Where to start?

[dohvb1]

I've got a 01 VX with 45000 miles. It has an Injen intake and PV exhaust. I bought it May 04. 4 months ago it stalled when coming to stop lights. I was worried but it seemed like a one time thing. I thought maybe bad gas or something and put it out of my mind. Things have gotten lately. It's happend about 5 times in the last 10 days.

My check engine light goes on off and a weekly basis for probably the last 6 months. I had a parts store check the codes today. 5 errors came up. I can't remember the exact codes since he said he would clear them and I should comeback if the light comes on again. It did on my 3 mile drive home from work. He said 3 of them were 02 sensors. Can't recall the others. Gonna have him check it again tomorrow and will try and get the numbers.

Also today I took it Tuffy because there had been a rather noisy and annoying rattle which I thought was from the exhaust and they could fix it.
They thought it was the heatshields so they took those off and it still rattled. He thought it might be the o2 sensor but he was having problems taking it out he called to see if I wanted to proceed and said if he damages the sensor taking it out it was $170 to replace. I said hold off please. But he thinks it's either the o2 sensor or the catalytic converter. He said his cost on the cat was $1000, but he said he talked to Isuzu and they said it's under warranty. I'm worried about it not falling under warranty since it has the aftermarket exhaust. Not to mention there is a Isuzu Service Center only(no car sales) an hour away next closest is 2 hours away in Lansing. I'm not sure on how good either place is.

I did replace the fuel filter over this past weekend hoping that would solve the stalling problem. Which it didn't it, stalled on me today.

I will try and post the codes tomorrow, but anyone have any ideas. I'm not sure if all the problems are related by something big or a couple small problems. I just don't know where to start.

[MachineVX]

The stalling problem sounds like it could be because of failing intake manifold gaskets. Do a search in the forums to learn more . . .

[Maugan_VX]

A fairly common cause of the stalling problem is the fuel pressure regulator. Do a search on the forums for stalling. Many people have reported the problem being solved with a new FPR.

[Tone]

Check fuel pressure with a gauge before spending $50 on a regulator. Post the exact codes and we can help you better - intake gaskets failing typically cause irratic idle high and low for no apparent reason and could cause stalling. Intake gasket issue usually shows at least a lean condition - use the search feature to find codes usually thrown. O2 sensors from Isuzu only cost $100 ea and the Bosch aftermarket ones work fine and are around $65.

Cats will start to rattle when they are coming apart and I would definitely go with aftermarket replacements for those at less than $200 each plus a little labor to weld them in.

[mbeach]

This comes from Bob in response to a similar Q:

Sounds like a Vacumn leak to me. Make a good visual - CK PVC at valve & rear of Plenum also EGR connection at back of Plenum also Vacumn line at throttle body and at fuel regulator (Fuel rails Driver side rear).If all else fails spray Carb cleaner with engine running at intake manifold gasket mating services if RPM rises Try tightening manifold, if that fails new Intake Gaskets req. order
PN 8-97237-538-0 two req at $18 + each - 1-800- 727-8066 ask for Merlin. S&H is free

Torque value is 13 FT LBS on all intake manifold nuts & Cap Screws.


I had a similar surging upon hot starts and found it to be a vacuum leak at the intake manifold gasket. Just to make sure, I stuck a length of 3/8 hose im my ear and used it as a stethoscope to find the exact point of (air) entry.
Depending on your VX's in service date, this should be a warranty fix.

As for the cat, a 'rattling heatshield sound' can come from INSIDE the catalytic convertor body (as Tone mentioned), this usually happens after the matrix has been blown out and the internal shielding no longer has any material to keep it in place.
Get your in/out pipe diameter and overall length then order an aftermarket (high flow) replacement cat for <$125. I'm a big fan of Random Technologies' units. Have it welded in for $20. Catco units also come highly recommended, but I have no experience with them.

