Z with L28 - Running rough

[Nick]

Sorry for the long message, but i'm hoping that someone can find where I went wrong.

 

I have a Z with a L28 in it and this weekend I decided to adjust the valve lash again. The last time I adjusted the valve lash, I was unable to loosen the 4th nut to tighten it a little, so I waited until I could get a wrench that had a better angle. I got the wrench this weekend to adjust it and went ahead to adjust the 4th valve, but skipped the rest because I had just adjusted them within the last 100 miles or so.

 

After putting the valve cover and everything back on, I started the car, and could hear a bit of a ticking sound, but I couldn't tell if it was from the injectors or the valves. I drove the car out of the driveway, and could tell that it lost a lot of power and seemed a bit like possibly not all of the cylinders were running, so I checked all of the spark plug connections and did not see any issues. Because I only adjusted the 4th valve, I went ahead and adjusted all of the valves. On the last couple valves, I realized that with I had been letting the wrenches push up a little while I was tightening the nuts, which may have messed the gap that I had just adjusted(although I believe that I double checked the measurements after tightening the bolts). Since it was 10pm already an dark out, I decided just finish up and see if there was a difference with the way it ran, although it was drove just like before.

 

This morning I decided to try adjusting the valve lash once more after letting it warm up for 15 minutes. Even though I was sure that I didn't make any mistakes, I had the same problem with the engine running real rough.

 

I changed the oil, which needed to be changed and also reconnected all of the spark plug wires, eventually noticing that the center connection for the 6th spark plug wire was pulled back in the rubber and was not reaching the spark plug. I went and bought some new spark plug wires, cleaned the spark plugs and started the car again. The car seemed to be running a little better, but it was still running rough so I couldn't tell if it was from the new oil or from the spark plug wires that made the improvement.

 

My only guess as to what could be the issue now is that gas or something could have built up in the 6th cylinder if it was not firing due to a bad connection with the spark plug wires.

 

This whole time I have not really bothered to try letting the engine go past 1500-2000 RPMs, hoping that I wouldn't cause any damage.

 

I would appreciate suggestions from anyone if they know what could be the issue.

 

Thanks

[Skib]

whens the last time you changed the plugs and what plugs are they?

 

 

also whens the last time you did your cap and rotor?

[Nick]

I changed the plugs about 2 months ago with some Bosch Plugs and they have less than 500 miles on them. I have not done anything with the cap and rotor, although I believe that it could be relatively new.

[Skib]

I changed the plugs about 2 months ago with some Bosch Plugs and they have less than 500 miles on them. I have not done anything with the cap and rotor, although I believe that it could be relatively new.

 

 

pop off the cap and check the tips in the cap and the edge of the rotor.

 

also I recommend using NGK BRP6 ES 11 plugs

[I'm BLUE]

How long or how many miles have you had this problem ?

 

Bosch are probably fine , but I only use NGK usually whenever I can.

 

I am just going to work the valve adjustment angle ;)

 

(1) Did you take the retainer springs off when adjusting the valves ? ( I missed this the first time I did it )

(2) What were the measurements ? ( Were your valves to loose or too tight ? )

(3) Did you make sure to adjust the engine HOT ? ( Important step at Operating Temperature , usually I like to do COLD adjustments where I can on other engines that allow it )

(4) Set the Spark Plug Gap to ? ( .031-.032 ) ---> I adjust .001 under specs to compensate for wear :D

(5) When tightening , did you check more than 2-3 times to make sure that the measurement is correct/complete before a final light tightening. ( some people will just hold the adjuster wrench , and crank it down , then quickly move on before going anywhere else with it.

(6) When adjusting valves , they were all adjusted on the same relative spot at each point on the cam , opposite of the point ?

 

Other Suggestions

 

(7) Dead or leaky valve if this is a pro-longed problem

(8) Compression Chesck ?

(9) Intake Manifold Gaskets sealed ? ( spray mating surface areas with carb clean or brake clean , if idle changes you have a leak )

(10) Carbs Adjusted correctly ? and if they are SU's are they clean/last time adjusted ? ( mine I had to play with every 3 weeks or so to keep in tune )

 

Fuel

 

(1) Changed your filters lately ? ( mine I have to change every few months since one can see the rust building in them :lol: :o )

[I'm BLUE]

pop off the cap and check the tips in the cap and the edge of the rotor.

