Hi everyone , two questions for you:

89 camaro iroc, 305tpi, auto, 163000 miles, 30k on rebuilt engine, 5k on rebuilt tranny.

1- My car was running a stored trouble code 25 and running rich , like maybe 12mpg when my check engine light started flickering on and off every 10 minutes or so. Normally I figure I got at least 15mpb. It turns out that the MAT sensor is missing
and theres a copper fitting pluggin the hole. No problem right? $30 part? Well they also say that the wire harness is missing and that's going to be at least 2 hours labor tryin to track it down/reset it up. What do you think?

2- While cruising with nothing on the gas pedal or riding the brake, there's a constant thud thud thud noise from the back. Also, while making sharp parallel parking moves, it screeches and crunches and isn't happy. I got sick of this, so had the shop check it out and they said so far they found a leaky pinion seal and cover gasket. Parts and Labor come to almost $300 to fix this. Will this help my described problem too you think, could I have been running on too little oil? Also, if this costs $300 or so, should I just go ahead and rebuild my rear end? I really don't want to spend more money than I have to. Approximately how much does that cost?

Thanks for all your advice?

 

300 dollars is way too much for a pinion seal. 100 dollars would be more like it with the parts included. the wiring may be more accurate but it's hard to tell what you have or don't have. it could be simple to fix. it's hard to think they can quote a price to fix the wires and then sound liek they don't know what they'll be getting into to fix it.

 

Save your cash, find the harness yourself, and install your own MAT/IAT sensor. You can get the sensor for about ten bucks (Wells SU109 - $9.99), and clear the stored codes. The MAT/IAT sensor is not that critical, so an aftermarket sensor should work for you with no problems.

Hopefully, the technicians that diagnosed your car understand that the MAT is located on the underside of the intake plenum, and is all but invisible unless the intake is removed. They may have missed that one.

This article may give you some hints about where to find the MAT/IAT sensor, the harness, the connectors, and what to do about it:

MAT Sensor.pdf

There is one connector right here (yellow arrow):

 

What rear axle do you have? Is it a 9-bolt or 10-bolt?