1993 Sidekick Engine miss

[Harry Mudd]

Hello all.
This is my first post and I was hopeing someone could help me with a problem I'm having with my Suzuki sidekick.
The basics first:1993 sidekick 4Dr,1.6 jx 16 valve engine,manual trans,4x4.

The problem:The engine starts and idles ok when its cold.After it warms up the third cylinder back starts to miss intermittently.Also when you start driving as soon as you let out the clutch it falters,bucks a little(misses??) then revs up and goes.This happens through all the gears when you try to accelerate.The harder you try to accelerate the poorer it runs.Let up on the throttle and it smooths out.Push in the clutch when you are moving and it revs up fine,let out the clutch and it seems to miss under load.

What I have already tried and figured out:I know only the one cylinder misses at idle because I pull that plug wire and it makes little difference in the idle RPMs.The rest make a BIG difference in idle when pulled.On the faulty cylinder I have,checked compression(its ok),have replaced the injector(didn't help),checked fuel pressure(its fine),Replaced the plug(same problem),Replaced the plug wire(still misses),replaced the distributor cap(it was bad but did not cure problem),Replaced some device that is connected to the distributer and screwed to the firewall on a heat sink(cant remember what it was called but it didn't help),and checked the connector on the injector for bad contacts.I have also checked for bad grounds,made sure temperature sensors worked and had good connections,checked the throttle position sensor,MAF sensor(best I could),checked all of the wire harnesses,cleaned if necessary,checked idle air controls,still same problem.
On some website somewhere I read that capacitors go bad in the computer so I replaced two electrolytic 47uf 50v/25v caps that supposedly go bad.Still does exactly the same thing.
I have checked the voltage at the injectors and they are the same accept for the one faulty cylinder has around 11 volts and jumps all over at idle and at higher RPMs.The rest hold somewhat steady? voltage.

The car also seems to run a little better if you pull the TPS plug.Still misses though.

I checked the computer codes and get a code "12"?? I think.

So I'm thinking this is a computer problem and not some other external sensor or control.I don't have a schematic of the computer to know what voltage in and outs are supposed to be.May be I need a service manual?

I really like the little car and hate to give it up.Great mileage,easy to park,drives great(when it runs good).I have already spent a couple of hundred dollars on it for parts that didn't help and I don't want to spend another $300 for a computer and not have it take care of the problem.
Any suggestions?

Thanks all in advance.

[jtgh]

great testing !!! Mr. 93 16V!

I can not imagine car running ok cold ( i bet it runs like heck of you put a load on it cold , right?)

on your car, the ECU drives each injector with a different driver. (92-95)
the signals are "on" for 5ms ( 5/1000 th of a second in duration) (takes a scope to see) but you can try AC volts with a DMM and compare to the others. NOID lamp is best test.
The ECU grounds the injectors to fire them on this engine.


cylinder #3 is misfiring.
compression bad, no you proved that's ok,
injector bad, no, you swapped it. ( one can be cleaned for $16 anywhere)

Lets focus on that:
Make sure you have 12.65 to 14.7vdc to the hot line of this #3 injector.
it comes from same place on each injector, the main relay under dash.

next using an ohm meter check the coils on each injector. (harbor freight $2.99)
they must the same. ( i can find spec for them ,let me know your reading)

then ohm the other side of injector wire back to the ECU pin B13.
B13 is the injector out for #3 .
must be less than 1-ohm. Its just wire, end to end.

I bet if you flog the car cold , it messes up too, not just hot.

You can use a NOID lamp to prove the injector signal is bad.
costs $1.20 and radioshack,


click>> http://carfix.stufftoread.com/NOID/91-noid-sf1.jpg

just plug lamp where you unplugged #3 injector.
this lamp is very sensitive (ultra low current) (and no polarity like LEDs)


Sorry you bought an igniter. ( a good spark tester is priceless )

click: >>
http://carfix.stufftoread.com/check-spark.jpg

keep in mind, on a 16Valve, hates air leaks, and self destructs on Tbelt slip.

THANKS for that DATA point on the TPS.
in theory the TPS removed was discovered by the ECU and then
it mimics a Vitural TPS using the MAF and or The MAP sensors.
that was part of the Limp home , feature ! cool.
on your car the MAP is only used to test the EGR , constantly.

so your MAP if working if you can accelerate with TPS disconnected.
That is a good diagnosis for a MAF !!!

thanks again. ( I love free diagnosis tricks and that a bell ringer).

good day to you , and happy holiday.

[jtgh]

http://carfix.stufftoread.com/flow-c...hesitation.jpg


the above might help.
it isnt perfect but , it tries to save money . hope it helps you.

