erratic idle

[yellowgizmo99]

OK, read other threads, does the idle go away or is all the time, mine seems to go away as it warms up, got parts on order, IACV and TPS, been cold here for the last couple days and yesterday it was in mid 80's and it started and ran fine, no codes. This morning it started fine but as was leaving it started the hunting and stalling and code came on, havent got code read yet. Is there a sensor for the "choke", I have looked and cannt locate in manual. checked for manifold leak and none showed up also.

[etlsport]

have you gotten the check engine light code read? thats where I would start

[WormGod]

Mine is currently in the shop for a similar fix. Cold starts are fine, but warm starts stutter and stall. The crankshaft and camshaft sensors started throwing codes. I replaced the crankshaft sensor (do not recommend on your own unless you have time, patience, and mutlijointed/skinny arms) but was not in the mood to tear down for the camshaft sensor. I actually stopped by the shop yesterday to talk to my new mechanic about the S/C install so he could get more accustomed to the mods to know what he was tackling. He did some head scratching as the cold vs warm boot is pretty elusive, but he is also confident that replacing the camshaft sensor so it can marry information to and from the crank sensor is the best place to start.

Like etl said though, get those codes read. You will be hunting for a needle in a haystack until you do so.

[tom4bren]

By all means ... get those codes read.

Until you do though, here are a couple of other things to try:

1. Make sure your AC & defrost are turned off when you start the engine & stay off till you reach operating temperature.

2. Clean/gap your plugs.

3. Clean the MAF.

4. Reset the computer by disconnecting the battery for 10 min.

These prolly won't make a difference but worth trying anyway.

[yellowgizmo99]

OK, ran by and had codes read, 101, 102, 1441. have cleaned MAF, new plugs gapped correct, reset computer, dont run AC or heat at this time. 1st 2 are MAF related, third is evap flow during non-purge(?), have new pcv valve, got IACV in today, havent picked up, is this looking like a MAF replace?

[yellowgizmo99]

hot start up is fine, when cold starts right up but the hunting and stalling when slow down thou will start right back up

[tom4bren]

... is this looking like a MAF replace?

Probably but worth cleaning again & replace the airfilter too before purchasing new MAF.

[samneil2000]

Fuel filter and fuel pressure regulator are possibilities.
I recently replaced both on mine.

[yellowgizmo99]

OK, changed IACV and cleaned passage(it was gunked up), cleaned MAP again, new filter from Ascinder, its huge and a pain to fit it in, took off TPS just to see, it runs better but the idle is a little high, are you able to change it by moving the TPS, there is not much movement in it though. will probaly change fuel filter while I am at it.

[WormGod]

TPS is a non-staged sensor. No adjustment. I wouldn't be so fast as to blame the MAF unless the 101 and/or 102 surface again. It wouldn't hurt to swap out the fuel filter and throw a dose of Sea Foam through her. I am leaning more towards your fuel flow since it seems dependent on gearing and throttle. If it persists, I would consider a new fuel pressure regulator as your next step.

[yellowgizmo99]

idled good this morning into work, still change fuel filter and may check about regulator, ran some PK44(?) fuel treatment thru it.

[Riff Raff]

Seems like you are hitting all the possible culprits. I'd say change that Fuel Filter and fill her up with a fresh tank of High Octane (Premuim Unleaded) gas. VX's like Premium Grade fuel-- it makes them happy. Keep us posted.:bgwb:

[Mile High VX]

Here's a MAF on e-bay.

http://cgi.ebay.com/ebaymotors/ISUZU-VEHICROSS-99-01-air-flow-sensor-meter-/400077009290?cmd=ViewItem&pt=Motors_Car_Truck_Parts_Accessories&hash=item5d2672b18a

[etlsport]

here's whats listed for the 101 and 102 codes


Circuit Description
The mass air flow (MAF) sensor measures the amount of air which passes through it into the engine during a given time. The powertrain control module (PCM) uses the mass air flow information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity or air indicates deceleration or idle.

The MAF sensor produces a frequency signal which can be monitored using a Tech 2. The frequency will vary within a range of around 4 to 79/s at idle to around 25 to 40g/s at maximum engine load. DTC P0101 will be set if the signal from the MAF sensor does not match a predicted value based on throttle position and engine RPM.