 

also I recommend using NGK BRP6 ES 11 plugs

 

+1 Highly Rec ^^^ what Skib said ;) , and do you have electronic ignition or points in your L28 Distributor ?

[Nick]

This problem started after I adjusted the valve lash, I didn't take off the valves at all, and when I adjusted them, I set them at 0.012 in.(exhaust) and 0.010 in.(intake). I had adjusted the valve lash a few times before and it ran great, except for the "ticking" sound that I was getting from the 4th valve (which could not be adjusted until now, since I was not able to get a wrench in there at the right angle).

 

The last time time that I adjusted the valve lash, I ran the engine for 15 minutes and had all of the valves set in about 50 minutes.

 

Every time that I adjusted the valve lash, I checked constantly as I tightened it and after it was completely tightened.

 

Each time that they were adjusted I also made sure that each tip on the cam was pointing strait up.

 

I forgot to add before that this engine is fuel injected, so no Carburetor.

 

Again, the problem just happened after I adjusted the valve lash this weekend, when I started the car, so it had to have been something that could have messed up/bumped as I adjusted these valves.

 

By the way, thanks Skib and DTP for the reply.

 

[I'm BLUE]

hmmmmmmmm , apologies I saw 240z and L28 so I immediately thought "carbs" :lol:

 

Fuel Injected Z systems are not my forte since I have never owned one.

 

Spark Plug Cross-Fire ? IDK :huh:

 

Is there a chance you can post a video so we can hear the ticking by chance ?

 

So you are saying you don't want to take above 2,000 rpm's in case of harm , but the car has no problem doing so ?

 

Ohhhhhhhhh , whatever you do , if you have a FRAM oil filter DO NOT USE THEM ! they are poop , will clog and starve your engine ! I have a thread explaining this when it happened to me and how it almost grenaded my L28 in my 240z after an oil change immediately . It started like a sound of a light "valve ticking" and all I thought was " I need a valve adjustment " ---> what actually happened is it was starving my motor for oil. Just a thought if anything else , I use WIX , NAPA GOLD , or Purolator/Bosch only now. ^^^ End result , a worn valve train system , but shortblock is good shape :)

[Nick]

The ticking is more of a minor issue. It was due to the 4th valve which I had not been able to adjust until yesterday, which shouldn't be an issue anymore.

 

Before I messed with anything this weekend, the engine ran great and was real smooth at any speed, the only exception was the 4th valve that I mentioned, but that was nothing compared to the trouble i'm have now with the engine.

 

My neighbors won't like me starting up the car again this late at night, but ill try to get a video of it sometime tomorrow, if I can. When I say that the engine is running rough, I mean that the engine shakes, so inside the car, it almost idles like one of those older V8s, if you know what i'm talking about. When I drove it down the street in 1st, at 5-10mph, you could tell the there was some kind of power loss, and with the way that it was running, I was not comfortable driving or revving the engine any higher than that, which was 1500-2000RPMs. Although, I'm sure that while not in gear, the engine could have went to 4-5000+ RPMs.

 

As for the oil, that was done after I made the adjustments, I mentioned that because it was done at about the same time as the new spark plug wires, and at first it seemed to run a little bit smoother, but the engine was still running rough.

 

It doesn't make much sense at all to me where I could have went wrong, but if I have a chance tomorrow, the compression check may be the next thing that I will check.

[banzai510(hainz)]

adjust valve lash. Make sure one of the lash caps are not missing.

if this is all good along with the new spark plugs ,Unless you put the New plug wires on wrong and the fire order is off.

Once you know this is good I would look at the injectors.

 

But like you said this didnt happen untill you fucked with the valve lash.so kinda rules out the injectors but you never know.

[Nick]

adjust valve lash. Make sure one of the lash caps are not missing.

if this is all good along with the new spark plugs ,Unless you put the New plug wires on wrong and the fire order is off.

Once you know this is good I would look at the injectors.

 

But like you said this didnt happen untill you fucked with the valve lash.so kinda rules out the injectors but you never know.

 

I ended up taking it somewhere this morning and found out that the 2nd Injector was corroded and also must have came loose somehow as I took the valve cover off, so thanks for suggesting the injectors.

 

Thanks also, to everyone else for the help, I really appreciate it.

[Skib]

did that fix it?