Idle drops when gas pedal is pressed

[Big Red]

Idle drops from 750 rpm to 400rpm just as I press the gas pedal, only for a fraction of a second and them the rpms climb normally.

This happens in neutural and when in 1st pulling away from a stop.

Once the car is moving it seems OK but if I am going along at about 25 mph in 3rd gear and coast, as soon as I hit the gas pedal again the engine seems to stumble before it starts producing power.

I had error code 13 (engine temp sensor), I cleaned the connectors and reset the ECM, no more codes but it's still doing the same thing.

Anyone know what this could be.

btw: it's only been doing this since I had the head off and had a valve grind done so I'm guessing that I missed something putting the engine back together.

Please help, I did the same thing with my wife's car and it's kind of doing the same thing so now I have an '89 & a '90 with the same problem:(

[spec-u-later]

Hmm, maby a vacuume leak?

[Big Red]

Is this typical of a vacuum leak?

[Big Red]

Where would I start to look for a leak???

[MikeMurphy]

I was thinking some sorta vaccuum leak along the intake pipe before the throttle body. The black plastic ****ty part after your MAFS.

Also, you can replace your coolant temp. sensor for very cheap and will likely gain some milage and considerable power.

[sleighty]

man!!! i am having the same problem and i was told that i shoukd do a tune up; plugs, wires, rotor & cap, fuel and air filters... was never told about checking for a air/vac leak. have not been able to do the tune up yet but i will soon, and now i will also check the vac lines too... let ya know what i come up with....

I thought that when youo had a vac leak your car will off idle/fluctuate in nutral and at a stop.

[Jookmasta]

knock sensor boys

[Big Red]

knock sensor boys

Interesting... but I can't find anything about the knock sensor in the service manual.

Where is it?

[Jookmasta]

i honestly dont know where it is located. my mechanic did it for me. but i can tell you that i had the exact same problem for about two years. the only way he could detect is by hookin it up onto the comp diagnostic machine. costs me about 180 tho.

[mutiny]

Sorry to revive old threads, but my friend is having pretty much the exact problem as this guy's. Is there any definitive solution to this problem? Also, does the ka24e sohc motor even have a knock sensor?

This problem highly likely just a vacuum related problem? Or spark/fuel related possibly?