Hey all. This problem may be difficult to explain but I will try my best.

Engine: D16Z6 in a 91 Si

OK. The engine idles fine (seems to dip down to 500rmp every once in a while but it has always done that) and it runs great above 3000rpm or the whole bandwidth when the car is cold (ie. morning driving).

Problem: when I am stopped and I try to accelerate the engine stops, it does NOT stall but just does not accelerate. I can hold the gas pedal down and the RPMs will try to go up but the needle just sort of bobs around 2krpm and grunts at me. If I launch carefully from about 3000rpm and am very careful when I release the clutch then I can launch.When shifting gears, if I go into 2nd in the low rpm range and try to press the gas, then again the engine just doesnt do anything.

It seems that I need to let off the gas and let it get back to idle speed and then SLOWLY press the gas(like barely pressing it until its gets up to 2500-3000) to get it to accelerate. Again, the car does not stall, i just need to let off the gas and go really slow.

I have 'floored' the peddle when this happens and the rev's just hang around 1500-2000 and the engine sputters for about 3-5 secs and then finally it catches and it shoots up to 6krpm.

The spark plugs indicate the engine is running lean (but it always has a little). I have replaced the plugs, wires and had the dizzy looked at and it is all good. I replaced my fuel filter and cleaned the injectors. I seem to burn through plugs in about 2 months. Im also not throwing any engine codes

It seems to me that there is no low end power because when Im cruising, and driving when the engine is colder, it runs fantastic. IT is just when I need torque that it does this. Being stopped on a slight hill (uphill) really makes this problem more prominant (again, I guess because no torque is required)

I had my Catalytic converter and full exhaust changed a few(maybe 8) months ago. I had a "hi-flow- cat installed. Now, I dont know too much about this stuff but my guess is that when the cat is warm maybe the exhaust gas is not getting through at low rpms so Im getting exhaust gas back into the engine and this may be causing this to happen?? Does this make sense? This makes the most sense to me but I could be way off. Or could it just be a fuel problem? I initially thought this but like I said the car runs great when cruising, idling and when cold.

Im apologize for the long description but it is a difficult thing to try and explain without seeing what Im talking about.

I would appreciate any help anyone could provide. I was thinking of hitting my muffler shop tomorrow but I wanted to advise first.

Thanks in advance

 

Not sure but check your TPS... or Dizzy