I just bought a 1997 Saturn SL1 last week. It was a new car trade-in at Saturn, then took over to the used dealer. Always garaged, previously old lady owned, only 62,200 miles on it. When I test drove the car it had a misfire and we let the dealer know. Came back a few days later. They said it had threw a code for a misfire on cylinder 1, so they replaced with new plug wires and thought that took care of the problem. So I decided to buy it and had them also install cruise. In doing so when they took it back to Saturn to get the computer reprogrammed for the cruise it still misfired. Saturn's computer said it was the ignition modules so they swapped it out and the computer accepted that as good. They were able to reprogram the computer and thought that was fixed.
So I purchased the car thinking it was fixed but it's still misfiring. I took it on a small road trip drove it over 800 miles, thought maybe it was misfiring from sitting on lot or the from the previous owner not driving it much. So I thought it might work itself out with some driving. With no improvement. Ran fuel system cleaner at 1/2 tank to run it a little extra potent. No improvement. When it idles, it fluctuates from 8-900 RPM until it misses, and then after choking it'll rev up to about 2000 and then come back down. So apparently the computer is recognising the problem and tries to correct it.
Ohm'd ignition module...ok. Ohm'd injectors...ok. Ohm'd crank position censor...ok. Checked compression on the cylinders...Cyl#1 is @180, Cyl#2: 170 Cyl#3: 190, Cyl 4: 180. Checked against my 92 Saturn with 145K and it's compression was 175, so...apparently that's within normal range? Air filter is clean. Doesn't seem to detect any leaks around intake manifold gasket. Oil was clean, so I don't think it's a head gasket leaking or anything. Plugs appear to be recently new. No carbon buildup. Plugs were checked & properly gapped. Also checked all fuses. I'm running out of ideas to check, I don't know what to check next. Hoping that I didn't buy a lemon. Any ideas what I need to check next?
And, is it possible for the dealer to manipulate the computer so it will not throw a code? It has never thrown a code for me. The dealer had said it threw a code when they were with it. I haven't seen the service engine light come on. I know the bulbs are good, they light up when the car starts. Thanks so much for your help.
So I purchased the car thinking it was fixed but it's still misfiring. I took it on a small road trip drove it over 800 miles, thought maybe it was misfiring from sitting on lot or the from the previous owner not driving it much. So I thought it might work itself out with some driving. With no improvement. Ran fuel system cleaner at 1/2 tank to run it a little extra potent. No improvement. When it idles, it fluctuates from 8-900 RPM until it misses, and then after choking it'll rev up to about 2000 and then come back down. So apparently the computer is recognising the problem and tries to correct it.
Ohm'd ignition module...ok. Ohm'd injectors...ok. Ohm'd crank position censor...ok. Checked compression on the cylinders...Cyl#1 is @180, Cyl#2: 170 Cyl#3: 190, Cyl 4: 180. Checked against my 92 Saturn with 145K and it's compression was 175, so...apparently that's within normal range? Air filter is clean. Doesn't seem to detect any leaks around intake manifold gasket. Oil was clean, so I don't think it's a head gasket leaking or anything. Plugs appear to be recently new. No carbon buildup. Plugs were checked & properly gapped. Also checked all fuses. I'm running out of ideas to check, I don't know what to check next. Hoping that I didn't buy a lemon. Any ideas what I need to check next?
And, is it possible for the dealer to manipulate the computer so it will not throw a code? It has never thrown a code for me. The dealer had said it threw a code when they were with it. I haven't seen the service engine light come on. I know the bulbs are good, they light up when the car starts. Thanks so much for your help.