[Harry Mudd]

Hi,Thanks for the reply.Yes it does not run "go?" well cold either.I just dont notice the miss untill it warms up.

The wireing diagram is going to help a lot.BIG THANK YOU! for that.

It will be a few of days before I get the tests done but I will post the results when I do.

Something that I did not mention is that last year I had a freezing weather morning start problem.Fires right up if its above 35-40deg below that it was a problem.What would happen is that the car would crank and seem to back fire against the starter and actually stop the cranking prossess.I would have to hold the accelerator to the floor and it would kind of slowly fire up.And yes I thought it was going to tear the starter motor right off the engine.After the first time it started up fine for the rest of the day.

Thanks again.

[jtgh]

my thoughs:
That Noid lamp will put you on track , Mr. Mudd.

crank kick back? oops. ( too much static advance)
consider:
check your ignition timing, if off , suspect a cam belt . slip.
These engines will self destruct with a bad belt or bad belt idler.
interference engine, it is.

Ignition is 8 degrees before top dead center. with proper jump in place to freeze ECU timing advance feature. at 800 RPM.
timing lights are cheap at Harbor freight for $11 (inductive to boot)

Time Freeze pins on Diag, connector (4 pins) front of battery.
Pins C jumped to D is for freezing the ignition timing
Ignition timing being off is a Bell ringer for TBELT slip.

how ever you could pull the Tbelt cover and validate that , but that is more labor.

ymmv:
I would never own a 16v unless I had put in a new belt.

$20 belt , can kill a $2000 engine.

[Harry Mudd]

I started it up this morning (25deg weather)just to see if it still had a problem and it cranked over just fine fired right up.Didnt have time to warm it up but I took a lap around my yard and it bucked and coughed when I hit the throttle.I havent been driveing it in several months because of this bucking problem but may be I fixed the cold start problem in all the other things I have done to it??

And yes i am playing with fire with the timeing belt.It has a lot of miles on it.Belt looks ok tensioner seems ok but with belts they can let go at the worst time when they are old.If I can get it running good again I promis to replace it.

Something I forgot to mention about the spark plugs is that when I pulled them to check compression they all had an evan pattern and were the same color.Evan the suspect cylinder looked great.

[jtgh]

your best had data point , #3 cylinder is dead
1- no spark ( easy to test with dummy Spark plug atteched to #3 lead)
2- no compression ( you did it and it passed) car idles and others are working.
3- no fuel to #3. ( most likely problem) < NOID lamp time. !


You have a bad #3 injector Signal , by your own analysis. (injector replaced)

I would not hesitate to test the signal to the #3 injector.
a simple NOID lamp will prove that the injector sig is bad. ( or your spare was bad too)

if it IS in fact bad, then we work backwards from there.

COLD run is SIMPLISTIC mode, always trouble shoot this mode first)

You car must run ok cold , if not that symptom is very serious because the ECU
runs Hard coded fuel maps, based on TPS values.
Those values are what create the injector pulse widths that are Rich.
The other factor is the temperature of the water sensor (not guage sender) , if the
water sensors says hot , when engine is 25degress , car will try to start lean if sensor lies.
So you have 2 critical sensors here (for A/F) , TPS and ECT.

all that ECU stuff, is pointless if #3 injector is dead.
we need to prove it is not. ( i suspect you can not) the noid lamp is an indespenable test tool. @ $1.20 .

All symptoms point to bad signal. @#3

[Harry Mudd]

Ok got some testing done last night.

I put the NOID light across the terminals of the #3 injector connector and it flashes when you crank the engine.I also put one wire to chassis ground and the light stays on steady when the key is on and dims a little when you crank the engine.Does not go out completly.Also is the same for the rest of the injectors I checked.

Testing voltages and injectors.

#1 cylinder:13.5? ohms across the inj contacts.12.1 volts on the connector.9.6 volts when you crank.13.9 when running.

#2 cyl:14? ohms/12.1volts on conn/9.6 cranking/13.9 running

#3 cyl: 13.7? ohms/12.1 volts on conn/9.6 cranking/13.9 running

#4 cyl:Ok it was cold (25deg).I got lazy.Its a bugger to get to without removeing air intake and did not check this one.My bad.If needed Ill do it...begrugingly.

Some other things I noted:There does not seem to be a miss if the TPS is unpluged at idle.When unplugged the RPMs go up a little to around 1100.When you plug in the TPS after a few seconds the idle drops to about 900 and it starts missing.Randomly.It does miss on #3 the most but seems to miss on others as well.This is what I think is happening based on pulling the plug wire/wires at idle.Not a good test im sure.
The engine always faulters when you try to rev it up then it revs ok and I dont hear a miss.At least at higher RPMs.Dosent matter if the TPS is plugged in or not warm or cold it does the same.Faulters more when its warm than cold.Faulty TPS??I need to retest it?

