Hard Engine Ticking on Acceleration not Deceleration

[BCbrad]

Hi folks,

I was having a lot of fun with my Fiat until yesterday. As I was driving the engine started ticking hard when accelerating. It doesn't seem to do it at idle or when shifting down. The ticking is especially loud when under load, so in the shop it is not quite the same.

At this point I have not had an opportunity to go through the trouble shooting. I have inspected the timing belt and all looks good. I will pull the plugs, and check the compression and verify the timing is still on.

There does not appear to be coolant burning out of the exhaust so I don't think there is fluid in the cylinders, but I don't want to rule anything out. Could this be a result of the cylinders seal on the head gasket failing?

Any suggestions or tips?

[hayesbd]

Sometimes an exhaust leak sounds like a mechanical ticking noise. Also, you might try putting a hose to your ear while the engine is running and use the other end to pinpoint noisy areas. This is helpful regardless of what kind of noise it is. My most recent noise was a rattling alternator fan/pulley that was surprisingly hard to pinpoint by just listening without the hose.

Brian

[So Cal Mark]

I'd suggest exhaust leak also

[BCbrad]

I will verify the exhaust seal.

In the meantime I have pulled the plugs and there was nothing to note. I checked the timing by rotating the engine until the cam pulleys mated with the pointed indicator and the crank pulley was right on the 10 degree marker on the belt cover. I have the computronix setup and I adjusted that by ear to help a little. At 3000 rpm it seems to run well but when ever I apply the accelerator it ejects fuel out of the carb, even ramping it from 3000 to 4000 rpm.

I have uploaded a video to better describe. Again this isn't under any load, so I am not sure if I am hearing the same thing.
In the Shop

Edit: I had to upload a video with the engine under load so I took it for a rip around the block. Hopefully, this will help.
Under load

[Jon124]

I think your timing is off. The timing should be set with the crank pulley at zero degrees and the cam pointers aligned to the cam housings. It is the ignition timing that gets set to 10 degrees BTDC.

[azruss]

sounds like you are running on 3 cylinders. pull one plug wire at a time. if you find one that makes no difference then you have found your problem child. Before using this technique, check with mark to make sure it won't damage your computronix unit. Wear thick gloves when pulling the wire, rubber soled shoes and don't lean against the car.

[BCbrad]

Instead of pulling the plugs wires, I used my timing light to get a signal from each wire. All worked except #4, so I installed a new spark plug, no change. So I swapped the #1 with the #4 to test the spark plug wire. #4 was still dead, which leads me to believe that the #4 terminal on the coil is the problem. Just to be clear, yes I made sure that that the wire matched the cylinder number to the terminal number on the coil. Kinda bummed, once on 20 years type of weather and I am stuck driving the pickup.

Is there an way to safely test the coil without damaging the system or myself?

[azruss]

not much of a troubleshooting guide at compu-tronix. They suggested making sure the plug wire is seated all the way down on the plug. Since your issue is #4 which is a PITA to get to, this may be your issue. I know mine was a real fight to get all the way on.

[hayesbd]

The "coil" you mention with cylinder numbers on it is the distributor cap. If the spark plug wire is fully seated on number 4 plug, then it sounds like you may have a cracked distributor cap or it has carbon tracking on the inside (google search will show you some examples of what this looks like). If that doesn't reveal the problem, pull the number 4 plug and see if it is damaged or fouled. If all this checks out okay, the next step would be to check compression.

Brian

[BCbrad]

Just a bit of an update. I had thought maybe I had a bum coil, so I installed a new one. It wasn't the problem. I did a compression check and I am getting 150psi on 1 & 2, and 30psi on 3 & 4. I am suspecting blow by on the head gasket. I am using high compression pistons. Is it possible that I could be bridging the 3 & 4 cylinders?

[silvadw]

My problem with similar symptom was exhaust manifold related.
This is my post
http://fiatspider.com/f08/viewtopic.php ... 91#p242685

[131]

Is it possible that I could be bridging the 3 & 4 cylinders?

I've done a couple of head gaskets over the years that have burnt through the fire ring between 3 & 4.

[bradartigue]

Just a bit of an update. I had thought maybe I had a bum coil, so I installed a new one. It wasn't the problem. I did a compression check and I am getting 150psi on 1 & 2, and 30psi on 3 & 4. I am suspecting blow by on the head gasket. I am using high compression pistons. Is it possible that I could be bridging the 3 & 4 cylinders?

That would do it.

Buy the best head gasket you can afford - not the $13 "kit" version.

[chrisfiat]

i strongly suggest you get allison automotives head stud kit to replace the head bolts, this is a much better solution to reusing old bolts, and insures better more even clamping, worth every cent of the cost

[BCbrad]

Update time!

Pulled the head gasket and the 3 - 4 cylinder burned through.
http://tinypic.com/m/izx2tj/2


So, I purchased a new gasket from Allisions Automotive. High quality.

http://tinypic.com/m/izx2ty/2
After putting everything back together I can't get it to fire. I double checked the timing and all seems well. Strange thing happens this time. When I force fuel into the motor the engine stalls turning over then ramps ups up to normal turn over speed. There is also a small amount of fuel getting ejected from the carb.

Question, regarding the 34 degree orientation of the aux shaft and using the computronix system, how accurate does that position need to be? It is about the only uncertainty I have regarding the timing setup. Also, is the installation instructions for the computronix for thr fiat available on-line. I can not locate the instructions that came with the system. I am thinking I shouold remove the sensing unit and set it up from scratch.