Hello all,


I'm new to the forum and a first time Corvette owner! (FINALLY!!!)

OK, let me run down the skinny on my issues.

I got the car a week ago. it started fine, although idled a little high and rough. You could drive it and it just hummed along. then when warmed up...was hard to keep running when stopped in gear.

Here is what I've done so far thanks to info I searched out on this great forum.

Checked all vacuum hoses for leaks...found one obvious one.

MAP test OK, Vacuum line bad....replaced hose.

Checked timing...it was well ATDC. unplugged connector and set timing at 6 deg. BTDC But when I go to start it, it still acts like it's out of time. I put a vacuum gauge on to check vacuum and it's steady at 18"

replaced all plugs, wires, cap and rotor.

when it runs it runs rich.

Checked TPS, it checked out OK. .5-5.0 OHMS

Put DVM on the IAC of each TB and I'm getting 52 ohms from A-B and C-D, but nothing when I cross A to C&D and B to C&D. The manual I have says it should be infinite. Is that correct?

I haven't checked the fuel pressure yet, as I have to go buy one to put inline after the filter, behind front tire. I'll go get that when my wife gets back from the grocery

I'm almost to the point of ordering a new ECM for the car, but don't want to buy one and have it not be it.

Long term goals for this car is a LS1, So I don't want to gut everything for a carb, just to sell it later when I do the engine swap if I don't have to.


Thanks in advance for your wisdom and advice,

 

I guess I should explain the idle is in the 1500-1800 range, when (and if) it drops....if it ever gets close to a "normal" idle speed...it'll die


there is a light to medium amount of white smoke out exhaust...

 

timing= pull nr 1 plug and find tds , mark it on the balancer !! ( balancer can be bad ; slipping !!

 

For the TPS connect your meter between the top 2 wires (I use 2 women's hat pins- others use paper clips) and adjust for .525 volts, key on engine off..

 

The engine coolant temp sensor can make it idle high & run rich. If you replace it then use the updated sensor & connector. Its in the front of the intake between the air pump & a/c compressor.

 

The TPS is at .5 key on, engine off. and the meter rolls smoothly up to 5.0 when you open up the throttle.

I forgot to mention that I bought the temp sensor for the ECM, but when I pulled the old one, it had already been replaced with the newer style.
I put my meter on the leads and ran it through the hot water, temp test. it tested fine, so I took back the one I purchased.


I pulled the #1 spark plug and with bumping it, the mark on looks right.

I'm going to pull the valve cover and that way I can turn it over by hand and make sure it's right on the money.

 

the temp sensor has to be the right one for 84 corvette !!

 

Well, true, there is no way for me to know if one of the previous owners received the right one when they replaced it.

Unfortunately, that's the curse of all used cars. trying to undo all the "upgrades" and "repairs" of the previous owners. LOL

I guess I'll go back and buy it again. it's only $18.

 

When it comes to 84 cts this is good advice, the oem style is unreliable.

 

Here's what my original one looked like before i replaced it with the newer style.

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Some light reading on the basics,

http://forums.corvetteforum.com/c4-t...er-wobble.html

 

Well, I pulled the valve cover off the driver's side and cranked over the engine by hand to find aprox. TDC.

The Balancer is WAY off. by about a 1/4 turn.

Picking up a new one today. see if the correct timing will help!

 

While you are there, you should pick up rolls of vacuum tubing and replace ALL the hoses, any leaks that you cannot hear or find will have your engine idling either too high or eradic. It's cheap and worth doing now while you are doing your initial settings.

 

 

Great advice. after 30 years that rubber is looking old.

I bought several feet of all sizes.

 

This is a friggin mystery waiting to see what it is.

 

That's good!! I bought the thermoid brand, it has thicker walls and is specifically for vacuum and a bunch of connectors and vacuum port plugs.

Needless to say this made a HUGE difference in how smooth mine starts, runs and idles now.

Do this before you set your intial timing so that it idles down to 600 nicely when you are turning your distributor to set the idle speed and ignition timing. 700 rpm is fine too.

You will find once your ignition timing is correct and your vacuum good, that most if not all problems vanish into thin air.

 

.525 ohms? Does that include the resisance of the hatpins?
(sorry, I couldn't resist -no pun intended).

 

Well, the balancer made the difference.....well, let me say finally being in time made the differnce.

I remember telling my wife over and over.."it's in time, but acts like it's out of time!"

Well, that's because it was out of time.

Idle is down to normal and it doesn't stall when in gear.

Idle is still a little rough, but no miss fires or stalling.

Plus it starts like it should. barely a bump and off she goes.

Thank you guys! I was loosing my mind.

now to get the wipers working so I can drive it to work! (that will be another thread)


On a side note.....
The GM engineer who thought it would be a great idea to have the power steering line come out of the rack and pinion directly in line with the crank shaft, should be drug out in the street and flogged by every mechanic who has ever removed and installed a harmonic balancer!

 

Glad to see success!! great job!