Also with the TPS plugged in,engine warm,there is no power.You can drive it but getting up to 50mph is difficult.Plug in the TPS and it is driveable but still faulters on takeoff and shifts.It will do 70mph.

How about fuel pressure.My father in law checked it with a home made gauge set up.Perhaps we did the testing wrong?

This may be unrelated but there is two vaccum solinoids mounted to the front of the intake manifold.One of them is plumed to the intake and there is a line going to a canister that looks like it has a hose going to the back of the car.Gas vapor recyler?I noticed that when you rev up the car it clicks and continues to click at higher RPMs.I pulled the hose and vaccum is present.I pulled the wire off and it stops clicking and vaccum stops.

There seems to be no problem with cold starting anymore.Fired right up in 25deg weather.

Did not check voltages at the ECU.figured that would be best left for another night.

[jtgh]

very sick car: 16v (code 12 ok)
"Dosent matter if the TPS is plugged in or not warm or cold it does the same."
good clue: Tps is easy to test on or off car, leave on. check ohms thru whole throttle range ( 0 to 3k ohms 3-5k at upper end)
forget #4 injector !

You sound lean to me , even cold , that is a problem!
#3 is just the weakest cyclinder and is sensative to lean more than the others. maybe?

Vacuum hoses,
pinch them one at a time, (closest to manifold) and if any cause a change in RPM, suspect that circuit.

exceptions: PCV , no pinch, ISC idel valve air tube, do not pinch. and fuel reg.
check brake booster hose must not leak or cause RPM change.

if the one you are doing (EVAP) then pinch it too, you can keep it pinched to drive.
same for EGR vac hose, pinch it , listen and drive like that.

the one hose I have this is not pinchable is the diaphragm in the idle TB shaft.
i call it a dash pot (16v have this?) it can increase idle under certain conditions.
make sure its diapharam is not leaking but sucking its tube with lips (yuk) or a vac test tool. ( i think you dont have this part)

disconnecting either the TPS or MAF will cause ecu to mimic the missing part.
it is my opinion that, that action will cause rich mixture.

I think that if pulling both will kill engine ,try it? (if it doesnt kill it then car will be richer)
{love to know what happens with that ?}
if it runs that means ECU is using the MAP sensor that manual says is never used. hummm

if by doing THAT, engine power does not improve then it must be spark.


It is true , that trouble shooting cold running , will fix this car easier and quicker.

Keep in mind, in a shop with no 4/5 gas analyser connected to oxy port , we would:
that fancy tester will give an instant answer to mix.
ALT:
1- bleed in more air to see what happens.?
2- or bleed in some propane gas to see what happens.
if more air helps, engine is rich.
if propane helps, car is lean.

the brake booster hose is a great air source. (dont just pull it off, as it will kill engine)
one pulls it , plugs hole (engine side) and then opens it up gradually, noting the effect.

if non of these tricks help the problem , then spark is bad.


your car has a fuel rail, on that rail is a plug that must be pulled and and adpator installed to measure rail pressure. its non trivial to do.
tests 1, 3 and 6 are critical to you:

bomba

you need 30 psi of pressure ! the FPR must be tested.


i am not sure if your problems is A/F or spark.

Clues: (kick commons)
compresson above 150psi? and equal ( will be low if Tbelt slipped)
ignition timing close to 8 deg BTDC when looked at first time, if it was way off and you changed it then that too is a clue to TBelt slip. IGN timing should NOT drift off with usage. ( ECU has timing freeze jumper to see correct static timing)

is crank pulley 17m bolt tight, 94fl/lbs torque and pulley not loose as is comon?
94 is new TSB spec.
IGN timing will bounce even with Time Freeze jumper in place. ( if pulley is loose)

( sorry we are at rich lean , spark still) but here are my Shade tree tricks.

[Harry Mudd]

Last time I tryed to disconnect the TPS and MAF the car would stall.One or the other plugged in It would run.I did not try this last night.

Have not tryed to pinch any hoses.Only checked for loose and cracked ends.Will recheck.

There are 4 contacts on the TPS.do you have the procedure for proper checking?Please and thank you.

Can I hold my harbor frieght propane torch over the air cleaner intake or is that a really bad idea?

I think we checked the fuel pressure at the fuel rail front plug.He had a hose and what looked like air pressure gauge.The best tool to use for this would be?

Plugs did not look lean to me but were plenty light.

Looks like I have some more testing to do.