Lower Intake Gasket / 02 Sensor
#1
Member
Posts like a V-Tak
Thread Starter
Join Date: Jan 2005
Location: Acton Ontario, Canada.
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
![300sflyer is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Recently changed the lower intake gasket on my 96 Series 2 3800. [non supercharged] While I was at it I installed a new upper intake. I was experiencing some unexplained coolant losses, which now seemed to be fixed.
However, after completing all of this work, I now have a slight hesitation, a slightly rough idle, and some shuddering in overdrive, none of which were present before the work was done. :? [At least not that I recall]
I took it to my local mechanic, he did code test on it, [the engine light was flashing if you pushed on the accelerator too much] and the 02 sensor showed it was very slow in responding. He thinks the previous coolant loss [lower intake gasket was pathetic] has ruined the sensor...?
He also found 2 less than perfect ignition wires. He suggested replacing all the wires and plugs, a new 02 sensor, and having the injectors flushed.
I replaced all the wires and plugs, and it seems slightly better, but still far from perfect. Three of the plugs were "white" instead of grey. Would cleaning the injectors and changing the 02 sensor help any further?
I’m wondering about a slight vacuum leak :? , but have not been able to find one in any of the lines, or by spraying break cleaner all around the lower intake and the injectors.
Any ideas guys?
Thanks!
![Smile](https://www.gmforum.com/gm/images/smilies/smile.gif)
However, after completing all of this work, I now have a slight hesitation, a slightly rough idle, and some shuddering in overdrive, none of which were present before the work was done. :? [At least not that I recall]
I took it to my local mechanic, he did code test on it, [the engine light was flashing if you pushed on the accelerator too much] and the 02 sensor showed it was very slow in responding. He thinks the previous coolant loss [lower intake gasket was pathetic] has ruined the sensor...?
He also found 2 less than perfect ignition wires. He suggested replacing all the wires and plugs, a new 02 sensor, and having the injectors flushed.
I replaced all the wires and plugs, and it seems slightly better, but still far from perfect. Three of the plugs were "white" instead of grey. Would cleaning the injectors and changing the 02 sensor help any further?
I’m wondering about a slight vacuum leak :? , but have not been able to find one in any of the lines, or by spraying break cleaner all around the lower intake and the injectors.
Any ideas guys?
Thanks!
#2
Senior Member
True Car Nut
Join Date: Sep 2004
Location: Farmington, Minnesota =MWBF '05 SURVIVOR= =CEBF '06 SURVIVOR= =August '06 COTM=
Posts: 9,130
Likes: 0
Received 0 Likes
on
0 Posts
![LakevilleSSEi is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Check for leaks where the upper manifold bolts to the lower. If they aren't all tight the way they should be and can cause a rough idle condition also. And changing the O2 sensor probably isn't a bad idea, as coolant isn't too good for them.
#3
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Make sure you reinstalled the o-rings around the PCV (they slip into the UIM, PCV housing). If the o-rings are missing and/or the PCV is bad (shake it to see if it rattles, if it does, then it'* good) then you will get a rough idle.
#4
Member
Posts like a V-Tak
Thread Starter
Join Date: Jan 2005
Location: Acton Ontario, Canada.
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
![300sflyer is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Thanks for the suggestions guys!
The upper intake bolts are tight. [I double checked them] The PCV valve is good, [it rattles] and the 0-ring is there.
Any other ideas?
Thanks
The upper intake bolts are tight. [I double checked them] The PCV valve is good, [it rattles] and the 0-ring is there.
Any other ideas?
Thanks
#5
Senior Member
True Car Nut
Join Date: Jan 2004
Location: Chicago,IL MWBF '04 SURVIVOR MWBF '05 SURVIVOR Napa Manager
Posts: 3,955
Likes: 0
Received 0 Likes
on
0 Posts
![Kennginn is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Originally Posted by 300sflyer
Thanks for the suggestions guys!
The upper intake bolts are tight. [I double checked them] The PCV valve is good, [it rattles] and the 0-ring is there.
Any other ideas?
Thanks
The upper intake bolts are tight. [I double checked them] The PCV valve is good, [it rattles] and the 0-ring is there.
Any other ideas?
Thanks
#6
Member
Posts like a V-Tak
Thread Starter
Join Date: Jan 2005
Location: Acton Ontario, Canada.
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
![300sflyer is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
I wondered about that too...
But then why didn’t I have these issues before the work was done on it? Does it make sense that the 02 sensor would suddenly cause these issues immediately after the gasket and the UI were changed? :?
Thanks
But then why didn’t I have these issues before the work was done on it? Does it make sense that the 02 sensor would suddenly cause these issues immediately after the gasket and the UI were changed? :?
Thanks
#7
Senior Member
True Car Nut
Join Date: Jun 2003
Location: Climax Springs, Missouri
Posts: 2,493
Likes: 0
Received 0 Likes
on
0 Posts
![LittleHoov is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
did you burn off a lot of coolant after you replaced it? i think that would possibly foul an o2 sensor...although i burned off a ton, and still had a little white smoke after itd been running for 5-10 minutes, and to my knowledge my O2 sensor is fine, at least its not throwing any codes, im getting about 20mpg at best, but i think thats due to my foot more than anything.
#9
Member
Posts like a V-Tak
Thread Starter
Join Date: Jan 2005
Location: Acton Ontario, Canada.
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
![300sflyer is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
My mechanic still says it could be an injector...... He suggested that when I had it apart a tiny spec of dirt may have entered somewhere in the system, and now its not functioning properly....
Can the injectors be cleaned one at a time off of the car somehow? Compressed air perhaps?
Thanks
Can the injectors be cleaned one at a time off of the car somehow? Compressed air perhaps?
Thanks
#10
Member
Posts like a V-Tak
Thread Starter
Join Date: Jan 2005
Location: Acton Ontario, Canada.
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
![300sflyer is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Ok...Finally found the problem
A bad ignition coil on #3 cylinder. Its running much better now with a new coil installed.!
Now with the LIM gasket leak all fixed, the coolant pressure is back up to where it should be, and now my water pump is leaking...
Hopefully once I replace that, everything should be good for a while.
![Very Happy](https://www.gmforum.com/gm/images/smilies/biggrin.gif)
![Cool](https://www.gmforum.com/gm/images/smilies/icon_cool.gif)
Now with the LIM gasket leak all fixed, the coolant pressure is back up to where it should be, and now my water pump is leaking...
![Roll Eyes](https://www.gmforum.com/gm/images/smilies/rolleyes.gif)
![Wink](https://www.gmforum.com/gm/images/smilies/wink.gif)