It's easy to get frustrated when so many things are going wrong with your truck, but when you look at the root cause of these failures, they all point to one, easily repaired problem.
Bad intake manifold gasket(s) = lean fuel/air mix (weird idle and CELs 017x),
Lean fuel/air mix = hot combustion temps,
Hot combustion = hot exhaust gas temps,
Hot EGTs = burnt O2 sensor(s) (and CELs again),
Burnt O2 sensors = burnt catalytic convertor,
crumbling cat = rattling noises.

Best of luck and keep your chin up, this board's value lies in its collective experiences with these same troubles.

Edit: I just noticed that you had an Injen intake. I don't know about the VX for sure, but there have been troubles with aftermarket CAIs on quite a few other vehicles. They cause the engine to run lean, even beyond what the ECM and fuel injectors are capable of managing. Just a thought.

[dohvb1]

Ok got it scanned again today. This time two codes.

PO101 MAF System Performance

PO140 H02S Circuit No Activity Bank 1 Sensor 2

I'll try and check for a intake manifold leak later today.

Thanks for Random Technology suggestion. Find them on for sale on the web for under $200. That sounds a little better than $1000.

[Triathlete]

Mine would stall every once in a while at stop lights on hot days. I would open the gas cap and reclose it and problem would go away. Worth a shot next time it happens.

[mbeach]

Internet copy/paste about your HO2S (heated oxygen sensor) code:
Electrical:
-Water in the harness connector
-Open/shorted HO2S circuit
-Corrosion or poor mating terminals and wiring
-Damaged HO2S
-Damaged PCM
Fuel System:
-Excessive fuel pressure
-Leaking fuel pressure regulator
-Low fuel pressure
Induction System:
-Air leaks after the MAF
-Vacuum Leaks
PCV system:
-Improperly seated engine oil dipstick
EGR System:
-Leaking gasket
-Stuck EGR valve
Base Engine:
-Oil overfill
-Exhaust leaks before or near the HO2S(s)

These pretty much highlight what the other board members have clue'd you in to. Triathelete's loose gas cap causing low fuel pressure, Maugan's bad FPR causing low/high fuel pressure, vacuum leaks etc.
I cut out some of the more odd scenarios (like running out of gas).
Just run down the list and see what's what.

I'm a big fan of using a can of carb cleaner to find intake leaks. I think that'll be the root cause of all of your troubles.

[mbeach]

That PO140 code keeps coming back as a dirty/clogged EGR valve. Search the cleaning procedure here -it takes 10 minutes and uses the same carb cleaner that will help you find your intake leak.

Also, most of the MAF issues that I've found can be fixed by a simple cleaning of the contacts with some electrical contact cleaner and some elbow grease.

[Tone]

I also recommend the 2 combination ODBII gauge units that read and reset codes that let you monitor quite a number of variables live while driving that can alert you to potential issues. Square Scan Gauge that sits on the dash is $125 delivered and the 52mm round unit for pod mount, it $249.00 - email me for more info if questions not answered on the lower left of .info home page.

[SGT.BATGUANO]

check the maf connector, unplug and replug. might want to pull the maf and inspect. check all injen intake hose connections for leakage. do you have an oilable air filter/ is it over oiled?

It looks like one o2 sensor may be bad or have a wiring problem. judging by the codes it doesn't seem too complex a problem or expensive to repair.... unless other codes show up. your orig. post said it had 5 codes.

[CowboyErik]

I just re-fitted entire exhaust system and am throwing the P0140 code/ PO140; gonna check some things out; hope my cats aren't bad!

[CowboyErik]

from what I see on the internet on PO140 / P0140 I need to swap out my rear O2 sensors after checking connections; just saw a you tube video on it, guy had live diagnotic data that confirmed and affirmed his repair before and after neat; I need that kind of scanner; mine was still a $100 something but no live data! Grrr! Sensors are amazingly cheap new now, even BOSCH O2 sensors are at $25 each; other brands at $20 bucks new;

[mdwyer]

And while you're shooting around with a can of carb cleaner, take out the Idle Air thingy and clean it up. That was what caused mine to stall at stops. Cleaning it out fixed it for me.

[Scott Larson]

Erik, didn't you just replace your muffler and tailpipe and "refinish" your cats? You mentioned protecting your O2 sensors, any possibility something went amiss there?