One last shot... Breaking up!
- Thread starter BoostedSUV
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WyoSyclone
Active member
Re: One last shot... Breaking up!
Logs never show the ECM voltage dropping during the misfire.
Logs never show the ECM voltage dropping during the misfire.
BoostedSUV
Active member
Re: One last shot... Breaking up!
I did add a ground to the ECM case and it made no difference, the voltage stays steady at 13.8 on DM. I'm trying to think of where there is a ground on the RH side of engine? I check the ones at the front of lower intake,and the LH head...
I did add a ground to the ECM case and it made no difference, the voltage stays steady at 13.8 on DM. I'm trying to think of where there is a ground on the RH side of engine? I check the ones at the front of lower intake,and the LH head...
WyoSyclone
Active member
Re: One last shot... Breaking up!
Set multimeter to DC volts, or millivolts.... probe each ground point between 'tested ground' and negative of battery. A higher voltage will indicate a bad ground... a low voltage, or 0 volts will indicate a good ground.
Set multimeter to DC volts, or millivolts.... probe each ground point between 'tested ground' and negative of battery. A higher voltage will indicate a bad ground... a low voltage, or 0 volts will indicate a good ground.
SY2455
70's Veteran
Re: One last shot... Breaking up!
If you have the manual it shows it on the right side, on the rear of the head in what would the top accessories mounting bracket hole if the head was install on the driver side of the engine :tup:. Hopefully that will make sense to you and not be a run on sentence :rotf:.
Note: I just trace it out and it is the main neg battery cable.
1. G 100 .......... RH rear of engine, below the rocker cover. 1 Wire = main neg battery cable.
2. G 101 .......... At the RH radiator support. 1 Wire = small neg battery cable.
3. G107 .......... LH rear of engine, near the rocker cover. 2 Wires = 1 goes to the ECM at C311 position E15. The other wire goes to alot of places due to a connection that is made in the harness. It goes to the ECM at C310 postion C13 and to ECM at C307 position A12, it goes to the heated O2 sensor, EGR vacuum regulator valve solenoid, to the fuel pump relay and the 4 wal module via C161 and C160.
4. G108 .......... Top front center of engine. 2 Wires, G108 goes to the ECM at C310 position D1.
5. G109 .......... Top front center of engine. ^^^^^^^^ G108 and G109 are at the same point on the engine lift bracket. G109 goes to the charge air cooler pump and the engine bulk head connector (C100) which is the engine side of the fuse block. Then a bunch of stuff inside.
If you have the manual it shows it on the right side, on the rear of the head in what would the top accessories mounting bracket hole if the head was install on the driver side of the engine :tup:. Hopefully that will make sense to you and not be a run on sentence :rotf:.
Note: I just trace it out and it is the main neg battery cable.
1. G 100 .......... RH rear of engine, below the rocker cover. 1 Wire = main neg battery cable.
2. G 101 .......... At the RH radiator support. 1 Wire = small neg battery cable.
3. G107 .......... LH rear of engine, near the rocker cover. 2 Wires = 1 goes to the ECM at C311 position E15. The other wire goes to alot of places due to a connection that is made in the harness. It goes to the ECM at C310 postion C13 and to ECM at C307 position A12, it goes to the heated O2 sensor, EGR vacuum regulator valve solenoid, to the fuel pump relay and the 4 wal module via C161 and C160.
4. G108 .......... Top front center of engine. 2 Wires, G108 goes to the ECM at C310 position D1.
5. G109 .......... Top front center of engine. ^^^^^^^^ G108 and G109 are at the same point on the engine lift bracket. G109 goes to the charge air cooler pump and the engine bulk head connector (C100) which is the engine side of the fuse block. Then a bunch of stuff inside.
BoostedSUV
Active member
Re: One last shot... Breaking up!
