TPS setting

the alternator has many failure modes. dead, weak , or a huge nasty noise generator, (not sonic noise, but output electrical noise)
we scope all Alternators, and all fuel pump (same deal there bad motor commutator., see current drop out here , bad pump motor!) i digressed but is same class of testing. (for noise)
Really on cars, for sure cars. the ALternator needs to be checked first.( if it makes noise, all others test may not make any sense)(dog chases tale acts)
Do not confuse, normal ripple with bad diode ripple. ALL 3phase bridges make small noise the battery hides,
rules . do not attempt running the car, with battery removed,(say after it starts and runs>> old 1960s trick is not allowed now.
#2 do not attempt to hot wire the alt, on any running car, or blow the PCM/radio and all other electronics up to Kingdom come),<< stop , steel yourselves.

TODO: 101
if the main ALT 3-phase diode bridge, 1 diode shorts or opens, it makes a huge noise, we have photos of it here.
when it does this noise wreaks havoc on , all electronics in the car, PCM and more.
The battery tends to shunt this noise ,yes,but not always.
here are some links (YT vids) to noise. alt. link1, 2volts ripple bad.. next up bad #2.
motor mag, covers it;
in electronic world, power is first , it must be at spec DC and no noise, 200mV is not noise, 2000mV is.
history:
(we ended real DC generators to use ALT that make huge power at very low RPM, so we used alternators for many decades)
tools:
I don't need $3000 tools, all my 3x $50 scopes all see this noise easy,. (no 5vdc cheap scopes work !hear) a.k.a a lab-scope. 300v min spec scopes only/


also know that using the car AM radio, off station static heard, volume up hear that ALTernator whine? oops
some folks even see all lamps on the car twinkle oddly and flash, alternator bad bad bad.

many videos, show only a good alternator not bad,. silly that. (good bad both matter , looking at a scope)
the low level hash noise is normal
we look for huge negative voltage excursions below 13vdc even to near 0vdc, (negative pulse) this is a bad ALT.
In fact the battery will hide the excursion below 12vdc, the battery is working so 15v to 12vdc so 3vdc noise is possible, and bad.
3phase ALT are not DC generators, they are AC gens. the diode pack creates 3phase pulsating DC. if 1 phase dies, you get hit,hit miss, hit ,hit ,miss over and over again and that is NOISE MAX.


AC INPUT, AND PULSATING DC OUT, BUT tiny < 500mV ripple , the battery filter out most of normal ripple. 3 phase rectification
also if 90amp at is bad (1 diode ) it is now 60amp alt now, so is double bad.
normal.JPG
 
Duane has videos now for over 13 years on youtube
check them out?, learn how to use a lab scope, when $15 DMM meters can't cut the mustard


many of his VID'S are from real dead or hard failing car /engines/etc, not only good examples ,
He even shows the bad, and the cure and the end full results.


injector tests, PRIME (even leak down testing and balance tests.)
PCM test (sensors)
fuel pump noise. (he told you it will fail harder soon ) and why. the Commutators bad never ever self heal.


hint if the bad alternator makes huge noise those old CAP's in the 30 year old PCM will not filter out that nasty noise!. <<<< something ponder
oops
 
Eric Haberli said:
We'll, I noticed something interesting today! While driving the YJ and the hesitation was happening as normal, I noticed the Amp meter was dipping in conjunction with the tachometer dipping! After all this pain chasing this gremlin could it be as simple as the Key switch. There seems to be a electrical connection. I have chased this and it all points to the ignition switch.
Click to expand...
please show real numbers, RPM and real volts. it matters huge.

