still looking to diagnose bog when accelerating

[maximus_pr]

ok guy i decided to open a new thread cause other was to long and out of subject

Truck-'92 Sidekick JLX, Auto, 4X4, 4Dr, 16V FED
problem-very noticeable annoying hesitation when accelerating first 2-4 minutes( then it hesitates every time it accelerates for maybe 1-2 seconds but can live with that)
conditions-after it have been sitting off for more than 45 minutes

what I've done so far:
replace cracked manifold
new Bosh O2 sensor
replace plug wires with NGK SE94
new plugs NGK as well
new fuel filter
new air filter
cleaned TB(while still on car)
cleaned MAF
new PCV valve
new grounds
no trouble code reads "12"
no overheating issues
so far i used 1 can seafoam,1 bottle techron and normally 4 ounces of lucas injector cleaner on every fill up
not smoke coming from tailpipe or anywhere for that matter
engine leaking oil from front seal and dizzy(16v o-rings ordered,some extra if someone is interested let me know)


one thing i noticed before changing the manifold and O@ RPM's where at 800 @ idle with or without A/C on

now is @1300 without A/C and 800 with A/C ,pretty weird i check for vacuum leaks and could not find any

at cruise speed truck feels normal,if i accelerates suddenly it downshift normal and seems to respond pretty well for a truck its age and with such a small engine and the kind of HP it has

i know muffler is very rusted and its leaking around the outlet tube but i'm pretty sure that's not the problem most of the time i run 93 octane i would say 3out of 4 tanks i use 93 octane just cause i'm paranoid

[zookini]

Hi, I had a very similar problem ...I changed fuel injector throttle positioning sensor, wires, distributor cap, rotor, fuel filter, throttle body. etc etc....turned out to be the fuel pump have someone turn the ignition key for you while you listen to the fuel pump...if it "HUMS" its toast...hope this help.....ZOOKINI

sorry forgot to mention....the throttle position sensor must be set to "0" as in zero with an ohms meter...if it is off it will also cause hesitation....just some things to check for..good luck

[kick-fix]

correct; TPS must close at idle ( < 300 Ohms (typical is 50) ) and must get set with a feeler gauge , use my TPS page on fast sensor testing page.

How to test sensor and actuators

your A/C is inverted. RPM wise. big clue!

you need to explain hesitation more clearly and within the context of HOT and cold block.

the motor should not hesitate cold, if it does , then you have:

• stuck open (slightly)EGR (not mentioned in list and is top issue)
• clogged injectors. ( or deadones ,motor shakes?)
• ECT is bad ,showing hot when cold.
• Fuel pressure is low.

now hot motor. (lean) cold good.

• Illegal air leaks.
• MAF bad. (easy to test , just unplug it see how car runs)
• fuel pressure low.
• TPS bad , not signaling a fast right foot. IT MUST.

now the better way to explain hesitation ( if you dont mind)
the TPS ONLY enriches for the first 1second.
then the MAF catches up.

see? see how this works?

when you nail the throttle, lets say 1 inch.
the AIR hits the valves first , and this causes a gross lean condition. (unit maf catches up and the attendant fuel with it)
the TPS is the early warning device. it ( the pot side) it tells the ECU at the speed of light that , ENRICH NOW !

this stops the hesitation, and as you know, heaps MPG go down with jackrabbit starts.

if you really want to save gas, break the TPS. (only the pot side)

what is hot idle?
if you unplug the hose HOT, to the ISC does idle drop way low?
if not , you have leaks for sure.

way low is way below 800, like 500-600 or lower)


questions.

hot motor.
on a hill do you have full power? (ignoring hesitation) yes?
on a hill do you have full power , WOT. 3rd gear WOT. yes?

if you do , then TPS.

[kick-fix]

key is , saying the good with the bad. really really important to diagnosis.

[maximus_pr]

Originally Posted by kick-fix

your A/C is inverted. RPM wise. big clue!

truck was idling normal today 800rpm no air once i turned air on drops for millisecond(not exactly) the goes back to 800rpm

Originally Posted by kick-fix

you need to explain hesitation more clearly and within the context of HOT and cold block.

is like it stutter for the period of time mentioned above,lack power,feel like a small misfire but after that it runs ok

Originally Posted by kick-fix

the motor should not hesitate cold

it does it only when car has been sitting for a while then when is just a small hesitation accelerating

Originally Posted by kick-fix

what is hot idle?
if you unplug the hose HOT, to the ISC does idle drop way low?
if not , you have leaks for sure.

way low is way below 800, like 500-600 or lower)

i'm going to double check cause i remember when removed the top hose to spray carb cleaner through the ISC it seemed to run normal,but again going to double check that

Originally Posted by kick-fix

questions.

hot motor.
on a hill do you have full power? (ignoring hesitation) yes?
on a hill do you have full power , WOT. 3rd gear WOT. yes?

if you do , then TPS.

truck seems to run ok when i floor it or when going uphill

[zookini]

Originally Posted by kick-fix

correct; TPS must close at idle ( < 300 Ohms (typical is 50) ) and must get set with a feeler gauge , use my TPS page on fast sensor testing page.

