I’ve got a 1985 GSL-SE that up until yesterday was running fine. Today I get it on the road and the idle is hovering around 100 rpm. When I step into the gas it’s rough and after 4000 rpm it cuts in and out in such a way that the car is almost lurching forward (in other words, it’s really choppy). Initially I thought that this was a fuel delivery problem but fuel pressure is a 40 psi. I’ve buggered around with this thing for a couple of hours now and nothing seems to work. Does anyone here have any ideas/suggestions?

 

check your tps

 

By tps are you referring to the throttle position switch?

 

yes

 

I did the following checks:

Adjusted the throttle position check as per Haynes manual two light method and checked resistance. 1K OH at idle, 5 K OH at full throttle. When the engine is warm it revs up quickly and smoothly without a miss, until about 4000 rpm where it's not able to hold it. Any sustained rpm and the engine seems to be hunting.

The green vacuum control solenoid valve was pulsing on and off. Disconnecting it when the engine is warm causes the engine to bog down. The same is true when I disconnect the orange pressure control solenoid valve.

When the engine is cold and idling, disconnecting the orange pressure solenoid valve causes all symptons to dissappear.

The Haynes manual explains how to do various tests and checks but it doesn't explain what exactly these solenoids do and what purpose they serve which makes determining the problem rather problematic. If anyone is able to give any more detailed insight, it would be greatly appreciated.

 

Three thoughts.

Just inside your intake and return fuel lines on your carb should be a brass screen that collects crap from your fuel line. Is it clean? A fuel pressure check upstream of the carb will not catch this.

Are your vacuum lines in good condition? If not, it wouldn't hurt to swap all of them out.

Not meaning to be insulting, but I have done the next one myself, so please forgive this obvious question... are your coil wires seated properly? More than once I have been working on my '82 and rather stupidly knocked a coil wire loose.

 

SE's are fuel injected... Try this link. Has some helpful ideas...http://www.nellump.net/peri/epi/firs...gslseIdle.html

 

Uh - he has a GSL-SE, which means fuel injected, not carb'd.

 

here's the explanation as to what all those do. if you got a timing light i would see whats happening when the green solenoid is clicking on and off, as it should only be energized at idle or during decel (when you throttle plates close.) Maybe your TPS still isn't set right, or the FSM explains how to test all the solenoids to see if they're functioning properly.

 

Thanks for the help guys, I'll keep you updated if anything develops (this might take some time).

 

Thanks for the posts and suggestions.

My Son and I have been working on this problem on and off for 2 years. The car has been off the road now for 3 days, This problem comes with the engine surging, I tweek something and it disapears. Then reappears latter. Seeing that the car is stored for the winter it only sees about 4,000 miles a year of use.

I printed out that link, all 18 pages of it. I am getting somewhere but I will tell you what I have done and what I now have.

Fuel pressure 40 PSI, New spark plugs and last year I changed the Dizzy and igniters. New wires, BAC is clean and working. Set the TPS as indicated with lights on green connector. Adjusted kick off from Therowax. Now the idle is rough but introducing more air before the throttle plates makes it run fast but so very smooth. To do this I plugged the hose to the BAC and left the fitting open at the rubber funnel or duct. This causes the Mass Air flow sensor sail or flap to change posistion ( more to the front of the car) and the idle is good, but fast, however running the engine up to 4000 RPM is rough, (possilby lean). Currently I must leave that hose off to start the engine hot or it will flood. I have removed the plugs twice, flamed and added oil to the rotor housing to get it started again.

I have a spare throttle body plate and will look at changing it maybe it is the culprit. The engine has about 120,000 miles on it.

Any more ideas or direction is a help and certainly needed.

Thanks again for your thoughts and comments.

TonyK

Ark1.

 

hmm in those pages you printed off there's a portion that explains how the throttle plates get a little wear in them and ever so slightly change position affecting the tps.

do you have a high idle? how does it run without the air filter in? does the AFM flapper move without obstruction and thunk shut? check the intake tube from the Air box to the throttle body for leaks, it swivels so potential spot for leak.

hard to put your finger on any one thing since you got more than one thing goin on. but read those gsl-se idle problems over good and see if any of the symptoms correlate to any problems your having.

one more thing, how did you check your fuel pressure? at a deadhead it should read 50~70psin from the supply line. if you put a tee in the supply line it should read ~29 @idle ~37 when you remove the vacuum line from the FPR.

 

Gavinjuice, thanks for the response.

Fuel pressure is with a tee as it would be accurate to what the fuel rail is seeing.

I have reset the throttle stop turned back the timing just a bit. Idle at 800 RPM smooth but must have the line to the BAC removed and plugged with more air going to the duct. By doing this the flapper on the Mass air flow sensor closes a bit. I know I am getting closer, but trying to find the problem or problems is time consuming. It is a learning curve that I am on currently. The surging appears at higher sustained RPM not when the engine is accelerating. I suspect that the timing is shifting, but do not know the cause. Air filter removed.

I have a spare GSL SE for parts, I mean the whole car and have been swapping parts. Currently looking into the Throttle plates, have a milling machine and metal lathe too, can rebush if I have to.

Closer, but not there yet.

Thanks for the comments.

TonyK.