Login Register

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Dies when i give it gas
i have a 1992 sidekick 1.6L 16v. i thought at first it was the MAF because when the MAF is unplugged it will run fine but when plugged in it will idle a little but when gas is pressed it will die. i have replaced the MAF and tested to make sure it is good. testing the input wire at the ECU to make sure it was not a broken wire. i have also tested the TPS to make sure it is good. i have checked and clean the EGR(it was dirty), replace vacuum lines, replace fuel filter. There is no fault codes when the MAF is plugged in. i have had this rig since 2012 and the fixkick testing pages has helped me fix alot of issues but i need help on this one. any help would be great. Thanks.
first off removing the maf, instantly puts the ecu in limphome mode and full maf simulations, making diagnosis doing that super hard. ( and with late retarded spark timing and very rich mixtures, gee its only to make it home with dead maf, ok?)
that is not a valid diagnostic test but does seem to show spark is ok. kinda. ? but then again some ebay clone china mafs are pure TRAsh and prove NOTHING. I got to tell you I start with basics, (compression, vacuum,spark timing then..)
the maf is good, as you learned at great expense? if a real maf and not fake are 2nd used dead one? (most costly sensor on the car, OUCH !)
welcome , 92 16v.

the engine has no power that is the only symptom.?
so what causes that, well lots of things,....

compression is 180PSI (wot, wide open throttle ) if all 4 are at 70 psi (or way low) the cam belt slipped or the CAT is melted blocking the exhaust near 100%)
that is one easy test, no? or inspect cam timing. (also easy , type sneak a peak in my search box, fixkick.com

next is fuel pressure at key on and it idle and then gunning the throttle , 3 test here, to prove the FPR works.
on this car 16v only the pressure fuel, increases as you increase throttle and vacuum drops.
the keyon only pressure is near the WOT pressure, due to near same vucuum.

also is does power return with gas cap off or loose???? wrong or bad cap cause huge vacuum in the fuel tank. even collapsing it, badly. (my pump page shows one collapsed)

(i can only assume no gross misfiring, as spark is king, cant burn fuel with bad spark ever. not with full power)
but your maf tests (limphome) proved spark must be ok..

1: engine cant pump air, melted cat.
2; engine compression low x4, cam belt slipped as all do ignored and run pas 60k miles.
3: fuel pressures wrong.
4: bad fueL, but gee runs better with maf missing.
5: spark bad, or timed wrong, but again ran ok maf gone.

id say off hand #3 but driving it and testing is a human and machine experience, that only works best.
a fuel pressure gage finds this, type pump , on my kickfix page, type search pump.
there it is.
(05-07-2019, 01:52 AM)fixkick Wrote: a fuel pressure gage finds this, type pump , on my kickfix page, type search pump.
there it is.

Thanks for the info. i will check the fuel pressure and may get a compression check also. i have run a couple tanks of gas thru it to make sure it wasn't bad gas and i am getting just as good of gas mileage with the MAF unplugged as when it was plugged in and no issues. It runs good other than check engine light on due to MAF unplugged. Don't make senseHuh.
that is so funny, you complain the MAF failsafe simulator works too good, WOW !
(too bad the air plane that ran off the runway few days back did not have backup reverse thruster, or better a LIMPHOME reverse thrust-er (fully joking but not the crash just the analogy) (the log books said do not use engine reverse thrusters and expect huge longer stopping distances and matching long run ways, oops..... ,)

my mpg is 26mph and up to 28.,...
if 15mpg is normal (unstated by you)]
then limhome at 15mgh would match that. right?. so the actUAL MPG has meaning for sure. I bet you dont get 28mpg no MAF, all call you on that, LOLl

have friend with G16 sidekick (unlicensed) and runs maf free pulling tree stumps. 15mpg is AOK here. sure. 1 tank a year? less.?

so run MAF free, it is your car and your cash. (for parts or gas)

so you ran 300 miles with 10 gallons of fuel with no maf plugged in, if yes, you need to put this car in the Guinness records.

Trying to make sense of limphome , is really too hard. why try,? its all emulation simulation of dead sensors. that is what it does, it does its best to get you home.

a refurb MAF is $400, and new at over $1200 from Suzuki.com (i bet you didnt pop for that, am I right?)
the ones on fleabay are either good or trash, there is no way to know before what china knockoff MAF works , no way in hell. (IT IS CALIBRATED SENSOR NOT A TOY)

i say drive, it , no State smog man , drive it like you stole it they say;.

