There's got to be a solution??? (THERE IS, PROBLEM SOLVED!)

From all indications and all the searches I've done here, my VX is running wayyy rich... black carbon residue on the tail pipe, constant... I wipe it off and it's back after about 200 miles driving.

Surging idle, goes down to like 100-200rpm (almost stalls) then goes up to about 1100rpm, then back down... does this 8-10 times then levels to 750rpm or so and purrs like a kitten.

The other day I was doing about 55mph and floored it to pass a truck (and to have some fun) and got up to about 70-75 mph and it bogged down and the CEL started flashing and then it died... lost all power, had to pull over fast 'n dangerous... turned it off for about 10 seconds and started right up and no problem pulled back onto the highway and about a mile later CEL on, was coding p0101... cleaned the EGR, and it was all full of carbon and I had just cleaned it 3 months ago, and it went away...

Now I had used acetone for 4 tankfuls and was getting better mpg's. I'm on the second tankful with no acetone and I'm still getting good mpg's. but now this started.

I've read through several searches different threads stating certain problems are caused by running too rich but what's the solution/fix? How do I get it to run a little leaner? Is there an adjusting screw? An ECU fix? Anything?

Thanks in advance for any help...

edit:
Oh yeah, I also cleaned the MAF... I think... I sprayed it out with sensor safe cleaner... is that all there is to do to clean it? Spray?
Also, Where is the MAS? Is it the little 'barrel' sensor on the air intake tube about half way between the MAF and the intake manifold? (throttle body(?)) If not, where is it?

replace your fuel pressure regulator.. its a 50-60 dollar part, its very well documented here. send a PM to joe isuzu I sent him a "kit" a few months ago that has a tool made to get the old one out easier as well as instructions from a former owner that show in great detail how to replace

the only thing you would need to get yourself is the part and a set of snap ring pliers

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Originally Posted by iamironman

edit:
Oh yeah, I also cleaned the MAF... I think... I sprayed it out with sensor safe cleaner... is that all there is to do to clean it? Spray?
Also, Where is the MAS? Is it the little 'barrel' sensor on the air intake tube about half way between the MAF and the intake manifold? (throttle body(?)) If not, where is it?

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I think the sensor you described is the intake air temp...in a rubber grommet on the intake tube, between the air filter & the throttle body?
The MAF should be cleaned with MAF cleaner only, CRC makes a good product for this.
I can't remember the loca of the MAS on the stock manifold, maybe someone will chime in with a pic. You might also be able to find it in the VX shop manual. (from the "downloads" section of the right sidebar)
FWIW, my tailpipe has been sooty & black for the last 4 & 1/2 yrs.
I think the FPR is a good place to start, also check out all the vacuum hoses.
Spraying brake cleaner or carb cleaner (anything that's extremely flammable) at the base of the intake manifold on both sides (while idleing), where it mates with the heads, & listening for an increase in idle speed, is a good way to check for intake gasket leaks...to be done at your own risk...:naughty:

Acouple weeks ago I had about the same probs. Of course I started with the easy (cheap things first) Fuel Filter...no help, FPR...no help but it's the 1st one put in 5 years so I feel better, It ended up being a Fuel Pump (2nd one in 4 years) I installed a Bosch this time. Cost is alittle more but it has a Lifetime Warrenty. Good Luck...

If you want I can forward it on to you PM me your address.

My tailpipe is always covered in black carbon deposits as well. I don't have the symptoms you have, but last weekend I got a CEL (1404) and I changed out my EGR. My VX is running better for sure. A lot more pickup and so far no stumbling or chugging like I was before. IMO, I almost think its a good idea to replace the following around 75k, symptoms or no symptoms:

1) Fuel Filter
2) Fuel Pressure Regulator
3) EGR Valve

I have done all of those swaps and so far so good. I hope to get to 100 with out any more issues, but we'll see.

