Need help with problem
06-16-2009, 12:16 PM
#1
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Thread Starter
Join Date: Jun 2009
Posts: 2
Need help with problem
Hey guys, I am new to the boards. I own a 94 LT1 car (it's in a B body sedan...I know I don't belong here but I figured it's all the same, right?)
I've been having a problem with it since I bought it, i'm just going to copy and paste what I wrote on the impala forums. Hopefully somebody can point me in the right direction. Thanks!
---
Well i've had a bad misfire and a bucking under load on my 94. I ended up fixing the bad misfire at idle with two new (used) injectors, but I still have the bad bucking problem. Here's what happens:
Car bucks/jerks very badly. It is normally felt when sitting at a stoplight. All of sudden (but not always) the idle will get very chug-like and you can feel it shaking the car. Let of the brake and the car will jerk along very violently. You can also feel it sometimes when under load while in OD at a very low rpm, but the chugging is less pronounced-it feels more like just a rough, shaky acceleration. There is also a lack of power at low rpm's under load that sometimes just goes away, meaning at a steady throttle position it will feel like a dog, then instantly the problem will go away and the motor will just kick in and pull smooth. All the problems are intermittent and in any given trip, sometimes the car will run OK. When it chugs, it doesn't sound like a misfire...the idle just gets really low. The second you give it more than 1/4 throttle it goes away. You never feel it when leaving a stop light, just when 'creeping' at idle or very low throttle. The idle in park is mostly smooth now after swapping injectors and cleaning the fouled plug but I do have a slight cough at idle every few seconds from bank 1. That's the bank where one injector still reads 12.9 OHMs vs the 13.1-3 of the rest (see below)
Here is what I have done:
-New opti cap and rotor (not the opti housing/sensor)
-new plugs and wires
-checked fuel pressure- 42 at rail w/ engine off, 38 at rail at idle, 42-45 when wot
-No fuel in vacuum hose for FPR
-ohm'd out the rest of the injectors, all but one are in the 13.1-13.3 range. One is 12.9. The two bad ones that I swapped out and fixed the misfire at idle with were putting out 12.2. (could that 12.9 one be bad? It was one of the replacement injectors and came off of a car that ran fine)
cleaned TB and MAF
EGR, AIR and cats were deleted and tuned out.
new header gaskets/collector gaskets, no leaks. No surging idle, checked for vacuum leaks but didn't see any obvious ones. Going to hook up a vacuum gauge at work.
Im going to hook it up on the scan tool at work and check all the sensors out but since it's an intermittent thing I dont know what i'll find. What do you guys recommend checking next?
Im going to go and check all of the plugs again, see if any one is rich/lean but when checking for the injector problem I found all to be good aside from the two ones that had bad injectors.
I've been having a problem with it since I bought it, i'm just going to copy and paste what I wrote on the impala forums. Hopefully somebody can point me in the right direction. Thanks!
---
Well i've had a bad misfire and a bucking under load on my 94. I ended up fixing the bad misfire at idle with two new (used) injectors, but I still have the bad bucking problem. Here's what happens:
Car bucks/jerks very badly. It is normally felt when sitting at a stoplight. All of sudden (but not always) the idle will get very chug-like and you can feel it shaking the car. Let of the brake and the car will jerk along very violently. You can also feel it sometimes when under load while in OD at a very low rpm, but the chugging is less pronounced-it feels more like just a rough, shaky acceleration. There is also a lack of power at low rpm's under load that sometimes just goes away, meaning at a steady throttle position it will feel like a dog, then instantly the problem will go away and the motor will just kick in and pull smooth. All the problems are intermittent and in any given trip, sometimes the car will run OK. When it chugs, it doesn't sound like a misfire...the idle just gets really low. The second you give it more than 1/4 throttle it goes away. You never feel it when leaving a stop light, just when 'creeping' at idle or very low throttle. The idle in park is mostly smooth now after swapping injectors and cleaning the fouled plug but I do have a slight cough at idle every few seconds from bank 1. That's the bank where one injector still reads 12.9 OHMs vs the 13.1-3 of the rest (see below)
Here is what I have done:
-New opti cap and rotor (not the opti housing/sensor)
-new plugs and wires
-checked fuel pressure- 42 at rail w/ engine off, 38 at rail at idle, 42-45 when wot
-No fuel in vacuum hose for FPR
-ohm'd out the rest of the injectors, all but one are in the 13.1-13.3 range. One is 12.9. The two bad ones that I swapped out and fixed the misfire at idle with were putting out 12.2. (could that 12.9 one be bad? It was one of the replacement injectors and came off of a car that ran fine)
cleaned TB and MAF
EGR, AIR and cats were deleted and tuned out.
new header gaskets/collector gaskets, no leaks. No surging idle, checked for vacuum leaks but didn't see any obvious ones. Going to hook up a vacuum gauge at work.