Oh ok that would make sense. The ground on the RH was the main ground to the Battery. Now I remember there being a ground there... I relocated the battery so I have the batt - cable going to the front intake bolt at G108 and G109. That would make sense why that one was "missing". All my other grounds are present and nice and tight. I have a service manual but I didn't have it in front of me last night. Thanks for doing my homework for me! :lol: :tup:
Oh ok that would make sense. The ground on the RH was the main ground to the Battery. Now I remember there being a ground there... I relocated the battery so I have the batt - cable going to the front intake bolt at G108 and G109. That would make sense why that one was "missing". All my other grounds are present and nice and tight. I have a service manual but I didn't have it in front of me last night. Thanks for doing my homework for me! :lol: :tup:
WyoSyclone
Active member
Re: One last shot... Breaking up!
Looking at things I doubt that it is a ground.
Matt, I did find a log (Don's) that shows similar swings in the O2mV during closed loop.... the one BIG difference is that Don's log shows a nice smooth ramp up, then a smooth ramp down of the mV, with a nice reversing curve at each end. Your O2 swings look more like a loss of signal - an almost vertical ramp up and down with a sharp reversing angle...
so, I'm leaning back to a bad O2 sensor, or a bad ECM... your truck has made my head hurt!
Looking at things I doubt that it is a ground.
Matt, I did find a log (Don's) that shows similar swings in the O2mV during closed loop.... the one BIG difference is that Don's log shows a nice smooth ramp up, then a smooth ramp down of the mV, with a nice reversing curve at each end. Your O2 swings look more like a loss of signal - an almost vertical ramp up and down with a sharp reversing angle...
so, I'm leaning back to a bad O2 sensor, or a bad ECM... your truck has made my head hurt!
BoostedSUV
Active member
Re: One last shot... Breaking up!
Your head hurt? LOL I can't sleep at night and I'm driving myself, and my girlfriend nuts because this thing has me talking to my self!
Anyways, I have 2 different ECMs in my possession and one was brand new from GM. I can't imagine both are bad causing the SAME thing. From the second I put the new one from GM in the problem was there so it's not like it went bad.... I'm going to pick up a new Bosch O2 tomorrow but I don't think that's it since the truck will do this with it disconnected. Another thing I'm trying as I type is, I pulled the ECM fuses to reset the ECM. Is it possible the ECM "learned" the problem with the old injectors and now needs to be reset to "re-learn"?
Looking at things I doubt that it is a ground.
Matt, I did find a log (Don's) that shows similar swings in the O2mV during closed loop.... the one BIG difference is that Don's log shows a nice smooth ramp up, then a smooth ramp down of the mV, with a nice reversing curve at each end. Your O2 swings look more like a loss of signal - an almost vertical ramp up and down with a sharp reversing angle...
so, I'm leaning back to a bad O2 sensor, or a bad ECM... your truck has made my head hurt!
Your head hurt? LOL I can't sleep at night and I'm driving myself, and my girlfriend nuts because this thing has me talking to my self!
Anyways, I have 2 different ECMs in my possession and one was brand new from GM. I can't imagine both are bad causing the SAME thing. From the second I put the new one from GM in the problem was there so it's not like it went bad.... I'm going to pick up a new Bosch O2 tomorrow but I don't think that's it since the truck will do this with it disconnected. Another thing I'm trying as I type is, I pulled the ECM fuses to reset the ECM. Is it possible the ECM "learned" the problem with the old injectors and now needs to be reset to "re-learn"?
BoostedSUV
Active member
Re: One last shot... Breaking up!
Well I was messing with testing grounds tonight, I had neg side connected to alternator case and I probed all the ECM grounds and the ECM case. I got .8ohms at each ground on the harness and 1.2ohms at the ECM case, and 0 to the block. I started probing other grounds around the truck and everything grounded to the body of the truck was 13.2 ohms at best, and with the truck running they were reading 35ohms! It seems to me the ground to the firewall and body of the truck is not a good one. Not sure that has anything to do with my problem, but I'm going to try and figure out a way to make a better ground to the body
Well I was messing with testing grounds tonight, I had neg side connected to alternator case and I probed all the ECM grounds and the ECM case. I got .8ohms at each ground on the harness and 1.2ohms at the ECM case, and 0 to the block. I started probing other grounds around the truck and everything grounded to the body of the truck was 13.2 ohms at best, and with the truck running they were reading 35ohms! It seems to me the ground to the firewall and body of the truck is not a good one. Not sure that has anything to do with my problem, but I'm going to try and figure out a way to make a better ground to the body
WyoSyclone
Active member
Re: One last shot... Breaking up!