ok , what matters here is , did engine really slow down, or just the tacho did?,I guess both. felt ,seen and heard.
and what were the 2 RPM's that dipped, from what to what.?
and what was your right foot doing at the dip? steady?
The VM (it's not an ammeter at all)it is volts on dash can dip for only these reasons.below.
alternator is bad. (or 1 battery cell shorts then un-shorts, yes they can . (the REG in the ALT does not want to blow up bad batteries,)_
engine rpm when below 500rpm and alternator went off line? it sure will. (exact RPM is at the makers data sheet of said alt )
bad wiring,.(the exact RPp DROP is not known. but is hear 500e engine or 1500rpm on gen pully/

can I assume the hesitation never happens at just a steady cruise speed , right foot not moving just steady, love to know that fact.
can I assume RPM never drops below 800 RPM
the VM in the dash sure can drop to 14v , not lower at any time,. as the ALT REG dictates unless RPM fails)_
keep in mind the ALT pulley spins way faster than the crank 4:1 speed ratio, possible. ours is 2.8!
so the ALT works at any normal ENGINE RPM, in fact.
this car is 7 div by 2.5 = 2.8:1 ratio crank to gen ratio.

here is a GM alternator graphic (data sheet)_

shows what the ALT does, RPM is only the ALT pulley RPM not the engine
so
I can not see your TACH so can not know if this rule below is occuring , low hot engine RPM is 800, never less. so that matters first.
800 x2.8 ratio is 2240 rpm gen. I do not have jeep data sheets on gens, for sure replaced later as all have been..
as you can see 1000 - 2000 rpm is the BAD zone of unknown, 500 engine RPM is stuck open EGR> and is bad.(rpm and it)

rpm.jpg

I can not not drive your car and see , hear and feel any of this.
can't see MPH/ RPM,VOlts or right foot actions/. ( please tell exact RPMs first) real; data wins in diagnosis.
nor if hesitation can be demonstrated parked , in neutral.????? with wild throttle actions.?
not saying I know what is wrong
and we all know one wire somewhere is loose. (the endless story)
 
Eric Haberli said:
Dorf: a couple of things come into play.
1. Throttle body has been rebuilt with new regulator and pressure set to 14 psi.
2 I have been going to Battery ground instead of terminal B???
3 This throttle body has an ISA which does not let me put the throttle on the ideal stop.
4. We don't have many hills here in FL but we do have bridges, I have no problem going over a bridge in 5th gear.

I will try and set the differential as you have laid out in this thread. should I back off the ISA to achieve closed throttle?
Yes I'm using a Chilton manual 40650.
Click to expand...

YES STEP 3 Above the FSM preamble steps to TPS calibration,
tells us to use the jeep ISA tool to retract (its plunger full) and even says the TV must be into
the TV to TB stops screw. (no gunk there either)
idle switch working and WOT switch working. both.
the other way is to defeat the ISA, I guess just unbolt it so it cannot mess with the throttle.
forcing it by hand the plunger the book says wrecks it.

sorry for hills missing, IDK that, so we use only WOT tests, to see if 105HP is real\(spec)
only you know if power is fully on tap ,via right foot actions.
and maters first.
EFI , we tune for power first. full,then with that we fix idle next or last. idle controls love to fail if other base line things are hard failing.
case in point, pump in tank only fails,at WOT. (goes weak)
the ISA is such a pain then.

now i see the chilton only takes JEEP errors and adds more.
sad.
nothing new about that.
 
The Alt. is a AC Delco (Rebuilt) purchased thru Rock Auto. Alt. voltage at Idle (800 RPM) is 14.2 higher RPM it goes up to 14.7 V. The stumble is actually like misfire, like a switch was thrown? Right foot is steady and it does it at around 1400RPM and sometimes higher at 2300 RPM,s I have cleaned all electrical terminals and applied dielectric grease. I'm going to change the Ignition switch and if that doesn't work then I'm done chasing this gremlin. I will also have the Alt tested, it off of warrantee with Rock Auto. Thats why I don't use Rock Auto any more, plus you can not talk to a human being!
 
