Well heres the deal

Christine car is throwing a check engine light....

So i check it with the volt meter....i get two codes outta it
1) O2 sensor
2) Mas sensor

Well then i thought what the hell ill try my logger and see if it works.
Behold.....my logger works in her car which i didnt think i would

The logger is telling me its the coolant temp sensor and an o2 sensor, so i know for sure one is right. (the o2 sensor)

Anyways the driveability of the car makes me lead to both the coolant and mas.

COOLANT: if she runs the A/C in the car while driving it for about 15 min straight it starts to over heat. And i did replace the sensor about 2 weeks ago. The funny thing is the car will only over heat with the A/C constantly running, if its shut off or not in use (the A/C) the car will not over heat. The thermostat was replaced and i did check it to make sure it works, got a different coolant cap cause the one on there had a bad seal, i did a pressure test of the coolant system and it holds pressure (15 psi) and there isnt any leaks. Also both fans are working. So what the deal with this issue?? Why would it still over heat even after a different sensor in it?? Unless that sensor was bad, but the car was fine for that 2 weeks with the new sensor??

MAS: The car in only low rpms seems to have a bit hestation/shudder until about 3000rpms then its fine, also seems to do it more when the car isnt totally warmed up. What i thought of is maybe if the mas is bad its running to rich (possiably flodding the car at low RPMs) or to lean (not getting enough fuel for those lower RPMs) What do you think?

o2 sensor: I did replace it about 2 1/2 months ago (when i did the borla exhaust with a new 3sx downpipe) and its a bosch, Not 100% on this but i think there is only one, my question on this is could it possiably be that her car burns oil the way it does would drasticly shorten the life of the sensor?? Damn things are about $85 a piece.

I dont wanna go into a big tailspin with all these issues and start throwing money at the car because of guess work. So if anyone has some good suggestions it would be greatly appreciated.

Thanks Brian

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1992 RT/TT Black.......lots of goodies.

I've got a MAS that you could throw on for a while, and see if that makes drivability better.

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Bad decisions make good stories.
Look at it! LOOK AT MY @SS AND TELL ME IT'S PRETTY!

Few thoughts:

MAS is fine. I've never seen a MAS go bad unless someone was playing around with it or was driving around without a filter.

For the overheating issues, how old is her radiator? If the fins are all banged up and there are a lot of leaves tucked between the radiator and the AC condensor, that would restrict a lot of the air flow.

How old is her waterpump?

When the motor is completely cool, pop off the coolant cap and start the motor. Does the coolant seem to "bubble"?

As for the O2 sensor, did you get the bosch sensor that needs to be wired in or was this one plug & play? Either way, double check the connections as I've had cars come into the shop where they just came unplugged.

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06 Blue EVO 9

If the mas is fine, then what is the cause of the shuddering/hesitation?

The o2 is wired and i soldered the connectons with shrink tube when i installed it. But i will check it out.

Radiator was replaced about 40,000 miles ago and i did the timing belt and pretty much everything inbetween including the water pump about 15,000 miles ago.

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1992 RT/TT Black.......lots of goodies.

Wouldn't hurt to check the timing. Just a thought, but if the valves were partially open during fuel injection, maybe it would cause some problems with the o2's?

Did you use tap water or distilled water when you refilled the radiator?

How old are the headgaskets? Did you pop off the thermostat cap and see if the coolant bubbles or boils with the motor running?

Regular tap water but even so ive done tyhis with many vehicles with no problems....

i will check the timing when i get a chance..

Brian

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1992 RT/TT Black.......lots of goodies.

I dont know how old they are but there isnt any with smoke out of the exhaust or i couldnt find anything in the oil either. With the motor the coolant does flow and i didnt notice any bubbles

Brian

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1992 RT/TT Black.......lots of goodies.

Is the overflow tank filled between the low & full lines?

The cat does a very good job of filtering out white smoke. That's one of the reasons if you have bad valve stem seals or something, the motor has to idel for a while before you see it. With the O2 sensor being so close to the cat, I could see the high moisture off setting the sensor or wearing it out prematurely.

Maybe you should run a compression test.

Overflow tank is filled and there is no cats with the new exhaust.....
But i do know the valve guides are bad and that whats causing it to smoke

Brian

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1992 RT/TT Black.......lots of goodies.

I have a compression tester if you need it.

_________________
Bad decisions make good stories.
Look at it! LOOK AT MY @SS AND TELL ME IT'S PRETTY!

Do both her radiator fans work?

Yes they do

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1992 RT/TT Black.......lots of goodies.

Thanks adam but i do have one

I really cant do anything to the car til the end of next week because christine went up to her grandmas for vacation. Im gonna bring my logger up there and see if the car is really over heating. Im starting to lean towards the coolant sending unit. Im thinking the guage is inaccurate And ill bring the compression tester also.

The car runs and drives fine, unless the A/C is used

Brian

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1992 RT/TT Black.......lots of goodies.

Brian:

You don't smell anti-freeze do you?

SJ

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