mdoffing Posted September 29, 2012 Report Share Posted September 29, 2012 So I recently inherited a 1992 Cutlass Supreme Convertible with the 3.1 from my grandmother and it's got this odd acceleration problem. When I press the gas pedal the car feels like its about to die (RPMs drop and engine goes silent briefly). Depending on how hard the pedal is pressed it will either die at this point or push past it and run normally. As for other problems, it's got a rough idle and I don't get very good gas mileage (well, worse than the car already gets.) With the exception of the this issue the car is in beautiful condition, and I'd love to get it back to good working order since it's such a classy and rare car. She's got about 165000 miles on her. Feel free to get technical. Here is a picture of the car because I know people will ask. Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted September 29, 2012 Report Share Posted September 29, 2012 Is it throwing a service engine soon light? That is a cool car. Nothing like dropping the top in a first gen. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted September 29, 2012 Report Share Posted September 29, 2012 my red tgp was doing that exact thing and that was a symptom of the throttle follower graph needing tuned and voltage dips. tuned it and it has went from a major problem, down to where I can hardly feel it. before it would sometimes stall when it dipped. voltage went from 13.4 running hot to a steady 14 during datalogs. Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted September 29, 2012 Report Share Posted September 29, 2012 Just tossing out a guess, but I remember my 3.1 did something similar and the throttle positioning sensor was going bad. The car is probably in need of a tune up. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted September 29, 2012 Report Share Posted September 29, 2012 did you verify with a datalog? Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted September 29, 2012 Report Share Posted September 29, 2012 I never dataloged it, but I did scan the car using TunerPro. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted September 29, 2012 Report Share Posted September 29, 2012 yeah, a bad TPS canl do this. a bad/slow reacting MAP sensor can cause it as well. as many old time tuners have said, garbage in, garbage out. if the ECM isn't getting a perfectly accurate picture of what's going on, it has no hope of performing perfectly. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted September 29, 2012 Report Share Posted September 29, 2012 only a good tuner will take the step to see the monitors for MAP and TPS to see if they work properly. thats why it should be datalogged and pull up those specific monitors to see if they match up. its very simple actually to diagnose something like that with tunerpro 5. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted September 29, 2012 Report Share Posted September 29, 2012 especially if you run mode 2 commands.... get something like a 70Hz refresh rate instead of the ~10Hz that a mode 1 command will produce. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted September 29, 2012 Report Share Posted September 29, 2012 need to look into that then. mine seems to be sufficient to get excellent data whatever mode it is. not sure? I guess I will check. but the key is to compare data in monitors from sensor to sensor to see if anything looks suspicious. like the battery voltage during an unexplained engine surge. you may need to buy tunerpro RT v.5 to get full datalogging capabilities. or just deal with the nag screen for awhile. I like doing it on the large triple screen computer in the comfort of my lazy boy. Quote Link to comment Share on other sites More sharing options...
rawdeal91vert Posted October 4, 2012 Report Share Posted October 4, 2012 I had a similar problem with my 91' 3.1. OBD1. It would shutter and cut out at 35-45 mph. I had to replace all the injectors. Problem solved. It was exspensive. Fortunately, I bought the car right. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted October 4, 2012 Report Share Posted October 4, 2012 you have to pretty much do that on 20 year old cars. just find out what they ohm out at. lotta times you can replace out of spec ones with used good ones for real cheap. sometimes that alone will not fix it. with my cars, seemed like nothing would fix it and it had to be tuned. Quote Link to comment Share on other sites More sharing options...
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