1993 GMC Van PO44 Error Code

Tiny
TYJ93
  • MEMBER
  • 1993 GMC VAN
  • 50,000 MILES
I have a 93 5.7L v8 vandura that is running rough. It's surging at cruise speeds, jolting when you take off from stops, idling bad at first start and while in gear. My car can't maintain speed at cruise control setting and dies when you put it Into gear from park. My car also often times does not shift when it's supposed too when going down the road. I've replaced the vacuum hoses, MAP sensor, o2 sensor and fuel filter. It comes up with a PO44 lean fuel error code. Any ideas on what's wrong?
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Sunday, June 30th, 2013 AT 2:07 PM

7 Replies

Tiny
HMAC300
  • EXPERT
Check the gasket under tbi unit for leakage, spray choke cleaner arund base and if rpm goes up then replace gasket. Also check fuel pressure should be 9-11psi
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Monday, July 1st, 2013 AT 7:31 AM
Tiny
TYJ93
  • MEMBER
I tested the fuel pressure and it was stable at 11-12 psi
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Monday, July 1st, 2013 AT 9:36 AM
Tiny
HMAC300
  • EXPERT
Did you spray choke cleaner around base of tbi unit looking for a vacuum leak like I said in previous post? They blow that gasket it's a common cause.
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Monday, July 1st, 2013 AT 9:38 AM
Tiny
TYJ93
  • MEMBER
Yes I sprayed choke cleaner around the tbi unit and determined that there was not a leak there.
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Monday, July 1st, 2013 AT 12:59 PM
Tiny
HMAC300
  • EXPERT
Ok then do the basics, check ignition, and compression all around.
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Monday, July 1st, 2013 AT 1:07 PM
Tiny
TYJ93
  • MEMBER
My car runs great with the ect sensor unhooked but as soon as I hook it back up the problems resume, I replaced the ect sensor and the thermostat and it didn't fix the problems. Any ideas?
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Friday, July 5th, 2013 AT 6:16 PM
Tiny
HMAC300
  • EXPERT
Some of those needed harness replaced but I forgot what years did that. I'd have to think there is a short in the harness or an ecm problem like a prom but findinga prom for your truck is like findinga needle in haystack. Are the wires good at the tbi unit an dmaking good contact so both units are spraying? When you disconnect any sensor it will go into open loop and is automatically richened with fuel. Other than a vacuum leak I can't give anyother suggestions.
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Saturday, July 6th, 2013 AT 5:42 AM

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