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Followup To
Question -
I have a 88 truck,305, 2 wheel dr automatic.my problem is rugged idle and gas consumption very
bad.I've had a tune up done at a chev dealer.new wires,new oxygen sensor,new egr valve,new
dist cap,new map sensor,all leaky exhaust was corrected.I change air filter n pcv valve regularly
even when it doesnt need changing.it starts off good then after it idles rough,after each
component change it did spectacular good gas mileage n good running then it would taper off n
go guzzling.I've also sprayed around the intake manifold and throttle body with no
change.tranny shifts good but sometimes it strains especially when idling is rough.its been
throwin out oil and I know its having a tough time(from previous vehicles)thanks for any help.
Answer -
Sounds like the only thing you didn't change is the ECM and temperature sensor.
When each of the items was replaced, was a stored code erased? Also, is your service engine light
working?
It may be going into limp-in mode.
Also, did you check the brake booster for leaking vacuum?
Van
Sorry I didnt fill you in on other stuff:I changed the tps also and once on a steep hill climb the
dipstick popped out and most of the time oil would be on the edge of the valve cover.It runs
good then starts acting up after it warms up.The ses light didnt work through all this just once
but didnt save a code.the motor is factory rebuilt approx. 100000 kms ago.60000 miles.tranny
was rebuilt 90000ks ago and I've had filter n oil change in it as well the motor gets it regular.I
havent contacted the service doin the tranny cuz its in other town but I'll do that yet.oh yeah the
valve cover gaskets were new when the oil was showin up.I have to find a good service station to
ask bout the items you mentioned.thanks.
AnswerHi P,
The engine runs on default values, rather than sensor readings when the engine is cold.
As the temp gets to normal operating temp, the ECM begins using sensor readings, and changing controlled values, such as fuel and spark timing.
All the sensor values can be tested with an ohm meter. The values can be found in Mitchell and Motors manuals.
A loose conection, or the ECM could be the problem.
Van
