Ok, I have a problem I have been unable to fix. I have a 1985 GSL-SE which idled fine and accelerated fine until I took off the UIM.

I had the injectors cleaned and sprayed the UIM with carb cleaner. Upon reassembly, car idles fine and drives fine. The problem happens when I accelerate above 2000 rpms, once that happens the idle surges between 1000 and 1500 rpms. Once this happens, while driving it feels like I'm releasing the accelerator every once in awhile, there's a slight drag every now and then even though I am keeping even pressure on the acclerator. As long as I keep the acceleration below 2000 rpms the idle remains smooth. I need to turn the car off and then on and then it idles smoothly again.

I have checked all the vacuum hoses, cleaned and lubricated the BAC valve and checked the throttle cable. I am at a loss as to what is causing this. I hate having to baby the throttle every time I drive. It is taking all the fun out of driving this car. Any of you Gurus have any ideas?

Thank you very much!!

 

Have you replaced the fuel filter?

 

Try to adjust your TPS. If it is not set correctly, it can cause surging like that.

 

Fuel filter was replaced.

I will try to adjust TPS. Does the TPS get out of adjustment by just removing the UIM? Do you think the TPS just needs adjustment or replacement?

Thank you!

 

Check this. Very valuable for any SE owner:

http://mrmazda.no-ip.com/gslseidle.html

I doubt it is bad. Probably just out of adjustment. Also check to make sure you plugged it back in. When you take off the UIM, you remove the throttle cable. When you put it back together, the tension on the throttle cable (and position of the butterflies) might not be exactly where it was before. If you do not adjust the TPS, the ECU starts to get mixed signals as to where the idle position of the throttle plates is. This causes the surging.

 

definatly tps out of adjustmant, or vacuem leak

 

+1 Im also dealing with this problem, though with a little messing around its not half as bad as it used to be.. But the link Gsl-seaddict sent you is a life saver!

 

Thank you very much for all the great input!! Many thanks to this fabulous forum full of Gurus!!

I didn't think that by just removing and replacing the UIM that the TPS could crap out. I checked the TPS and it idles at about 538 ohms and as the throttle is increased it gives a reading of OL at about 800-900 ohms. It maxes out at about 5200 ohms and when it comes back to idle the reading goes blank about the 800-900 ohm mark again. Maybe the TPS did crap out. I will check the reading on a spare TPS and let you know what I find. I hate to mess with trying to adjust the TPS since I don't have one of those light thingamajigs.

In the mean time, thanks again for all the great info!!

 

checking the ohms works just fine in tuning the TPS so all u need is a multi meter not one of those light thingamijigs.

 

Hmmm, I checked another TPS and it had the same type of reading as mine. It would read OL at about the same resistance. I guess I'll have to try messing with trying to adjust it. I'll let you folks know how it goes.

 

Ok, I adjusted the TPS. I had to do about 3 full turns of the screw. That brought the idle down which I had to adjust up. It is way better now. It idles smoother but upon reaching 2500 rpms or higher, there is still slight surging although it is faster and covers a smaller range. It appears to surge between 1200-1500 rpm instead of the 1000-1500 rpm range before.

I guess I'll try messing with things a little more and if anything thing developes I'll let you folks know. Thanks gsl-se addict, that article had a lot of useful information and thanks to RX7 allnight, the multimeter way was easier than expected. Also, thanks to all the other gurus! Great information!!