Wow, dude, that is WAY too high (13.2 and 35).... I always shoot for around .2 ohms, but that can be hard to get. Taking a reading with the truck running doesn't do a lot of good due to the ground currents flowing through the chassis back to the alternator and battery... even hitting a pothole in an older car can change how current flows through the chassis (we used to study this a lot when I was at Fujitsu Ten/Eclipse).
Have you powdercoated a bunch of stuff in your engine compartment? Just run a temporary ground from the firewall to the alternator and see if it makes a difference.
Wow, dude, that is WAY too high (13.2 and 35).... I always shoot for around .2 ohms, but that can be hard to get. Taking a reading with the truck running doesn't do a lot of good due to the ground currents flowing through the chassis back to the alternator and battery... even hitting a pothole in an older car can change how current flows through the chassis (we used to study this a lot when I was at Fujitsu Ten/Eclipse).
Have you powdercoated a bunch of stuff in your engine compartment? Just run a temporary ground from the firewall to the alternator and see if it makes a difference.
SloGN
9Sec Alky V6
Re: One last shot... Breaking up!
Matt
Did you do a battery relocation?
If so you may need to add a ground from the batttery to the body near the battery. Then add a ground from the firewall to the engine.
if you have a bad ground. the power source (ecm) will try and seek a better ground regardless of location or what its connected to.
hope you find it!
one more thing... your not tring to ground the engine thru the truck are you? what i mean is using a large cable bolted to the body and then another large cable bolted to the body then to the engine. if your grounding the truck that way you actually need to run a large cable from the battery to the engine and then ground from the engine to the firewall. and add a small ground to the body near the battery like i mentioned up top.
did you get the injectors yet?
Matt
Did you do a battery relocation?
If so you may need to add a ground from the batttery to the body near the battery. Then add a ground from the firewall to the engine.
if you have a bad ground. the power source (ecm) will try and seek a better ground regardless of location or what its connected to.
hope you find it!
one more thing... your not tring to ground the engine thru the truck are you? what i mean is using a large cable bolted to the body and then another large cable bolted to the body then to the engine. if your grounding the truck that way you actually need to run a large cable from the battery to the engine and then ground from the engine to the firewall. and add a small ground to the body near the battery like i mentioned up top.
did you get the injectors yet?
BoostedSUV
Active member
Re: One last shot... Breaking up!
The battery is relocated to the driver side, don't ask, that was the easiest place for me to put it. Anyways, I have a 2 ga running from the NEG terminal to the Intake bolt, a 4ga running from the alt bracket to the shock tower, 10ga from the NEG terminal to the rad support and a 10ga to the inner fender well. The ground strap is in place from the back of the head to the firewall near the wiper motor.
Like I was saying, I was probing grounds and everything inside the cab, behind kick panels, dash bracket, the ebrake bracket, throttle pedal bracket etc I was reading anywhere from 12-17ohms which is wayyyy to high! Again, I'm not sure that has anything to do with my issue at hand but that is an issue I need to address.
Rob, I don't have anything powder coated under the hood. Everything was painted when i had the motor out a few years ago but I ground down everywhere a ground or strap touches. I'm going to run a new ground strap as you suggested and see what that does for my readings. You worked for Fujitsu/Eclipse huh? Pretty Cool! That's all I use for Car Audio in both my Ty and my El Camino :tup:
The battery is relocated to the driver side, don't ask, that was the easiest place for me to put it. Anyways, I have a 2 ga running from the NEG terminal to the Intake bolt, a 4ga running from the alt bracket to the shock tower, 10ga from the NEG terminal to the rad support and a 10ga to the inner fender well. The ground strap is in place from the back of the head to the firewall near the wiper motor.