Eric Haberli said:
We'll, I noticed something interesting today! While driving the YJ and the hesitation was happening as normal, I noticed the Amp meter was dipping in conjunction with the tachometer dipping! After all this pain chasing this gremlin could it be as simple as the Key switch. There seems to be a bad electrical connection. I have chased this and it all points to the ignition switch.
Click to expand...
90 yJ /m/t 2.5L
now I see the throttle pedal was steady ! at 1400 up and engine power (hp) surges or cuts out or something, (high or low/)(CUTS LOW)
TPS can't do that (its new) THAT IS if not indexed wrong to its tabs. or the wires damaged (wires /pins damaged x3)
The TPS voltage must be steady at cruise, about 2vdc. not 0v ,not 5v, but at the voltage normal say for 2000 rpm. 2v and steady as you cruise.

what amp meter, ? none there stock.!~
I guess you meant dash center section, Voltmeter (IGN wire feed that is) drops?
Tachometer drops, from what to what RPM 800 is normal hot, ISA holds that RPM hot normal.
hear engine RPM drop too?, or only gauge seen to drop?>
that's a tough one ,Grimiln's are.

alternator is in spec, range and can change , as it wants, if it thinks battery needs more charge. so VM can move at anytime.
14.2 to 14.7 v is fully in range there,
the other new clue is.(best of all)

the stumble is actually like misfire, like a switch was thrown? Right foot is steady.that
surging (up/down) is ISA going nuts, at cruise it must be OFF LINE.

some call this bucking, like if spark dies hard at cruise, or surging. but if it cuts 100% dead, is spark loss., that is very violent and is not fuel loss but spark cut out. ( i find it using a timing light, and work from there) hard part, is driving hood removed to do that wild act. (duct tap trick)

caused by EFI spark devices all,. (for sure bad CKP/CMP) wiring to all all that.
newer jeeps:
1996 would set p0300 or some P03xx errors or a bunch. and for sure pending codes OBD1 has none.
all jeeps.
swap the horn relay to ASD relay spot yet.?

bad ground or any major wire for spark. failing,
power feeds, would not drop spark if voltage is 13vdc or higher, 10v on the bus yes fail , the PCM can drop out. Gen never goes below 13vdc, running
at battery or at dash VM, or on IGN On RUN power feeds. (out of IGN switch.)
RPM drop is fully normal for spark loss. 100% normal. (but the EFI system is failing)

I'd make sure DC power is good first using a real DMM meter set to volts mode.
and
the make sure CKP is ok and CMP too inside the dizzy.

it will not self heal, only get worse until dead. (my guess, soon spark dies and now easy to fix)_

Gross misfire is the only evidence we have now, steady foot told too, cruising.
OBD1 loves to hide misfire causes. it see it then if goes good, it does not set code. (or resets it too fast for humans to see it)
no DTC codes #11 ign failure, or 42 set. or 47 or 43 code.
no cruise controller options ,right? installed and failing hard. if yes unplug it. all off it and its own throttle cable too.
keyon CEL lamp glows and never comes on idling or driving ,correct?
I'd be all over finding spark drop out, prove it happens and then find cause.
OOPS renix PCM has no ASD relay.

yes ignition switches do fail, it's one of many things to kill park
if the RUN switch(on) drops below 10vdc, spark ends the 1sec later fuel.

a real voltmeter catches this, if has min/max features.(DMM )

the service manual cover IGN swaps, it shows the easy way. do not guess.

8D-55 , fsm
easy is can be this. no pulling steering wheel then, ,

easy.JPG
 
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most intermittent do not self heal, the go to worse and dead. and now 10x more easy to find
spark loss (if true x4) has many causes. even 1 wire loose. (bad grounds to PCM?)
  1. IGN switch bad/
  2. bad ICM . fire wall ign module.
  3. 02 heater shorting (intermittently) 02 heater wires hitting exhaust pipe and shorts, just unplug it and drive wires safe'd off. easy no?
  4. 1-injector power wire shorts or there wires at INJ, orange wire.
  5. HV spark coil primary wire shorts. the coil bad or its feed 14YL wire shorts. pdf pages 1870+
  6. the GEN has 15ohm protection resistor to not overload 14YL ign run power feed.
  7. CMP or CKP bad. (CPS =CKP) CMP is distributor trigger sensor. Distrib wires top pin B of ICM.
  8. bad PCM.REMIX.
  9. bad grounds at any of EFI devices.
  10. 14YL (means 14 gauge yellow) goes to idle speed disconnect too. this is a dealer installed A/C device. ,just unplug it.
  11. A new distributor maybe the only cure. it has a model called sync signal generator ( we call it CMP today) cam signal pick up coil,etc. if dead ,that TBI injector goes dead this sensor sets 1,3,4,2 injector firing order. it can even misfire for sure the CMP tone ring inside filthy. called pulse ring, ch.8D

the car uses FSM wiring sheet code 80/81 wrangler, all else , not this car.

