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I have myself a TBI ignition problem...

midnitewarya

midnitewarya

Sounds like a problem for future me.
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:::UPDATE:::
Got a timing light and timed it to TDC. (So I think, my timing indicator is rusted, but I seem to remember that 0 is at the bottom of the large "v" notch.) It runs smooth without the computer hooked up, but shudders at 2400 rpm and up. If I shut it down and hook up the computer it won't even start.

Am I missing something? I'm loosing my mind on this.

Original Post:

So, today I attempted a revival of my ignition system. I have a 91 K5 TBI 350. I put in new BOSCH Platinum 2 spark plugs, a new MSD Blaster coil, a new Holly Billet aluminum distributer and a new cap/rotor. Also new wires.

Go to start it for the first time with the computer still hooked up (that little brown on white wire with the circular plug) and it won't start at all. Unhooked it, it starts fine. Can't get it to rev more that 2500 rpm before it starts shuddering and knocking. Only starts without the computer hooked up.

I don't have a timing light, I'm fairly certain I have my firing order in line, and I'm positive I didn't install my distributer 180 off. I've done timing before without a timing light and have never had this problem.

Anybody have any advice?

Thanks,
Al
 
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This is not your whole problem, but unless it came with them, lose the platinum plugs. I don't see it as often as I used to, but when those darn things first came out, they caused more skipping than you would believe.
They sounded great, but regular ignition systems just would not fire them reliably.

I'm sure someone else will jump in soon to tell you about the wire.

J.
 
First off get those platinum plugs out of that engine. If the engine did not come with platinum plugs from the factory they generally will not work very good and in many cases have been known to blow holes in pistons when used on engines that they were never intended on being used in.

Now, it sounds like your timing is off by probably 20-30*. The EST wire removes the ECM from the system as far as timing is concerned and that is why the engine will start with it disconnected (the computer isn't adding the extra 20* of timing). You need to start the engine with the wire disconnected and then time the engine to zero (TDC) then reconnect the wire and the timing should advance about 20*.
 
Question 1: Could you please link the distributor you used.

x3 on ditching those plugs. Good ol AC delcos.

and forget the factory gap .035 ftw. I picked up 2-3mpg from going for .025 to .035
 
Use NGK V-power plugs. Those are the best plugs i've ever ran and i've been running them now for at least 15 years.
 
Get a timing light. You must have one to set the timing on TBI. You cant just do it by ear like a carbed engine. The ECM expects timing to be set at 0 * with the bypass wire disconnected.
As said ditch the plugs. .Not good to use in older engines IMO
 
I just wanted to make sure you got a distributor that was computer compatible.

Set the timing,change the plugs. From there I would say you have a bad coil.

Before you throw money at it though take a hose and set a sprayer to mist. Spray your wires with it while its running and see if it starts missing.
 
I would say your distributor is in wrong as well. If you have not installed many distributors in your life, then the chance of reinstalling it back into your engine correctly is about zero.
 
distributor reposition is easy so I bet he got it in right. Mark rotor point on old and install new at same spot. Done! no really it's that simple unless you make a silly and crank the engine without one.
 
really the only hard part about a dizzy install is getting the number 1 piston to TDC on the compression stroke, once you figure that out, its a cake walk. but OP said he was positive he did it right (how many times have I said that :doah:) so Ill ignore that for the time being.

other than that, i concur with whats been said thus far. Proper plugs, proper gap. and get a timing light. The only thing that little wire controls is timing advance or retard. so if it starts without it, and wont start with it, its a timing issue. wire should be disconnected, then vehicle started, then timing set to 0*, then engine shut off, then wire reconnected, then restarted to verify it was done correctly. unplugging and reconnecting the wire while engine is running or with the key in the ON position confuses the computer.
 
Double checked my wires and install. Everything looks good. This is my first TBI dizzy, but not my first. Im thinking it just needs to be timed. Just waiting for the timing light now! Thanks for the input guys.
 
If it runs period theres no way its more than a tooth out. Seeing as how it has a small size to it the TBI dizzy should be able to adjust out a tooth.
 
It sure sounds like it is one tooth off. Like you are able just barely to compensate for it by turning the dis. but only by going to the limits.
When the computer kicks in you are out of range.
 
Fordum said:
It sure sounds like it is one tooth off. Like you are able just barely to compensate for it by turning the dis. but only by going to the limits.
When the computer kicks in you are out of range.
Click to expand...

Can the dizzy be one tooth off and still sit all the way on the oil pump? There is no gap between the bottom of the dizzy and the manifold.

If so, how do I go about correcting it? I'm at the point where I'm going to stop assuming I know what I'm doing, lol.
 
midnitewarya said:
Can the dizzy be one tooth off and still sit all the way on the oil pump? There is no gap between the bottom of the dizzy and the manifold.

If so, how do I go about correcting it? I'm at the point where I'm going to stop assuming I know what I'm doing, lol.
Click to expand...
Sure, no problem. The oil pump is free to turn 360degrees, so it can line up with the dis. no matter where it is located.
Plus, if it wasn't, you would not have any oil pressure.

As for checking, good question. Best way I guess, is to look at the dis. It should be sitting fairly normally on the engine. Find a picture or look at another one to see how it sits. It should be pretty much in the middle of the adjustment range.

Take the cap off, and bump the engine around until the timing pointer is on TDC.
Look at the rotor. It should be pointing straight at the no. 1 post on the cap, or straight away from it.
If its away, just bump the motor around one more time.
If its pointing slightly off, turn the dis until it does.
Now look at the dis. If its off one tooth, it should be sitting cockeyed. Turned way off more than normal.

Hopefully someone else will jump in and give a better way. Its one of those things, that I could tell if I saw it, but I just can't describe it very well.
 
Sounds like the module might be bad, this sends a signal to the ECM for the ECM to advance timing. The modules are a known GM weak link anyways so I would replace it regardless and IF the problem isn't fixed then at least throw the old module in your trail fix box.
 
Scott, if the module is not bad, what do you thing about my one tooth idea.
More importantly, what about my way to tell if its off?

I have a kinda distracting situation here right now, and I am not as sharp as I should be.
And I did not want to steer him wrong.
 
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