I checked my codes today, and according to the blinking leds i wired up according to the rotorwiki website it was throwing the AFM code. So does this mean the AFM is bad? I checked it according to the S4 FSM and it is within the specs as far as resistance goes, so im really unsure as to weither or not that is the problem.

As many of you know, my car will some times shut off one of the rotors and run on one. After playing on the throttle you can get it to ignite the other one again, but it really makes the car a bear to keep running. Could it be caused by some bad injectors? Or maybe the ECU?

Also, can i use a non turbo S4 AFM or do i need to purchase an S4 Turbo AFM?

Thanks for the help guys

 

do they make any aftermarket afm's? I think mine has one, and that might be the problem...?

 

No aftermarket AFM. If its flashing an AFM code, check/clean the AFM connector.

 

but will an S4 N/A AFM work with my N333 S4 Turbo ECU???

 

For testing purposes, yes.

 

but i cant drive with it?

 

No, it means the ECU is getting a bad AFM signal. This might mean the AFM is bad, or it could mean the plug is loose or dirty, or the wire is broken. The FSM Fuel System chapter has a troubleshooting section with a check procedure for each error code. Follow what it says.

It's very unlikely that's caused by the AFM, but you still need to find out why you have an error code.

Possibly, but far more likely is a loose, broken or dirty connector on one of the primary injectors, causing an intermittent connection. You'll need to remove the UIM to inspect and repair.

Probably the least likely cause. ECU's are very reliable, and most problems are caused by the things attached to it. Eliminate all other possibilities first.

An NA AFM will make a turbo run very rich, so not recommended long-term.

 

bad injectors/bad wire to the injector connections/poor grounding / poor connections at the resistor box / failing resistor box (unlikely but possible)/poorly grounded resistor box.

I thought all S4 AFM's were identical? How do you even tell them apart?

 

*****I thought all S4 AFM's were identical? How do you even tell them apart?*********

The part number.

Try something else while watching you code tool/LEDS. Key on, pull the plug off the air intake temp sensor on the dynamic chamber OR pull the plug off the boost/pressure sensor

Do the code lights match the item you removed?

Or how about installing that non turbo afm and checking for codes once more. The car will start and run/drive like that. It might well idle different than the afm you had on there, for obvious reasons.

IF you have had a SAFC installed now or at another time...........look at where the afm signal was butchered by the SAFC install. That would make sense if you have a afm code.

 

He has an 88 so his car has no resistor box, and even if it did it would not be grounded!

NA and Turbo AFM's are calibrated completely differently.

 

ill try those things, i know at least the secondary injectors have some sketchy wires going to their clips. Oh and BTW, NZconvertible, thank you for changing the title of my thread, i wasnt sure what to call it.

 

Not me, I'm not a mod.

But if you want help with a problem, always describe the problem in the title. I tend to ignore threads with meaningless titles, and I'm not the only one.

 

Ok, so i checked those connections, and they are good, along with the injectors, they are good. Im lead to believe that the AFM really is the problem. SO now the question is, are there any differences between S4 turbo AFM's? or will they all work the same? Thanks guys.

 

oh and also, is $75 a fair price for a used one?

 

If you're absolutely sure it checks out as per the FSM, why do you think it's the problem. They're actually very simple devices (open it up and look ), so if it does what the FSM says it should I'd keep looking for other causes before spending money replacing it. Have you performed all of the checks listed for code 02 on page 4B-24? Are the pins on both the AFM and connector clean, and do they make good contact?

They're all the same.

 

Actually I would beg to differ in regard to the AFM's being the same. They carry different part numbers. Several authorities that I have talked to have taught me that the part numbers being different on the AFM's mean there are differences in them.

I have an 87 TII, my AFM is bad and am replacing it. I could not use your AFM from the 88. Also, the tolerances in regard to resistance per the FSM are different between NA and Turbo and mine would not run right using an NA AFM. I could test that it would run, but that's about all.

I'm going through this learning experience right now.

 

NA AFM's are different to Turbo AFM's.
S4 AFM's are different to S5 AFM's.
He asked if all S4 Turbo AFM's are the same. They are.

 

Again, I beg to differ though I could have been clearer in my response. The 87 and 88 turbo AFM's, speaking to those, carry different part numbers and are apparently different. Check the number and lettering codes. From memory, the prefix on the 87 is "A" whereas the prefix on the 88 is "NA", if I recall. I do not remember the rest of the numbers. But, I'm not here to argue with you. If you believe they are the same, I'm good with that.

The OP will now be sensitized to double check the part numbers and make his own decision and really, that's all we can ask.

Now if you say that even though they carry different part numbers, they do the same thing, I would have to take you at your word.

 

Okay, I'll take your word on that. I can't think of any reason for them to be operationally different, and I've never heard it mentioned before. Maybe someone with an 87 FSM can compare the resistance specs with those in the online 88 FSM.

 

Alright, I got a used AFM from another member on here, its an 87 TII. I plugged it in, and it works, so no more AFM code. However, it is still shutting off one rotor some times, and im confused on what to look at now. I plugged my code reader back into the port, and now its telling me the O2 sensor is bad. This i already knew because the wire at the top of the sensor is frayed, and looks like crap since all the insulation is cracked on it. Could that cause my car to sometimes run on one rotor? It seems as though now the car wont idle at all, without my assistance. Could the TPS be out of adjustment? Thanks for all the help guys.

 

Explain exactly what happens. Under what driving conditions, etc.

No.

Vac leak?

Could be. You have to check it and see...

 

87 and 88 afm resistance values are mirror images.

Nothing I know of will kill just one rotor, even the tps. Other than a bad plug/plug wire.

A 02 sensors *wire* is a cable. It is a shielded cable. IT has a center conductor surrounded by a *shield* made up of weaved wire that is grounded on the end of the cable near the ECU. The center conductor is not allowed to touch the *shield*or the voltage out of the 02 sensor will be shorted to gnd.

So don't let the center conductor touch the shielded wire strands. 02 sensors are bullet proof on the whole unless you gnd it's center conductor. Fix the wiring.

 

Here, this is exactly what it does. You can hear it drop a rotor a little above 2300rpms. Oh and BTW i was reving it in the beginning to see how it responded to abrupt throttle inputs.

 

sorry i forgot to post the vid

 

Loose, broken or dirty primary injector clip or (less likely) bad primary injector, like I suggested at the beginning...

Not AFM.
Not O2 sensor.