VX Starts ok, but runs terrible...

[l.ectric]

Hmmm.. well, I'm new to the whole VX thing, and I've got to say that you all are the nicest group of people! Anyway, I bought a 99 VX last month and had to tow it home because it was running really bad. :confused:
Here's what happens when I start it up:

Runs ok for first 15-20 seconds, then starts to idle rough. If I give it any gas it revs slowly then wants to idle very low. Almost no power at all when I put it in gear and try to drive it. It "pops and coughs" when the gas pedal is depressed.... Also, there is a strong hissing noise coming from the throttle body area, which leads me to believe that it might be the IAC motor... even though I did pull it out and looked to be funtional when turning the key in the on/off positions multiple times. Could it be the MAF? MAP? O2 sensors? Plugged CAT? Timing? I'd love to see if anyone else has had this problem. Thanks a ton in advace!

[MSHardeman]

Sounds like it's starving for fuel and/or air. Don't know how many miles are on it, but maybe replace the fuel filter and the fuel pressure regulator to see if that helps. I know when I replaced my fuel filter at 60,000 +/- I could barely blow through it so it was pretty clogged.
This might be way off, but have you taken a look at the air filter? Is it clogged and not allowing the VX to breathe?

Oh, almost forgot....welcome to the family.

[tom4bren]

Yes, welcome to the family ... and to the adiction.

I'll second what MS said. Start with the more simple solutions and work upward from there. Most of that should probably be done anyway.

Replace the fuel filter
Replace the air filter
Clean the MAF sensor
Clean or replace the PCV
Clean the EGR system
New spark plugs wouldn't be a bad idea
Clean the Idle Control Valve
Clean the Fuel Pressure Regulator

Also don't forget to keep an eye on your oil consumption & on your CV boots.

There are threads on just about all of this. Let us know if you have any trouble utilizing the search function to find stuff.

Read this: http://www.vehicross.info/forums/showthread.php?t=16008&highlight=intake+manifold

[circmand]

spark plugs and make sure the wires are in the correct firing lorder. PO may have tried to do a tune up or something and put the plug wires back in incorrect the order,

[newthings]

Welcome
There are about 5 of us on the coast near the Oregon Washington border.
Roy

[l.ectric]

The VX has 60,0000 miles, plugs are in correct order, remove the air filter, oil level looks good. I'll change the fuel filter and IAC this week and see if that helps. Thanks newthings, I'll let you know when I get it all fixed up and when I'm headed down to Seaside... it's one of my favorite vacation spots!

[nfpgasmask]

The problem you are having sounds like a problem I once had. In my case though, I let the fuel get to low and the truck started running REALLY rough, SCARY rough in fact, and I got a CEL. I changed the spark plugs and that didn't help. I then went and filled up with a tank of premium and everything went back to normal. Are you getting a Check Engine Light in the dash?

Bart

[l.ectric]

Yes, it comes on almost every time it is started, and it has flashed at me once.... I haven't been able to reproduce the flashing CEL, though... it was a one time thing, i guess. I'll try the gas trick... I'll drain the old stuff first. Thanks!

[circmand]

your local parts store and have them see if you are getting an error code? That will be better at helping diagnose than any of us can do without actually hearing it.

[l.ectric]

Awe, schucks... (No Pun Intended) I might tow it over there later today or tomorrow.

[nfpgasmask]

Exactly, if you got a CEL, you might be able to still read the code (the ECU stores it I think) even if it is not lit anymore. That would be a good start. If you have gas in the tank, you are probably ok, I just ran mine to low and I think there was some water in the fuel. Unless you are really low on gas like I was, I don't think that is the problem. I'm not sure how you intend to drain the fuel, but I would not recommend doing that unless you know you have to.

You could also try a jug of HEET fuel treatment, that should get rid of any water in the tank. A can of Sea Foam in the gas tank also can't hurt.

But anyway, get the code read, and bring the number back to the forum and we can tell you what it means.

Good luck,

Bart

[ScottinMA]

My bet...vacuum leak.

[VXorado]

My bet...vacuum leak.


+1 Thats what i was thinking since there is hissing from the engine. A vacuum leak can mess with the air/fuel mixture

[blacksambo]

Is the check engine light on? If so are you getting a 171--- OBD2 meter code? If yes, change the common chamber gaskets, top and bottom. It will run like dream. It's a very common problem and easily fixed.

