pinging around the peak torque area, etc). if you are in a lean part of the cycle and go in power enrichment, the software makes the car run too rich until you release the gas.
here's the fix:in the software, when it goes in power enrichment, there is a test to determine if it is in the lean part of the cycle, it needs to be removed from the code and then the stumble will be gone.
at least that's how the 95 obd1 system works, not sure about the others.
kindalso, I'm using datamaster, and the latest scans have been done on a scanning tune borrowed from a friend. I only have a couple of logs for free left on Datamaster and was trying to save them. I have a couple I could send you if you want.