Im going to hook it up on the scan tool at work and check all the sensors out but since it's an intermittent thing I dont know what i'll find. What do you guys recommend checking next?
Im going to go and check all of the plugs again, see if any one is rich/lean but when checking for the injector problem I found all to be good aside from the two ones that had bad injectors.
Last edited by KriSS396; 06-16-2009 at 12:19 PM.
06-16-2009, 06:12 PM
#2
Registered User
Join Date: Jul 2002
Location: Kissimmee, Fl, USA
Posts: 1,942
Hey guys, I am new to the boards. I own a 94 LT1 car (it's in a B body sedan...I know I don't belong here but I figured it's all the same, right?)
I've been having a problem with it since I bought it, i'm just going to copy and paste what I wrote on the impala forums. Hopefully somebody can point me in the right direction. Thanks!
---
Well i've had a bad misfire and a bucking under load on my 94. I ended up fixing the bad misfire at idle with two new (used) injectors, but I still have the bad bucking problem. Here's what happens:
Car bucks/jerks very badly. It is normally felt when sitting at a stoplight. All of sudden (but not always) the idle will get very chug-like and you can feel it shaking the car. Let of the brake and the car will jerk along very violently. You can also feel it sometimes when under load while in OD at a very low rpm, but the chugging is less pronounced-it feels more like just a rough, shaky acceleration. There is also a lack of power at low rpm's under load that sometimes just goes away, meaning at a steady throttle position it will feel like a dog, then instantly the problem will go away and the motor will just kick in and pull smooth. All the problems are intermittent and in any given trip, sometimes the car will run OK. When it chugs, it doesn't sound like a misfire...the idle just gets really low. The second you give it more than 1/4 throttle it goes away. You never feel it when leaving a stop light, just when 'creeping' at idle or very low throttle. The idle in park is mostly smooth now after swapping injectors and cleaning the fouled plug but I do have a slight cough at idle every few seconds from bank 1. That's the bank where one injector still reads 12.9 OHMs vs the 13.1-3 of the rest (see below)
Here is what I have done:
-New opti cap and rotor (not the opti housing/sensor)
-new plugs and wires
-checked fuel pressure- 42 at rail w/ engine off, 38 at rail at idle, 42-45 when wot
-No fuel in vacuum hose for FPR
-ohm'd out the rest of the injectors, all but one are in the 13.1-13.3 range. One is 12.9. The two bad ones that I swapped out and fixed the misfire at idle with were putting out 12.2. (could that 12.9 one be bad? It was one of the replacement injectors and came off of a car that ran fine)
cleaned TB and MAF
EGR, AIR and cats were deleted and tuned out.
new header gaskets/collector gaskets, no leaks. No surging idle, checked for vacuum leaks but didn't see any obvious ones. Going to hook up a vacuum gauge at work.
Im going to hook it up on the scan tool at work and check all the sensors out but since it's an intermittent thing I dont know what i'll find. What do you guys recommend checking next?
Im going to go and check all of the plugs again, see if any one is rich/lean but when checking for the injector problem I found all to be good aside from the two ones that had bad injectors.
I've been having a problem with it since I bought it, i'm just going to copy and paste what I wrote on the impala forums. Hopefully somebody can point me in the right direction. Thanks!
---
Well i've had a bad misfire and a bucking under load on my 94. I ended up fixing the bad misfire at idle with two new (used) injectors, but I still have the bad bucking problem. Here's what happens:
Car bucks/jerks very badly. It is normally felt when sitting at a stoplight. All of sudden (but not always) the idle will get very chug-like and you can feel it shaking the car. Let of the brake and the car will jerk along very violently. You can also feel it sometimes when under load while in OD at a very low rpm, but the chugging is less pronounced-it feels more like just a rough, shaky acceleration. There is also a lack of power at low rpm's under load that sometimes just goes away, meaning at a steady throttle position it will feel like a dog, then instantly the problem will go away and the motor will just kick in and pull smooth. All the problems are intermittent and in any given trip, sometimes the car will run OK. When it chugs, it doesn't sound like a misfire...the idle just gets really low. The second you give it more than 1/4 throttle it goes away. You never feel it when leaving a stop light, just when 'creeping' at idle or very low throttle. The idle in park is mostly smooth now after swapping injectors and cleaning the fouled plug but I do have a slight cough at idle every few seconds from bank 1. That's the bank where one injector still reads 12.9 OHMs vs the 13.1-3 of the rest (see below)
Here is what I have done:
-New opti cap and rotor (not the opti housing/sensor)
-new plugs and wires
-checked fuel pressure- 42 at rail w/ engine off, 38 at rail at idle, 42-45 when wot
-No fuel in vacuum hose for FPR
-ohm'd out the rest of the injectors, all but one are in the 13.1-13.3 range. One is 12.9. The two bad ones that I swapped out and fixed the misfire at idle with were putting out 12.2. (could that 12.9 one be bad? It was one of the replacement injectors and came off of a car that ran fine)
cleaned TB and MAF
EGR, AIR and cats were deleted and tuned out.
