Background: 1994 trans am 201k miles. sat in a junkyard for a little while before i got it. the previous owner couldn't figure out how to fix the locked up security system. he brought it to my house on a trailer and i ended up cutting the vats wire and it started right up. i have put about 7k miles on it since then. about 3 weeks ago i decided to get rid of my annoying belt squeak so i took out my radiator fan and put the new belt on and in the process of re installing the fan i broke the water temp sensor off the water pump. this is when it hit the fan, hard. this made it run rich and not want to start. i fixed it and changed my oil. for some reason it wasn't any better so i changed the plugs and wires...still wasn't better, and by better i mean it still idled rough and ran super rich and broke up after 4k rpm. i had recently got my opti wet so i took mine apart and put the Mitsubishi sensor in a brand new rich porter opti (i didnt trust the Chinese sensor). this still did not solve my problem. i also put a whole new opti on, so im sure its not an opti problem. i replaced the iac and it fixed the idle but it was still running rich. i replaced both o2 sensors (no cats) and this didnt help. after this, it developed a hesitation under 2.5k rpm and it started surging at idle from 600 to 1200 rpm. i replaced the maf and now it is extremely hard to start, usually i have to hold the pedal to the floor and crank it for 10 seconds and it will run for about 2 seconds and eventually it will start running decent untill warm. when its warm it will hesitate when taking off or getting on it hard. the hesitation is gone if the maf is unplugged. the car is still hard to start and is running rich. i have a whole slew of codes, i cleared them and these are what came back 11,16,23,25,26,27,29,43,44,45,46,50,52,55,61,62,64 ,65,66. my car seems to have a few electrical problems, probably field mice ate some wiring in the junkyard but i dont think its the problem. can anyone help me and my car of a billion problems?

 

44 and 64 are o2 sensors reading lean. Remember that when flooded, o2 sensors will read "lean" because o2 sensors are just that: oxygen sensors. If the car is running way way too rich, there's lots of fuel and air in there.

 

thanks for reply it smells like gas when it cranks so i had a feeling it was running rich. when the water temp sensor on the water pump is unhooked it defaults to -40 and makes it run extremely rich. i hooked it up to a buddys scanner and the ecm water temp was fluctuating between -40 and 190 and when it was around 190 it ran fine and when it was around -40 it kept self reving from 600 to 1200ish rpm. i replaced the almost new sensor yesterday and it seemed like it helped a little bit but it doing it again. i have no idea if the sensor actually helped because this is an intermittent problem and doesnt happen at idle all the time. it runs rich 100% of the time, hard start 25% cold, 96% when warm. hesitation 0% with maf unplugged, 99% with maf plugged up

 

I can't help you with the MAF side, I have 93 so I'm only MAP sensored. I too need a water pump PCM sensor. What's the part number you used?

 

well i took mine to autozone and bought one there because i didnt have time to order an oem one. the first time they gave me the wrong one so check it if you go this route. i think this sensor could possibly be too cheap to work right so i may go to the dealership and order one, any thoughts?

 

Not sure man. I don't have autozone, or anything like that around here. I'm in the land of the rising sun.

 

so today I had 2 wires completely burn up while I was driving. I pulled over after I seen a lot of smoke and unhooked the battery. i unhooked the wires and drove it home and it seemed to be ok


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Sounds like that car just needs to be gone through. Have you checked compression? fuel pressure?

Try to unplug the MAF and start it. Sometimes pirate air gets in if the manifold is leaking and causes all types of problems. You may also have vac lines that need replaced. Is the EGR still there? Is the fuel pressure regulator good? Is the AIR system still complete?

Are you sure you replaced the coolant temp sensor on the waterpump correctly? Sounds like this is when all your troubles started. Did you hook everything back up afterwards that was taken apart, sometimes one connection is all it takes. Are you sure the plug wires arnt crossed? Have you tried a new ICM? Are you 100% sure you installed the opti spline correctly and the opti was seated 100%? The splines can only go in one way correctly, forcing it together will screw everything up if your unaware of the keyed spline.

Car honestly just sounds like a mess, maybe it was just happy in the junkyard lol

 

it will die if you give it gas with the maf plugged up so i always leave it unplugged. i have not checked my vac lines, after all these years they could be bad. im assuming the egr is still there, where is it located and how hard is it to remove and clean? i deleted the AIR pump, and i have not checked fuel pressure or the regulator. im positive the coolant sensor was installed correctly and im 90% sure i hooked everything back up, i need to go back and check. the plugs and wires are correct and so is the opti. ive heard of people replacing the icm and it fixing there problems but i hate to throw another 80 at this problem. if i can get this issue fixed its really a great car, and i dont have much in it either. one of the wires that burned up was a blue wire that ran from the connector block a few inches down the positive battery cable all the way around the engine and through the firewall and under the dash. everything seems to work ok without this so i may not run a new wire. i got lucky because when i popped my hood i seen this wire burn a clean hole in my almost new battery. i guess ill see if silicone will fill the hole and hold.

 

so I found out the whole problem was the brand new water temp sensor. I put a 330 ohm resistor in the plug and it works great now


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and your MAF is plugged in and working properly now right?

 

yup, everything is back as it should be

 

I avoid autozone parts like the plague. When I changed my waterpump, I broke the same sensor you're talking about and replaced it with one from O'Reillys Auto and didn't have any problems. If you have an O'Reillys, Autovalue, or Napa parts store near you, try getting a new sensor from them. I can see a dealership ripping you off for a sensor of the same quality as these other stores.

 

i went and got a new one from napa today and it works great so far

 

Hey! When your shitty saga of terrible running vehicle was happening due to the sensor, when it broke up was it backfiring through the intake? (A clear indication of a timing issue, IE firing late) Just curious if that little guy affects timing at all.

 

do you mean was it backfiring through the intake after 4500+ rpm? if so, i didn't notice it backfiring, it just kinda cut out as if someone was switching the ignition on and off very quickly. to this day the sensor is still working great.

 

I changed my sensor. No change accept timing stopped jumping all over the place. I currently have a 12v 330ohm resistor in there because it keeps it in closed loop with an advanced timing so I can actually drive it lol.

 

Astrunk93.. just bought a 93 Trans Am m6, did a clutch on it today and when I hooked the battery up the VATS locked up the engine. Can't start it normally, but it will kick start and run. Where is the VATS wire that you cut and have you had any problems with that system since? thanks

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93 Trans Am 6 speed, Flowmaster catback, CAI