giantrobot9000 Posted June 2, 2007 Report Share Posted June 2, 2007 My car hesitates when you first accelerate.It will eventually rev smoothly and boost just fine,but it seems to always have a pause after it shifts up a gear (auto) or I press down on the throttle smoothly.My other 850R didn't do this...it was smooth (the car is a 94 850 Turbo,btw). Link to comment Share on other sites More sharing options...
AlvinL Posted June 3, 2007 Report Share Posted June 3, 2007 Any codes? Vacuum or intake air leaks? Link to comment Share on other sites More sharing options...
greasefingers Posted June 3, 2007 Report Share Posted June 3, 2007 Yes old plugs, wires, cap, & rotor can cause this if the engine is seeing multiple mis-fires. Since you already know the above is old, then replace it and eliminate it from the equation.Since you also have 1994 it is easy to pull the codes as Alvin suggested. Link to comment Share on other sites More sharing options...
AlvinL Posted June 3, 2007 Report Share Posted June 3, 2007 Good point. I totally forgot about answering your question! I want to share this. I was experiencing a mild hesitation on one of the cars when cruising along so I replaced the plugs and noticed no difference. The wires and dist. cap I knew could last much longer. Other than that, car runs and boosts normal. Few days later, my CEL came on and code 435 for O2 sensor slow to respond. I thought I was due for a new sensor. I wasn't looking forward to that because I knew it's expensive. Anyway, I cleared the code and CEL otherwise I'd be burning more fuel since having that code shuts off the fuel trim. I checked into that code and top of the list for this problem was air leaks (or was it uneven compression?), not defective sensor. Drove the car for a couple of days and the CEL stayed off. Day before yesterday, I ran some water through the intake (read about it so thought I'd try), through a vacuum line with the engine running and reving and that smoothed it out. And, yesterday I took almost the whole intake system apart (air filter up to the throttle body), cleaned the PCV (on intake pipe), found no leaks. Well, actually, I found a small leak at the CBV so I repaired that. A small vacuum leak like that shouldn't matter since my vacuum gauge was showing me 19 in Hg at Park. Now, car runs smoother and no hesitation. Not sure which fix was the fix! It's only been a day but I hope the CEL stays off!Very satisfied that it didn't cost me anything but my time and stained hands! Link to comment Share on other sites More sharing options...
greasefingers Posted June 3, 2007 Report Share Posted June 3, 2007 I have a funny feeling that you are not out of the woods just yet. The response time of the sensor is a property/behavior of the sensor, regardless of the engine condition. It must be able to rapidly switch from high to low in less than 1 second. The output of the sensor is a sinewave that oscillates from about 0.1 to 0.9 volts. Low values are a Lean condition and higher voltages are treated as a Rich condition.The water injection can burn off some carbon/coke. It does the same thing as seafoam but it must be introduced slowly to avoid vapor-lock, which is why most people stay away from it. I have tried it as well. It was funA vacuum leak downstream of the MAF goes unmeasured by the MAF.Time will tell … good luck. Link to comment Share on other sites More sharing options...
AlvinL Posted June 3, 2007 Report Share Posted June 3, 2007 Appreciate the info. Thanks! Link to comment Share on other sites More sharing options...
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