hey guys when my car is warmed up, and when i idle, the idle is around 700-800 rpm but then it drops sometimes by itself and feels like the engine is gonna turn off but it doesnt and then the revs go up to like 1100 rpm then goes back down to 700-800 rpm. have no idea why. ive used seafoam through the brake booster line and in the gas tank. but it didnt help.

 

Tune up done recently? Check all basics.
Plugs, cap, rotor, wires, vacuum hoses,
Several threads regarding fuel injectors below should help.

 

Sounds like an air leak after the MAF. In the intake manifold, the Throttle body or vacuum lines, or the bellows between the Air Cleaner and the Throttle Body.

 

bump11111111111

 

My car was doing the same thing. Above 1k rpm it would be fine but after stopping at a light and being at idle for 20 sec the rpm would drop and it would sound like its flooding and gonna die.

It turned out one of the small vacuum hoses on the back left of the intake popped off....I stuck it back together and the problem is gone.

If that's not it then maybe try a tank or two of premium gas. Sometimes you do get bad regular gas.

 

where would the leak come from? ive looked around the intake an stuff but everything seems to be normal

 

My car has the same symptoms as the first post described and my vaccum hoses are new and the rear left intake manifold vac. hose is on.

Where are other common places for vac leaks to occur ?

Please help Thanks!!!!!!!!!!!!!!!!!!

 

Unfortunately I'm finding that as I do my VTCs there are a million places you can get a vacuum leak on this car. The Bellows or clamps on it can be loose or cracked. There are a half a dozen or so hoses that come from the bellows and throttle body, to the IAAC, to the valve cover vents (to the front of the bellows, from the IAAC to the Throttle body, Fuel pressure regulator to the throttle body (TB), TB to EGR valve and EGR valve actuator soleniod, TB to the power valve actuator and Power Valve Vacuum motor, PCV valve, Heater Coolant flow valve, power brake booster, Fuel Vapor recovery canister, Fuel Injector seals to intake manifold, The various gaskets on the TB, plenum, intake manifold, EGR gasket. Someone can correct me if I haven't remembered them all. I don't know how many of these apply to the 1990 as I have a 92 SE or if there are others on your engine.

 

wow I will definitly never find this retarded leak !!!!!

I have a question

Will putting your car into gear at 1500 rpms hurt your transmission

I want to make it last !! ( I ask because I prob. will not find this leak soon and in the mean time my car starts and revs to 2000 rpms because of my vac leak ...... I wait till it reaches 1500 rpms then I turn the AC on and fans and bright lights to help slow the idle then I change gears into reverse!! A lot of work!!! )

Auto>


Thanks !!!!!!!!!!!!!!

 

sounds like a great way to destroy ur car....ur abusing several systems at one time here.
vacuum hose is exponentially cheaper than a new car. there's no reason for u to be doing all of that

 

Try Spraying down these hoses and areas with spray carb cleaner. If you spray an area and the idle settles down, then that's where the leak is. The carb cleaner seals the leak for a few seconds with something the engine can burn and the idle effect goes away for the time it takes for the carb cleaner to suck into the line. The cleaner is flammable so be careful.