7mgte mkIII
 

I have a 89 7mgte engine. at 3000 rpm I aquire a miss in the engine. If I accelerate above thi rpm it goes away. Below or above that rpm all seems ok. Can anyone point me in the proper direction to figure this out?
Thanks, Lou

Have you managed to figure this issue out? If not start with checking for diagnostic error codes stored in the ECU (see the FAQ section for details on how to do so) and check for the presence of oil in the spark plug galley (there's a FAQ about this common issue too).

7mgte hesitation
 

Hi, thanks for your reply. I have owned a non turbo 89 for 10 yrs. I built this one from a shell. I know the car pretty well. I have replaced the cam seals. That stopped the oil in the galley.I do get an ox code telling me the sensor is bad. I have a toyota service manual. I followed procedure to check the electrical. everything seems to be in order. At 3000 to 3300 I experience a hesitation. Above that it kicks ass. Below that it kicks ass. I'm thinking a hesitation in the waste gate or blow by valve. Would you have any input on this issue?
Thanks, Lou

A boost leak, bad air flow meter, leaking bypass valve aka blow off valve are all possibilities. There's also the possibility that the fuel pump resistor relay is failing althought it usually either works or flat out dies.

The wastegate isn't the issue. A bad wastegate will have you seeing spikes and hitting fuel cut not the other way around. If it were to fail open you'd see low boost across the board on top of the lag.

Fouled plugs, improper spark plug gap, bad high tension wires, oil causing a misfire or improper mechanical or ignition timing could also cause this.

It's all really easy stuff to check and shouldn't take long to work through the list. With the BPV/BOV just pull it and plug the ports on each side with a rubber cork and hose clamp from the hardware store to see if the problem goes away.