CHEVY TRUCK HESITATES WITH LOW POWER AND POOR MILLEAGE
1994 Chevrolet Silverado
September, 6, 2007 AT 12:24 AM
1994 Chevy truck, 2500, 350, 142K miles.
Hey guys, about 3K miles ago my truck was running great as usual but I noticed a slight hesitation or stumble at a stoplight when I went to accelerate from a stop. It was very brief and then the truck ran fine. Over the next few weeks I started paying more attention to the truck's behavior and noticed the fuel milleage was getting worse and the little hesitations from dead stops were more pronounced and it felt like I had to push harder on the gas pedal to get it to go. Now I really have to feather the gas pedal to get it moving. If I am moving at a slow speed and it has shifted into second, I end up pushing on the gas so hard to get it going that it is downshifting a lot more now. On the highway it will accelerate fine sometimes then feels like the power falls offs then comes back on again. It idles fine in park, it starts right up no problem. I have also noticed that it seems to run fine right when I start it a go a couple of blocks but it quickly goes into its behavior of poor power within a minute or less. I have replaced the fuel filter. No change.I cleaned the distributor cap contacts. No change.I took it to a repair shop and for $300 they said they found the problem and replaced the EGR valve.I picked it up and drove it home and it proceded to act up the same way a couple of blocks from the repair shop. No change. I put the old EGR back in the keep the baseline. The shop did say the fuel pressure was good. Before I start randomly dropping money on it and changing things. Any ideas? Oh and there are no codes coming up. Help!
It doesn't run rich. Check Engine light does light up when key is on.
Poor milage? Running rich? Check the convertre and 02 sensor, after warm up the 02 sensor is most responsible for mixture, there is input from other sensors too. MAF and MAP are big causes of stumble. MAF you can try to clean, use a q-tip and alcohol on the heated wire element. Make sure you check the ecm, does the MIL come on when key is in on position? If not either the bulb or the computer isn't working!