[Riff Raff]

Welcome to the family and addiction fellow Washingtonian. VX Member "ROWHARD" also hails from Olympia with his Dragon VX and he is a wealth of VX information. I'll shoot him an E-Mail for him to be on the look-out for ya'.

By the way, follow all of the advice already provided. Lastly, always run Premium High-Octane fuel in the VX!!!

By chance, did you happen to buy your VX from the vicinity of Yelm, WA??? I know there was a Ironman VX 4-sale on Craigslist recently from Yelm, WA.

[l.ectric]

I purchased it from a kid who got it from his girlfriends mom, who took great care of it, as far as I can tell... but the kid, not so much. The interior looked as though a landfill and a bowling alley got together and threw-up in it... there was so much trash and debris in it, i debated if I really wanted to spend the money on it... But then again I did get a great deal! (at least I hope so!)

[l.ectric]

Ok, so changed fuel filter and throtle position sensor and cleaned MAF... but no change in problems... next I'm going to check the catalytic converters.... weird that there are 2... the more I think about it, i wonder if the muffler is clogged?

[mrtew]

I'd clean or replace your EGR valve. That made mine run very rough and caused the check engine light to be on. Make sure it's an Isuzu one if you replace it because my dealer used a generic one and had to replace it again in a month or two. Now it runs like brand new!

[rowhard]

HEY new member from Olympia. Sorry I didn't see this thread earlier and thanks Brian for the email, been busy kind of. Anyway, PM or email me and I will get back to you with a phone number and then get with you to see IF I can be of any assistance. I live just past Priest Point Park on Boston Harbor RD

[l.ectric]

At last, the beast roars!... and it really does, due to an exhaust leak. So, the whole stupid problem was that the kid who had it last mixed up the left and the right O2 sensor wiring harnesses... I don't know WHAT he was doing messing with that stuff... but it caused me three and a half weeks of headaches. Also, FYI, 31x11.5x16's are pretty much the biggest tires you can stuff under a vx without a lift... :bgwo:

[mrtew]

... Also, FYI, 31x11.5x16's are pretty much the biggest tires you can stuff under a vx without a lift... :bgwo:

Picture? Photo? Pix?

[Riff Raff]

Also, FYI, 31x11.5x16's are pretty much the biggest tires you can stuff under a vx without a lift... :bgwo:

Well; I'd say you're close, but off by a full inch. According to my calculations, the biggest 16" tire you can fit on a OEM stock 1999 VX without lifting is 32x11.50-16LT or LT285/70R16 (both in 32" O.D.). Tires in these sizes are currently manufactured by Interco, Pit Bull, and Toyo. Due to its 11.5" width, this 32" O.D. tire may possibly require slight hammering of the back portion of the front wheel-wells to clear when turning in addition to normal trimming. The biggest culprit for possible rubbing is the far inner bolt on the back portion of the front-left (driver side) wheel-well. Some VX owner's simply remove this inner bolt entirely without further issue.

Whether a tire rubs or not depends greatly on the wheel it's mounted on. If you use the stock OEM (16x7 or 18x7)wheel when mounting aftermarket tires; this will greatly reduce any rubbing issues, as it has the correct offset and backspacing to help keep the tire neatly tucked within the front wheel-wells.

As a general rule of thumb, the biggest possible tires you can mount on a 100% stock OEM "non-lifted" VX using the stock OEM wheels are:

1999 VX w/16x7 stock wheels:

32x11.50-16LT (32" O.D.)*
LT285/70R16 (32" O.D.)*
*Creative trimming and/or hammering required.


2000/2001 VX w/18x7 stock wheels:

P255/70R18 (32" O.D.) - Bolt-on Perfect.
P275/65R18 (32" O.D.) - Bolt-on Perfect w/slight trimming.
LT285/65R18 (32.5" O.D.) - Creative trimming and/or hammering required.
LT275/70R18 (33" O.D.)**
**Yes, it is possible to mount 33" O.D. tires on a "non-lifted" VX in the narrow 275 series width due to its narrower turning swing-arc. Creative trimming and/or slight hammering required as necessary. Typically; the narrower the tire, the less rubbing interference.

By both not-lifting; and using taller aftermarket tires, you increase both ground clearance and save your VX from possible CV related issues.

[tom4bren]

IIRC, tire diameter is measured at the body of the tire & does not include the tread depth. A more agressive tread tire can be significantly taller than the same sized tire with a mild tread.