Learning About and Testing the Van’s MAP Sensor’s Operation

Sunday October 23, 2016 Guerneville CA.

Frustrating, but also challenging

Today, I planned to stay home and  do some more work on my van’s rough idling problem. I wanted to test out the MAP sensor with my volt meter and a little hand held vacuum pump to make sure it was working as it should. Map stands for manifold absolute pressure, which basically tells the computer how much gas to inject into the engine, so it’s very important.

YouTube helps out

To do this, I watched a couple of videos on YouTube to see how it was done and what values I was expecting to read during the test.

Where the heck is my vacuum pump

I have lots of tools and stuff scattered just about everywhere around here, so my next task was finding what I did last with the little hand held vacuum pump. That took some time looking for that and of course that’s always an excuse for another break. I finally found it right were I left it.

Map test good

I hooked things up and did the testing and the map sensor looked like it was working like it should.

Next I hooked it up to the engine and hooked my volt meter up and ran the engine to see if it was reading the right voltages and it was so things looked good.

Moved the map back to it’s original port

I did move the map back to the back of the TBI unit were it was originally and it seemed to work better on that port than the front port I had moved it to yesterday.

I think the hose was leaking

During that process I replaced the too big gas line I had used originally and hooked this up with the proper size vacuum line and I think that may have helped a bit.

I set the rpm with the meter

Next I thought I better get a reading on what the idle was actually that I had set by ear, so I hooked up a timing light that had an rpm meter on it and played around some more.

I used a special process they recommended to set the idle and  think there may be some improvement. The idle is set to near 700 rpms.

Here’s where I spent a good deal of the day, working in here on the V8 engine.engine


My brother Barry and his wife came by late in the day so I spent a good deal of the day shooting the bull with them.

Just didn’t get to the timing

I had planned to check the timing, but ran out of daylight so I’ll have to do that later.

I mostly just puttered around today taking it easy and enjoying the day and hopefully making little progress on this idle problem.

Map sensors might not be of interest to most, but just the same that’s what I did today. :O)

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Moving Wood, Measuring the Valley Water Level and Working on the Van’s Engine Idling Problem

Saturday October 22, 2016 Guerneville CA.

Yard chores

Being a weekend, I decided to stay home and do some yard chores and just take it easy.

I started with the hard stuff and moved several loads of firewood to the woodpile.

I picked up the cut wood here where this big Chinese elm tree fell down last summer. There’s not too much wood left to move, but there is still a lot of brush.wood2


What’s the cat after

While I was getting the wood in the wheel barrel, I noticed my neighbors cat chasing something up in an apple tree. By the time I got the camera, kitty was sitting under the tree looking innocent enough.kitty


She knew she had a little pine squirrel up in the tree. I spotted the little critter clinging tightly to the tree and not making any moves. It sat still like this for quite some time.pine


The cat hung around for about a half hour doing some preening before wondering off. The squirrel took off sometime later as when I checked it had gone.


I moved five or six loads of wood before I got tuckered out and had to quit. This is most of the wood from the tree which I will now cover up so it doesn’t get rained on too much.woodpile


Valley water level

I wanted to measure the depth of the valley water level so I dropped a line down this unused well to see. The water level is down to about twenty three feet, three more feet than about a week ago when I measured it. I’d like to see it down to about thirty feet before we drill the next well so I know any water we get is not coming from the valley water supply.

Here’s the string and tape I used to measure the old well’s water level which is also the level of the water in the valley at this location.well


Of course I took some breaks and puttered around a bit.

Working on the engines rough idle problem

I’ve been having some rough idle problems with the new V8 engine I just installed in my van and did some work looking into that.engine


Something to do with the MAP sensor

Steve identified a problem with the map sensor while I was up visiting with him at Gold Lake. I found some gas in the  line then and cleaned the sensor out and tried it while on my last trip. It worked ok for a bit then started running rough again.

This time when I looked in the line that the Map sensor plugs into, I found it full of gas which should not be.

Changed ports

I cleaned the gas out of the the sensor and installed the proper vacuum line on the unit. I also moved the vacuum tap from the back of he unit to a new port in the front of the unit as there just should not of been that much gas in the rear port, so I plugged that port up for the front port.

I started the engine and found it operated a lot different. I had to increase the idle screw a lot to keep the engine going, but then it seemed to work better.

More pep

I took the van for a little test drive down the road and it seemed to have a lot more pep so I think I’m on the right track.

Tomorrow I will reset the computer’s memory and set the idle as the service manual specifies and see how things look. It’s no longer idling rough, but I think it needs to be calibrated.

By then it was evening and I just sat around and chair hopped mostly. I did move one more load of little pieces of wood to the woodpile and that was it for my day.

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