Tom400CFI

1. ANY decent OBD I scan tool should be able to display the real-time readings of everything the ECM "sees"; sensors, outputs, everything.

2. You don't need to use starting fluid. You can use something NON-flamable and it will "kill" or "bog" the engine when you that the spot w/the leak. You can also use a poor-man's stethescope (sp?); a piece of fuel or vacuum hose held to your ear. Run the orther end around the engine and any suspect areas. When you get near it; the hissing noise will becomd VERY prominant.

jhammons01

That little amount of gas from the blue propane tank isn't enough to make a large POOFFF..

It's not like your gas grill with gas filling an enclosed area with lots of outlets.....It's a small single outlet......

Do and experiment, Sit the Blue bottle on the ground and open the valve.....let it flow for a minute......then spark it with a match.......all the gas that came out prior has dissipated into the air and only the tip now burns.......no explosion

Tom400CFI

YES. Also, WD40, carb cleaner, brake cleaner, what ever. If there is a leak, and you ingest SOMETHING -anything, it will change how the engine runs. You'll hear it, and you'll know where you just sprayed the liquid.

dchoran

I finally did it after 55 years - bought a freaking scanner (OBD 1 capable) that I hope will make my life easier with SEVEN vehicles in this family.

Only new vehicle is the OL '09 Rav 4. The rest of them are 2000 and earlier.

Was getting tired anyway of all the self diagnostic attemps and/or visits to Autozone/Advanced/my mechanic and this PERSISTENT Vette idle problem.

I hope this little orange bugger has an ROI within a year. If it figures out my '84 issue, it was well worth every penny

THANKS for all the advice so far.

Dave H.

dchoran

While we are on the topic of scanners:

There is a good deal going on at Sears that ENDS TOMORROW - SAT 5/8/2010.

Picked up the Actron Elite Autoscanner Pro CP9190 kit (OBD II and OBD I capable).

Base 9185 unit with ALL the adaptors and cables.

http://www.actron.com/product_detail.php?pid=16317

List for $520 (and is what Advanced Auto is selling it for today).

Sears has 15% off their $400 selling price.

http://www.sears.com/shc/s/p_10153_1...ctron%20cp9190

“$339.99 after deducting applicable additional savings”

Being Sears they'd probably take it back without a hassle at the sore if there are any issues with it or I hate it (unlikely, computer geek here).

Just thought someone else may be interested.

Now I gotta go sell something else on the C4 parts thread

Dave H. 5/7 2:15pm

RichardR63

Do a "crossfire intakes" search in either of the tech or discussion forums. There are several discussions in both that may solve your issue. I'm betting it's an intake leak. I know because I read an article in a corvette mag some time ago about the crossfire intakes warping or cracking or the gaskets failing from the engine heat over time.

qws

Personally I don't think the $399 scanner is gonna find your problem. The $30 torch will though along with the $3 can of WD40

OBD1 PAPERCLIP scan tool is free and can usually be found in any household
Actron OBDII cost me $100 and is worth the investment for cars that are 96 and newer.

Just my opinion

ARCHIEDUR

I found that my TPS was bad .
Replaced & set to .54 v & all is good.
This is on my 1984 crossfire.
It wood not adjust to below 4.81 volts so the computer thought it was at wide open all the time.
Archie
jad5629@hotmail.com

dchoran

TCP??? Don't you mean TPS or is there a part I haven't replaced yet on my crossfire

dchoran

That is $339, not $399.

I really don't expect it to find anything on my '84 - but this scanner will come in handy on the other SIX 2000 and earlier vehicles in our family.

NONE of my kids, who all drive, are mechanically inclined.

It'll make life a little easier/cheaper for the big Daddio when there is car trouble

Dave H.

dchoran

I'm gonna try this stuff to see if I have any vacuum leaks

At least there will no chance I torch my car or garage, even though it says extremely flammable????

johnnyboyC4

Well, if you don't succeed in blowing it up, at least you can fool the neighbors with all the smoke!

johnnyboyC4

I just went to AZ and asked for an OBD I key and they gave one TWICE! The first one chewed a hole in my pocket and I lost it up at work.

CFI-EFI

race on!!!
Jim

ex-x-fire

You can pinch off or unhook & cap off all the vacuum hoses except the map, to see if the idle improves. If you have a bad vacuum leak you can even plug both the iac ports, it still may run. If it stalls then the leak is small, or see if the idle improves. Did you put a vacuum gauge on it? What's the reading at idle? Is the needle steady or not? Did you do a compession test? Todays oil arent made for nonroller cams (they took the zinc out for emissions), maybe one of your lobes is going flat.

ARCHIEDUR

YES SORRY TPS

dchoran

OK guys - I do not think this is a vacuum issue on my car. Could not wait for the smoke-in-a-can.

So yesterday I went through an entire 12 ounce can of Carb/Throttle body cleaner while the car was idling hot.

Sprayed around every square millimeter of the throttle bodies and intakes and hoses - top, bottom, sides, front, back - I mean everywhere and lots of it.

I'm talking even up by the headlight/canister area too - around those vacuum lines - EVERYWHERE but the interior of the car

Did it more than once too. 30 minutes of spraying this and that. Even went through part of a second can. It was like I was degreasing my engine.

Result - the warm/hot engine continued to surge at idle as "normal". NO CHANGE IN THE "LOBBING"!!!

Only difference was noticed when I sprayed it directly into the intake throat(s).

So I think it is safe to say - no vacuum leaks are present.

Dave H.

dchoran

OH YEAH, THIS COULD BE OF NOTE:

(happened before and after my engine was degreased above)

While idling in park and surging as normal, I VERY GENTLY and VERY VERY SLOWLY depressed the accelerator to speed the engine up.

If this is done right, I can get that surging AMPLIFIED so it fluctuates like this: 1000-1500-1000-1500-1000.

And that happens as I hold the gas pedal ROCK STEADY - a surging range of 500 rpm or like +/-250 rpm!!!

It is really pronounced and dramatic at these rpms as you would expect.

And the injectors appear to be functioning normally.

Once I get past like 1500 rpm, she'll just run steady and smooth.

What is kinda weird is the fact that this is NEVER noticed during normal driving, at speed and/or acceleration (pushing the pedal a little harder/further maybe?).



Does this help in the diagnosis - maybe fuel pressure, regulator or pump related?????? (don't have a gauge yet).



THANKS.

Dave H. 5/10 5:30pm

HdRider04

I am having the same problem on my 86 and I have done/replaced everything you have, I am now looking at the Fuel filter and sock in the tank even though they have both been replaced in the last few months. If you find the fix PLEASE let me know..... Good luck

dchoran

Tension arm???

I replaced the coil, wires, rotor and cap. When doing that, I tried to rotate the distributor just to insure it was tight.

Didn't budge even with allot of force.

I'm thinking fuel compensator (front) or fuel regulator (rear).

Dave H.