EFI update...

[Donbecker]

...well I got the car back from Doug the other day.

The new exhaust looks and sounds a million times better.

I got the O2 sensor wired, installed and calibrated last night, and I got it running with the EFI controller tonight, I'll post some screen shots of the data logs later this weekend.

I sealed the IAC passage in the throttlebody with a 'custom' gasket. The crazy loud sucking sound coming from the engine is completely gone now, and I was able to adjust the idle to 800-900.

It still idles really rough. I tried to adjust the timing but I couldn't see the damn mark on the balancer.

On stock balancers is the mark actually in the balancer or just paint or something?

I don't want to try to turn the engine over by hand as I am too weak.

I think everything I have says to set the timing at 8 or is it 12 degrees? Also, is this with the vac. advance plugged? And do I plug the hose going to the manifold, the vac. advance itself or both?

I am hoping that the rough idle is timing as it will be an easy fix after you folks post how to do it right....

[Donbecker]

BTW, this is that nice LC-1 Wideband controller that I got for $200. Came with the O2 sensor as well.

I will be tuning all weekend, so anyone that wants to come by and check it all out or help me play with the settings is welcome to it....

[BSeery]

The TDC mark is a notch / grove in the balancer. Best bet is to lay under the front of the car and try and find it. Once you find it, clean it well with carb cleaner and then paint it white / yellow / orange.

Set your timing at about 10 BTDC and that is with the vacuum advance removed and plugged. You then want to have someone rev the engine and check you timing again at about 3200 RPM. You will want between 32-36 degrees of timing at 3000 - 3300 RPM. You will need a "dial back" timing light or a timing tape on the balancer to figure this one out.

Go to Corvettefaq.com and look for Lar's paper on setting timing. Read through that.

Remove and plug ALL of your vacuum lines except the vital ones (MAP sensor) and then see if you still have a bad idle. Put a vacuum gage on the engine and see if you have steady vacuum or if it bounces.

[BSeery]

I will be tuning all weekend, so anyone that wants to come by and check it all out or help me play with the settings is welcome to it....

Saturday I will be doing the Hooters lunch / Pavilions / Toys for Tots day (whew!!) and all day Sunday I will be under a Vega removing headers and a bad starter.

[Donbecker]

Bryan, thanks for the reply! Sorry for the newb-esqe questions.

I found the balancer mark and painted it white.

I tried to hook my timing light up, but it was weird, like I couldn't always see the line on the balancer.

It's a really cheap timing light from Harbor Freight, so I'm wondering if it just sucks and I need a better one.

Also, I have crappy plug wires, so I was wondering if that could be it, but the light seemed to flash, so I guess it was fine there?

Sometimes when I could see the line, it was below the marks on the gauge, as I brought it up about a half inch from the gauge, the timing mark wouldn't show anymore...it was weird.

I'm wondering if something is really screwed up, like the balancer ring slipped or something.

I plugged the vac. advance line and I just rotated the distributor until it smoothed the idle abit.

Can someone tell me where I screwed up?

I know about finding TDC, but last time I tried I couldn't turn the engine over by hand, I'm too weak....

Let me know if there is any other info I can give to help you help me...

[Donbecker]

BTW, www.rockauto.com has balancers for around $45-$50 so I think I could afford to replace mine, has anyone on here ever replaced theirs?

How bad a job is it?

Thanks again,

-Don

[BSeery]

BTW, www.rockauto.com has balancers for around $45-$50 so I think I could afford to replace mine, has anyone on here ever replaced theirs?

How bad a job is it?

Thanks again,

-Don

Not too bad of a job. Well, on mine it's not. I don't have the fan and the radiator shroud in the way. Your may be a different story.

[Donbecker]

Arg. Yeah, I have both.

I guess I really need to figure out if that's it.

Maybe I should rent a nicer timing light down at Autozone? I know they have free tool rentals, they probably could let me use it in the parking lot or something.

I'm guessing/hoping that the idle stumble is an ignition timing thing, as that would take alot of head-scratching out of the equation that I'm doing on the fuel injection side.

I took it out on the highway again today and it seemed to be ok. It's still running a little rough and the acceleration isn't what the carb used to be yet, but hopefully we'll get there in due time.

I took a nice log of the highway trip, so I'm hoping to take a look at it tomorrow morning.