new header gaskets/collector gaskets, no leaks. No surging idle, checked for vacuum leaks but didn't see any obvious ones. Going to hook up a vacuum gauge at work.
Im going to hook it up on the scan tool at work and check all the sensors out but since it's an intermittent thing I dont know what i'll find. What do you guys recommend checking next?
Im going to go and check all of the plugs again, see if any one is rich/lean but when checking for the injector problem I found all to be good aside from the two ones that had bad injectors.
06-16-2009, 11:55 PM
#3
Registered User
Thread Starter
Join Date: Jun 2009
Posts: 2
That is one of the things that i wanted to try but never actually remembered to do it when it was happening. I never experienced the problem in park while idling before but I have yet to throw it into N when it is happening. I will try that, i'll let you know tomorrow how it turns out. Thanks!
Edit: thinking about it, this makes sense as I often notice the problem first while braking... I haven't paid attention too much, but since the bucking always seems to be first noticeable towards the end of a stop, there is a good chance it is because I was in OD with the TC locked and it's not unlocking. Wouldn't the car stall though? It does seem like it could be something along those lines, the idle gets real low while stopped and waiting at a light when the chugging happens as if it is under a lot more load than it should be. It doesn't sound like a misfire or anything, just a steady, low, idle that chugs the car violently forwards.
Edit: thinking about it, this makes sense as I often notice the problem first while braking... I haven't paid attention too much, but since the bucking always seems to be first noticeable towards the end of a stop, there is a good chance it is because I was in OD with the TC locked and it's not unlocking. Wouldn't the car stall though? It does seem like it could be something along those lines, the idle gets real low while stopped and waiting at a light when the chugging happens as if it is under a lot more load than it should be. It doesn't sound like a misfire or anything, just a steady, low, idle that chugs the car violently forwards.
Last edited by KriSS396; 06-17-2009 at 12:03 AM.
06-18-2009, 11:25 AM
#4
Registered User
Join Date: Apr 2005
Location: NY
Posts: 35
Well, the only mechanic with a good scope was out yesterday so I never got a chance to hook it up. We have a Snap On mt2500 for shop use but I never got a chance to hook that up...
I drove it around in D, problem is still there. When the idle gets slow and chug like, it still feels rough in N but obviously doesn't chug as much as it's not under load...
The problem is very sporadic. When leaving work, I felt the chug almost right away after driving away when the motor was still cold. I was at the light and in started chugging, so I went to back it up back into the lot to see if i can mess with some wires and get it to stop but it was gone before i could park it. The fact that it did it when cold leads me to believe it's not an ICM issue but im still going to test it just to be sure.
I am hoping it isn't the opti because i just did the cap and rotor a month ago. I have had opti's go bad though and the problems usually aren't intermittent and normally are more of a breaking up/misfire vs. just a low chugging idle.
Raining out today so I can't check anything. Bwa....driving me crazy!
Edit: BTW I am KriSS396. I realized I had previously signed up for this forum...I didn't even remember, I made a new member name with my new e mail then I realized that I came here a while back and posted a few things.
I drove it around in D, problem is still there. When the idle gets slow and chug like, it still feels rough in N but obviously doesn't chug as much as it's not under load...
The problem is very sporadic. When leaving work, I felt the chug almost right away after driving away when the motor was still cold. I was at the light and in started chugging, so I went to back it up back into the lot to see if i can mess with some wires and get it to stop but it was gone before i could park it. The fact that it did it when cold leads me to believe it's not an ICM issue but im still going to test it just to be sure.
I am hoping it isn't the opti because i just did the cap and rotor a month ago. I have had opti's go bad though and the problems usually aren't intermittent and normally are more of a breaking up/misfire vs. just a low chugging idle.
Raining out today so I can't check anything. Bwa....driving me crazy!
Edit: BTW I am KriSS396. I realized I had previously signed up for this forum...I didn't even remember, I made a new member name with my new e mail then I realized that I came here a while back and posted a few things.
Last edited by SSandman; 06-18-2009 at 02:00 PM.
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