GSL-SE Rough Idling Problem
Thread Starter
Junior Member
Joined: Oct 2003
Posts: 31
Likes: 0
From: Brandon, Florida
gsl-se rough idling
I am currently having problems with my car's idling...checked ignition, everything seems to be working fine from coils to wires to plugs (which I replaced). I get the feeling the car is running way to rich and I want to know if anyone has some kind of specs to tuning the efi on the gsl-se. Car starts right up but has a very rough idle. Please advise...
http://www.nellump.net/peri/epi/firs...gslseIdle.html
Start here - this write up covers most of the bases on the SE idle issue
Start here - this write up covers most of the bases on the SE idle issue
Thread Starter
Junior Member
Joined: Oct 2003
Posts: 31
Likes: 0
From: Brandon, Florida
thanks northern...great help but...i may not have explained myself fully....even though it has a rough idle, it is also rough when accelerating and being driven....can that be solved with what you referenced or is there other possibilities???? i checked ignition and spark and it seems doing good and engine is starting up just fine so i am assuming engine compression is acceptable, and i dont think exhaust problems are the blame because even with the rough exhaust you can feel a strong exhaust so i dont think a clogged exhaust system may be to blame...any other areas i should address, thanks in advance for the help!
Last edited by inittab; Nov 30, 2003 at 11:33 AM.
84SE-EGI helpy-helperton
Joined: Oct 2002
Posts: 3,584
Likes: 542
From: Phoenix, AZ
Fuel injectors? Since your SE is now about 20 years old, if those are the standard SE injectors, you may have an injector that is not flowing well, or is seriously out of spec, which will result in rough idle, rough driving conditions, and surging under steady state driving conditions.
At the very least remove the injectors and have them sent off to RC Engineering for cleaning, flow balancing, and testing. They will put them on a bench test unit, pressurize to spec to check for leaks, then flow test them to assure an even spray pattern and volume over time. Ideally, you'll want your injectors spec'd out to within 10% flow to each other - this is flow balancing, and ensures that each rotor gets the same amount of fuel to burn for efficient combustion and smooth power delivery.
If one injector is way out of spec, this can account for many idling and driving inconsistencies that are quickly cured by installing new injectors. Factory injectors aren't cheap, however, but since the SE only has two (of 680cc flow at nominal 55psi), they are a good investment in performance and will increase both throttle response, mileage, and overall performance.
Fuel injectors and the systems that drive them may seem to be problematic to troubleshoot, but in truth, once you get them tuned and running correctly, they require much less routine intervention and maintenance to keep them running well - and they provide a performance edge as well.
In order for your car to run 'closed-circuit' fuel mapping, which is very simple in the 84/85 SE's, it will need to have a properly operating O2 sensor, which is mounted to the exhaust catalyst #3, downstream of the manifold. This sensor tells the ECU how much fuel should be added to make minor adjustments in the rich/lean during all driving conditions. At idle, there is a simple rich/lean adjustment at the passenger side strut tower, but this should only be adjusted as last resort.
You should be able to use the tips in the link provided above to get your car to idle smoothly, but this will take both time and patience as you work through each system. I've found that the car will idle most smoothly at about 1000 rpm once you get all the bugs worked out.
Also, check for fuel system leaks in your system which could indicate an injector which is either cracked or leaking, and replace seals (top and bottom) when you change injectors - cheap insurance to avoid an engine fire. Good luck,
At the very least remove the injectors and have them sent off to RC Engineering for cleaning, flow balancing, and testing. They will put them on a bench test unit, pressurize to spec to check for leaks, then flow test them to assure an even spray pattern and volume over time. Ideally, you'll want your injectors spec'd out to within 10% flow to each other - this is flow balancing, and ensures that each rotor gets the same amount of fuel to burn for efficient combustion and smooth power delivery.
If one injector is way out of spec, this can account for many idling and driving inconsistencies that are quickly cured by installing new injectors. Factory injectors aren't cheap, however, but since the SE only has two (of 680cc flow at nominal 55psi), they are a good investment in performance and will increase both throttle response, mileage, and overall performance.
Fuel injectors and the systems that drive them may seem to be problematic to troubleshoot, but in truth, once you get them tuned and running correctly, they require much less routine intervention and maintenance to keep them running well - and they provide a performance edge as well.
In order for your car to run 'closed-circuit' fuel mapping, which is very simple in the 84/85 SE's, it will need to have a properly operating O2 sensor, which is mounted to the exhaust catalyst #3, downstream of the manifold. This sensor tells the ECU how much fuel should be added to make minor adjustments in the rich/lean during all driving conditions. At idle, there is a simple rich/lean adjustment at the passenger side strut tower, but this should only be adjusted as last resort.
You should be able to use the tips in the link provided above to get your car to idle smoothly, but this will take both time and patience as you work through each system. I've found that the car will idle most smoothly at about 1000 rpm once you get all the bugs worked out.
Also, check for fuel system leaks in your system which could indicate an injector which is either cracked or leaking, and replace seals (top and bottom) when you change injectors - cheap insurance to avoid an engine fire. Good luck,
Full Member
Joined: Dec 2003
Posts: 76
Likes: 0
From: uk
Oh my god Northern 7 you are a god for posting that site. I think now i can finally find out why my car has been hesitating when it starts, the fusible links. Plus it give us EFIer's tons of remedy's to fix idling problems. This site is the bomb. 
No longer New
Joined: May 2010
Posts: 31
Likes: 3
From: Palm Springs, Ca.
idle drop with ac on
Help....85 Bone stock GSL-SE with 65,000 miles. Runs perfectly until I hit the ac. (I live in Phoenix). Then idle drops to 500 rpm. Checked BAC...works perfectly. Suspect its not getting signal from ac relay. Shop manual wiring diagrams printed in "Pharmese". Just started doing this recently. Haven't fiddled with anything yet, because I don't want to screw it up. No other driveability problems at all. Any ideas where to begin?
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