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Topic Review (Newest First)
02-11-2013 06:36 PM
Steven Pisonero I took the shops word for it. I guess we will see. My tinkering is with older cars and am a real novice when it comes to anything after about oh 1978!

would low fuel pressure account for a bouncing idle at start up? I would think if it was the fuel pump it would happen in and out of gear. MIne only has problems in gear at idle when it is cold
02-11-2013 06:26 PM
T-bucket23 Did you check the fuel pressure regulator. Unplug the vacuum line on it and make sure it is not full of fuel. You can also try pinching off the erturn line to see if the pressure goes up. I would not install a pump unless you are sure. It is an expensive guess.
02-11-2013 06:14 PM
Steven Pisonero Just some house cleaning.. The check engine system worked. I had it checked at Oreillys and they told me it did not. Sorry for throwing the thread off.

Also, there are no drivability issues other than the one mentioned. After it warms up, it runs like a top!
02-11-2013 06:06 PM
Steven Pisonero check engine is now working, but not throwing any codes. I took it down to the shop and they tell me everything is testing well except fuel pump. They say fuel pump pressure is 40-50 and should be 55+.

He says we must replace the fuel pump. It does not make sense to me this would cause the problem. According to him inadequate fuel pressure will throw off the ECM and would be the problem.

I dropped about $300 on a delphi fuel pump.

Any thoughts?
02-07-2013 05:44 PM
LATECH O2 sensors dont have any effect on a cold start run condition.That is where he has his driveability complaint.
I am sure there are others too...
02-06-2013 07:43 PM
AFX If headers were installed The O2 sensor needs to be after the Y pipe maby.
02-06-2013 04:44 PM
T-bucket23 Before you go crazy, check the fuse for the cigarette lighter. This is generally the same fuse that supplies power to the DLC connector. Once you can access the system you can start to troubleshoot. Fuel injected systems usually dont work well with "stuff" disconnected.
02-06-2013 09:11 AM
sbchevfreak Guys, we can't be throwing out "check/replace this" scenarios on this one. The OBDII has to be fixed, so he can get a starting point, or he could spend thousands on "maybe it's this". something the pcm is looking for is missing or out of range, and with OBDII, you need to see the data that the PCM is providing to accurately repair it. Get the scanner communication thing fixed, and get the codes and some of the data stream, and it will be much easier and less expensive to repair. There are literally hundreds of parameters that the PCM is using to monitor and adjust this engine, which one is off kilter?
02-05-2013 07:36 PM
ssmonty Something you might look at is the MAP sensor. I have a 2000 with a 4.3 that had probems with a seal around the sensor that would seem to get worse when it was cold, but sealed up once it got warmer and more pliable.
Not saying thats what it is, but you might squirt some thick oil around it to see if it makes any difference. If you pull it out you might see what I'm talking about as far as being loose.
I don't know about a 6L but I know I had intake gaskets that went bad because of the dexcool or whatever it was called coolant from the factory.
I also had to replace the central fuel injection with a multi port kit that got rid of the poppet valves. Don't know if thats on the 6L or not.
Your computer is working or it wouldn't run period as that is what turns on the fuel injectors, as well as the spark control I believe.
02-05-2013 05:17 PM
LATECH Joe Padavano is correct in what he said here. If the scanner wont power up then someone clipped the 12 volt + wire in the OBDII ALDL pin #16. That will keep the scanner from powering up. The check engine bulb probably has been removed.
Be sure ALL the fuses are good .
You need to adress the engine / pcm communication problem first as you need that to read codes , live data and possibly to perform bi directional testing etc. in order to diagnose the problem correctly and quickly
Or you could spend a buttload of cash just throwing parts at it ,so you then can take it to a mechanic and complain you dont have any money to pay him to fix it.
02-05-2013 05:08 PM
obd 2

u just may want to ck with your DMV before u get carried away. in my state when u take it through inspection they plug in and take readings..when u last took any of your veh's in did they plug in ??? if your state does the same and your system ain't working??? your wasting your time if u don't get it to work, you will fail..
02-05-2013 12:04 PM
killeratrod I would try to figure out how to get the computer plugged back in. and go from their. This would be your best bet .
02-05-2013 11:38 AM
Steven Pisonero I thoroughly sprayed carb cleaner around the intake and so no change in idle. Temp sensor did nothing. I had the auto parts store plug in the reader and it was dead.

I believe the overall idle is low as well. In park it idles at 500 - 600 RPM

Any other ideas???
02-05-2013 09:46 AM
joe_padavano First of all, you cannot "disable" the "check engine system" on an OBD II system - it's integral to how the computer works. What was likely done is that the Check Engine light on the dash was disabled (ie, bulb removed) or something similar. Plug a diagnostic tool into the OBD II port and I guarantee you'll get a data stream out.

Of course, the first problem will be all the codes pertaining to the cats being gone...

Given how little restriction modern cats add, I continue to struggle with why people waste the time and money to do this.

Work through the codes and figure out what is going on.
02-05-2013 09:31 AM
s-10again! if not intake gaskets it could be a temperature sender/sensor. if the sender does not work the computer runs a default setting and adding fuel for a cold engine is not in the default settings. try your temp sender, or if not that maybe the computer itself is not compensating for the temperature mandated fuel needs. had this problem on my 99 tahoe 5.7. it was the temp sender/sensor.
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