GSL-SE Surging problem
05-09-05 | 01:50 AM
#1
Thread Starter
Cuisinart on Steroids
Joined: Aug 2004
Posts: 124
Likes: 0
From: Napa, CA.
GSL-SE Surging problem
Just yesterday I noticed that my se had started surging while maintaing a set speed, could it be my fuel filter? If anyone has had similar experience with their se or has found a cause and fix for this, any suggestions would be helpful. By the way the car was very low on gas when this started and even after filling up it has continued. It stumbles a bit at idle as well. hth.
05-09-05 | 02:39 PM
#3
84SE-EGI helpy-helperton
Joined: Oct 2002
Posts: 3,366
Likes: 380
From: Phoenix, AZ
'Surging' is a specific description of what happens when a 13b EFI engine (cold or warm, but usually when cold) idles at 1500rpm reving to 3000rpm and then back down to 1500rpm (and then back up to 3000rpm). Over and over with about a second interval at the higher rpm setting.
This phenomenon is due to the throttle body rods which control the butterfly valves 'sticking' in their holes and causing a feedback loop between the Idle Air Compensator valve and the Bypass Air Control valve. This feedback loop is what causes the surge in engine rpm at idle. Once you get on the throttle, it changes the TB plate position and you don't notice the surging because you've got considerably more airflow going under acceleration or off-idle driving.
The fix; remove the air pipe going from the AFM to the TB with the 2x12mm cap head nuts (chrome), and then remove the throttle linkages going from the gas pedal and Cruise Control to the TB. Remove the heater hoses from the back of the water pump and then going to the rear housing of the block. Remove the TB (4x12mm nuts), and use a light oil (teflon, PTFE, or equivalent) on the outsides and insides of the throttle shafts where they enter the TB. The reason why you've removed the TB from the DEI chamber is so that you can rotate the TB 90degrees Left and then Right - lubing the left side rods, and then letting the lube run down into the TB, then turning to the right 90degrees and doing the same for the other side.
The problem is that the TB rods are steel and the TB is aluminum. This difference in construction materials results in aluminum 'galling' where the steel rods pass through the TB. This galling results in 'stiction' (friction) of the rods when they're under the control of the cold start system for the Secondary Throttle Plates, and the ACV/Idle Compensator. Lubing the rods will remove the problem for awhile, but the problem will arise when the lube dries out (usually lasts about a year or so between lubing).
Consider it your indoctrination into the joys of owning an SE! HTH,
This phenomenon is due to the throttle body rods which control the butterfly valves 'sticking' in their holes and causing a feedback loop between the Idle Air Compensator valve and the Bypass Air Control valve. This feedback loop is what causes the surge in engine rpm at idle. Once you get on the throttle, it changes the TB plate position and you don't notice the surging because you've got considerably more airflow going under acceleration or off-idle driving.
The fix; remove the air pipe going from the AFM to the TB with the 2x12mm cap head nuts (chrome), and then remove the throttle linkages going from the gas pedal and Cruise Control to the TB. Remove the heater hoses from the back of the water pump and then going to the rear housing of the block. Remove the TB (4x12mm nuts), and use a light oil (teflon, PTFE, or equivalent) on the outsides and insides of the throttle shafts where they enter the TB. The reason why you've removed the TB from the DEI chamber is so that you can rotate the TB 90degrees Left and then Right - lubing the left side rods, and then letting the lube run down into the TB, then turning to the right 90degrees and doing the same for the other side.
The problem is that the TB rods are steel and the TB is aluminum. This difference in construction materials results in aluminum 'galling' where the steel rods pass through the TB. This galling results in 'stiction' (friction) of the rods when they're under the control of the cold start system for the Secondary Throttle Plates, and the ACV/Idle Compensator. Lubing the rods will remove the problem for awhile, but the problem will arise when the lube dries out (usually lasts about a year or so between lubing).
Consider it your indoctrination into the joys of owning an SE! HTH,
05-11-05 | 03:16 AM
#4
Thread Starter
Cuisinart on Steroids
Joined: Aug 2004
Posts: 124
Likes: 0
From: Napa, CA.
Hey LongDuck, I think I may have not been clear. The car Idles perfectly, but when I am maintaining a set speed, the car shudders rapidly and it doesn't matter if it is with cruise-control or not. Any other ideas would be a great help. I'm trying to diagnose this before I just start throwing parts at it that I don't need.
Thanks
Thanks
