| Author | Message | ||
     Greg French (Gregfrench) Senior Member Username: Gregfrench Post Number: 351 Registered: 11-2002 |
I was wondering if a misfire could be caused by a leak around the plenum. I took mine off a while back to replace some injectors and didn't seal it. It wasn't sealed when I removed it, which I thought was rather odd, but since that is how I found it, I decided to leave it. How likely is this as a cause? I replaced my plugs this weekend, but it didn't help this time. I put magnecore wires on a few months ago and that fixed it until last week. What else could it be. (I don't want to hear the dreaded "V-word") | ||
| J E Robison Service Co (Robisonservice) Member Username: Robisonservice Post Number: 76 Registered: 10-2002 |
A steady misfire is not caused by sticking valves. A steady misfire is a burnt valve, which you can detect with a compression test. A plenum leak will not generally cause a specific cylinder to misfire. Rather, it will cause a lean condition that may make several cylinders miss intermittently at idle only. A bad injector could cause the problem also. | ||
| Greg French (Gregfrench) Senior Member Username: Gregfrench Post Number: 355 Registered: 11-2002 |
Replaced some of the injectors last summer hoping to fix the problem. It didn't. Guess I need a compression test. How hard is it to do? Do I need to take it somewhere or is it something I can do at home? | ||
| Roland Kutasi (Disco1) Member Username: Disco1 Post Number: 75 Registered: 10-2002 |
Not difficult to do. All you need is to get a compression tester, get the engine up to operating temperature then pull all the spark plugs and screw in the hose on the tester into each cylinder. Remove the coil lead from the distributor and short it on a good earth (engine). Start your engine (high revs) and read the result. Assuming your compression ratio is 8.3:1 (refer to your owners manual), the reading you should get on each cylinder would be 140-150 psi. If your reading is low, remove the compression tester, and squirt into the cylinder a couple squirts of oil and redo the test. If the compression then does up to specs you have faulty rings. If the compression reading still stays low you have a faulty inlet or exhaust valve. Hope this helps. | ||
| Greg French (Gregfrench) Senior Member Username: Gregfrench Post Number: 358 Registered: 11-2002 |
Thanks. I'll give it a try. |
