Erratic idle: only when @ op temp. Sets p0171 w/ increasing frequency

Question

@ op temp idle goes from smooth, to missing, back to smooth @ varying intervals. R p m drops 50-200. Sometimes shudders when missing. Seems worse when restarted after being driven and then sitting awhile. Shudder more pronounced just after restart w/ brakes applied. Sets code p0171 w/ increasing frequency: was about 1800 mi 6 mo ago, now every 20 mi. Cannot find any vac leaks. Replaced int man gaskets (upper & lower), I m r c (both), m a f (twice), air filter, plugs & wires. p v c seems ok. Egr trouble ?

Answer 1

Hi there

It is possible there is an egr issue, but also this lean code can be the result of a bad front O2 sensor on bank 1 or a bad mass air flow sensor. usually you will get a code for both banks if the issue is the result of a fuel pressure problem.