[Scott Collins]

Hey Friends-



Hoping to get some advice troubleshooting a couple of problems:



Problem #1. 2 start ups required every morning, beginning about a week ago. First time she starts and rumbles, appears

to be missing a cylinder. I shut her down, then start again and the 2nd time is very smooth, just like you would

want. Temps have been in the 50-60's overnight here in Central New Jersey. But wait, there's more.... <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" />



Problem #2: After the 2nd startup, there is a rattle and vibration, emanating from the engine bay, very pronounced, that will last for about 15 or so minutes. It can be heard and felt, and it's a rather low pitched tone. After that, it will gradually diminish until gone. If I park for a few minutes and start up again, the vibration will usually last about 1-2 minutes and be much less severe. I have replaced the front motor mounts within the past 2 months with new mounts. I also swapped DME's. Nope, not it...



Thoughts? Are these two related, or is it as they say, "dismissed as coincidence..." Anyone have anything similar and know what gremlin lurks beneath that beautifully sculpted hood? Thanks for chiming in with any tips.



Cheers!



-Scott

Partial Post: Please Login or Register to read the full post.

[flash]

rattle sand vibrations are worrisome, but not always serious - they may or may not be related



first - check your spark plugs - one could be loose - this could account for all of the above - it happens more often than you think - a loose one will cause starting issues if that is the cylinder it lands on when it stops (not as random as you think either) - heat then expands the materials enough to get a seal and it runs fine until it cools down again



good time to change them if you haven't recently - torque to 18-22 ft/bs



failing that being the problem, we can poke around and see if we can find some more symptoms, or more detailed descriptions, to help nail it down

Partial Post: Please Login or Register to read the full post.

[94SilverCab]

No answer for question #1, but question #2 my first thought was heat shield. These tend to break over time and can cause a severe rattle that doesn't affect performance.



Good Luck,



Jay

Partial Post: Please Login or Register to read the full post.

[Scott Collins]

Thanks guys. I will be checking plugs and heat shield on Saturday after about, I don't know,

anywhere between 2-6 cups of coffee... Thanks for the tips. I will let you know if I find anything.



-Scott

Partial Post: Please Login or Register to read the full post.

[rxter]

Another electrical thought. Plug wires. I have a low RPM stumble similar to Cloud9_68 from some years ago (and I've seen a few threads with similar problem). He worked it to death and finally saw arcing plug wires after running the car and observing the engine in his darkened garage. I also have the wildest low RPM vibration that I have ever experienced with this car. Starts OK, reverse out of the drive, get into first and go down a gentle grade away from the house at about 2K RPM - major vibration. I thought it was the tires at first, but I am now pretty convinced that it is the same issue as causes the stumble. Reason? Goes away after about 2 minutes - coincidentally the same time that it takes to warm the engine.



Once the car is warm both the stumbling and the vibration are rare, but do happen occasionally when pulling away from a stop light. I can avoid both by reving to 3K before I clutch.



Anway, I am ordering a new set of ignition cables (mine appear to be the original Bosche, and I don't see a replacement in the limited PO service records that I have) to see if that clears it up.



I have not done the arcing test yet, but it is very simple and very cheap.

Partial Post: Please Login or Register to read the full post.

[flash]

diagnosing these kinds of things is tough - remembering what kids of conditions that can cause changes after warm up helps - warm up causes two things to happen - first, mixtures are adjusted, as is timing - second, materials expand or contract (metal expands, rubber contracts)



looking for things that are subject to expansion are usually the first things to look at - heat shields and such tend to be suspect because the are rigid when cold, and the least little bit of energy causes them to vibrate - then, when they warm up, they become more flexible, and absorb some of that energy and quiet down



spark plugs frequently are the cause of problems, especially in aluminum heads - people are often afraid to torque them, and as a result of the dissimilar materials of the plug and the head, they back out enough to leave a small gap when cold - when the engine warms up, they seat back down enough to form a seal



periodically checking torque on these (and pulling them to clean or change them while you are there) is a good remedy



spark plug wires can do this occasionally too - usually it is the metal fibers that are the cause - cold, the wire sits more rigid, and the connection can be weak - warm, they are more flexible, and either gravity puts them into a different position, or the contacts expand enough to remove the gap - this one is pretty rare, but does happen quite a bit at the coil



periodically pulling these, cleaning and tweaking the connections to fit snugly is a good remedy for this - do not flex the wires much though, and never let them kink, as you could break the internal lead



rxter - you could bring the car here and we could try to figure it out

Partial Post: Please Login or Register to read the full post.

[rxter]

[quote name='flash' post='54071' date='Jun 6 2008, 09:19 AM']rxter - you could bring the car here and we could try to figure it out[/quote]



Sounds like a romp up the 5 is in order. I'll check on the wkend siteation adn give you a ring.

Partial Post: Please Login or Register to read the full post.

[flash]

saturday works - sunday i am going up to buttonwillow to watch pablo blast his car around the track - you're welcome to come with me

Partial Post: Please Login or Register to read the full post.

[Scott Collins]

[quote name='Scott Collins' post='54050' date='Jun 5 2008, 10:13 PM']Thanks guys. I will be checking plugs and heat shield on Saturday after about, I don't know,

anywhere between 2-6 cups of coffee... Thanks for the tips. I will let you know if I find anything.



-Scott[/quote]

Update:



Pulled the plugs and wires and found #3 spark plug was loose. Threads were "fouled" along the entire

length, unlike the other plugs. Wire appear to be in good order, no visible damage of arcing. Threw it

all back together and she runs much more smoothly. But that's not all... <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" />



Rattle noise and vibration still present. Checking the heat shield next. Even at idle, the motor is just too noisy to localize the source of the rattle. Other than that, could it be:



1. Cam cover seal and/or plug seals gone bad?

2. Bad alternator bearing?



.



Thanks.



-Scott

Partial Post: Please Login or Register to read the full post.

[Scott Collins]

OK - finally got to the bottom of the initial vibration and rattle issue:



1. Plug #3 was loose and tightened accordingly - no more problem starting



2. Front sway bar had "walked", and come about halfway out of the front left (when sitting in car)

bushing at the control arm. This caused it to come into contact with the "ear" at the bottom of the

a/c compressor. (This "ear" is not attached to anything, and I am wondering about sawing that sucker

right off...) Once I reset the sway bar and added a few hose clamps to keep it from walking it was

purrrrrfect!



So, I guess I dodged a bullet because the repairs cost me $5 for the clamps, and did not involve

anything major or mechanical. Heat shield is in good shape and "Claudia" is back to her old

self. <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" />



Cheers!



-Scott

Partial Post: Please Login or Register to read the full post.

[flash]

is the sway bar installed upside down?

Partial Post: Please Login or Register to read the full post.

[wolfeman]

Here's another path to travel... I had similar symptoms. Checked my plugs (they were fine) and asked my mechanic - he suggested checking to make sure the battery was fully charged and that the alternator or A/C compressor didn't have a failed bearing. Everything checked out. The additional symptom I had was belt squeal at idle. In chasing down everything (including taking both the battery and alternator to a repair shop for testing - MAJOR pain) I discovered that the front upper mounting bolt for the A/C compressor was GONE. Simply not there anymore. $3.04 later for a new hex bolt, I was back in business. Everything was fixed - belt squeal, idle rattle, chirp when A/C came on. So, for those of you still chasing a similar problem - make sure all of your mounting bolts are there and that the belts are properly tensioned!! (PS - a dishonest mechanic could've easily sold me a new alternator and/or A/C compressor to the tune of hundreds of dollars and I never would have known).

Partial Post: Please Login or Register to read the full post.