how important is it to set the iac and throttle sensor? my problem is when its cold out it realy jerky and not fun to drive. once its warm up, its fine. also i do run it on 1/4 of tank always, because of the price of the gas, mayb my problem?

 

Its VERY important to make sure the IAC and TPS are set correct for proper engine operation. See the tech article on this website for how to set them.

 

With EFI cars and electric fuel pumps, the gas helps cool the fuel pump. Running with low levels of fuel can cause the fuel pump to prematurely burn out. And a "dying" fuel pump can result in poor running conditions. Also, a full tank helps reduce condensation developing in the gas tank.

As for adjusting the IAC & TPS (TPS depends on the particular year...some TPS are not adjustable and don't need to be adjusted) - I agree with Kevin. Especially with the IAC which can really affect the idle.

But, as for your driveability issues, I would do a FULL tuneup first (all filters including the fuel filter & air filter, spark plugs, rotor, cap, PCV valve, plug wires and coil (if it hasn't been changed before). I would even clean the Throttle Body by spraying carb cleaner into a running engine. AND make sure you adjust the base timing to the stock setup.

Also, disconnect the battery to clear off any codes that may have been triggered in the past. Some of those codes can affect the operation of the ECM.

Lastly, I would fill the tank full with a grade of gas one step higher than you typcially use and put in a bottle of Injector Cleaner: and do it twice. You may just find that this fixes your problem. If not, then you will need to start looking at other things.

And don't run the tank so low on fuel Other than the "initial cost" of filling the tank - maintaining the tank at a full level will cost the same as maintaining the tank at a 1/4 level.

 

Ditto on VERY important for setting the minimum idle speed(IAC) and TPS. If things are way off,, it might take you a couple times setting them in conjunction with timing adjustments.

As far as always running on a 1/4 tank due to money,,, reaper is right on. There's a false sense of saving money by getting no more than you have to for the week,,, but you're spending the same money.

 

I experimented with the tps and iac adjustments on my 86. Either one had to be way off before it had any effect on the idle. According to my 86 fsm, the computer adjusts for tps just like the later non adjustable units. And my iac I tried from 20 counts to 120 counts at idle and it was smooth and never stalled anywhere in that range.

 

thanks. i will take your advice and do taht. one more thing i didnt mention is that i change over from a auto to a manual. never change the auto prom, how impantant should that be on the things to do list?

 

just wait to your gas lines freeze, never go below 1/4 tank in winter. Just treat the 1/4 mark like its the new E, your not spending anymore that way.

Reaper you forgot to mention cleaning the IAC out with carb cleaner too.

 

Not likely to happen now that gas has 10% ethanol. Still a good idea though to keep the pump cooler.

 

its not the gas that freezes its the water in the tank.. ive seen it happen

 

I realize that. But the 10% ethanol absorbs the water. It's the same thing as adding a few bottles of dry-gas like we used to in the old days.

 

I guess thats true then, but i still wouldnt go below a 1/4 in the winter just in case. They should only use E10 in the winter, that **** sucks I wish we had regular gas again.