How to test sensor and actuators

your A/C is inverted. RPM wise. big clue!

you need to explain hesitation more clearly and within the context of HOT and cold block.

the motor should not hesitate cold, if it does , then you have:

• stuck open (slightly)EGR (not mentioned in list and is top issue)
• clogged injectors. ( or deadones ,motor shakes?)
• ECT is bad ,showing hot when cold.
• Fuel pressure is low.

now hot motor. (lean) cold good.

• Illegal air leaks.
• MAF bad. (easy to test , just unplug it see how car runs)
• fuel pressure low.
• TPS bad , not signaling a fast right foot. IT MUST.

now the better way to explain hesitation ( if you dont mind)
the TPS ONLY enriches for the first 1second.
then the MAF catches up.

see? see how this works?

when you nail the throttle, lets say 1 inch.
the AIR hits the valves first , and this causes a gross lean condition. (unit maf catches up and the attendant fuel with it)
the TPS is the early warning device. it ( the pot side) it tells the ECU at the speed of light that , ENRICH NOW !

this stops the hesitation, and as you know, heaps MPG go down with jackrabbit starts.

if you really want to save gas, break the TPS. (only the pot side)

what is hot idle?
if you unplug the hose HOT, to the ISC does idle drop way low?
if not , you have leaks for sure.

way low is way below 800, like 500-600 or lower)


questions.

hot motor.
on a hill do you have full power? (ignoring hesitation) yes?
on a hill do you have full power , WOT. 3rd gear WOT. yes?

if you do , then TPS.

Hi, can you explain what you mean by breaking the TPS?...thanks

[kick-fix]

sorry, if you defeat (break is poor choice) the tps the car will bog and then slowly cautch up. this saves gas. there is a way to slow the TPS down just a little and ECU will still be happy with it and will save fuel. its a ecomodder trick.
sorry this comment was off topic, only a side comment.

[kick-fix]

Originally Posted by maximus_pr

truck was idling normal today 800rpm no air once i turned air on drops for millisecond(not exactly) the goes back to 800rpm



this says ECU an not controlling ISC !, may be only a symptom of something more serious

is like it stutter for the period of time mentioned above,lack power,feel like a small misfire but after that it runs ok
it does it only when car has been sitting for a while then when is just a small hesitation accelerating

HOT or cold or both or only Hot soak restarts.?


i'm going to double check cause i remember when removed the top hose to spray carb cleaner through the ISC it seemed to run normal,but again going to double check that.

Pull top air hose on iSC, then block it and idle MUST go below 800 hot. or you have a massive air leak.

truck seems to run ok when i floor it or when going uphill

MAF IN or MAF OUT.? HOT OR COLD ??????


i keep asking all these questions because the ecu operates in many modes.
1: cold start run. rich
2: warm up. tad rich.
3: hot Stoich.
4: hot restart. tad rich then quickly Stoch.
5: WOT , tad rich. (for passing)


and each my act different with load.

best is to ignore bad idle if the ISC block test passes !
as idle is the last thing to work correctly on any sick motor.


is your car hesitating cold? , (not hot restart) cold morning starts.?

[maximus_pr]

Originally Posted by kick-fix

MAF IN or MAF OUT.? HOT OR COLD ??????

MAF IN

Originally Posted by kick-fix

i keep asking all these questions because the ecu operates in many modes.
1: cold start run. rich
2: warm up. tad rich.
3: hot Stoich.
4: hot restart. tad rich then quickly Stoch.
5: WOT , tad rich. (for passing)

it only happens on cold starts or when sitting after a long time,if i go to gas station turn it of buy something quick and start truck and start accelerating is almost unnoticeable,if i park truck and let it sit for about an hour when i start it again and start driving it hesitates and lacks power unless a press the gas pedal to the floor then it slowly catch up and after a couple of minutes it goes away

Originally Posted by kick-fix

best is to ignore bad idle if the ISC block test passes !
as idle is the last thing to work correctly on any sick motor.

idle is normal now don't know how but is idling ok now

[kick-fix]

very odd symptoms.
hot soaks make it it act up.. could be lots of things.
not sure i fits misfire spark, or lean .

sounds to me like lean AFR , at hot soak restarts until the O2 wakes up and goes closed loop an then pulls the mixure from too lean to perfect. sure seems that way.


could be an air leak ( do my block the ISC air tube trick)
if TSP was bad , it would fail full time or random and not care about hot soak.
if car has full power hot ,the MAF is ok.


if car has hesitations cold , that is one sick EFI.
it should not.

the question remains is it spark or fuel related.
very hard to diagnose that , unless we can prove some way.

some , try feeding propane or instant start in tube , remotely.
long hose, duct tape ,etc.
drive and when it hesitates ,can you stop it with extra fuel.
no then it must be cutting out.

id start replace ign parts 1 at a time until it fixed if you are sure its spark.

this car has no MISFIRE monitor so we are blind, ( I LOVE it on my 96)
and not short term fuel trim to tell us what is happening.

blind is bad.

what is cold idle speed.? i think you said 1200.