AFM Adjustments

GeminiCoupe · Post by **GeminiCoupe** » Sun Dec 11, 2005 5:50 pm

Need to know the standard adjustments for the 4ZC1 Turbo AFM. Theres a lock nut/adjustment screw on a springloaded disc which adjusts the mixtures manual. I think mine is wayyyy out as the car chews fuel and is generally running abit rich. Anyone got any service notices that say how to adjust it, which way to go etc?

Nick-

poida · Post by **poida** » Sun Dec 11, 2005 6:44 pm

WARNING

That screw which holds down the flat disk lets the spring unclamp suddenly. Be really careful if you do happen to loosen the screw that you keep a firm hold on the disc part. Move it back or forward a notch at a time then test run it.

I'd also suggest you mark the disc and the base so you have a starting point reference. That's what was loosened off in my twin cam by the previous owner and it took off and totally unwound. Since then it has never worked right. It's a risk to fiddle with it. I'm at a loss as to how much preload to even start with. I have no idea if they fiddled with anything else as well. All I can do is guess and play trial and error.

Rodeobob · Post by **Rodeobob** » Sun Dec 11, 2005 7:00 pm

I might like to add that it wont have moved and be where its not meant to be unless someone has fiddled with it previously.

I would also suggest that you leave it alone until you have a chance to fit in a known to be right AFM and see if that improves the way you car runs. (PS. and no im not gunna drop one up. You know where i live

. Besides id have to test it before i gave it to you. nah correction youd have to swap it on and test it. lol.)

I would also suggest changing the air filter if you havent already done so. You could also try a short run with no air filter (IE: no restriction) in place and see what that does.

Id minium, put a sniffer up its arse before adjusting anything. Measure the C02 etc. It could be that you 02 sensor is stuffed. Hell it could be heaps of things. Could be as simple as a bad connector.

There should be a test procedure as far a voltage for the AFM goes in the factory manual. Spend the $20. If its anything like the Rodeo one ive got here its pretty thorough and has step by step fault finding instructions.

And lastly, wait till the paint drys.

Cheers. Bob.

Bugle · Post by **Bugle** » Sun Dec 11, 2005 8:06 pm

Yeah most of the time it's adjusting the air/fuel ratio off the feedback from the oxygen sensor. If the o2 sensor is bad i'd imagine that would hurt the economy alot.

You got a service manual yet? The ECU has self diagnostics for all its sensors has the test procedure in the service manual.
Faulty coolant temp sensor might make it run rich all the time too.

brendan · Post by **brendan** » Mon Dec 12, 2005 6:35 am

Faulty coolant temp sensor might make it run rich all the time too.[/quote]

how could a fautly coolent temp sensor make it run rich? i have no coolent temp sensor as i have a aftermarket guage in my car
cheers Brendan

GeminiCoupe · Post by **GeminiCoupe** » Mon Dec 12, 2005 7:42 am

I knew i shouldve elaborated more...

I have 2 x Piazza AFM's - one off the car and one on. The one thats on the car looks abit rough and has been tampered with at some stage. Some moron has fiddled with it, broken the clips on the lid and just siliconed it into place. I *could* just swap the other one into place and see if it does anything but I like doing things the hard way, which means finding out if my assumptions are correct and the one thats on there now is out of whack. Id like to keep the hopefully-properly setup spare as is for now, in the event the one thats on there now is too far out of adjustment to be fucked with.

I was thinking of taking it down to the local dyno shop and getting it tuned, but i want to wait until ive got a 3" exhaust, a cooler and a boost controller to take full advantage of the dyno time.

Thomas, yeah im suspecting the O2 might not be the best, but one thing at a time for now

BTW Bob, i have run the car without an air filter and it made no adverse affect on it running lean/rich. Only thing was did is make it sound crazy, you can actually *hear* it spool now

Nick-

Bugle · Post by **Bugle** » Mon Dec 12, 2005 2:33 pm

Brendan the ECU uses a coolant temperature sensor to determine whether to run rich while the engine is warming up like a choke on a carby. If the sensor goes bung I would assume it would just run rich all the time as it will still run ok but use alot of fuel. The ECU has a separate sensor to the gauge so replacing the gauges sensor won't matter.

Yeah Nick best to get it done on a dyno, or get a wideband o2 sensor setup for yourself they seem to be getting cheap these days.

Rodeobob · Post by **Rodeobob** » Tue Dec 13, 2005 1:10 am

One other thing on the temp sensor, make sure your thermostat works properly before you spent money changing the sensor. The water wont get hot because the thermostat is stuck open.

Nick, yeah do it the hard way. lol. Just get the thing on the road already. lol.

I could still beat you too it you know.
I had that dual cab rodeo here and not much intrest when i was trying to sell it. I was thinking of registering it so i could drive it while i give my spacecab a bit of a 2.6 birthday. Ive had two people call interested in it and one is coming tomorrow. So it might be the Piazza i put on the road so ive got something to drive. Ive got all the bits, its just a matter of doing it.

I might have an 02 sensor spare that you could borrow to try out. The new turbo i got had the new dump pipe bolted too it with a new 02 sensor in it and thats on the car now.

Bob.

Bugle · Post by **Bugle** » Tue Dec 13, 2005 2:52 am

I thought the thermostat stays shut if it fails? I think thats what caused the Gemini to blow a couple of head gaskets over the years.

Rodeobob · Post by **Rodeobob** » Tue Dec 13, 2005 4:27 am

Bugle wrote:I thought the thermostat stays shut if it fails? I think thats what caused the Gemini to blow a couple of head gaskets over the years.

Depends i suppose. Ive only ever seen em stuck open. The spring colapses to open them and thats usualy what happens when they stuff up the springs expansion properties or some shit stuffs up.

GeminiCoupe · Post by **GeminiCoupe** » Tue Dec 13, 2005 11:12 am

You blew a few gaskets on a Gemini engine? Thats a first.

I drove about 4hours with a full carloadin the middle of summer with a blocked radiator, it sounded like a boiling kettle everywhere i went...and nothing. Car wasnt happy but the thing held together. The old man cooked an engine on his old car - headgasket didnt fail, but it go so hot the thing siezed.

Nick-

Post by **wedgenut** » Tue Dec 13, 2005 6:12 pm

I thought the thermostat stays shut if it fails? I think thats what caused the Gemini to blow a couple of head gaskets over the years.

Years ago thermostats were nasty and used to fail and jam shut and that was okay with three ton cast iron heads. With the introduction of Alloy heads and higher temerature running engines this became a problem and Mr Thermostat limited got tired of crowds of angry and mostly ugly people chasing him down with bent cylinder heads and threatening to kill his babies so he invented the modern thermostat which fails open...........mostly

Rodeobob · Post by **Rodeobob** » Tue Dec 13, 2005 10:03 pm

I changed the one in the dual cab today. Its been sitting around for months with basically degreaser in the cooling system. Thought id better flush it out and fill it with coolant and low and behold the thermostat is stuck open. Ive had a bout 7 or 8 Pulsars thru here of late and only one of them had a thermostat that worked, all the others were stuck open. Including the N13 Pulsar which has a thermostat thats more than $50 because its built into the housing.

Bob.