padgett Posted March 26, 2012 Share Posted March 26, 2012 Good friend has an LS1 Roadmaster that runs very poorly on startup from warm.Feels a lot like vapor lock (chuggle, low rpm, stall).Replaced MAF, fuel pump, fuel filter, fuel regulator (last after poor start showed only 15 psi on rail).Trims show running very lean & codes show lean only.Ideas ?Thank you, Link to comment Share on other sites More sharing options...
D-a-n-i-e-l Posted March 27, 2012 Share Posted March 27, 2012 O2, even without a code they can cause many symtoms. Link to comment Share on other sites More sharing options...
handmedownreatta Posted March 27, 2012 Share Posted March 27, 2012 LTX and LSX - Third Generation F-Body Message Boards Link to comment Share on other sites More sharing options...
2seater Posted March 27, 2012 Share Posted March 27, 2012 Assuming there isn't one or more plugged injectors, does this engine use EGR? I have a Ford Ranger (different system) but the EGR is stuck open, which kills engine vacuum at idle (10"-12") or so making the brakes ineffective and it runs horribly at low speed. If I plug the EGR port so there is no flow, I get a lean code on both banks. Vacuum leak or exhaust leak near the O2? I have also seen a very bad timing chain cause hard starting, no power and bad low speed manners (this was 5.0 Ford V8 circa 1988). Link to comment Share on other sites More sharing options...
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