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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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MAP Sensor Issues
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Sun, 13 February 2005 01:16
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I don't know if anyone's had this problem before, but now my car's back on the road again and running much cooler than before, the MAP sensor issues are kicking up again. I'm not sure exactly where the problem lies, but every now and then it will shut the car off at worst, and at other times it will cause a brief hesitation in power. At first I thought it was spark or fuel, but both of those have been good (new fuel pump, new Iriway 8 plugs, dizzy rotor/button and cap are new too).
This issue first came to light when the re-wiring was getting done late last year, and Mos didn't know what the problem was either, but it turned out to be what we think is a dicky wire somewhere in the 3 wires that go to/from the MAP sensor. Now it's getting worse... when it does eventually shut the car off, the conditions it seems to be under are either turning right at low speed (hesitation, sometimes shut-off) and going uphills or a fairly sudden gradient change (mostly hesitation). At first I thought if it was doing it while turning right, the steering column was hitting something, but it's not (power rack-and-pinion), and it's completely in the wrong area. I can't figure it out, but I need to know if the MAP sensor wires route directly back into the ECU or is there a junction in between the MAP sensor and ECU where the problem could be.
I tried the vacuum line leading from the throttle body to the MAP sensor (disconnected it while running), then reconnected it. Seems to only drop the revs a few hundred RPM when it's disconnected.
I wanted to know if anyone else here had the same issues either with a GT-Four or a MAP sensor in general. I want to get an A'PEXi AVCR unit with it's own MAP sensor built-in a bit later on, but first I need to know if anyone's experienced this same problem before.
Thanks.
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I Supported Toymods
Location:
Sydney
Registered:
December 2002
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Re: MAP Sensor Issues
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Sun, 13 February 2005 03:24
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That vacuum line of yours thats blocked off with a bolt... that doesn't happen to be tee'd onto the map sensor does it?
If yes then double check that it isn't leaking / preferably remove the T piece.
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: MAP Sensor Issues
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Sun, 13 February 2005 03:34
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Nah, the vacuum line you're thinking of is T'd, but not to the MAP sensor. I'll upload a file of my engine bay soon so you can understand (briefly) what's going on...
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: MAP Sensor Issues
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Sun, 13 February 2005 07:31
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Thanks to river for this nice pic of my engine bay. Toobs, I've outlined the areas of interest in this pic. Is the MAP sensor getting vacuum from the proper source? Remember it's only occasionally and under certain conditions that it happens... 
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: MAP Sensor Issues
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Mon, 14 February 2005 02:16
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Update:
The problem doesn't occur when it's cold, but I have noticed that it presents itself when standing at idle for long periods of time like in peak hour traffic. The engine is hot, but the coolant temp says otherwise. It doesn't go above 68°C.
It's a hesitation that mostly just jerks the car intermittently, at worst it shuts the car off, which in peak hour traffic is a bit unnerving. 
I've taken off a couple of the front panels to let a bit more cool air through, just in case it is engine-heat related. This problem seems a bit complex, but the jerking under acceleration feels very intermittent, sudden and sharp.
At first I thought it was the MAP sensor because it was presenting a similar problem, but now I'm not so sure. I'll check over the basic electrical connections before I go home today and see what I find that could cause a problem.
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: MAP Sensor Issues
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Mon, 14 February 2005 13:26
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Got out to my car this afternoon and tried to start it, but couldn't. It was getting fuel and spark, and it hadn't been anywhere since I got it there this morning, so I know that it WAS working before.
I tried several times to get it going by fiddling with the MAP sensor itself, the wiring, the vacuum hose, hell even the mount that it sat on, just to see if it had any difference. Nothing. 
I sat in the car for about half hour trying to figure out what could possibly make it do what it was doing so soon after it was all re-assembled again. I kept going back to the MAP sensor, but not before checking over just about every electrical connection both in the engine bay and in the cabin. Disconnected battery, ECU, checked relays, fuses, etc.
Everything seemed fine, so I honed in on the MAP sensor once again. I disconnected it and checked the connections inside both of the halves of the MAP sensor (male and female side), and discovered that it had three pins in which it connected up to. Out of these three pins, only one (in the middle) looked like it could line up to make a proper electrical connection, while the other two (on either end) looked like they were recessed into the connector a bit, and needed a bit of prying out to get them lined up properly again. Reconnected the MAP sensor, hooked up the ECU and the battery, gave it a kick in the guts and it started and ran.
I'm still not 100% on the connector or the electrical connections inside, or indeed if the structural integrity of the wires leading to the MAP sensor are all that great, but with a minor adjustment I got it to run nice all the way home, without trace of the problems I had earlier. 
Rates about an 8½ out of 10 on my weird-shit-o-meter. 
