More pesky hesitation-and alternator/fan issues

[Dave G]

I can't find similar hesitation symptoms in other posts. My 94 SS has new injectors, plugs and knock sensor, all replaced within about 2 months ago but an intermittant hesitation remains. It happens when pulling out from a stop, after going maybe 1 or 2 car lengths, it acts as though I let my foot completely off the gas. It may happen once a week or once a day, but seems more frequent lately. This lasts no more than a second or two, and does not stall the engine. If I pump the gas pedal, it makes no difference. I have the impression it is gasoline related, and not spark. I can't say exactly why I think that, it is just an impression. It has been going on from time to time for over a year, but used to be very rare. My check engine light has been on for several years. My mechanic said it was coding for at least 7 engine sensors and could not be reset, so he suspected the ECU. I have had an MBC on for at least a year, set at about 9pounds. This was due to irregular reduced boost levels. Mileage is 128,000. Electric grounds/connections are good. Any ideas?

[evolutionmovement]

Sounds like timing retard or ignition related hesitation. When were the plug wires last replaced? A bad fuel filter can also cause off the line hesitation issues.

Steve

[azn2nr]

replace your wires. the way mine was sounds similar to what your expirecing. i changed my wires and now have no problems

[douglas vincent]

Look very very carefully for a vacumn leak.

[J-MoNeY]

Could be a pump on the fritz? Could be fuel cut? Do you have a boost gauge?

[Dave G]

Yes I have boost gage. It acts normal at all times. Wires are probably due, and fuel filter as well. Looks like time for a minor tune up. Thanks for the advice. I want to sell the car in a month or so and I would like to have the hesitation gone.

[Dave G]

This is getting more interesting. After reading other posts where the alternator had caused drivability problems, I decided to turn off my headlights and fog lights, and defroster, which I usually have on at all times in the winter. There has been no more incident of hesitation, even though the previous day it happened twice after two stops in a row. I further decided to check the alternator and after starting the car cold, ran it until the idle fell to normal. At this point, the idle dropped to normal, and both cooling fans came on and stayed on, even though the temp gage was barely touching the bottom of the line. (The heater was set to 'off'.) With all accessories off, except the fans, my charger/tester read a 'fault' -but it gives no specifics. The 4 month-old battery is reading 12.1 volts. I just had it replaced after less than a year due to an internal short. I also changed out the fuel filter and plug wires, which made little difference.. I will disconnect the fans and check the alternator again with no load. If still showing fault, I will get it to a qualified alternator shop.

[Dave G]

Well, before I got to do any further checking, the hesitation showed up again without A/C or lights on. It is rvery abrupt, always occurring after pulling out from a stop. I can cruise on the highway all day without a problem.