I have had a "studdery" engine problem which I tracked down to a cold #4 header pipe and a somewhat cooler than the rest #1 pipe.

I sent my injectors out to Rich at Cruzin Performance to have them cleaned, but they didn't need any cleaning! They were all flowing perfect. (thanks Rich!!!!)

I put a noid light on all the injectors and I get pulses. I also put an induction timing light on those spark plug wires and I get blinking light.

I pulled #4 plug and it was wet. I took off the dist cover and it all looks good. Less than 10 miles on all tune up parts.

I had bought a new dist off of ebay. It really was new. I swapped out it's new pickup coil and module with other ones I had with no better results.

If anyone has any ideas on this problem, I would appreciate any advice I can get! This is driving me nutz!

-darren

 

Sounds like a blown head gasket at no. 4, when you pulled the plug was it wet with antifreeze or fuel?
Seen the same thing happen on a guys mustang, blew the head gasket and the corresponding header pipe was cold, if thats the case go ahead and change it, dont drive it around.
Hope this helps

 

The plug looked wet with fuel. It smelled like fuel.

I didn't notice any smoke or any foamy oil? Don't you usually get antifreeze mist out of the exhaust with a blown head gasket? Or, you get a foamy milky oil?

I sure hope I don't have to change the head gasket, but I will if necessary.

Thanks for the tip!
-darren

 

Check to see if that plug wire sparks out the end when disconnected. Could be a bad wire. Could be a vacuum leak to that cylinder also. Make sure you don't have that wire on the wrong cylinder (18436572) = maybe 1 & 4 are swapped.

 

I'm going to check the plug wire positions again. I checked them and they all looked right, but I'll double check.

I'm hoping it's a bad wire. That could certainly cause this I would think. I do have an old wire I can try on that plug.

What are the chances of having a bad spark plug out of the box? Has anyone ever had a bad plug - is it possible? I'll pick up a new one anyway after work today.

Thanks!
-darren

 

It's definitely possible, I've run into that before. If you've got a collapsed lifter or valve problem (not closing) that could also be the problem. I'd suggest running a compression test as well. If litttle or no compression in the "cold" cylinders, can trouble shoot that with a leak down test, then valve adjustment, etc.

 

Yes, I really should do a compression test. I'll see if Autozone rents a tester.

 

yep a compression test would be good. You could get away with sticking your thumb over the spark plug hole. If it shoots your thumb out, it should be good enough compression to fire the cylinder. Did you clean the plug and try to fire it after that?

I had a coil spring break that caused a dead cylinder. LIke the other guy said, it could be a lifter too.

check the simple things before you yank the heads.

 

I tried a few more things.

I put a new spark plug in. I switched the plug wire. Then I pulled off the valve cover and rotated the crank as I watched the valves. Both valves for #4 cylinder moved up and down under hand power.

I will try the compression test. I can't think of much more to try!

 

are you sure the plug was wet from Fuel?

check the WIRES of the injector connector.

i had the same problem and it turned out to be the spark plug wire was grounding out on something, causing it not to fire..

 

The plug was wet and it smelled like gas. I don't know if there was any coolant there or not. All I know is that it "appeared" to be gas. I will try to crank the engine without any spark plug wire attached. That should really load up the gas on the plug if it's getting gas at all?!

I will probably try to replace the cap/rotor/coil again, even though those are new. This is just too wierd, and to me, it seems like an ignition problem now that I have verified my injectors.

The #4 plug comes off of my distributor at the very back near the firewall. It has to cross over all those other wires. I don't have any separators on the wires yet. Can I be getting some induction between wires? I would think that would give it a miss instead of a non-fire?

I'm still not ready to pull the head. I will if I have to, but I hope I don't!

-darren

 

Why does it come off the back of the distributor? You must not have it installed quite correctly, but that won't cause a problem by itself. You've verified the 18436572?

I'm betting on an ignition problem, but, you can verify the injector wiring by swapping the injector connector with a nearby cylinder, and see if the symptoms follow the wire or not (before spending money on other parts).

 

It took someone to actually say it to have me actually do it...

Since Red&Gold said move the injector wire, I did it. The problem followed that plug. That is really strange to me, and I never thought it would be that because I tested each injector wire with a noid light before.

What can cause this? If the noid light blinks the same on each injector plug, then what can cause this problem for me? Is the electronic pulse somehow different enough that the injector doesn't fire? Is it not strong enough, or not the right freequency??

What really pisses me off is that this is a NEW painless wiring harness!

Thank you everyone for all their suggestions. That really helped me learn and narrow this down. I really appreciate it!

-darren

 

There could be a bad crimp (wire to plug terminal) or the terminal itself is bad. Look into the end of the terminals and see if they are possibly sprung open. Also check that the terminal(s) aren't being pushed out the back as the plug is seated onto the injector.

Al.

 

That was it! The end of the terminal was sprung open.

The reason my noid light worked and the injector didn't is because the connectors on the noid light are much thicker than the thin "blades" of the injector.


Thanks everyone!!
-darren