Hi All

 

i have a 97 Outback EJ25 DOHC engine. the car accelerates properly, idles well, but when trying to maintain speed it is like the engine cuts in and out. well the engine does not completely cut out, it is like the fuel suddenly decreases.

 

it does not do this while going upo a hill i.e. the engine is working to maintain a constant speed. it does this when going on a flat surface or going down hill.

 

Can anyone help? does this sound like a MAF sensor? or and Oxygen sensor?

 

thanks in advaance for your replies.

 

Greg

Automagic or manual transmission?

When was the last time it had a good tune-up? NGK Plugs & wires, air & fuel filters, PCV valve, oxygen sensors?

Any recent work done?

No Check Engine Light?

I have just changed the engine (including all engine mounted sensors). the old engine was doing the same thing (but it also had a blown head gasket spraying oil evereywhere).

 

Really the only two things that i have not changed are the Oxygen sensor and the MAF sensor. I did however change over the intake manafold and use the old one, as the new one had a blockage in the fuel rail.

Sorry, and yes it is an automatic transmission.

Did you keep the old throttle body as well?

yes, i used the entire old intake manifold, but this had a new throttle position sensor in it.

Did you adjust the TPS so the voltage reading at the ECM is within spec of 0.45 - 0.55V when the throttle is closed?

yes, it was right in the middle at 0.5V

That's good.

 

What other sensors have you replaced? Were they new or used?

the engine came with all of the other sensors, it was a japanese import. there are three sensors that were not changed, they were the TPS, O2 and the MAF sensors.

 

I suspect it has to be one of these, as the problem is the same in this engine as it was in the previous engine.