Conditions for Setting the DTC


The engine is running.
No TP sensor or MAP sensor DTCs are set.
The throttle is steady, TP angle doesn't change by more than 1% .
System voltage is between 11.5 Volts and 16 Volts .
Calculated air flow is between 25 g/second and 40 g/second .
Above conditions present for at least 1 second .
MAF signal frequency indicates an airflow significantly higher or lower than a predicted value based on throttle position and engine RPM for a total of 12.5 seconds over a 25-second period of time.
Action Taken When the DTC Sets


The PCM will illuminate the malfunction indicator lamp (MIL) after the second consecutive trip in which the fault is detected.
The PCM calculates an airflow value based on idle air control valve position, throttle position, RPM and barometric pressure.
The PCM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.
Conditions for Clearing the MIL/DTC


The PCM will turn the MIL "OFF " on the third consecutive trip cycle during which the diagnostic has beer run and the fault condition is no longer present.
A history DTC P0101 will clear after 40 consecutive warm-up cycles have occurred without a fault.
DTC P0101 can be cleared by using the Tech 2 "Clear Info" function or by disconnecting the PCM battery feed.
Diagnostic Aids
An intermittent may be caused by the following:


Poor connections.
Mis-routed harness.
Rubbed through wire insulation.
Broken wire inside the insulation. Refer to Intermittents under service category Symptoms.
Any un-metered air may cause this DTC to set. Check for the following:


The duct work at the MAF sensor for leaks.
An engine vacuum leak.
The PCV system for vacuum leaks.
An incorrect PCV valve.
The engine oil dip stick not fully seated.
The engine oil fill cap loose or missing.

[etlsport]

here is whats listed for the p1441 code

Circuit Description
Canister purge is controlled by a solenoid valve that allows manifold vacuum to purge the canister. The powertrain control module (PCM) supplies a ground to energize the solenoid valve (purge "ON "). The EVAP purge solenoid control is pulse-width modulated (PWM) or turned "ON " and "OFF " several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. The duty cycle is calculated by the PCM and the output is commanded when the appropriate conditions have been met.


Conditions for Setting the DTC


No active ECT sensor, IAT sensor, MAP sensor, or TP sensor DTCs set.
BARO reading is above 85 kpa .
Engine coolant temperature is below 70°C (158°F) .
Start-up intake air temperature (IAT) and start-up engine coolant temperature (ECT) are both above 5°C (41°F) .
The difference between start-up ECT and start-up AT is less than 25°C (45°F) .
TP sensor indicates a throttle position above 12% .
Battery voltage is between 11.5 Volts and 16 Volts .
Engine speed is between 800 and 6,000 RPM .
Canister purge duty cycle is below 3% . All conditions are present for at least 3 seconds .
Action Taken When the DTC Sets


The PCM will illuminate the malfunction indicator lamp (MIL) after the second consecutive trip in which the fault is detected.
The PCM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.
Conditions for Clearing the MIL/DTC


The PCM will turn the MIL "OFF " on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
A history DTC P1441 will clear after 40 consecutive warm-up cycles have occurred without a fault.
DTC P1441 can be cleared by using the Tech 2 "Clear Info" function or by disconnecting the PCM battery feed.


Diagnostic Aids
Check for the following conditions:

Poor connection at PCM - Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
Damaged harness - Inspect the wring harness for damage. If the harness appears to be OK, observe the EVAP vacuum switch display on the Tech 2 while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault.
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.




The canister purge vacuum switch is normally closed when no vacuum (purge) is present. With the ignition "ON " and the engine "OFF " there shouldn't be any vacuum (purge) present in the EVAP system.
Determines if the PCM is able to control the EVAP purge solenoid valve.
Determines if the DTC will set under the conditions present when the DTC was originally stored. If not, the fault is intermittent.
Checks for a grounded EVAP purge solenoid driver circuit, a faulty EVAP vacuum switch, or a leaking EVAP purge solenoid valve.

[yellowgizmo99]

thanks for the help, ran for a good while yesterday and it idled like it did before it started this, all engine codes disappeared, all seems well, thanks again. seems that replacing the IACV was the best move as far as I can tell, it was gunked up.