Bogging/hesitating acceleration and idle probs

[Blast7]

I have not run any codes yet but when I get some time on Tuesday I will do the jumper thing. However, maybe somebody could help me figure out some ideas in the meantime. When idling my tach bounces up and down about 50RPM constantly. As I accelerate there is a hesitation/stuttering problem and there is a huge power loss. Also, my SHO accelerates faster when I use half throttle and below. Sometimes when the weather gets colder she runs a little better and sometimes it is not weather dependent. My guess is that the problem is either the MAF, TPS, IAB valve, or fuel pump. My fuel pump is not any louder than it was and I did clean my MAF. I'm leaning more towards a bad MAF or fuel pump.
EDIT:My gas mileage has gone from 26-27mpg to 20-21mpg.

<small>[ May 12, 2002, 10:00 PM: Message edited by: Blast7 ]</small>

 

[sdpatt]

You mentioned checking the codes, but you didn't say whether or not the CHECK ENGINE light has come on. If it has, don't ask us, ask the EEC. If it hasn't, your stumble sounds like a secondary ignition fault: a spark plug or plug wire problem and these don't usually result in a CE light. Incorrect, damaged or improperly gapped plugs, old or poor quality wires or oil or water in the spark plug wells can cause a misfire.

 

[luigisho]

How did you clean your MAF? Did you decide to clean it because of your stated problem or did the problem occur soon after you cleaned it? To see whether or not it's the MAF you could unplug the connector and see if it runs smoother in open loop. Isn't the IAB out of the loop on acceleration?

 

[Blast7]

There is no check engine light coming on. A new symptom to the problem is that when I disengage the clutch the RPM's drop down to around 500 and then go back up to 950. Sometimes it will stall out. I just replaced the plugs, plug wires, valve cover seals, and plug well seals around 5K miles ago. I cleaned the MAF because of this problem and it has not been any worse since I cleaned it. I have run the car without the MAF and it runs worse.

 

[luigisho]

O.K. so even if you haven't noticed a check engine light have you checked for any stored codes? You could always clean the IAB to see if it helps. TPS is a cheap replacement item. It sounds like ignition. Maybe it's PIP or CID malfunction. If it ran worse with the MAF unplugged, I would think it is not the thing you're looking for.

 

[Blast7]

I just looked on the SHOtimes website and it appears as though the problem is either my MAF connector or speed sensor. I am going to run some codes tomorrow and find out. Thanks for the help.

 

[Blast7]

Update: I tried to find out the codes but that didn't work out for me. I did go ahead and replace the MAF connector. After replacing that I don't have the hesitating/stuttering and my idle has smoothed out a little. When I depress the clutch the RPM's still drop and I still have a loss of power. The loss of power is more of bad throttle response. For instance, when go WOT the car just does not move very much. If I am going 75, have it in 5th, and floor it then it does not go any faster or move the tach. The exhaust gets louder but nothing else. I could replace the speed sensor but that is $40 and I don't even know if that will fix it.

 

[luigisho]

That's certainly a problem. Just for laughs I'd go back and make sure all the plugs were gapped within spec. After that I would consider replacing the tps. How long since the fuel filter has been replaced? Vss is not out of the question.

 

[Blast7]

I will check the gaps on the spark plugs and the fuel filter has been changed within 6k miles.

 

[Denny]

sdpatt:
You mentioned checking the codes, but you didn't say whether or not the CHECK ENGINE light has come on. If it has, don't ask us, ask the EEC. If it hasn't, your stumble sounds like a secondary ignition fault: a spark plug or plug wire problem and these don't usually result in a CE light. Incorrect, damaged or improperly gapped plugs, old or poor quality wires or oil or water in the spark plug wells can cause a misfire.

Secondary ignition fault refers to the plugs or wires? I'm chasing down a stalling problem/loss of power problem still and I get vibration when stalling

 

[SHOcker]

Blast7, I'd be willing to bet that the idling problem and the loss of accelration could be caused (partially at least) by a bad fuel pump! I know this because I took my SHO into the shop because of some rough idling problems. The weather is getting pretty warm now, and when the temperature gets warmer, the fuel pump has to work harder. If it's going to go, it'll go when it starts to get warm. That could explain why it runs better when it's cooler out. I would seriously recommend checking it out!
Best of luck

 

[Blast7]

Update #2: I cleaned the IAB valve and voila, my RPM/stalling problem is fixed. I also notice better power. It feels as though the power gets kicked on at 4500RPM instead of 4000RPM. I was driving around and experimenting things in all different gears and RPM's. Thus, I came to the conclusion that I don't think it has anything to do with the secondaries. Then I jacked up the car and I found that the right rear wheel is dragging hard. It will not spin unless I put significant effort into doing so. My new question is, how do I know if it is the slider pins, brake line, or caliper. I don't think it is the caliper because I replaced it 50K miles ago as well as both sets of slider pins and anchor plates. Any suggestions?
EDIT:Upon closer inspection I have found that all 4 wheels are sticky and dragging. They don't drag very much but if I spin them they will stop after about 1 revolution. You can hear the rotor sliding against the brake pads and it gets to be more so in one area than the rest of the rotor. I guess that would mean my rotors are warped but I wouldn't think that this would cause that much dragging.

<small>[ May 15, 2002, 04:03 PM: Message edited by: Blast7 ]</small>