Help needed 02 P5 stalls when AC is turned on.

[wildcrazyjoker8]

Okay so a little background. I have an 02 P5 manual that will stall if I turn on the AC. If the just the blower is running it is fine, as soon as the compressor engages when the ac button is turned on it drops the RPM down to sputtering when sitting still. If I rev at all and let it drop it stalls. This only happens with the AC and I do not have stall issues any other time other than getting the car warmed up, but I consider that pretty normal. I recently changed out to the Denso SKJ16CR-L11 plugs from the NGK V-Power BKR5E to see if it would help, but nothing. I also changed out the EGR to the Canadian version and that made the idle a bit smoother, but didn't changed the AC issue. Any ideas? The compressor clutch maybe dying? It blows cold air instantly when it engages.

 

[MrGiggles]

When you start the car from cold, does it rev up to 1500 or so and drop down? It should, if the IAC is doing it's job. The PCM commands a slightly higher idle when the A/C is running, if the IAC is faulty it can stall.

 

[wildcrazyjoker8]

When you start the car from cold, does it rev up to 1500 or so and drop down? It should, if the IAC is doing it's job. The PCM commands a slightly higher idle when the A/C is running, if the IAC is faulty it can stall.

I have to stay on the throttle when I start from cold for 15-20 seconds or it stalls. After that it sits right at 700-800. I think I am going to just replace the IAC to see if it helps. I was really hoping changing to the Canadian EGR would solve it.

 

[Hank3]

If you're trying to save money, you may want to try and clean the IAC valve first before replacing. It might be wise to order a new gasket for $7-9 in case your current one can't be re-used. Part number for the IAC gasket is FSD713W89.

http://www.mazdas247.com/forum/showthread.php?123768800-IAC-Valve-Pro-5

 

[wildcrazyjoker8]

If you're trying to save money, you may want to try and clean the IAC valve first before replacing. It might be wise to order a new gasket for $7-9 in case your current one can't be re-used. Part number for the IAC gasket is FSD713W89.

http://www.mazdas247.com/forum/showthread.php?123768800-IAC-Valve-Pro-5

I have been cleaning the EGR and IAC every oil change. I have a box full of those gaskets actually. The IAC typically looks pretty clean. I think I may replace my coils too as I haven't done it since I have owned the car. Couldn't hurt right ha ha.

 

[Hank3]

I have been cleaning the EGR and IAC every oil change. I have a box full of those gaskets actually. The IAC typically looks pretty clean. I think I may replace my coils too as I haven't done it since I have owned the car. Couldn't hurt right ha ha.

How many of those gaskets you have? Been meaning to order one, but shipping is killer for such a little/light part. If you have one to spare, would you be willing to sell me one?

 

[wildcrazyjoker8]

How many of those gaskets you have? Been meaning to order one, but shipping is killer for such a little/light part. If you have one to spare, would you be willing to sell me one?

Sorry just now seeing this. I have a bunch, but I am keeping them as I change them out quite frequently. Just do what I did and buy a bunch at once off rockauto or somewhere and only pay shipping once.

 

[wildcrazyjoker8]

Okay so I have replaced the IAC, coilpacks (beck/arnley), and wires (nology) and still having issues. I really wish my car would at least throw a code at me to let me know what is acting up. Going to replace my belts this weekend, clean the MAF, and check out my o2 sensors next. Any other ideas? Maybe I will have to get a new ECU?

 

[MrGiggles]

Okay so I have replaced the IAC, coilpacks (beck/arnley), and wires (nology) and still having issues. I really wish my car would at least throw a code at me to let me know what is acting up. Going to replace my belts this weekend, clean the MAF, and check out my o2 sensors next. Any other ideas? Maybe I will have to get a new ECU?

Could have a blockage in the IAC passage causing it to not work correctly. I would remove the throttle body and give everything a good cleaning, ensuring that the IAC can function like it's supposed to.

 

[wildcrazyjoker8]

Okay so an update. I replaced both belts and that helped out a little. The car starts smooth and idles really well with the AC off. I pulled the IAC off again and it is spotless still. Checked the resistance and it is spot on. Now to the bigger issue. I pulled the sensor plug off the IAC and no change in idle at all. So does that mean my ECU is acting up? Is there a way to test the wiring that I would be able to understand? I pulled the sensor for the MAF just to see and the car stalled about 10 seconds later. So that one is working fine.

 

[hotcracker69]

alternator voltage has been check when AC is on?

 

[wildcrazyjoker8]

No I haven't done that yet. Do we know what it is supposed to be before and after? Or should it not change?

 

[MrGiggles]

I would be looking over the harness for broken wires. Not likely to be the ECU, but the signal from the ECU may not be reaching the IAC.

The factory service manual only shows a procedure for checking the circuit for continuity and shorts using a breakout box.

 

[wildcrazyjoker8]

I would be looking over the harness for broken wires. Not likely to be the ECU, but the signal from the ECU may not be reaching the IAC.

The factory service manual only shows a procedure for checking the circuit for continuity and shorts using a breakout box.

Yeah Ive seen the diagram/instruction for using a breakout box and that is a definite no go for me. Guess I will have to try and trace out the wire. Can anyone here run a meter for me to see if the ECU is sending voltage with the car running/off so I can bounce that off of what I am getting?

 

[wildcrazyjoker8]

Bump. Can anyone try and give me the voltage readings in my last post please.

 

[Natey]

A clogged cat will make your car stall and idle weird too too.
How many miles are on the car? If it's been running rich I'd take a look at the exhaust.

EDIT: Sorry I can't help with the reading. I don't have a P5 anymore and my MSP is at the smog shop.

 

[wildcrazyjoker8]

Interesting on the exhaust. Car has 140k miles on body/exhaust, but only 73k on motor. I think I have a performance cat laying around my garage somewhere. Maybe time to get an aftermarket header and install a new cat. Car seems to running fine. I don't smell fuel or it running rich. Im getting about 350 miles to a tank so not horrible gas mileage either.

 

[wildcrazyjoker8]

Okay just wanted to come back and provide an update. So I ended up breaking the IAC Valve connector on the harness and had to rig it back together until I can get one from eBay or a junkyard or here. However it works at the moment. So I tried a brand new IAC valve from Mazda and had no changes in the AC making the car stall out. Now to the weird part. I bought a cheapy IAC Valve from eBay and it not only allows me to use the AC, but it also works even with the harness connector off. If I hook up the connector it causes the car to randomly jump idle and or speed between 2500-3500 RPM up and down. I even took back the one I bought from the dealership and called it faulty. I explained my car issues and he said its impossible. So I brought it in and sure enough he had the exact same results with yet again another new IAC Valve. So for now I am running without the connector and got a service engine light, but I have ice cold AC and no stalling.