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+--- Thread: Intermittant limpmode (/thread-intermittant-limpmode)
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RE: Intermittant limpmode - fixkick - 04-01-2015
nice work !
maf ok !
the FPR seems stuck
good, the injectors don't leak
the pump seems great.
pressure, keyon great. 36-43.
40 psi at idle says PFR is DEAD> 30-37 is spec but,,,,, but need to drop from 40 lower. about 6psi lower, its not, the FPR is dead.
and should rize at wide open throttle (vacuum very low, and cause, that too is dead. so double dead FPR.
the PFR is not reacting to vacuum at all., when you start it engine at 19"HG vacuum. the pressure drops, (fuel)
and drops even more.
on this car, id expect.
40 psi key on
35 psi idle
40 wide open throttle (a goal or target, that can not be fully attained, but you see the RISE) (down so fast rpms never get to high)
and if you gun engine and pull a huge vacuum by dropping the throttle fast (25"HG?) then the pressure goes very low, say to 30psi. (closed but not fully there)
i say the FPR is dead.
and acting like above will run very rich, anytime you accelerate and will misfire, heavy. black smoke or hot CAT. effects.
the FPR seems jammed inside, hit it hard to get it to start up (hope) working again, might go a week, who knows.
seems lots of FPR fails of late. old age kicking in,.... many leak... making detection easy.
cheers
and i do hope its the only bad part.
my ugly graph of FPR
this is how it works .
this FPR starts at 36, new in box, keyon. and can drop to 21psi under extreme plenum vacuum conditions,
http://www.fixkick.com/INJECTORS/PUMP/reg-graph-mpi-g.jpg
rap it with back side of screw driver handle, smartly
once fixed car starts running like new car.
i said that wrong, the engine will be way too rich, except at wide open throttle.
because the PFR is stuck there.
RE: Intermittant limpmode - fixkick - 04-01-2015
i forgot to stay, the obvious. no vacuum to the FPR, one guy , found the port feed packed in gunk.
the gunk is the PCV/EGR gunk cloud that covers the plenum in black goo.
and covered this nipple.
easy clean of nipple fixed it. so it now sucks air. (vacuum good)
RE: Intermittant limpmode - Azplinker - 04-02-2015
After rereading description of failsafe mode & limp mode I must conclude this car goes to failsafe due to the fact it can be restarted.
Are you implying that since there were no codes generated but the FPR isn't regulating exactly correctly that the ECU is "lost" and eventually it gets enough bad data to go into failsafe?
Why would it be rich? There's no black smoke, just bogs down.
RE: Intermittant limpmode - fixkick - 05-03-2015
no.
failsafe is always, ECU (sees what is wrong, and sets a code, and goes to failsafe and mimics what is dead)
sorry so slow, email failed.
lost means just that, the ECU shows no errors. at all, no CEL , no DTCs; no errors."data to humans"
lost means , for example, (just one of many) the fuel pressure is say at 60psi (say the FPR is bad as most are now) or return fuel line crushed from wild offroad events)
if the cat is the car is very very good, it eats the black smoke, that is it's job to do that, some fresh cats can to this , IMO , amazing amounts seen....
the bog down is , usually low fuel pressure.
if you feel it misfire, then that is just that, bad spark bad compression or flooding, with or with out black smoke)
The bog down, if not felt misfiring, i check fuel pressures. carefully.
if engine has full power , say cold, then its not a melted cat.
and is not a bad engine,
its EFI related.
if if can't feel misfire, it's not spark. see?
if it's a pure bog, its fuel starvation. keep i mine i cant drive car and feel this...
nor can i smell that hot stench from the cat ,eating up all the (unseen black smoke) the cat can glow red hot. doing this, and smells nasty !
this comment assumes nothing...
the EFI system here. will get confused for: (no DTCS) in no order.
1: fuel pressure wrong.
2: exhaust leaks near the upper 02 sensor;
3: dead cylinders. compression bad. 170 min.
4: 16v induction air leaks, excessive, will cause lean, (due to unmetered air reasons)
5: FPR gone wrong (stuck or leaking inside, or just wrong in some way, so many) really this is #1 just in more details.
6: a bad 02. (the early cars allowed the 02 to have too much control...... way too much "authority" , fixed in 1996 usa, and 1998 canada.) or caused by #2
7: maf weak, clean it.
im assuming engine reaches and holds 180F + temps. and good fuel.
and not at 10,000 altitude. (ee gads no air>?)
the maf is hardest to test. for accuracy. (dead is easy)
oops we found a bad FPR way back ?
the FPR must raise pressure (fuel) fully at wide open throttle.
it must. and does so from idle up to WOT>
you map is bad or the pump weak
do the shunt test yet.?
block the return line like the fsm shows for 1 second to see if the dead head hits 60psi, (55 is spec, IIRC)
your fuel pressure is bad , at idle, and all other modes are moot , if idle fails , and does.
key on, pressure is same as WOT, on a good car.
but your idle pressure is all wrong.
it will rise by 6PSI from idle to wot.
![[Image: reg-graph-mpi-g.jpg]](http://www.fixkick.com/INJECTORS/PUMP/reg-graph-mpi-g.jpg)
OK, here goes.
fuel press. @ key on= 41 psi (this is ok, its just the starting point before vacuum hits FPR)
after 5 min key off = 40 psi (this is great, it dont leak. nor injectors leak , nor pump check ball leaks, all good)
@800rpm= 40psi )(this is hard failure. see why? the VACUUM never lowered it to 41-6 = 35psi , showing FPR is DEAD ! (its bad, or vacuum to it Dead)
@5000rpm no load= 38psi (this is irrelevant, as the above must work for all other modes to work)
as you can see, the FPR, is totally Asleep (16v only , 8v works differently)
the ecu gets lost.
why?
because it (the brain) is hardcoded, for fuel pressure to be in spec. at all times.
if not in spec. the 02 can not correct the error and the 02 is shut down accelerating and is not part of the fueling equations.
so the MAF must work and the FPR must have pressures correct.
if the pressure is too low, the injections will below. (bogs)
its a moot point but fuel pressures flogging it up hill , must be 41psi, on this car. 41 is legal key on pressure, but not at idle. ever.
but is moot because the pressures are way too high at idle. so will be wrong all the time.
if the PFR is fixed.
and it still bogs,
then all 4 injectors are clogged, (partially)
one guy in Napal , here, fixed the bad injectors, (clogged) by monkeying (not him personally) the PFR to run super high pressures to hide the bad injectors.
we fixed the FPR now it bogs (from rich idle ,spark failing)
so end the end , the new clean injectors, no like the legit PFR.
as you can see , it is possible to have 4 clogged injectors and all 4 injectors flow the same (weak), and pass the balance test. (a rare thing)
i say all this because these old cars usually have 2 or 3 major parts bad, in the EFI.
also driving all day with 12s flashing. its harmless do it. on all 89-95 for best (diagnosis of all)
and not skipping the beat,, if you see the 12s act odd, in any way the ECU is bad. bad caps.
we've see the ECU halt mid flash sequence, (a sure sign of rebooting horrors)