Like I was saying, I was probing grounds and everything inside the cab, behind kick panels, dash bracket, the ebrake bracket, throttle pedal bracket etc I was reading anywhere from 12-17ohms which is wayyyy to high! Again, I'm not sure that has anything to do with my issue at hand but that is an issue I need to address.
Rob, I don't have anything powder coated under the hood. Everything was painted when i had the motor out a few years ago but I ground down everywhere a ground or strap touches. I'm going to run a new ground strap as you suggested and see what that does for my readings. You worked for Fujitsu/Eclipse huh? Pretty Cool! That's all I use for Car Audio in both my Ty and my El Camino :tup:
BoostedSUV
Active member
Re: One last shot... Breaking up!
I'm going to make up a ground strap tomorrow to try and get a more solid ground in the cab of the truck, Not sure it has anything to do with my issues but I definitely need tp address this issue. I know I couldn't get that lucky and have it be something that stupid!
I'm going to make up a ground strap tomorrow to try and get a more solid ground in the cab of the truck, Not sure it has anything to do with my issues but I definitely need tp address this issue. I know I couldn't get that lucky and have it be something that stupid!
WyoSyclone
Active member
Re: One last shot... Breaking up!
Yup, I was North American Product Development Manager from 1988 through 1990.... that was after Reese Haggott had left Alpine and gone to Eclipse (I had just left Scosche)... it was a lot of fun but things in Southern Cal were getting ugly at that point so I went to Crutchfield.... good thing - one of the intersections that they showed on TV during the LA riots of people getting pulled out of their cars and beat up was the exit to my house
Now, back to the Ty.... I've been looking at logs all day and found another one of Don's logs where it shows a similar O2 reading/pattern as what you've got.... only dif is that his AFR's remain steady.
If we use his truck as an example that this type of pattern is normal, we may be able to rule out an O2 issue.. so, now what???
We know that the O2 is swinging in a nominal fashion (at least compared to one of Don's runs) while under closed-loop operation. The difference is that your AFR's are going lean while his remain constant...
....possible causes...
- clogged fuel filter? your problem does change with FP changes.
- spark/ignition issue? I'd think you'd show rich rather than lean on the AFRs.
- ECM issue? maybe a bad component in the driver section.
- ???
Anyone else have any ideas??
Yup, I was North American Product Development Manager from 1988 through 1990.... that was after Reese Haggott had left Alpine and gone to Eclipse (I had just left Scosche)... it was a lot of fun but things in Southern Cal were getting ugly at that point so I went to Crutchfield.... good thing - one of the intersections that they showed on TV during the LA riots of people getting pulled out of their cars and beat up was the exit to my house
Now, back to the Ty.... I've been looking at logs all day and found another one of Don's logs where it shows a similar O2 reading/pattern as what you've got.... only dif is that his AFR's remain steady.
If we use his truck as an example that this type of pattern is normal, we may be able to rule out an O2 issue.. so, now what???
We know that the O2 is swinging in a nominal fashion (at least compared to one of Don's runs) while under closed-loop operation. The difference is that your AFR's are going lean while his remain constant...
....possible causes...
- clogged fuel filter? your problem does change with FP changes.
- spark/ignition issue? I'd think you'd show rich rather than lean on the AFRs.
- ECM issue? maybe a bad component in the driver section.
- ???
Anyone else have any ideas??
turbodig
Active member
Re: One last shot... Breaking up!
Disconnect the battery when probing the same grounds... see if it changes.
This all really seems like a voltage/ground issue.
Disconnect the battery when probing the same grounds... see if it changes.
This all really seems like a voltage/ground issue.
WyoSyclone
Active member
Re: One last shot... Breaking up!