TBI throttle body injector (1) aka, single point Injection. here is the IGN switch 14YL is the feed that because spark. (or fuel)
ign1.JPG


14YL goes here. and spark from ICM. we do no want opens on 14YL main feed or any kinds of shorts, cruising.
ign2.JPG

this post is for loss of spark cruising only. by no means fully exhaustive.
 
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the real problem, Sadly is the gremlin chases US.
IFYP!

the lack of scan tools for renix is ,never good.
my guess is DTC #11 , happen intermittently, bad distrib. or CKP
try one of these? inside dizzy, make sure dizzy main shaft not loose as goose.( lateral play huge due to bearings shot) or so dirty the mag pick up fails.
cmp.JPG
 
drive with O2 unplugged yet?, easy test and wires tied safe? so it can not short out wires .
clean the CMP (mag pickup, bearing not loose in dizzy )
makes sure distributor plug pins not rusty. (means corroded)
does not the car have that funky , spark coil Y yoke connector thing that can fail, so easy vibrating
i think not this, as listed as export or is for Canada. spark coil
or icm or its connections rust pins.
icm.jpg


coil-funky.JPG
 
spark dies random, tests. (that last resort) for cars that only fail driving, never parked fails.parked is easy , moving never easy(OBD1 renix)
proof
  1. hood off (safe is off)
  2. timing light (strobe) connected to spark plug 1or 4 what ever is most easy, mag pickup to HV wires, HV wires new, old ones are pure trash.
  3. tape tool to wipers, (duct tape)
  4. tape tools trigger to on, more duct tape ! duct tape solves all problems we are told ,does it?, we will see.
  5. key on idling and flashing like mad, good.
  6. now drive, and make it fail what ever does.
  7. and see if flashing ends. at HESITATION. (repeat for all 4 spark wires to prove none fail)
  8. bingo.? even a bad spark plug, even new with its tip cone cracked can fail at random or higher cylinders pressures.

HV = High voltage spark, 15KV. up.
if passes all tests then SPARK IS NOT IT.
if fails we work spark per above post , 27.
if all testing do not prove cause, it may be a bad PCM.
the first RENIX jeep I had 88, , the manufacturer Jeep recalled it for CKP fails. it was defective. out of the factory. so there is that;
and recalled Alternator, bad bearings at 10,000 miles. on brand new car. then.
 
rockauto, yes no more phone calls, gee they are expensive , on world scale of callers (like this part did not fix my cars problem of 50+ causes)?endless.

here is how my last (rare) RA error played out. (yes I buy local first. napa, for sure) yes,
20 new wheel stud , one is wrong
I have tool box with like 100 rockauto magnet (car collections)
I go back and click returns, and answer the simple questions ,I picked wrong parts.
then
they (only AI) asks what was wrong , i type in box. 1 part of 20 was wrong, showed photo.(proof , and crazy wrong them)
they sent it fedx next day for free.( I was floor'ed_)
I bet no online source does it that good. just saying....

wrong.JPG

yes shipping can spoil the savings. but gee nobody had it town so..... YMMV ,
 
Well: I changed the starter switch with STD US95 from O'Reilly. The old switch was toast, all terminals were a nice shade of green. Changing this switch was not easy for me! Some of my body parts don't work or bend like they use to. I had to remove much more to gain access for me. Now that I have said this. There is a noticeable change in the YJ with the new switch. The Alternator, Volt meter and Tack are now steady no more hesitation. I think I'm going to run a check on all the sensors. Every sensor now on the Jeep has been changed with the acceptation of the manifold air temp sensor as it doesn't exist? What I have notice its now running a little rich. Plug burn and milage check. I'm off to play with the TPS again. I have a new 1990 Mopar Service Manual in route.
 
