RICK323 Posted September 18, 2007 Share Posted September 18, 2007 I'm really puzzled by a persistent problem with bucking at 40 to 45 MPH, especially when going at constant speed. If accelerating, it smooths out, or if you drop out of overdrive, the additional rpm's seem to smooth it out also. New fuel filter, fuel pump and computer installed first and a cleaning regimen performed on the injectors. Then new spark coils, caps and rotors. The mechanic says he tested the mass flow sensor and it's OK, so he thinks it's "the computer". Has anyone had this problem? The car has 145K and has run smoothly and well since we bought it over 5 years ago until just recently. Quote Link to comment Share on other sites More sharing options...
JIBBBY Posted September 18, 2007 Share Posted September 18, 2007 Did you try cleaning the Throttle body and changing out your air filter?.... It almost sounds like an ECU problem maybe.... Quote Link to comment Share on other sites More sharing options...
johnsonhuang Posted September 22, 2007 Share Posted September 22, 2007 get a bottle of throttle body cleaner and clean that thing out. It could be because of your MAF sensors that are dirty and the ecu picks up weak signals which messes with the A/F ratio. Quote Link to comment Share on other sites More sharing options...
john_sc400 Posted October 6, 2007 Share Posted October 6, 2007 95 SC4. Same problem here. I even removed the throttle body to make sure I got all parts of it really clean. No difference. In addition to plugs and replacing some hoses to eliminate leaks, I also replaced the fuel filter and PCV valve. Had it put on a computer at a dealer. They said that the O2 sensors were 'a little slow', but couldn't assure me that changing them (about $900) would fix it. Another dealer told me that it was a typical issue with 95s. They said that 95 was the first year of drive by wire and they didn't get some things exactly right. They suggested replacing the TPS, (throttle position sensor), another expensive part. Again, they couldn't assure me that it would be a total fix. I wonder about the EGR valve, but have not yet removed it to inspect it. Along with the 40mph surge, I also get hesitation when accelerating normally from a dead stop. I don't get it under hard acceleration. It makes me dislike this car. Quote Link to comment Share on other sites More sharing options...
DILLA400 Posted October 10, 2007 Share Posted October 10, 2007 i have the same problem as both of you.. im running a diagnostics on my car tomorrow so hopefully that will tell me something ill be sure to post if i find anything else out. Quote Link to comment Share on other sites More sharing options...
john_sc400 Posted October 17, 2007 Share Posted October 17, 2007 i have the same problem as both of you.. im running a diagnostics on my car tomorrow so hopefully that will tell me something ill be sure to post if i find anything else out. Wondering how that came out... Quote Link to comment Share on other sites More sharing options...
smooth1 Posted October 19, 2007 Share Posted October 19, 2007 Could be a fuel supply issue, more than likely, fuel pump, or filter clog. Quote Link to comment Share on other sites More sharing options...
DILLA400 Posted October 25, 2007 Share Posted October 25, 2007 sorry for the slow reply, the diagnostic computer at my school hasn't been running correctly. Once thats fixed ill run a diagnostic again. Quote Link to comment Share on other sites More sharing options...
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