Other little problems I discovered while on road trip

[MagikDraggin]

One thing about a road trip is it's a good way to find out all the little things wrong with the vette.

Besides the excessive carbon in the exhaust I've already mentioned and the shifter not wanting to go into first gear (it's an A4), I encounted these other things that need attention. Any suggestions would be most appreciated.

1. After driving at hwy speeds for awhile and coming to a stop, the idle speed remains up around 1200 rpm for a minute or so before finally dropping down to 850. I figure it has to be some setting in the Throttle body, but what?

2. I had to really clamp down on the "binders" when everyone suddenly decided to stop on the interstate and while the vette stopped fast enough, it tried to swerve first to the right and then the left. Suspension parts are fine with no slop, so it wasn't that, and all four corners have new carbon metallic pads. Any ideas?

3. While in Calif, where the elevation was less than 1000 ft, I had an occasion to "jump on it" off the line a couple times, and even with the big cam, 2600 converter and 3.54 gears, the motor bogged off the line for about a second and a half, before finally digging in and taking off like it should. No wheel spin or anything. It was almost as if I had the old 2.59's back in there again. Any ideas on this?

4. Going down hill on the interstate at 75 mph, I would get backfiring through the exhaust if I were to let off the throttle and "coast" while still in gear down a sharp decline. Is this normal? There are no cats or smog crap on the motor.

 

[Ken]

After driving at hwy speeds for awhile and coming to a stop, the idle speed remains up around 1200 rpm for a minute or so before finally dropping down to 850. I figure it has to be some setting in the Throttle body, but what?

That is normal. It has to do with emissions.

I had to really clamp down on the "binders" when everyone suddenly decided to stop on the interstate and while the vette stopped fast enough, it tried to swerve first to the right and then the left. Suspension parts are fine with no slop, so it wasn't that, and all four corners have new carbon metallic pads. Any ideas?

The rotors and/or pads probably only needed to be swept clean. If the brakes aren't used hard every now and then, there could be a posssibilty of crud building-up on one or the other, or both, and simply need to be wiped clean by hard braking. Does the problem persist? How is your alignment? What about the rest of the suspension components such as shocks, bushings, etc.?

While in Calif, where the elevation was less than 1000 ft, I had an occasion to "jump on it" off the line a couple times, and even with the big cam, 2600 converter and 3.54 gears, the motor bogged off the line for about a second and a half, before finally digging in and taking off like it should. No wheel spin or anything. It was almost as if I had the old 2.59's back in there again. Any ideas on this?

I haven't a clue.

Going down hill on the interstate at 75 mph, I would get backfiring through the exhaust if I were to let off the throttle and "coast" while still in gear down a sharp decline. Is this normal? There are no cats or smog crap on the motor.

No cats or smog? It's probably normal to have some popping (backfiring) if that's the case. Have you never heard glasspack mufflers?

 

[MagikDraggin]

Thanks for your comments Ken. The braking thing only occured that one time.

The acceleration thing occured only in Calif near sea level. At elevations of 4k and above there was a noticeable drop off in power levels, but nothing severe. I understand the higher elevations losing power, but near sea level has me baffled.

Yes, I know cars pop on deceleration with carburators and the like, but didn't think it occured with computer controlled fuel injection.

Another thing that happened that I forgot to mention, is that on sharp rises in the highway pavement, the body would "float" and then come crashing down on the suspension.....on more than one occasion, completely bottoming out the rear suspension. I have the gas-filled Bilstein shocks with the standard suspension (not the Z51).

Is it the shocks that need replacing or are the "springs" shot? Or maybe both?

 

[Ken]

Definitely sounds like shocks to me. I'd replace 'em, or rebuild 'em (Bilstien still offers the service, but at double the cost ) as soon as possible. It'll get worse and will really affect your handling then.

_ken

 

[jmccloud]

1, 3 & 5

Sounds like you have a vacuum leak. Higher elevation, less Oxygen, less effective vacuum leak.
The backfiring down-hill can result from running lean (vacuum leak) because the mixture doesn't fire in the combustion chamber but lights off in the exhaust system.

 

[MagikDraggin]

Re: 1, 3 & 5

Sounds like you have a vacuum leak. Higher elevation, less Oxygen, less effective vacuum leak.
The backfiring down-hill can result from running lean (vacuum leak) because the mixture doesn't fire in the combustion chamber but lights off in the exhaust system.

Ok, assuming it is a vacuum leak.....what with the heads having been off recently for the cam and head work, plus the addition of the 52mm throttle body, that is a possibility.

But how would I ever track it down with this lopety-lope cam it now has, not allowing the engine to idle smoothly to begin with?

I didn't have this condition before the mods were done, so obviously it is attributable to those mods.

Any ideas as to how I would check for a vacuum leak?

 

[MagikDraggin]

Definitely sounds like shocks to me. I'd replace 'em, or rebuild 'em (Bilstien still offers the service, but at double the cost ) as soon as possible. It'll get worse and will really affect your handling then.

_ken

Your advice will be heeded and I will replace the shocks immediately. Are Bilsteins the recommended replacements or is there another (better, not necessarily cheaper) shock I should look into? I don't do autocross or anything of the like, but I do not object to driving the vette the way it was designed to be driven on occasion, if you follow my drift, heh heh heh.

 

[Ken]

I'd stick with the Bilstiens. At least, that's what I did.

Now when it comes time for me to drag race it, I will be looking to change to something like the adjustable QA1s (formerly HAL) or Konis or something. I'd have to shop around but I'm leaning towards the QA1s, maybe even in coil-overs if I can figure a way to afford it.

 

[vader86]

I'm betting that 1 & 3 are related.

You might want to check the TPS settings, and make sure the IAC is clean. Its also possibly related to a vacuum leak.

 

[jmccloud]

Vac leak check

Start by closing off (disconnectiing and plugging or pinching flexible hoses) vacuum connections to the intake. Some of these will mess up the engine's operation so must remain a mystery. Check the ones you can.
Test the intake/head surface by dribbling a small amount of water along the mating surface. If you find the spot, the engine should smooth out momentarily. Conceivably, anything that connects to the intake is suspect, even injectors, etc. but it's usually the head/intake seal or a bum hose or hose connection.

Don't get the opti wet.

Good luck

 

[MagikDraggin]

Thanks for the tips. I'll get to checking out what I can and see if it is something obvious.

And yes, I will be careful around that opti.

I already got new Bilsteins on the way to tighten up the suspension, as well as a pair of mini-cats to cut down the fumes and smell of the exhaust.

All in all, the vette performed marvelously and without any trouble. These are excellent road cars and not "uncomfortable" at all on an extended trip. I even made a believer out of my wife on that point.

I can't wait to do it again.

 

[Ken]

... not "uncomfortable" at all on an extended trip.

Except for the fact there are only two seating positions: left cheek or right cheek. Been there, done that. :L

 

[MagikDraggin]

Except for the fact there are only two seating positions: left cheek or right cheek. Been there, done that. :L

Hahahaha. Well said. At first, I cringed at the thought of a drive of any length in a vehicle with such a limited amount of "squirm-room", for feet, legs AND the butt as that vette has.

But I found out the seats are so damned comfortable, that about the only squirming I do is to occasionally, as you say, shift from one "cheek" to the other, and to engage the cruise control and every now and then, draw both legs up, rest my elbows on the arm rest and center console, recline the seat as far as it will go back, and settle in for the long haul and enjoy the sights along the way.

The best advice I could pass on to anyone contemplating such an extended cruise, is to remove the wallet from their hip pocket and store it in the armrest, as that thing will definitely cause major discomfort in about 90 minutes of driving.