I need engine advice 2000 Expy 5.4

[bigcat203]

Im still having problems with my Expy. I dont know what else to do. I have started over from the basics. I have ohm'ed and volt tested every sensor(metered values coinside with the values listed in the Chiltons manual), but the knock sensor. I was not able to conduct a compression test, and it does not sound like there is vavle train interferance. I have replaced the TPS, DPFE, Coolant sensor and theremostat,pcv, all 8 new injectors, all 8 new COPs ohmd pri 1.2 and sec 6500, and 8 new plugs gapped at .52. I have Inspected the pcv elbows,cleaned the MAF, IAC, and ATS. I cleaned the grounds and greased every electric connection. I wrapped tape around the intake hose to stop, if any unmetered air from getting in. After all this I still have a stumble and no power under 2000 rpms in any gear, and get a occasionally misfire in the 300's. I get a constant P1151 and P1131 code. I changed to O2 sensors(put new one upstream on bank2, put the bank2 in upstream bank 1 to see if code changes) still get P1151. After 2000 rpms it runs like there almost nothing wrong. Anyone please help this has been gooing on for a month now.

 

[bigcat203]

Damn forgot to add. I have to put the pedal to the floor to get the engine to start.

 

[2000eb]

just reading that i want to say maybe tps... i swear your gonna hate me but im thinkin maybe computer... ill ask a buddy when he gets off work. he seems to see alot of these expys in his shop. he also said he has seen problems with the throttle bodys alot if you know someone else with a 5.4 its easy to swap them out real quick worth a shot.

 

[toms89]

I believe those codes are 02's reading lean, both banks. This would lead me to believe either a fuel delivery problem, vacuum leak or faulty mass air. It sounds as if you covered the latter two somewhat so that would leave fuel delivery. Can you check fuel pressure at the rail. Should be 38-42 without vacuum line attached at regulator.

Bad fuel pump, bad fuel pressure regulator and clogged fuel filter are things that come to mind if it is fuel deliver issue.

I would check fuel pressure before replacing any items unnecessarily with the exception of fuel filter...that would not hurt.

 

[rburch]

Most of the time this points to a dirty or bad MAF, given that you have checked and replaced all other possibilities i would change MAF.

 

[Thermo]

bigcat, have you checked the PCV valve hose that runs to the back of the intake? That is the big offender on our trucks. After that, I would be checking the wiring going to the 2 upstream O2 sensors to make sure that the wiring is good to those. I say this as normally when you have a vacuum leak, it will toss the P0171 and P0174 codes. But, because you are getting different codes, this is leading me to believe that we are dealing with either bad O2 sensors or the associated wiring.

 

[00 Expy Police]

Im still having problems with my Expy. I dont know what else to do. I have started over from the basics. I have ohm'ed and volt tested every sensor(metered values coinside with the values listed in the Chiltons manual), but the knock sensor. I was not able to conduct a compression test, and it does not sound like there is vavle train interferance. I have replaced the TPS, DPFE, Coolant sensor and theremostat,pcv, all 8 new injectors, all 8 new COPs ohmd pri 1.2 and sec 6500, and 8 new plugs gapped at .52. I have Inspected the pcv elbows,cleaned the MAF, IAC, and ATS. I cleaned the grounds and greased every electric connection. I wrapped tape around the intake hose to stop, if any unmetered air from getting in. After all this I still have a stumble and no power under 2000 rpms in any gear, and get a occasionally misfire in the 300's. I get a constant P1151 and P1131 code. I changed to O2 sensors(put new one upstream on bank2, put the bank2 in upstream bank 1 to see if code changes) still get P1151. After 2000 rpms it runs like there almost nothing wrong. Anyone please help this has been gooing on for a month now.

what kind of cop r u using,,i had the same issue and i chased it for over a month,,come to find out the BRAND NEW COPS i orderd from summit were no good,,i put the used factory ones back on and it hasent missed a beat.

(reason i ordered new ones from summit is cause the motor was blown when i bought and wanted new cops so i dont have any probs but was i wrong)

 

[bigcat203]

what kind of cop r u using,,i had the same issue and i chased it for over a month,,come to find out the BRAND NEW COPS i orderd from summit were no good,,i put the used factory ones back on and it hasent missed a beat.

(reason i ordered new ones from summit is cause the motor was blown when i bought and wanted new cops so i dont have any probs but was i wrong)

I bought Rally COPs, but I just found out what problem might be. The driver side cam doesnt spin past the first cap. I think its broke under the cap. i get into it more when I get paid.

 

[rburch]

Well that sux!

 

[bigcat203]

The offender

[/IMG]

Its broke under the first cap. Not happy.