PS : i think your mafs are bad, if all else is ok, it is.
the ECU does not know a weak maf ever. (READ THAT 2 TIMES)
only dead mafs set the DTC error for dead maf. (dead output near 0v or stuck at 5vdc)
the maf is chicken and the egg device. (WHICH CAME FIRST?)

if the maf is weak , the engine will have very low power, but if the engine is weak the maf will read weak see how that works, tricky no?
lets say youR cam belt slipped, anD now the engine is weak (cam timing retarded)
and you test the maf with a voltmeter and it will read weak but is 100%^ GOOD. (SEE THAT, YOU CAN NOT TEST A MAF WITH A WEAK ENGINE BUT.
the maf is very tricky indeed. in this way.
lets play game #2

lets say fuel pressure is very low, but not too low to end idle RPM .
then you measure the maf it will will read low after all fuel pressure is say 20psi not 36. (for full power 36psi is minimum) at sea level with 14psi atomospheric pressure 43 is needed)
WOT is max fuel pressure and at sealevel. even more pressure fuel. the FPR does this MAGIC unseen... (and KEYON only pressure is max max at sealevel)
the maf is 100% good,
then you remove the maf, then the MAF simulator goes on line (pure software/firmware) and goes super rich, as all do this way.
It goes rich for 3 reasons, On purpose, to not burn up exhuast valves (LEAN) and to not make NOX smog, or cause deadly Ping (detonation damage)
then with the SIMULATOR running (IT IS) the fuel pressure works seems OK now and engine wakes up.. due to limp OVER-INJECTION rates the SImulator uses. see?
also know this if the fuel pressure is low say 25psi then limhome hides this fact, from super lean AFR to more normal and not too rich see why?
see that balancing act, and the funny rule of MAF, 2 wrongs making right here? Classic, this is.

the silly simulator has no air flow data at all ! NO DIRECT WAY TO GAIN THAT DATA PERIOD and is KEY here.
nor is there a fuel pressure sensor on this car, at all. (like new cars have)
it uses INDirect or crude inputs:
only it has TPS throttle angles and RPM.) it does crude air flow CALC's based on this poor set of inputs, and GETS YOU HOME,.that is it's only purpose this. (this is not confusing, at all)
Your car has no MAP sensor (96 has EGR MAP but is not a real MAP)
so computing Air flows are super hard lacking a good MAF. (removed map)

the 2 wrongs are
fuel pressure low, maf missing (unplugged) and in limphome,
these 2 wrongs make and almost right, (Correct)
see why?
if not just know that it hides mostly that low fuel pressure.
what you did to the maf.
fuel pressure 101:

here is the FPR chart I made using real Car real live data...

mostly all we car is the 0 vacuum data point, (means actual fuel pressure in PSI)
ignore BAR readings for ROTW, rest of the world metic.

0 vaccum 36psi, keyon, not started yet.
then idle., see that? a tad over 32psi.
this is all FPR actions here. the pump can do 60psi easy.
you may have bad FPR is all. if it does not do those 2 test correctly it is bad. (if the shunt pump test PAsses )
if you off the vacuum nipple here and it leaks fuel the FPR IS BAD>

[Image: reg-graph-mpi-g.jpg]
my joking green is for Grengo;s... yes,i am sick.
AT WOT, FUEL PRESSURE TRies TO REACH 36PSI BUT DOES NOT. (some vacuum remains)
Now to really cook your noodle (matrix quote) the pressures across the injector never changed with throttle actions, (air/fuel) making injection rates super more easy to compute.
The FPR did all that magic. holding that a constant.
Thanks for all the info. yea you got my head spinning a bit. lol. I am getting 25 mpg with 235 tires with MAF unplugged which is about what its always got. i want to fix this problem cause i just don't like things that don't work right. The vacuum and or leaf blower is a great idea. i will have to try that or what do you think about putting a calibrator on the input wire(MAF) going back to the ECU. With the MAF unplugged i can simulate a MAF. i use one of these to test electrical equipment. i can source a 0-5vdc signal back to the ECU and that would tell if my MAF is no good or something else. When i checked the MAF, i was getting 1.4v with key on and 2.0v at idle. i could get the signal to go up to about 2.5-2.8 when i gave it gas but that was about it before it would die. i am going to have to get a fuel pressure gauge at harbor freight as i am having trouble getting my hands on one.
the first thing to do is measure fuel pressure, you MAF works great, leave it be.
The fuel rail adapter seen on my PUmp page, or the fuel filter banjo test port 6mm ISO theaded. (on fixkick.com search Pump ,first hit there are 2hits first and 2nd is I know its wrong now.)

my post above says long way.
if the pressure is low , the car will bog (lean burn, bog no power all cars will MPI)
and removing the MAF forces the ECU to over INJECT(LIMPHOME)< hiding the above failure! this is what it does . and is not a bad maf.

It is THAT simple (2 wrongs can make a right in the computer world, (this ECU is dump so...)

if the car was new you'd you'd have this, (easy to understand no?)
1: lean DTC. 171 T , ALL OR SOME.
2: FUEL PRESSURE LOW DTC. P0087 (varies by maker this)

is the fpr vacuum nipple leading fuel
FPR and the pump are 2 top G16B failures on this old card
both are tested at the same time and same why with a test gauge, all shops have a gauge, or chase their tails.
ever auto store on earth has fuel pressure gauge, even Harbor Fright(pun)
no shop working fuel injection can make progress lacking this first gauge.

I bet the FPR is dead. that is whaT i BET, BUT I CAN BE WRONG WITH pressure test data, then guessing ends.
data = cures. = evidence.
The tests are there 5?
keyon (bet you if this test is done first it fails, yes,shunt test is next to see if pump is bad next) key on is the high reading so is first.
idle (lower by 5psi)
wot (rises to near keyon)
shut test proves pump good or bad in 5 minutes work 55psi?
leakdown test is not too important but will find leaking injectors , a far worse horror.

Forum Jump:

Users browsing this thread: 1 Guest(s)