OK so I'm trying to figure this out. My car lately has started to have a slight hesitation, almost a stumble. When i start it my rpm's are at like 400 to 500 and i have to let it run for a minute to let them raise to normal (850-875 rpms) or else it will die when I put it in drive. I also have started to get a ses light but it is intermittent. I just put a new fuel pump and gm opti in last week and it was running fine. Before that it sat for about 3 weeks while I trouble shot the whole fuel and spark systems on the car. I was praying that it was not the opti but of course it was. In the process I found out that my check ball was bad in my fuel pump. So after ordering and replacing both parts it ran great. For the last 2 days I have been having these problems and it is getting worse. I checked the vacum lines and all around the intake. I replaced the fuel filter. When I tried to check for a code there is not one in the pcm. I was thinking about the map sensor any help is appreciated. Thanks

 

How did you check for codes? If the SES light goes on, the code is stored, unless you pulled the power to the PCM and cleared them. Is it possible the MAF sensor is dirty, or you have a tear in the inlet elbow?

 

No tear, i checked that and I checked for codes with datamaster. I also adjusted the plug wires at the optispark. Also I forgot to mention that I changed the coil when i changed the pump and the opti. I thought that since i have the air and egr deleted sometimes it would throw a code and reset itself. Anyway, no codes are being stored.

 

OK so it finally got bad enough that the car now idles at about 500 and it is set to idle at 1100. I scanned it again and it gave me two codes dtc 33 and 64. I know what the 33 is Manifold Absolute Pressure (MAP) sensor circuit (signal voltage high, low vacuum). And the 64 is Bank 2 (right) Heated Oxygen Sensor (HO2S) Circuit (lean exhaust indicated) Bank 2 (right) Oxygen Sensor (O2S) Circuit (lean exhaust indicated). My ? is what is causing this? The 02 sensors are pretty new and i kind of feel like the map code is being set due to another problem. I reset the codes and they came back. It was running fine up until this point. I am going to check my map connector to make sure it is good and I will let you guys know how that goes. Thanks for all of the help and please keep it coming.

 

Ok with KOEO it is reading 100+ Kpa idling it is reading anywhere from 59-84 Kpa. Does this help anyone?

 

Checked datamaster o2 sensors are all over the place as they should be. Long term fuel trim value stays at 160 for both sides. Short term counts the right side lags constantly behind the left. What could cause this?

 

Unplugged map and it started right up. I am gonna go and get 1 now.

 

The map sensor did not work. BTW the plug for it checks good(4.7v). I am gonna revisit my maf.

 

I found an o2 sensor that sometimes rested against my y-pipe. I pulled it off and ohms tested it. It checked out good. The plastic cover was just a little melted. The car has steadily gone downhill all day. I guess I will start over tommorrow.

 

Ok to further update everyone, the car starts immediately but will shut off instantly. Funny thing is, it began as a hard start. I checked the fuel pressure and I am getting almost none. The guage reads half a tank. I put 5 gallons in and it will stay running but it is still very bad. When it is running the pressure is only 20 psi. This is a brand new walbro pump installed 2 weeks ago. Could the fpr cause this? I just need to know before I go through ordering a new pump.

 

"Lean" = not enough fuel


You do not indicate a cam in your signature. 100kPA KOEO is normal, as long as you are near sea level. 59-84kPa at idle indicates poor vacuum, often associated with a large cam. Its a problem if you have the stock cam. Timing could be way off, valve could be incorrectly adjusted, excessive misfires. Should be around 35kPa. When it goes over 68kPa at idle, it sets DTC 33

Long terms at 160 = not enough fuel.

Should be closer to 5V, if measured across the gray and black wires with the connector off the sensor.

Was it the Bank 2 sensor? Short to ground will cause a "false" lean. How do you "ohms test" an O2 sensor?

20psi = not enough fuel.

Are we beginning to see a pattern here?

Yes, a faulty fuel pressure regulator can cause low fuel pressure. Pull the vacuum line and see if its wet. But it could also be a hose on the pump install came loose.

 

Fred, in my sig it says that I have an LE1 package. I don't have every little thing listed because there is not enough room. I am going to change the fpr and if that doesnt do it then I can easily pull the pump and check it since I can pull it from the top. I have to find my reciept for that thing if it is bad.
Thanks for the response

 

Actually, it says you have "LE1".... I have no way of knowing that is a "package". I have way more mods than can fit in my signature, but you can access the list simply by clicking the link..... might want to try that approach. Hard to help without all the info.

 

You are right and I apologize. I was just posting my findings since no one was responding. I figured that I could help someone else troubleshoot that may have the same problem. I often use the search function on here but very seldom post. As far as my mods list I will add package to the LE1, plus all that is needed for it to work right to my sig.

Again, thanks for your response

 

Hey Fred, I pulled the bucket that my pump is in and the seal had started to seperate. Therein lies the problem. Thanks for all of your help and I hope that this helps someone. Thanks.