is my AFM broke? (TESTED!)

[Guest szlash280z]

Here is the problem. runs and idles fine, until I floor the throttle while under load. heavy stumble, a light backfiring and some popping from the exhaust under full throttle. It will not rev past 4500 rpm. it has pretty much stock '83 ECCS but it's in my 78, and it used to run fine. I haven't been driving the car much, which might have been a factor here.

 

I am thinking it's got something to do with the AFM, but I don't have a multimeter to check it anymore (broke and lost) I have checked and reconnected all the ground connections, cleaned the afm contacts, tps contacts (I even made a new TPS connector using a partially disassembled FI connector) cleaned the head temp sensor, unplugged and replugged the ECU. pretty much standard troubleshooting.

 

Since it only does this on full throttle, under load, and no matter what RPM, it makes me think AFM AFM AFM. I have never messed with the AFM, but who knows about anyone before I got it. The cover is NOT sealed all the way, so it might just have some corrosion on the interior contacts. I need to get a new multimeter tomorrow. Am I on the right track?

[cygnusx1]

Connectors, Connectors, Connectors! Open them, spray clean them, and reassemble them. Do the AFM, The TPS, the ECU, the Temp sensor connectors. Usually its the AFM. And, do it again. You are on the right track. All your symptoms point to a bad signal to the ECU. Spray the inside of the AFM electronics while your at it.

 

Oh, and very often neglected, take out the fusible links, clean those connectors too and/or replace the links.

 

Let us know.

[Guest Cronic]

10 bucks says your AFM electronics got wet inside. The top to mind fell off somewhere between 100 and 150mph, it got wet yesterday and I have the SAME symptoms you do. perfect idle, but any throttle and the guage goes dead lean, if I floor it, it jerks to high hell, and backfires something mean!

[fl327]

try swapping ecus, a bad ecu just wont go over 3000 rpm at all.

[Guest szlash280z]

well, I don't have any spare ECU's, but that was the first thought I had. It's kinda loose down there and probably takes a beating. (it's not fully secured)

 

But I think the AFM electronics got some kinda moisture and corrosion inside. The thing is NOT sealed properly and it did sit for a while.

 

I did the TPS thing. I even made a new connector for it. I used a regular fuel injector pigtail, broke the outter edge away so it would fit inside the TPS connection and then wired it up since there are only two contacts. I then sealed it up with dielectric grease. It didn't do anything to help.

 

I sprayed into the AFM connector, which might not have done anything. I don't have any brake cleaner, and we all know how crappy contact cleaner is (doesn't work for $hit!) Next thing is to take the AFM off, clean it up and test it because I got a multimeter yesturday. I will do that shortly if my wife doesn't make me do something else. I had to fix the plumbing yesturday... plumbing sucks when it's broke.

[Guest szlash280z]

ok, my multimeter was a piece of shitza, so that may be why my results were... iffy.

 

I found NO corrosion on the inside of the AFM. Damn! That would give me obvious reason why the thing doesnt' seem to work. But here are my test results.

 

Test number one from the 83 FSM. test resistance between pins 33 and 34 on the AFM. resistance should be 280 to 400 ohms... I couldn't seem to get a good reading, it would show between 170 and 195 ohms but the number would just flash for a second and disappear. on the 20K scale it would show up as .21 ohms. is that 210 ohms? I judge this to be a bad reading. FSM says replace component.

 

Test 2

while sliding the flap, measure resistance between terminal 34 and 32, anything other than 0 and infinate is a good reading. A Zero would be perfect continuity right? and infinate would be what exactly? would it be no resistance because there is no connection? My test showed around 180ohm resistance and then stopped showing any resistance when I moved the flap (I guess it went to infinate when I moved the flap.)

 

Test 3

check resistance between AFM body and pins 33, 32, and 34. it's bad if any continuity exists. I had none, so this test shows good.

 

Test 4

Flap moves fine. test ok.

 

The air temp tests went fine. I sprayed contact cleaner on the sensor to make it cold and the values changed accordingly.

 

is there any part of this that is hard to understand? I might not be explaining very well. That POS multimeter is really making me question my skills with it.