Now my up shift light is not working??? I checked the bulb and is good. with key on no voltage to light. There is a switch some place but I can not find it? It's not on the right side of may A5 transmission that is posted on Youtube, the switch that is there is my back up light switch.
 
90 yJ /m/t 2.5L
running rich has many causes, O2bad, fuel pressure way too, high, FPR bad,
and this is not true. manifold air temp sensor as it doesn't exist, back then IAT was called MAT, manifold air temp , later named IAT, by SAE.
the oldest 2.5 has on top of the intake manifold
page 8w-92 there is your IAT, marked Air temperature sensor (too of intake man/,pcm pin 14 runs it.tan wire to it.
map sensor bad, makes it run rich
or map hose vac, connected wrong port, or hose bad, clogged/cracked, or vacuum does not make it to the MAP at all for ANY reasons at all.
engine vacuum is like 19"inches HG at idle and not bouncing allowed if vacuum bounces, foot off gas the MAP goes nuts, stuck or burned intake valves yes.
learn to use a vacuum tool, check engine compression,. it is 33 years old, we do not assume engines this old are good, we do that tests.
misfire from bad spark will make it go richer. all spark parts good, on 33 year old cars.

this is RENIX./ how it dues shift up lamp , ID not know
there are 3 ways to do that ,and the M/T 5 speed box has PRNDL like switch ever.
no 1,2,3,4,5, switch but R switch runs backup lamps sure
the 3 ways are, pCM renix possible is
RPM
MAP readings, map is engine load in fact.
and VSS the rear of the transfer case, 4wd the speed sensor is only there. so it does know, MPH speed.
so is the tacho working prefectly yes/no
is MPH working perfectly.

there are other factors.
sure TPS not calibrated.
sure idle regulation failing,
sure wot sensor dead
sure idle switch dead.
all of those RENIX inputs must work, or it gets confused, this PCM is one of the first EFI at jeep. I had an 88 cherokee and commanchee. both
it can not be scanned at all. using any over he counter scan tools.
when you get the FSM ,all those renix inputs you then discover must be checked out.
I drove my 2 , for 500k miles and never once, looked at the upshift lamp , ever. so and daft on that. and is firmware programing into the PCM.
this logic.
the FSM says upshift switch (except california) is cluster switch.
and say clearly it is RPM and vacuum (map) regulated. this lamp
and says(sure) the lamp is dead in 5th gear (gee no 6th" LOL)
so hood sticker shows CALIFOFORNIA, open hood look up see this.
mine below is FEd if words calif show there it calif.
they banned the shift switch claiming the RPM is too high and make smog, in calif not compliant,

HOOD.jpg

Capture.JPG
the switch is missing and the Renxi is California there is such thing
Renix ECU,(Pcm) is not the same fed/calif at all
the ax5 box> is it. has upshift swtch , just in front of reverse switch only on FED car.
no transmission told exact, but if did, id show the switch to you./

ok here
us.JPG
 
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that's a huge problem watching any youtube vids
there are these ECU (PCM)for this car in the free parts list.
  1. USA FED
  2. USA commiefornia. ( + strict visual inspections too)
  3. Canada
  4. USA? high altitude ECU
  5. and export models (i do not have those books, nor want them)

nobody on you tube has a clue about that, nor what it means!
it means smog rules are not the same in all countries. or states, even the silly up shift lamp
some cars then had up to 25 ECU sold for 25 countries.
facts
modern cars are flash programmed top all; that,
calif was the first to ban TBI , I guess that is what you have, I can't see top of your engine. calif banned it on most cars, TBI in 1995 year,.
TBI is nasty ,on cold starts and stresse the CAT big time cold,. runs rich cold and worst yet in Alaska temps.
MPI cured that, port injections did.
I do personally love TBI, gee 3 less injector to ,leak, clog or fail. bliss TBI
here is your missing IAT (mat) this is EFI 2.5L only 1990. not the silly C2DBB carb engine then/

iat.JPG
 
that seems very good , the engine. (VAC steady)
so just a bad dimmer switch, that all? super easy fix that. (and sold he parts)
IAT is there, on top of intake man, back then ,called MAT, manifold air temp, new name is IAT... parts book OEM shows it is there, and not optional.

