pulsing acceleration

[Seanathen]

I have a 95 Explorer XLT 4wd. Just bought it and I love it! It's all stock. On acceleration, there is a noticeable pulsing of power. It's a relatively slow on and off of power. It doesn't matter if you floor it or accelerate slowly, it's there, but you can tell more on slow acceleration. Also, it doesn't really seem to change with engine speed. The check engine light isn't on, and it doesn't really seem to affect anything other than I can just feel it. I first noticed it when I got a smog check and it was doing it during the 2500 RPM test (I drove it straight from the guy I bought it from to the smog shop). Fluctuated about 200 rpm up and down. I passed the test, but still I noticed it. I also just put in an air intake system, but it didn't change the pulsing issue. I'm just looking for some obvious places to start looking....

 

[Seanathen]

Bump! 225 views, and not a single response? No one's heard of this issue with an Explorer?

 

[koda2000]

super wild assed guesses... a vacuum leak? warped brake rotor, hanging caliper? have you cleaned the MAF and throttle body? also, throw some Chevron Techron and/or Heet in the gas tank.

 

[Seanathen]

I'm almost certain it's a vacuum leak, but I have no idea where to start looking for it. The throttle body was spotless when I put the new air intake in. If it were a sticky caliper or brake issue, it wouldn't happen while in park and just opening the throttle like during the smog check.

Any vacuum leak places to start looking that you can think of?

 

[koda2000]

I don't see where you say which engine you have. if it's the 4.0L SOHC V6, upper/lower intake manifold gaskets/O-rings are a common source of vacuum leaks, but it can happen on any of the engines. a vacuum leak anywhere will cause the same problem (PCV hose, grommet, elbow, power brake booster, a cracked vacuum reservoir ball, any number of vacuum lines, cracked intake hose). getting a smoke test done would narrow it down. we see multiple posts like yours every week. I guess people just get tired of answering them.

 

[my98nnj]

Is the A/C compressor cycling on and off? That could very well be the load you feel.

 

[Seanathen]

It IS the 4.0 engine. It's not the A/C compressor, it does it whether the A/C is on or off. The ABS light is on, but because it's a '95 instead of a '96, I was told it has the older style computer connector so i can't get it checked for free at AutoZone, but that could be a clue. I didn't know it could be sooo many possible places to look. Sounds like the smoke check is really going to be the only way to find it. Sounds spendy though...

Thank you for the ideas guys!