Bart

MAF = Mass Air Flow (sensor)
MAS = Mass Airflow Sensor
MAF = MAS? I've heard them used interchangeably. Autozone lists our MAF as an MAS. I'm just speculating... I'm supercharged, so all of my plumbing is different. But it would be helpful to identify what part you mean by part number or full description.

I don't think there is a separate intake air temp sensor - the MAF measures this value (since it measures airflow by it's temperature and how much current must be put through a heated wire to maintain temperature).

Anyway, surging idle often is associated with unmetered air getting into the intake, often through cracked intake gaskets. Try the carb cleaner test - this may identify the problem. If not, check for any poorly-fitting intake components that may be letting unmetered air in.

If you run an oiled air filter (like a K&N) you may have mucked up the MAF to the point that cleaning it won't help. CRC is the only company that makes an MAF cleaner - if you used a regular electrical contact cleaner, it may not have done anything (it made the MAF on my 928 worse!). I would suggest getting a NEW MAF (no rebuilds!) and see if your problems go away. The MAF could just be dying, too. It happens. It's an evil part - just because it's so critical to fuel injection. If it's off, so is your fuel-to-air ratio.

The acetone you have been experimenting with wouldn't affect the MAF.

Good luck!

Get a MAF/MAS from Napa (They carry some oem) and try it and if it doesn't work return it. But being electronic make sure they will take it back. It gathers info on the amount of air going in and tells the computer how much fuel to deliver...worth a try.

I have had this exact issue for a couple months now. The fluctuating idling at startup that. If it happens to stall during these fluctuations, I get a CEL. ONLY if it stalls though. Did the whole new Air Filter, cleaned MAF, cleaned EGR, and it was good for about 2 weeks, but it came back. The scary part is, if the VX isn't running at a normal temp/warmup, it will do it. and when you are stepping on the brake and it suddenly wants to rev, you gotta be ready to step on that brake just a bit harder. Once she is warmed up, she cuts that out though.

I have been trying to troubleshoot whether I was running lean or rich. Both can cause fluctuations, but both also have different exhaust signatures. I don't have dark emissions so I am leaning towards running lean. My next step is to replace the FPR and clean the S/C fuel rails, in case of some residue/blockage. Probably replace the EGR while I am at it. I have been saying this for a few weeks now, but with tight pockets and winter starting to shadow me, I think I am allowed to continue to procrastinate. ;)

Quote:

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Originally Posted by WormGod

I think I am allowed to continue to procrastinate. ;)

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lmao...Classic

I will try everything suggested... but... is there a way to adjust the rich/lean? Or is it totally controlled by the MAF/ECU? Or other sensors communicating with the ECU.


THANKS!!

Quote:

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Originally Posted by iamironman

I will try everything suggested... but... is there a way to adjust the rich/lean? Or is it totally controlled by the MAF/ECU? Or other sensors communicating with the ECU.


THANKS!!

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I am probably speaking out of turn here.. but I think the only way to adjust the parameters is with a computer and isuzu software. These don't adjust like a carb.

good luck
Jeff

I thought so... thanks for all the info. I ordered the FPR and MAF/MAS... 'twill be here tomorrow...

:) Ok, it was the FPR!!!

I got the parts in and first tried the MAF... for obvious reasons... it was easier... NO change... still 'idle surged'... left the MAF on... new fuel filter... NO change... so I put the original MAF back on and did the FPR... WORKED like peanutbutter-smooth n creamy.................
perfect idling, perfect acceleration-WAY better pick-up, just all around smoother in EVERYTHING it does... so I put the new MAF back on and it seemed to do even a little better... (the onl reason I switched back to the orig MAF was troubleshooting 101, eliminate all possibilities to see what the root cause is).

Thanks for ALL the input... I think I'll keep her, she's muh huckleberry:p

Way to go, dude! But wait, you didn't tell us how much fun it was to change the FPR!

:) Bart

PS - Stick a new EGR Valve on and I bet it will run ever betta! Like butta!

EDIT: How was your old FPR? Mine had several small holes in it when I changed it out.