I'll take some screen shots and post'em for you folks to look at.

[Donbecker]

BTW, which part of the gauge is BTDC?

[Desertdawg]

Don,

The harmonic balancers are well known for slipping the outer ring. Spend a couple of bucks more and get a Summit or Jegs brand SFI approved balance.

But,

I don't think it's going to be slipping around that much while you watching it with a timing light, it takes some WOT blasts and some cranking to make the ring move...

How good is your distributer? is there play in the shaft? Are the terminals inside the cap in god shape, or are they pretty scarred or corroded? Whats the gap from the rotor to the pickups on the cap???

Plug wires could also be a problem, but your timing light should be picking up the reluctance from every fire. And even the cheapest timing lights usually work good enough to set the timing, I believe they either work or they don't. There's no "sort of" with a timing light...

[Desertdawg]

Also,

Be careful driving it much without knowing where the timing is, you could easily cook the motor of burn a hole in a piston if it's way off....

[Donbecker]

Dude, yer scarin' me now...

The distributor is the original.

New cap, rotor, coil. Plug wires are old but they still work.

As for play in the distributor shaft, how do I check? I don't know what the gap is either, how do I check and / or adjust? What should the gap be?

Okay this is probably going to sound weird. But I was playing with the timing light and I noticed that sometimes I could see the white line on the balancer. Sometimes it would just disappear. So I thought that maybe the timing light was getting triggered from the other wires. I tried hooking the light to the other wires and on most of them I could see the line in what appeared to be the same spot.

Does that make any sense?

[Donbecker]

BTW,

Bryan posted this and I still have to try it:

"Remove and plug ALL of your vacuum lines except the vital ones (MAP sensor) and then see if you still have a bad idle. Put a vacuum gage on the engine and see if you have steady vacuum or if it bounces. "

[Donbecker]

Another crazy point here, is I don't know what the idle RPM should be...I have it set now around 1000, as I have had trouble getting it lower.

The book on my 76 says to set it to 800, but I've read in 2 places now that the 86 the intake is from had an idle of 400-450?

That doesn't make any sense to me, does it make any sense to you guys?

[Desertdawg]

For the idle, Your carbed 76 setup was higher to compensate for AC, power steering pump, and other items running that would pull down the idle.

With the TPI, the computer will compensate for the loads ny upping the idle when it see's an added load. So what you are reading is correct, TPI should idle around 450rpm.

To check the play in the distributer shaft, just pull off the cap and grab the main shaft. It really shouldn't move at all, but what you will (should) feel is about 2 or 3 thousands of play. It rides in a bushing, so there has to be some play in it to prevent it from binding. If you want to pull it out of the motor, then You need to find online the amount it should move...

It almost sounds to me like the timing ring has slipped, and you might be having problems with your dist also... seeing the timing mark "sometimes" while on #1 is wrong. and then seeing it pretty consistent on any other wire.....

2 problems at the same time can really confuse you...

[knkayotte]

Wasting your time if you don't know what your timing is. As dawg said, you could damage your engine as well. I just bought a t-light at Checkers for $99 that has tach built in, real handy when tuning the car. Takes a herd of wild buffalo to drag my wife out to the garage to help, so it was worth the money, not to mention my tack doesn't work right now.

They have cheaper versions in the $35 to $60 range.

I bought the el cheapo summit balancer, actually seemed like a quality unit. You'll need a puller, no way around that. I tapped mine in with a 3 pound hammer with a section of 2x4 for protection against the face of the balancer. Not the way you should do it, but it worked. I worked it in far enough until I could get the old balancer bolt started and used the bolt and washer to work it the rest of the way in. You could alway get a longer bolt to start the balancer.

Compared to a C5 it?s an easy job, but it does help to have the fan shroud and pulleys off the water pump.

[knkayotte]

BTW, which part of the gauge is BTDC?

-8

-6 BTDC

-4

-2

-0

-2

-4 ATDC

-6

-8

I this what you are asking?

[Donbecker]

Thanks a ton guys!

knkayotte, that's the gauge I was talking about. So viewing from the driver's side fender, the 'upper' marks are BTDC and the 'lower' is ATDC?

If so, the few times I saw the mark it way WAY past ATDC. WAY.

