2004 jeep wrangler 2.4 motor bucks on hills.
W.O.T. MISFIRE< that is what you have.!
is the CEL lamp glowing running , and for sure WOT?
yes, then scan it, get the codes, P0300? P030x? what is it?
DON'T NOT IGNORE THE CEL,
hell, id scan it and look for pendings,!!! and freeze frame fails.
i would, id not leave that stone unturned, not me....ever.
it is the first after a tuneup full, i look for troubles even marginal.
Ever to a full 60,000 mile tune up? (fuel filter?) not just plugs?
spark wires, see the list. , ,wires and plugs and filters.. skip this service, means long hard and difficult troubleshooting.
if fuel pressure is good on hills its not the pressure side. 49psi.
but the car has a fuel pressure regulator, and we test that at the pump test, its part of pump, if not skipped. with gauge, we make dang sure it regulates.
new fuel pump , means zero to me
49 psi pressure now that matters, what if the reg is bad or the
12v power to pump is 6v, bad.
and not doing the leak down test at the pump pressure
test , misses the injectors leaking, or the balance test shows
clogged injector on say #1 . (not equal)
Real tune up done, and no DTC errors store, or pending.
only hills, can be
MAP reading wrong, (clogged vacuum input to it)
when you WOT the throttle (wideopenthrottle) the MAP pin1 voltage
changes to 1Bar, (atmospheric, or 0 vacuum)
see page 31 in fuel system section of FSM.
the page is weak, no graph, but 0v (near) is very high vacuum and
4.6V at WOT, sea-level reading)
using absolute pressure method not vacuum (which i like)
is 0v is zero pressure (huge vacuum)
is 4.6v at full atmospheric pressure wot, the butterfly TV is wide open.
at keyon, no start the map is at atmospheric, pressure, 14.7PSI
or 1 bar, pressure. (about)
so if you monitor the mAP voltage output and it goes new 0v at WOT
then its done its job. an the misfire is caused by other reasons.
just one voltage test, and bam. not MAP or clog there.
i check map key on, idle and wot. 3 readings. to prove good maps.
in most cases the clean map works every time. see that its nipple
end is clean, (vac, port)
the ecu reads the MAP and the IAT temp, and computes AIR FLOW
and MATCHES that. with 12.5:1 Air top fuel ratio.
(fuel injections works just like this on Speed Density Systems)
and makes full power. if spark is good, and compression is good.
if the injectors are clooged, it misfires, if the spark plugs foul, missire
if the injectors leak, again, misfire.
that is how it all works, cept the magic fuel; tables in the ECU.
the scan tool ECT showing, 180F or more holding hot engine?
no , then thermostat is bad and AFR is rich as heck.
Is IAT reading odd? not equal to ECT first check key on , in morning not started, is bad IAT. they become equal as you sleep. overnight
the air temp matches the water.... a very easy trick this test.
by careful observation, key on, no start.
the 2 sensors report in , even key on,. all the time.
using any scan tool (not old)
Feb 03, 2014 |
2004 Jeep Wrangler