Hello all, I have a 95 eg sedan, stock d15b7 with an automatic transmission. I've been having a problem for the longest time which I simply cannot solve.

The symptoms are: slow acceleration from idle-3500 rpm, especially worse before 2000 rpm.
Example: If I floor it from a stop, the idle will drop, almost die, and then slowly start to accelerate, then at about 3500 rpm its like a surge of power comes in and it runs fine above that 3500 rpm point.

Things I've tried:
Tested voltage on tps sensor (.49v closed throttle, 4.5v WOT)
oxygen sensor
seafoam
removing the catalytic converter (possibly plugged cat, it wasn't it)
clean throttle body

I'm stumped. If anybody has any ideas please do tell.

Thanks,
Dana

 

Well it is an auto....don't expect much. but as for bogging off the line any codes mech/ign timing "on" ?

 

When was the last full ignition system tune up?

Have you replaced the fuel filter?

Any CEL codes?

 

yes, fuel filter was changed less than a year ago. Ignition timing was set about 2 months ago, wasn't far off at all and didn't seem to change the performance either.

I forgot to mention it only does this when it has reach operating temp. Once the engine is warm is the only time it does this. When the engine is still cold and the idle is still at 1800 or so, it does not do it.
CEL isn't on either.

I know its an auto but it still shouldn't bog down and almost die from WOT starts. The only way I can accelerate is if I give it just a little gas, until the rpms are above 1400, then I can mash it down with out it stalling, but it still is extremely slow.
I've pretty much run out of all ideas.

 

Does the CEL work?

Did you replace the O2 sensor with a new one?

 

Yeah, CEL works because it comes on briefly when I turn the key to "on". I did a cap and rotor about 2 months ago, plugs all look good, tried to different sets. Wires were replaced 3 years ago or so and all have resistance within spec. 02 sensor was replaced with a brand new one from autozone, I believe its a bosch.

 

The plug wires are a little old. Are they OEM?

Does the problem go away if you unplug the O2 sensor?

You also may want to measure the fuel pressure and test the FPR.

 

Will the engine rev freely in park or neutral? If so it sounds like it could be a trans problem.

 

I don't believe they are OEM plug wires, they are blue and have some white text on them. I measured the resistance in them and they all came out good, so I don't think ones broken at all if thats what your thinking.

I'll try un-pluging the o2 sensor and getting back to you tomorrow with the results.

I don't think I have a gauge to test fuel pressure but I'll check tomorrow as well.

When idling in park or neutral, and I rev the engine very lightly, it is responsive, however when idling and I mash the gas, it bogs down for 2 seconds or so and then revs. The problem seems to go away if I hold it at about 1,000 rpm and then mash the gas, it is more responsive.

I hope I'm explaining this ok, it's kind of hard to explain.

 

I tried unplugging the o2 sensor today, didn't make any difference. I don't have a gauge for fuel pressure but I'll ask around and see if one of my buddys can borrow me one. I'm selling the car soon, so I'd love to get this fixed before its sold.

If anyone has any more ideas, please share. I'll try to post a video of the symptoms to make it more clear.