Desertdawg,

In regards to idle speed. EFI systems use either a 'Fast Idle' or an IAC (Idle air controller) to put more air into the intake. My throttlebody has an IAC, but the version of the fuel injection controller that I'm using doesn't control the IAC.

Originally I was just sucking in air thru it at all times, I've since plugged it off. So it makes sense then that my idle is so high, and that it isn't anywhere near what it was on an original 86.

[BSeery]

if the mark was showing "low" it was after top dead center. It needs to be 8-10-12 degrees before top dead center. Start with 8 and go with that.

To verify your balancer - that's a hell of a procedure. I did this once with a screwdriver sticking in the #1 spark plug hole. We turned the motor over by hand (using a breaker bar on the balancer bolt) and watched the screwdriver move up and down with the piston. Once it was all the way at the top on the compression stroke then you can look to see where your mark is. If it's close to "0" then you are ok. If it's more than a few degrees off (remember using a screwdriver is not exact) then you need a new balancer or your timing pointer is screwed up.

To do it "exact" you will need a piston stop. It's a piece that screws in instead of the spark plug. You slowly turn the engine one way until the piston comes up and hits the stop --- carefully. Then you mark your balancer where it shows up next to the "0". Then turn the other way until the piston hits the stop again. Make another mark. To figure TDC you measure between the two marks and find the center. That will be TDC.

[Donbecker]

Bryan,

first, love the avatar...

Anyways,

Yeah, I've read the Lars paper on finding TDC, I was just never able to turn my engine by hand.

When I was doing all the initial work in Ohio last year, I read the paper and bought a bolt that would thread in the spark plug hole just for that task.

I ended up not being able to do it, even though I wanted to because I had heard alot about the old chevy 350 balancers slipping.

I'll be going out in abit to get a better timing light.

If you're interested in seeing the crappy numbers I'm getting:

Here is my log file:

http://www.elizabethvaughtonline.com/DotNe...-datalog-02.xls

And here is the little app to view it with:

http://www.elizabethvaughtonline.com/DotNe...PS/mslv2200.zip

It looks like once I get around 2000 RPM the tach signal gets screwed up and isn't smooth. Ack. I'm hoping to figure out a way to smooth it.

Also, it looks like my WB O2 sensor is saying that I'm way rich at idle and then everytime I step on the gas I go way lean. That isn't good. Running too lean at WOT is a very bad thing.

[knkayotte]

knkayotte, that's the gauge I was talking about. So viewing from the driver's side fender,  the 'upper' marks are BTDC and the 'lower' is ATDC?

Yup. Barely got my car started when the timing was ATDC, when it did start ran like crap.

[BSeery]

bypass the tach filter and see if it gets better or worse.

[Donbecker]

I bypassed the tach filter already, it wouldn't start with it inline as it was bad and the fuel injection controller wouldn't start without a tach.

[Donbecker]

Okay, I bought the best one I could find at Pepboys.

Has a digital tach readout, a VERY bright bulb and digital advance adjust.

Since this bulb was really bright, I could see that the same place on the balancer was coming up everytime.

So I'm about 99% sure at this point that my ring has slipped. Cr@p.

The light wasn't triggering correctly all the time, the instructions point to the plug wire as being the culprit. This also explains why the tach isn't showing up on the timing light correctly.

So...

I think the best thing reliability wise is to replace the balancer. Rock auto had some for like $40, so it's not exactly going to break the bank.

Hopefully I can get most of the stuff off the car without breaking anything else. I think I need to read up on the replacement procedure first.

In the meantime I'm wondering if I could pull plug #1 and tap the starter to try to get close to TDC. Then I could mark the balancer and get a little bit closer.

Although I wonder if it would be worth it as it seems to be running. Not great mind you, but it's making it.

What'cha guys think?

I'm gonna call around about plug wires, worst case I can get some MSD cut to length ones that will fit right from Loper's tomorrow.

I'm just hoping when this is all over that I won't have to replace the distributor as well.

Liz just might kill me....

[Donbecker]

BTW, almost forgot.

I was playing with the advance adjuster, and I was able to get the line to show (somewhat reliably) with it set at about 60o offset. So I'm guessing that the balancer is offset by that much?

Can anyone double check me that if I somehow didn't put the distributor in correctly after the manifold swap that it wouldn't run at all, right?