intermittent missing fault in lowrange

[Deadduck]

Hi I have a suzuki vitara 1994 g16b nz new market. I have a weird missing fault in only lowrange high range and 2wd are fine so when I'm driving along in the bush at a mid - slow pace i will have my foot down enough to just where it is keeping a constant speed and it will all of a sudden miss for a few seconds then come back in and it will keep doing that I have the hotwire mas that has been changed so i know its not that has a new 02 sensor done one old one as well im just not sure where to go or what to test next timing is all set correctly.
Thanks

[fixkick]

hotwire mas ?

[Deadduck]

Yes the 13800-58B00 mass air flow sensor that I have replaced a few times

[fixkick]

sorry the hot wire, MAF, yes, and in Europe its van flapper type, not hot wired,
i was thinking you hotwired, the maf, to fool the ECU , LOL !
more later

[fixkick]

does the diagnostic jumper
inserted inTO the DLC, (CONNECT0R)
running ENGINE , make the CEL lamp , flash code 12?
1:KEY ON CEL GLOWS. Check engine lamp, = CEL
2:START ENGINE,
3: CEL lamp turn out, insert jumper , code 12 flashes, means OK

[Deadduck]

Yes has code 12 all clear.

[fixkick]

misfire. 101 (only under load,) did you know spark plugs that are really bad , always fail under load (high cylinder pressures, do that) This can be demonstrated in old days we had a tester that did that test, to prove to tight wad customers (1960s we had it), see, your plug here fail. see it misfire in this nice DELCO tester?(bench)
we have spark plugs here (oem stock) sold in stores here, for $1.49 cents. its called a no-brainer tuneup, harmless , easy fast and can be magic. (by not means fixes them all)

bullet list.

code 12s while it misfires? and while driving, do know that you can drive for a week, with 12s flashing , with no harm at all.
after all it might pop a code from CMP? be super important to know that for sure.
misfire has over 50 causes. (parts bad and more) but in Physics pure far less and even less doing 1 to 10 tests.

is car a daily driver.?
was it a BARN FIND? parked for years.
or just old "Nelly Bell", that is the farm used, stump puller.? only.
or a trailer-ed only , offroad only machine, that sits all winter in a garage?

ever do the 60k mile (repeats) full tune up in the last decade? if no ,why delay this?

misfire pure physics we do tools way more easy, (scanners , 3 gauges, and tools, meters etc)
misfire 101:
1-bad fuel
2-never ever tuned up, spark parts, air /fuel filters.?
3-the EFI is is not getting full 12vdc power all the time (bad wiring to power source battery, called 12vdc power drop out, and cuts spark dead in 1 nanosecond fast. instantly.
4: engine compression low, x4 , or the crank pulley never torque to 17mm large bolt at 94ft/lbs (or 128-N/M) and the crank snot is now wrecked
5: Spark failing, plugs , HV wire set bad, cap , rotor? see #2.
6: bad fueling (called high AFR) , flooding, and spark tips black? fuel pressure wrong, 02 bad.?
7: TPS bad causing Tip -in acceleration lean outs and misfire.? will do it, car moving at any time right foot moves.
8: weak maf, or air leaks past it making it read wrong. clean the hot wire from 150mm distant, using maf cleaner safe for plastics. only.
9: air leaks to the engine Plenum , will go lean and bog or feel like its starving for fuel, vacuum leaks small are corrected by working 02 , larger are not and goes lean on all vacuum leaks.
10: scans show the 02 sensor (Front) is stuck? exhaust leaks near it , is hopeless.
11; low fuel pressure, it must be at spec, and the FPR tests must all pass, (vacuum over fuel pressure bar tests) if not the FPR IS BAD. most now are failing BTW. to old to be any good.
12: the main AIR intake on our 16v has this huge pipe that an leak air. seen them crack or seals there fail. lots. it must not be allowed to leak. air.(suck air from non maf end)
13: A WONKY CMP , cam sensor , never fails on ours. ever. but the wires to it x10 more likely. bad wiring, to all EFI parts same deal. HALL Sensors RULE !

that it. hope it helps in some small way.

good luck.

[Deadduck]

Thanks for that not a barn find drive on the road sometimes done quite a few long distance trips and is completely fine 100% on the road it's only Lowrange for some reason under sort of half load engine has ben fully rebuilt top and bottom o2 sensor was bad from extractors hitting body and chopping wire off so got a new bung welded in all the spark plugs were done when rebuilt but it also done this before rebuild I have a feeling it could be my cam position sensor(hard to find over here) or ignition side of it as when it does it it blows black smoke so tells me it's not burning the fuel it has no cat and 1 muffler I will get into it and check what you have said and do some more tests. Thanks

[fixkick]

only 4wd LO fails, 4LO? only, makes no sense. at all why any engine would fail in 4LO. the engine nor EFI knows you are in 4LO at all. only that RPMS are high. after all its huge gear reduction.

the engine has one cam and a distributor
and no cam sensors on the cam its in the distributor bottom. base.
that sensor is a Hall sensor, that never ever fails, and is not sold, only sold as ebuilt distrib. the Hall sensor there , there is no contact from the star reluct or the hall, so lasts , until the distib bearings go horribly bad, if it did fail, code 12s fail. as it misfires, the book says, 1 in 10 misfires of the HALL sensor are reported, and is, one has to be looking then to see that. driving

the wires on side of said distrib can fail as are those pins.
The coil can fail.
new spark plugs, not saying your new plugs are bad if new, but if they turn black , on the tips, then its running rich and misfiring.
4L only, never in 1st gear , wound out. 2wd.
all i can think of given that as TRUTH, is engine torque reaction cause wires (EFI) to stretch on engine and fails.
keep in mind code 12 means little, it only means key parts didnt fall off the engine, like MAF, ECT, IAT, spark coil , CMP died , and that.

we look at spark tips first see if its running rich. no scan tool to see fuel trim so, one has to gander at plugs, called reading the plugs.


nobody sells the CMP, sorry, not even SUZUKI shows it in the parts cat, no after market seen either, if you look on rockauto, there is nothing.
not only that but you have different distributor than ours, are you in market 24?

see this , number 24, yours different is different market and has its own parts.
some have non hot-wire MAFs called AFM air flow meters, looks like toilet punger to me. LOL

see this? this tells the helper exactly what is under the hood.
http://www.fixkick.com/specs/Body-TAGS/J...4plate.jpg

-

[fixkick]

our G16b (16valve) 92 to 98 , no cmp sensors sold, usa, /canada
but outside USA,, same on on -70E00 and E10 distributors, the suzuki book shows no parts inside sold but the dust over.
Suzuki never sold it, only 8v had it in very early years, with VR pickups and ignitor inside, the distrib, and sold by all. but that is only on 8v.
when the moved changed the Distrib (here in 1991) to HALL sensor, all this changed,