calif PCM has no up-shift featurre, or wrong PCM put into car. The tranny switch 4/5, named is not there in calif car. so if tranny from calif put in to FED car it is missing or plugged.
the hood sticker is what matters, its it lost? all USA cars have it, and with California in the text ,. that word means , CALIF CARB certified car with all calif, smog related parts that means PCM tool.
most every old car like this, has wrong parts on it, and expected. , or missing, The are all discovered 1 by 1.
the top sensors can be tested with a volt meter DMM, no need to throw parts at this car, like (ECT/CTS) chapter 14 page 45, shows OHMS chart. for temperatature. about 200ohms hot. ECT, and same chart for IAT,(MAT), just not as hot. say 1500 ohms hot engine.?same page photo of mat
then the MAP sensor,same page. and the next p46, it tells the voltages output PIN B.
the page calls MAT a switch ,it is NOT switch both sensors are just a simple Thermistor. (thermal resistor) ECT and IAT are thermistors.

Key on not running = 4 to 5vdc,
idle , voltage, map = 1.5 to 2.1vdc. and varies with throttle action (vacuum is with it measures, )
Pin C map is named 5v. but is really 4.5 to 5.5vdc, and never changes unliss new PCM is installed, this is power supply pin, out of PCM to this sensor.
Pin A map is special ground, 0vdc.
I posted the free FSM off the sticky post, here, see that yet?.

the O2 sensor from NTK or Bosch is best, on old cars. and if it shorts out the ASD drops out and engine is now dead. it has 100,000 mile design life rating.
check out the switches on page 48 and 49. (pdf page 1374) the PDF above has 2 books in one,. so do not get confused, the 2nd book inside is for EFI.
idle switch and WOT switch tested?
see the ISA waring page 49 no ISA motor death?
Chapter 14 covers all this.
 
i made an excel sheet on the ECT/IAT rules (plotted using the log mode excel (MS) (to find 180f) using graph it mode.
the IAT is same as ECT but the IAT is a faster low mass sensor or AIR only.
same ohms rules. it is.
using log equations below to find 180f , resistance,
about 300 ohms with hot engine, 180f thermostat .ECT reading , unplugged. keyoff. use DMM ohm meter mode to discover this.
red is jeep spec, mine is log rules. estimate.
pretty good no?
180.JPG
 
my JK jeep map does this. 2008, so may yours.
key on and WOT are near the same. (at 0 HG for sure)
the PCM uses the MAP and IAT and RPM to calculate injection rates. (it does math in the PCM to computer air flow ) and is trimmed by 02 readings.
keyon is let side. if PCM is 4.5Vdc out then the MAP is 4.0v max.see how that works. ? The map depends on the 5vdc pins actual voltage for DC power.
a GM map works the same way, linear out put. not log like ECT/IAT. or cars with MAF.
MAP-sensor-output-real.jpg

the power pin is in fact 4.5 to 5.5vdc spec, it is not 5.0vdc unless it is. eacH PCM you try is different for this one pin, power.
you can not get more out than what comes in, on power pin. so we measure that power pin first. (for sure it being dead)
no sure why but , jeep fails to post MAP data. in their FSM. (new cars, sure tell you it is dead)but not so much 1990.
the map sensor can also be tested. (even engine missing!)
just key on (dmm back probing pin B)
and vacuum hose removed
and stuffed on the end of my hand vacuum tool.
and see 4vdc out, the I hand pump it to 20" and see 1.5v and I see the voltage falls from 4 to 1.5vdc in slow linear way, no drop outs, or odd actions
the sensor is fully predictable and easy to test,
only 02 sensors are hard to test for many reasons, (long story, full stop)
TPS is easy to test too, on car, and back probed with needle probes.

learn to test them, replacing them all invites , adding new problems, , like wrong or bad new sensors added, CHAOS ensues.
 
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