Saturn 02, SC1 P0172 code. Need help

Question

264000 km and getting the P0172. Changed the EGR, tried another MAP sensor, ENgine Idle and throttle position sensors, change the coil and wires and 3 of the 4 plugs. Still got the code. Car idles rough, and hisitates when driving at low rpm and again at higher rpm when trying to push it. I took the injectors out and sprayed them with cleaner and put them back in. No luck. Do you have any suggestions?

Answer 1

Check the fuel pressure at idle the specification are 40 psi minimum.

Comments

I will check the fuel pressure but last night I tried unplugging each fuel injector at a time and noticed on the fourth on that when it was unplugged a ticking that I have been hearing in my engine would go away then return when I plug it back in. Could this be related?

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Do a compression test , on all cylinders ,there  should not be a 25 % difference, the goal now is to determine a mechanical condition

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Thanks for the suggestions. Could the temperature sensor cause the same symptoms? The ticking noise seemed to go away when I changed the oil. I also notice today that the engine light went off for a while and then Came back on. I have no way of testing the fuel pressure. Is there a way to diagnose if it is the fuel pressure without something to measure it?  Thanks.

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You have 2 code written P1128 and P0172, P1128 is 02 sensor swapped and P0172 is lean bank, When you get a lean bank the causes are vacuum leaks and or low fuel pressure, There is a way to tell and that is the scan tool that you use. If it has live data go to fuel trim , there is short trim and long trim, If the long trim is greater than 20 and short is greater than 10, you will need a fuel pump. When you disconnected the coolant temperature sensor all you did was richen the fuel condition, by increasing the fuel injector pulse width. let me know

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I couldn't measure the conpression as I do not have a device to do this. Unless there is a simpler way? I did change the fuel filter as it has the fuel regulator built in for the 02 Saturn SC1. Still no change. I measured the ohms on all the injectors and they are good. I also put a new front O2 sensor in. I plugged the meter back in and got some interesting readings on the freeze frames. I did it once as soon as I started the car and then again after the idle settled out and was idlin rough. First of all I got the following codes: P0455, P0304(I know this is 4th cylinder misfire- it is the same cylinder that the ticking would go away when I unplugged the injector. Could it be related?) Freeze frame After started: Fuel sys1- CL, Load_PCT 42.4%, ETC-117deg C, SHRTFT1= -2.5%, LONGFT= -6.3%, MAP- 13.3KPa, RPM 1482?, VSS- 30km/h, TP- 0% and I also took Sys Status as soon as I started: MIL status-ON, misfire monitor- OK, Fuel sys Mon- OK, Comp component-OK, catalyst min-INC, Htd catalyst- N/A, Evap system mon- ok, Sec Air system- INC, Oxygen sens Mon- Ok, Oxygen sens Htr- ok, EGR system- ok.  Then I waited for a min and got several changed in the readings. Ill only type the ones that changed: for the Freeze frame: ETC was now at 47deg C, SHRtFT1 was now at -2.3%, LONGFT1 stayed at -6.3%, MAP was now at 45KPa and stayed there, VSS was now at 49km/h.  For the system status: Oxygen sens Mon was now INC, and EGR system was now INC. everything else was the same.

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The temperature sensor is not correct, this is 242 degrees F. The ECT at 47 C is 107 F. which is a cold engine. You are correct about the ECT. As for compression test. Disable the spark, crank the engine the cranking sound should be rhythmic,no long rhythmic then steady then long, just even.  The injector spray cleaner you used, go to the intake manifold at number 4 intake spray there and see if there is a engine change.

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I took the temp sensor out and tested it with a meter. the ohms changes as the temp changes so it appeared to work fine. With the short and log term fuel trim in my post above, do you see any rear problems maybe with the fuel pump or something else? The compression appears to be fine as well in each cylinder.