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: MAP Sensor Issues
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Mon, 14 February 2005 21:30
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| CrUZsida wrote on Tue, 15 February 2005 01:08 |
| RAV-GT4 wrote on Mon, 14 February 2005 10:16 |
The problem doesn't occur when it's cold, but I have noticed that it presents itself when standing at idle for long periods of time like in peak hour traffic. The engine is hot, but the coolant temp says otherwise. It doesn't go above 68°C.
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I take it you don't run a thermostat?
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Actually I run a 71°C thermostat. Now, according to my temp gauge, it hardly even troubles the 165°F line, whereas before it was venturing past 212°F (100°C) with that same thermostat in. That's when I knew I had the head problem.
PS: I do wish AutoMeter would bring out °C temp gauges...
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: MAP Sensor Issues
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Tue, 15 February 2005 00:30
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| RAV-GT4 wrote on Tue, 15 February 2005 05:30 |
| CrUZsida wrote on Tue, 15 February 2005 01:08 |
| RAV-GT4 wrote on Mon, 14 February 2005 10:16 |
The problem doesn't occur when it's cold, but I have noticed that it presents itself when standing at idle for long periods of time like in peak hour traffic. The engine is hot, but the coolant temp says otherwise. It doesn't go above 68°C.
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I take it you don't run a thermostat?
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Actually I run a 71°C thermostat. Now, according to my temp gauge, it hardly even troubles the 165°F line, whereas before it was venturing past 212°F (100°C) with that same thermostat in. That's when I knew I had the head problem.
PS: I do wish AutoMeter would bring out °C temp gauges...
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If you are running a 71°C thermostat, and your temp doesn't get above 68°C, you have issues, or the temp guages are faulty.
A 71°C thermostat doesn't begin opening until 71°C.
ie, at 70°C, it is still fully closed.
At about 75°C, its about 50% open, and won't get till about 80°C before its fully open.
Why would you want to run the motor so cold?
Mine runs at 88°C, and gets to 94°C before I let the thermo's kick in.
I realised your factory thermostat is probably a few °C lower than mine, but not 20°C
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: MAP Sensor Issues
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Tue, 15 February 2005 02:47
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Did I also happen to mention that I run both my thermo fans full-time? I don't have a thermo-switch in mine anymore, so one stock RAV4 fan and another 11" thermo fan (thinner to accommodate the turbo) run together at the turn of the key. The 11" thermo fan runs off it's own relay, loom and fuse due to problems experienced earlier with the factory connector being used.
When I had only one thermo fan operational, the thermostat would get to about 75°C before it opened the full way, where the needle paused at that point for several minutes, until the engine got too hot because only one thermo fan was cooling the coolant, and so the needle ventured up past the 85°C mark (and kept going), at which it was the point of no return unless you switched the engine off. This was also exacerbated by the crack in the exhaust port letting CO-gases into the coolant, thereby pushing the coolant through the system until it created an air bubble in the radiator, and the coolant had nowhere to go but out through the reserve bottle.
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: MAP Sensor Issues
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Tue, 15 February 2005 02:58
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You shouldn't need to run the thermo's at any speed over 20kph.
If you car overheats at speeds, you have cooling issues.
Radiator not big enough, or just maybe blocked.
I'd assume that the whole cooling system is new.
Have you tested it since its been rebuilt?
You should really run something to control the thermo's.
Even if its just a sensor from a FWD car.
My thermo's only come on when I sit idle, and it takes about 2 mins. And then they switch off after about a minute.
By running them all the time you are significantly reducing their life.
After a 2 hour drive, my thermo's will be on for probably 2-3mins, tops. Depending on conditions of course.
I know this doesn't help the MAP sensor issue, but its good to sort out other issues while you are at it.
All I can suggest is that maybe 68degC is too cold for an efficient motor?
And regarding the MAP sensor, test continuity between every wire at the sensors, and the ecu.
Make sure its 0ohms.
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I Supported Toymods
Location:
Sydney
Registered:
December 2002
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Re: MAP Sensor Issues
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Tue, 15 February 2005 03:07
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Dude if you need another MAP sensor connector I'm sure we'd have one or two laying around the shed somewhere... but then MOS probably has hundreds under his house somewhere.
Also I have a gen3 MAP sensor you can "borrow" for a while if you want to make sure yours isn't fudged.
Probably also have a good thermoswitch you can bung in your radiator to get the thermo's working properly.
Ultimately if you really want to eliminate wiring, vacuum line, plug and the sensor itself as being faulty you should...
1. Run a good vacuum hose directly from your intake to the MAP sensor.
2. Swap the MAP sensor for a known good one.
3. Run new wires and connector directly from your MAP sensor to your ECU... no need to loom shit up and redo the whole loom... this is just a test.
Do each change one at a time in that order and run the car for a few days until you find your problem. Then fix it properly.
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