Hey guys,

Transmission fill plug is still stuck, but I got the rest of the car together.

Unfortunately im pretty pissed off.

My car is still running rough, not terribly rough, but its evident that its not smooth.

This engine has less than 60,000 miles, new spark plugs, new spark plug wires, new cap and rotor, new ignition coil.
I just put in the stock Delphi replacement injectors, brand new, and no apparent leaking.
I don't seem to have a vacuum leak anywhere on the intake. All the vacuum hosing is new.

I've got a new fuel filter, pump, and sending unit.
New(ish) o2 sensor
New harmonic balancer
MAF sensor appears to read well. Is a BOSCH unit.

New exhaust + cat

Also an alleged fresh bin (ANYS) from an 89 Iroc of the same specs as I've deleted my cold start injector.
Timing is good
Compression seems strong.

The car starts well, and can hold a fairly steady idle around 775
however the whole car vibrates, and oddly, when checking my timing, (6ish) with the tan and black wire disconnected it seemed to run a bit smoother.

After I concluded and plugged it back in, there is a definite "sputter" that's audible.

Firing order is correct, as I've just re ran the wires..

The reason I started the whole injector business was due to not being able to achieve a steady INT and BLM, it seems to be hovering properly at 128 now.

While driving on the highway the engine vibration (yes in neutral, even at idle) prevents me from speeding up anywhere near 70.

The rear end is essentially freshly rebuilt..

I've tried multiple driveshafts in both phasings

And I've determined it must be my engine.

Visually it seems to "shake" a normal amount, but I don't have any reference. You can feel the vibration in the driver seat and in the shifter ****. If the hood is up, you can see the spring on the front of it vibrating.

I'm all out of ideas. I'm pissed, and I'm simply at a loss.

Please, anyone, any ideas as to what could be causing me this trouble ? I love this car, and want it to just run optimally stock, but I've had nothing but trouble the last 8 years and I've certainly dumped a ton of money into it.

There was a brief window maybe two or three years ago where it ran great on the highway, and I can't tell you what changed.

Any ideas would be very much appreciated.

Thanks.

 

How old are the motor mounts?? My Camaro has manual linkage and I broke 3 Z-bars before realizing the motor mounts were the issue. The Z-bars attach to the block for support with a stud and the engine movement was torquing on the bar causing it to fail....

 

The mounts are original. I was kind of afraid of it being the mounts.

 

Are you sure you are firing on all 8? Running on 7 will shake the crap out of the car. I'd check fuel and spark at each hole. Maybe check for a split wire.

 

IS this an original engine/trans/clutch setup, or something pieced together recently? Sounds to me llike you have the wrong flywheel...

 

What caught my attention was that you installed a new balancer, and then you seem to have the vibration issue related to timing with the difference being when you have the EST connected/disconnected. Are you sure that the marking on the balancer is correct with the #1 cylinder at TDC?

 

I haven't swapped out anything significant as far as drive train goes since I've had it. I believe its all original. I did have a minor accident a few years ago that im still swearing over however.

It was my first balancer install, if I understood what I was reading correctly, I believe it was... I can't be sure.

Would this be a matter of adjusting the timing in order to smooth it out? Or is it a balance thing that needs to be corrected?

 

SBC crank dampers haver had the timing mark in at least 3 different places over the years. Unless you bought a replacement specifically for one of these cars, it could easily be wrong.

Mostly, that would make the engine run REAL lazy (the most usual mismatch would retard the ignition timing HIDEOUSLY if you screwed up and used a timing light) but wouldn't cause a miss or vibration.

If the clutch is pushed in, and you rev up the motor, does it vibe? Then, when you take your foot back off the gas and the engine speed is coasting back down (essentially, the engine is not running at that point) does it STILL vibe? If it vibes under that condition, then it's mechanical, not ignition-related or a "miss" or any such. I'd be looking at things like, is the flywheel indexed to the crank properly. Which there should be a dowel pin for that; is that still there?

 

I used a GM Genuine:12551537 for the balancer. As far as the flywheel goes, I have yet to get a visual inspection on it. Id have to assume the dowel pin was still there, unless they're known to fall out?

I'm going to confirm spark and play with my timing a bit.

At the very least, when I disconnect the injector plugs, there is an impact on idle. This would lead me to believe that everything is firing, but perhaps im mistaken.

 

I know nothing about GM part #s. No idea whether that one's mark matches your car's tab. Of course, if you have a different timing cover, that would also cause a mismatch; that's actually more common than the other way around, as it's always been popular to "dress up" engines with "krome" garbage.

Regardless, it's beyond eeeeeeeeezzzzy to eliminate "timing" as a suspect in ANY driveability or similar complaint. And that is, to simplyu adjust the timing to what THE ENGINE wants, not to what YOU THINK IT SHOULD HAVE. THE ENGINE knows when the timing is the best it can be: it runs the best there. Too simple. Too eeeeeeezzzzy.

As I've told people countless times, there's a phrase that applies to this situation, that came from one of the GOATs in a totally unrelated field. Had that giant of accomplishment been working on cars instead of doing what he was doing, he would have answered the question "how can I tell if it's any good" by saying "if it RUNS good, it IS good". Very wise man.

Try it. Advance it until it starts to ping, then retard it in small increments until it quits pinging. How eeeeeezzzzzy iz that. Now, there's no guarantee that that's "right" or "perfect"; butt if you discover that wherever you've had it set is like 40° from that point, then you can be PRETTY DAMN SURE whatever you were doing to set it before, has led to GARBAGE. Best of all, YOU get to decide what "runs good" looks like to YOU. It might be any combination of best power, best gas mileage, cool running on the highway, no pinging, easy starting, crisp throttle response, maybe even no vibrations. Factory "spec" is based on NONE of those things: it was chosen based on emissions, CAFE, emissions, insensitivity to altitude (we build the cars all the same wherever, ship some to Denver and some to Miami, they run OK in either without changes), emissions, insensitivity to temperature (same deal except think Fargo and Phoenix), lack of complaints from grandma about NVH, emissions, compatibility with the fuel available at the time, emissions, ... and oh by the way, in case I forgot to mention it, the SINGLE most important criterion the factory writes the "spec" to contend with, which is, EMISSIONS. If none of those things matter to you, but the first list DOES, then close "book", forget "spec", put down "light", ignore "mark" and "tab", and adjust it to where YOUR car runs the best it can, in YOUR opinion, driving where YOU drive, the way YOU drive it, on the fuel YOU can buy.

So, try that first, since it's completely free and nearly effortless.

Come back and let us know (a) how much better you were able to get the car to run, and (b) whether it had any impact on vibrations. We'll go from there.

 

Rock and roll man, ill do this when I get home in a few hours.