I have a weird surge when my A/C is turned on, it's just up and down when i'm idling. Is this a different issue? Normal?

(sorry if i'm going off topic here)

 

might be same issue but different solution. How high does your idle go up when the A/C is turned on? Could be the A/C idle up valve set too high.

 

Not sure, i have no tach...

I'll check out the idle valve though, thanks.

 

X2, the idel with the A/C on is too high. Turn down the A/C idle up speed. I can *exactly* duplicate that problem on my '85 if I set the A/C idle speed up to around 1100-1200 RPM and hit the brakes it'll cut out until the idle drops then will go back up. If I turn it down under 1000 or so, no surging. Full explanation below (2nd Q&A):
- http://www.4crawler.com/4x4/TLCA_Tru...ech.04.09.html

 

sweet thanks guys!

 

My idle on my 88 is adjustd all the way down it can't get any lower. No egr, or hidden vacuum leaks I should know about? I checked my booster and the booster line and it dosent change.

 

If you can't adjust your idle via the idle screw then you have a vacuum leak somewhere. Or your adjusting the wrong screw.

 

Could also be your timing is advanced too far, if I push mine (22RE) much beyond 5 BTDC, I can't get the idle low enough. Timing set with engine warmed up and timing test jumper installed.

 

Thanks for this. I was able to fix the surging while pressing the brake at idel.

 

My rpm fluctuation stopped after changing battery terminals beause battery terminals consist of battery temperature sensor and if battery temperature sensor is week it will raise battery temperature and battery temperature is raised due to faulty temperature sensor in the battery terminal then battery will not be able to provide equal power to sensors and therefore when brakes applied sensors do not send correct information to computer due to high temperature in battery and therefore rpm fluctutes in addition terminals may get corroded or loose even if they are full tight in that case also rpm can malfunction therefore rpm fluctuates. Bottom line my rpm fluctuatipn solved after changing both battery terminals. Thos information may help others unable to solve rpm fluctuation when brakes applied.

 

Good effort sir, English is not your native tongue I presume?

Assuming this is a 22re there isn't a sensor, but the battery voltage will drop due to high temperature in the wiring. A good thing to check is the voltage drop across the primary fuse, which carries the alternator current, and is between the battery and power distribution box. This is a "fusible link" wire.

 

I recently encountered this same problem on my pickup and it does have to do with the idle being too high, or rather, the throttle butterfly not seating all the way. At first I thought the throttle body was gunked up and so I removed the throttle body from my parts truck, cleaned it and lubed it, and installed it on my truck. I had to swap over the TPS sensor as they were differnt from 1990 to 1994. And the problem only got worse so I adjusted the idle down, but I noticed that I could physically turn the throttle counter clockwise just a hair, and the idle would settle down. The fault is in the throttle dampener, looks like a little diaphragm with a rod, holding it open slightly enough to raise the idle. I took mine off and it solved the issue

 

I feel it's alright to assume too, that after 20+ years of opening and closing that the throttle return spring may weaken, and not have enough pressure to overcome that little dampener

 

I have a 94 toyota pickup and was experiencing engine surging at all throttle positions. My brother adjusted the air screw on throttle body and it fixed that problem. A day later it started surging when i applied brakes.. I removed air screw, wrapped 4-5x with teflon tape and readjusted, no more engine surge. Of course this was after removing and cleaning throttle body and checking iacv, checking timing and searching for vacuum leaks. Currently screw is set @ 1 turn out. Such a simple fix for a very annoying problem.