help, Revs going wild up and down

[james1_10018]

Hi Guys

Everytime I put my car in park after driving a bit it rev up and down like a wild cat for a sec or two from 700 rpm to 2000 rpm.
Sometimes it revs a few hundred rpms and stimes more but it doesnt just go down quietly
I wonder if anyone has experience this. Any ideas

[-x-]

i get a high idle once in a blue moon, though it doesnt fluxuate. Anyone else in this boat? ....x

[EclipseGSX]

yup, hi revs once in a while moving slowly. some times it startles me and i have to jump on the brake hard.

[ron]

Just last night, I had a similar but more weird experience. While on the freeway, at stop and go traffic, I noticed my rpm at a real high level like around 2000. I literally had to hold the brake down with more effort during the stop and go traffic to keep the VX in control. I pulled the shifter out of drive and into nuetral and the needle jumps up to 2000 or so rpm. Once the traffic lets up a bit and regained to 60 mph for a few miles or so then coming back down to stop and go traffic again, the rpm drops real low this time. I pulled it out of drive and the needleregisters around 250 rpm. I thought that sooner or later the engine would stall out as the needle would hover within the 250 or lower range so I kept my foot o the gas just in case. Once traffic let up, the rpm settled back up to around 500 to 750 range (normal?). Hasn't done this behavior since.

Anyone else experience this or have any suggestions what the cause might be?

[SPAZZ]

Every once in a while...at least twice a month... my VX will attempt to start, but die, attempt to start but die...to no avail...it will not start unless I hold down on the gas pedal...let off it dies...if I put it in Neutral it dies...if I put it in driving gear it will go.
After I drive to my destination when it does that and then shut it off...do my thing and then get back in and start it up...it revs like 2000 to 3000 RPM and it will stay like that for a couple more starts. Reving the gas pedal doesn't work to lower the RPM's...as it would if it was cold and it needed to rev high to warm up and then reving it to make the RPM's go normal.

[-x-]

Mines wouldnt start just like your spazz...it was a morn after the temp drop and hasnt done it since so i didnt think much of it....x

[VX_PA]

Check your fuel injectors. Had to have mine replaced at 42,000 miles, they wouldn't spray but just dripped or they would flow too heavy. It caused my VX to fluctuate the RPM's. The dealer never said what caused this problem, just replaced them. I run fuel injection cleaner through them every 3 months or so and told the dealer that. I think there may be a problem with the factory injectors.

[jamessmith]

I had the same problem with my VX..she only had seven hundred miles on the clock.The folks at the dealership told me that my idle speed had to be reset.I do not drive my VX much,she only has fifty-seven hundred miles on that clock.I consider the VX to be a museum piece, she is in my garage resting.Since my visit to the dealership the idle speed has be working properly.Hope this information helps.
YOU VXER's ,include myself, are a bunch of fanatics.

[Andrey]

during hot weather after I arrive home and while parking or in newtral engine will rev up and down - I have no explanation to that :confused:

[Anita]

Just came back from my 60K service at my dealer. I learned a couple of things about this RPM thing.

1) Isuzu put out a bulletin about the EGR valve getting stuck/clogged, with the result of the potential of burning oil to piston failure.

2) My Izusu mechanics told me that a particular wiring harness in the engine bay contains a wire that controls idle which has on several Isuzu's frayed or even shorted out. The wild fluctuation of and high RMP's were a symptom. THey showed me where the harness was located and said that if the symptoms of high or fluctuating RPMS's happens, to giggle the harness and see if that causes a change.

[-x-]

;wtf; So where's that harness so i can track it down... :smack:

And was that EGR or ERG? I think i know what tha egr valve is and does but not sure of an ERG?

RE: EGR - For all of the mechanically modificatin kind in here....

I had a prelude that had and egr tube that basically ran from the headers to the intake manifold ;wtf; . Its "purpose" - to help heat/warm up the engine. Well as we all know hot air is bad air ;) And since it does get or stay too cold here in bright orlando, fl. - I had a little plate fabricated to block off where it went into the intake manifold and had where the tube came out of the headers welded shut. No more (unneccesary) hot air in my intake. ;)

I though it made a difference, but then again i was young and niave :p , anyone think this be something benificial to undertake?

Just letting out the creative juices, now everyone please jump on the "just my $.02 wagon".....x ;Db;

[Dallas4u]

Originally posted by Anita
1) Isuzu put out a bulletin about the ERG valve getting stuck/clogged, with the result of the potential of burning oil to piston failure.

Anita, do you mean the EGR valve???

Trying to find info on an ERG valve on the net (in case I've never heard of it)!

[Anita]

oopsie typo

I will change the original post and I will take some pics of the harness.

[skunkworks]

Blocking out the EGR can hurt performance. While it does sent a metered amount of exhaust gas back into the intake to reduce NOX, it also actually cools the intake charge and reduces pinging. If this does not take place the knock sensor will retard the timing to stop the pinging and that will dog it out.

albert
________
Yamaha Zuma specifications (http://www.yamaha-tech.com/wiki/Yamaha_Zuma)

[Jolly Roger VX'er]

E.G.R. Valve----Exhaust Gas Recirculation Valve.

I removed the one on my '88 Fiero that became defective by making a blocking plate out of a $0.68 Light switch wall plate from Lowe's and some gasket paper. Used EGR as template to trace out on switch plate and used tin snips to cut out blocking plate then passed it against a grinding wheel to smooth edges. Traced out EGR on gasket paper to make a gasket. Drilled out holes in plate and gasket. Bolted plate and gasket on engine using same EGR bolts. Voila.
Now Fiero has more hp and a couple miles per gallon better on the fuel mileage. Removed vacuum hose and plugged off source with rubber nipple.

I don't think you can do this on the VX without tripping a code and seeing the check engine light. Someone chime in if they know for sure.

[Anita]

This is a pic of the harness that I spoke of earlier.

My mechanics explained that if the RPM's ran high or were fluctuating, to giggle this harness and see if any change occurs.

Located in this bunch of wires is one that controls idleing. My Isuzu mechanics have found in a number of Isuzu's that that wire can fray and even ground out.


Granted there are other reasons for an idleing problem that are more common, but here is another possibility.

http://www.vehicross.info/gallery/data/500/7harness_long.jpg

;Dr;

[Wulfgott]

This is similar in a way to the problem my VX had and took the dealer 2+ weeks to figure out.

In the mornings when cold the car would NOT hold idle. Turn her over and drops from 800 to 0 and dies. After 4-5 times starting the car would sit there and hold idle at would I kind of figure is around 300 RPM. (not enough to do anything). Shut her off and back on 2-3 more times never having moved and WHAM jumps to 2000 rpm and sits there. Drive it for a block and then it is fine. The problem then stops for 2-3 weeks. Then this last Friday in stop and go traffic it did it on the freeway (that really sucked). Took it to the dealer and they ended up replacing the idle control sensor, some intake gasket, and about 6 other things. (which I think were just replaced to take on to the labor they get paid as it was under warranty still).