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| Unexpected miss on this morning's drive. https://slantsix.org/forum/viewtopic.php?t=24157 |
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| Author: | Sam Powell [ Sun Jul 22, 2007 11:58 am ] |
| Post subject: | Unexpected miss on this morning's drive. |
Went out this morning, and the engine stumbled badly a couple of times in ways that felt sadly reminicent of the times last year when it would not run at all when it hit 170ECT. Unfortunately, I did not have the laptop hooked up, and don't know what was going on. The AF ratio looked good most of the time, but when it stumbled, I did not glance down at it. Just panicked, and began to pull off the road and it picked back up, and ran fine. It did not back fire, so I concluded from this it was not a rich miss. I rich miss is followed up by a bang as the unburnt fuel gets caught up to in the exhaust once the engine fires again. So, I am suspecting lean. The thing is, it was cooler this morning than it has been for awhile. This has been a wierd, unseasonal cold spell for DC in July. So the air was cooler. But I don;t understand why the IAT sensor would not have adjusted for this. Why do you suppose the sensor does not feed the right info to the ECU to enrichen the mixture when the air is cooler? I have watched this on the computer, and it does not seem to respond very quickly to changes in the intake air charge. I have an open air element sensor there. One thing I have been planning on doing is doing a nicer job of routing the spark plug wires away from each other and from the block. The guy who worked on the engine last fall, and did the awful job of tuning it up, restrained the spark plug wires by clamping them to the engine block with cable clamps under the rocker arm cover screws. He also bundled them together, and wire tied them to each other. This seems like a bad thing. It seems as if their could be some cross fires here, or missfires if the spark got sent right through the insulation to the block. I know he was trying to eliminate the spark plug wire field from interfering with the distributor pick up wire and thus maybe messing that up,since we were not getting proper RPM count from the distributor to the computer at the time. For this reason I have been happy to leave it tied back, but think there must be a better way to do this. I wondered if maybe there was a spark misfire that was compounded with a lean mix, or maybe too much advance for the mixture present. Boy, this can be complicated: just when I thought I was sailing high. Any ideas? Sam |
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| Author: | emsvitil [ Sun Jul 22, 2007 1:17 pm ] |
| Post subject: | Re: Unexpected miss on this morning's drive. |
Quote: The thing is, it was cooler this morning than it has been for awhile.
Cooler than normal......... How about some water dropped out of suspension in the fuel (gasoline can hold a little bit of water in suspension; but the cooler it is, the less water it can hold) The stumble would be when the water made it to the injectors...... |
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| Author: | Sam Powell [ Sun Jul 22, 2007 4:32 pm ] |
| Post subject: | |
That sounds encouraging. I should be putting some gasline antifeeze in the tank. It did sit all winter. Thanks. Sam |
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| Author: | mpgmike [ Wed Jul 25, 2007 2:21 pm ] |
| Post subject: | |
Do you have the enrichments set-up for colder ambient air? The IAT will not trigger change if you haven't programmed it in. Mike |
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| Author: | Sam Powell [ Thu Jul 26, 2007 5:35 pm ] |
| Post subject: | |
ARe you familiar enough with the Accel ECU to know how to program that in? I thought it was a default of the program. Thanks Sam |
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