Could a bad diode tree let a bunch of ripple through and cause these problems Dig? I was going to say it seems very RPM specific, but with the ranges changing with the injector change it makes me wonder...
The cab ground sounds suspect, but from Matt's DVM tests at least the ECM has a good ground.... but, if the PLX is grounded to the cab and it truly has a 32ohm reading to the battery I guess the wideband could be providing bad info? Or, would that just be a display issue??
Could a bad diode tree let a bunch of ripple through and cause these problems Dig? I was going to say it seems very RPM specific, but with the ranges changing with the injector change it makes me wonder...
The cab ground sounds suspect, but from Matt's DVM tests at least the ECM has a good ground.... but, if the PLX is grounded to the cab and it truly has a 32ohm reading to the battery I guess the wideband could be providing bad info? Or, would that just be a display issue??
BoostedSUV
Active member
Re: One last shot... Breaking up!
I'm going to address my cab's ground issue tonight as soon as I'm done putting a starter in my mom's Bonneville :rant: it's always something! Whether or not that's my problem is unknown but I'm going to address it. Rob if I didn't have this issue prior to the WB install I would point towards that as well. The WBO2 just provides a display and datalogging, it does not have any control over the ECM. The truck still uses the factory O2, WB is for monitoring purposes only. I could use its narrow band signal in place of my O2 but it's not wired that way.
Dig I will disconnect the battery and re probe my grounds. If I get difference in my reading what would that suggest? I will report back in a few hours.
I'm going to address my cab's ground issue tonight as soon as I'm done putting a starter in my mom's Bonneville :rant: it's always something! Whether or not that's my problem is unknown but I'm going to address it. Rob if I didn't have this issue prior to the WB install I would point towards that as well. The WBO2 just provides a display and datalogging, it does not have any control over the ECM. The truck still uses the factory O2, WB is for monitoring purposes only. I could use its narrow band signal in place of my O2 but it's not wired that way.
Dig I will disconnect the battery and re probe my grounds. If I get difference in my reading what would that suggest? I will report back in a few hours.
BoostedSUV
Active member
Re: One last shot... Breaking up!
Well I ran a 40" 4ga cable from the same bolt my battery grounds to on the block, into the cab and bolted it to the brake booster bolt/ brake pedal bracket. Turned my ground readings from 13.2 to 4.6 ohms inside the cab, and they dropped to around 2ohms with the truck running. I also cleaned up firewall grounds and thats the best I can get it to be.
I tried the truck again and it made no difference. I also tried testing volts to the firewall junction block and I'm getting a steady 12.4 to it with the truck off. When I start the truck that same point at the junction block jumps around from 16 - 19 volts even though my readings off the ALT and BATT are a steady 13.8. The only other place I get those high voltage readings is right off the Coil side that isn't plugged in (MSD adapter). The strange part is my ECM feeds off of that junction block and it reads a steady 13.8.
I'm so ready to just give up... there's nothing left!
Well I ran a 40" 4ga cable from the same bolt my battery grounds to on the block, into the cab and bolted it to the brake booster bolt/ brake pedal bracket. Turned my ground readings from 13.2 to 4.6 ohms inside the cab, and they dropped to around 2ohms with the truck running. I also cleaned up firewall grounds and thats the best I can get it to be.
I tried the truck again and it made no difference. I also tried testing volts to the firewall junction block and I'm getting a steady 12.4 to it with the truck off. When I start the truck that same point at the junction block jumps around from 16 - 19 volts even though my readings off the ALT and BATT are a steady 13.8. The only other place I get those high voltage readings is right off the Coil side that isn't plugged in (MSD adapter). The strange part is my ECM feeds off of that junction block and it reads a steady 13.8.
I'm so ready to just give up... there's nothing left!
BoostedSUV
Active member
Re: One last shot... Breaking up!
400 replies, almost 7500 views and still no solution.... this sucks!
400 replies, almost 7500 views and still no solution.... this sucks!