Now have what seems to be a miss

[hcoles]

Hello 3.2 Experts,

I have what seems like a miss after engine was reinstalled, not too noticable at idle, but my idle was never very smooth before. The miss or vibration is consistant and seems to get more noticable as the rpm's go up with power on, also noticable at med. and low power settings. The engine power seems down, just has no snap.

I just installed my engine after being out for 4 months or so.
Things done to engine while out:
- new rebuilt fuel lines on the engine
- new fuel filter
- new plugs - NGK
- remove replace rockers
other
- rebuilt Wevo trans mount - black plastic donuts
- new starter ring
- new starter
- rebuilt clutch fork shaft asm.

Ideas?
- change to Bosche WR7DC plugs - mechanic suggested this.
- check resistance of spark plug wires - they are Magnecor red - been in for 8 years without issues so far?
- an injector is clogged
- an injector electrical connector is loose
- other suggestions?

Thanks,
-Henry

[Tigerrat]

Could easily be an injector mucked up after sitting 4 months. Might try an injector cleaner for starters. If you think its one cylinder, try identifying it by disconnecting plug or injector wires one by one and see if one makes no difference in its running. When I had my engine out I sent the injectors out for cleaning. Ken

[hcoles]

Ken, yes that could be it. I'm running a bottle of Techron through now. May have to pull the injectors and send to WitchHunter. I'll check a few other things first, like pulling wires (plug and injector). Thanks for the comment.
-Henry

[stlrj]

The first thing I would do is verify my ignition cables are on the correct plug as well as the firing order on the distributor cap.

[hcoles]

Big Update - Here is what was just completed.
1 - took to mechanic, he said right bank spark plug wires were bad. Some were measuring open. Mechanic said compression was good. Mechanic installed new cap/rotor. So I ordered a new set of Magnacors.
Today I:
1-removed plugs, took compression readings, my guage reads low I guess all very close at 120-126.
2-plugs are new NGK, look almost not used
2.5-I checked the "old" Magnacore wires through the cap and off the cap. Off the cap measured 3-9kohms as a function of lenght, I think that means the wires are good. I didn't measure the new wires. When measured though the cap I found one open, and then discovered a few that were not pushed down on the cap. Conslusion is that the old wires were good. I did find a broken clip, so I needed a new set I guess at this point anyway.
If I had time Magnacor would probably send me one, I hear they are a good company.
3- put in new Magnacor wire set
4-checked firing order
5-pulled one plug wire at a time, huge difference, all the plugs are firing.
6-road test, runs with the same vibration that sort of increases with a peak at ~2500rpm.

My current conclusion is the spark is good, it must be something else.

What was changed during the engine drop? New starter ring gear. New transmission mount, black donuts Wevo.

The onlyl two remaining ideas for the root cause are:
1- vibration - the engine had a vibration but now I feel it because of new trans mount or something with changing the starter ring added an imbalance
2-injector is clogged because of sitting 4 mos. - however it idles as good as it ever did, but the power seems down

Anybody got ideas for the next step?
Thanks.

[mca]

Have you verified correct mixture?

[Rev-it 84]

You said you replaced the rocker arms, did you double check valve clearance?

[hcoles]

Did not double check the valve clearance.... the compression checked out. The guy that set the valves did it with the engine out and he has likely done as many 911 valve adjusts as anyone. So I'm thinking that is a low probability. But could be...

Mixture - my mechanic hooked it to the sniffing machine and no odd readings came out. This was at idle. The car idles at least as good as ever.

We are now thinking to check the WOT switch to be sure it is working, this could resolve the low power.

The vibration is another thing.... we think. Two other 3.2 drivers drove my car today and are thinking on what could be wrong.

Thanks much for the thoughts.....

[Scott R]

Have you checked the air boot for cracks? A small one will set off a miss on a 3.2.

[hcoles]

Okay, didn't think of that, I'll look and poke around
Thanks.

[hcoles]

A thought that came to mind. What would cause power loss and vibration. How about something changed in the exhaust. I stored the muffler outside during the engine drop it could have got some rain in it. I noticed when I initially heard the car after engine was back in it sounded a bit different. What if something let loose in the muffler, creating back pressure and somehow a vibration? IMO is sort of follows that at idle the back pressure would be low and not cause much of a vibration. Also, the idle seems a bit smoother that in the past. Could be the result of a perfect valve adjust or maybe an increase in back pressure is causing the idle to be a bit smoother. Guys (gals also) what do you think?

[signature65]

Or someting crawled up inside that exhaust and made a nest up.....could be restricting your flow