newkid2rotary2012

iTrader: (3)

Alright I really didn't want to have to post on the forum but ive officially ran out of trouble shooting ideas. I've been trying to tackle this new problem that came up just a couple days ago. My car starts like it always has since i had it, when its cold it does its 3k jump and what not, but soon after it will attempt to idle and then die. this is followed with a lot of shaking from the motor and sputtering and spitting from 2300 rpms down to me making it idle by controlling the gas. I thought it might be the AFM sensor but I don't exactly know. I also disconnected the TPS while playing around with it today and it takes a little longer to start but it does the same thing as if it were connected it also pulls a check engine light if its disconnected. I have disconnected the AFM and it will not start at all with it disconnected. I cleaned out the AFM with MAF sensor cleaner and also cleaned out the throttle body butterfly valves. I have checked for a misfire and also pulled my spark plugs and it doesn't seem like its running rich. I do have a very strong exhaust smell like its running rich and im getting a lot more exhaust pressure than I normally do. Any advice or recommendations would be greatly appreciated guys!

Car:
1990 GTU N/A
racing beat header-racing beat silencer-no name muffler
new fuel filter
new plugs (less than 500 miles on them)

satch

iTrader: (1)

One thing you can check is the Water Thermosensor. Pin 2E of the ECU (Green/White wire). Should read 2 to 3 volts cold engine w/key to on and would drop down to .3 volts fully warmed. And also verify that the lead coil is working.

newkid2rotary2012

iTrader: (3)

Lead coil I have checked and believe is working the thermosensor I replace a couple months ago. but I will go test it. This problem happened about a month ago but when I had it running it just "fixed it self" I didn't touch nothing just started it let it run and after like 5 minutes of running it went back to normal but not this time.

newkid2rotary2012

iTrader: (3)

Thermosensor is reading 0.97 warm

satch

iTrader: (1)

Perhaps you have not let the engine fully wam up but it should drop down to .3 volts. And perhaps the engine is flooding. And checking compression always helps to eliminate the obvious cause. Unplugging the TPS will default to a full throttle situation so that won't help much if the engine is receiving too much fuel. And does the car act this way only after a true cold start or does it still behave problematically even after the car has been started w/the engine warm?

newkid2rotary2012

iTrader: (3)

the car has cooled down some since earlier today. But I thought it was flooding problems as well but the plugs don't show it. It will do it regardless if its cold or warm. the only difference I can tell between it is that when cold I notice a lot of sputtering around the 1500 rpm range and below. When its warm it doesn't sputter it just runs really bad. Compression I checked a two or three days ago. im getting strong pressure on all three faces on both rotors. I think its getting too much air. Possibly AFM but I do not know how to test it.

satch

iTrader: (1)

The FSM details how to check it (provides ohm readings to test it). Pin 2B (AFM), Green wire measures 4 volts w/key to on and 2.5 to 3.5 volts while idling. Pin 2K (air intake sensor within AFM) measures 2 to 3 volts w/68 degree air temp w/key to on. You can also try disengaging the Thermowax on the rear of the throttle linkage by pressing downward on this linkage and placing a large vacuum hose cap on top of the upside down screw which rests upon the Fast Idle Cam.


EDIT:

If you unplug the AFM you'll have to jumper the fuel check connector or the car cannot start. If it starts it will run rich.

newkid2rotary2012

iTrader: (3)

FSM?
And where is the fuel check connector?

satch

iTrader: (1)

Factory Service Manual. Connector is located between the passenger side shock tower and the engine.. It's part of the emission harness and is Yellow and surrounded in a rubber boot. Has two wires.

newkid2rotary2012

iTrader: (3)

Ok....well just got back in from messing with it. The AFM green wire is pulling 3.8 volts with the key on and the thermosensor is pulling around .4. About the thermowax, I was looking for what you talked about and found a hose capped off with a bolt. I took out the bolt and started it up but it didn't seem to make a difference, I tried looking for where it might possibly plug in at but no such luck.

satch

iTrader: (1)

The thermovalve is a piston which sticks out as the engine coolant wams up and presses down on an upside down screw that is part of the throttle linkage. The thermovalve is controlled by the thermowax. It has a coolant hose connected to it and the thermowax has a plastic piece w/a couple of nozzles that connect to vacuum hoses. This system allows the idle to go from 1500 rpm and slowly drops down to 750 rpm while in neutral when the engine has warmed up. Perhaps yours was removed?

newkid2rotary2012

iTrader: (3)

ok I found the thermowax its got three vacuum hoses connected to it. do you want me to disconnect that whole piece that they are connected it too and plug off the hole or the harness with the hoses? I unplugged the afm and jumpered the fuel check connecter. it ran rich but held a idle for a minute or two my afm reads 2.3 volts from the green wire at 900 rpms.

satch

iTrader: (1)

No, not at all. Wasn't there something mentioned (two times) about an upside down screw resting against a rod sticking out of the thermovalve?

newkid2rotary2012

iTrader: (3)

ok I know what your talking about. the upside down screw your talking about, is it a sprung screw? this is the only screw I see close to the thermovalve.

That is upside down.

satch

iTrader: (1)

So do as was suggested. Press down on the linkage and place a large vacuum hose cap on top of the screw to force it down as far as it can go so the top of the cap rests upon the piston directly above it. All this would do is override the fast idle warmup. This is probably not your problem as it appears you have an AFM issue which can be checked via an ohm meter as stated in the FSM. And when you measured the Green wire previously, which measured 2.3 volts, where did you measure the voltage from? The ECU or elsewhere?

newkid2rotary2012

iTrader: (3)

My green wire coming off the AFM reads 3.8 volts with key on. When I have someone in the car keeping it at around 900 or so rpms the green wire from the AFM reads 2.3-2.7 volts from the harness connected to the AFM not the ECU

newkid2rotary2012

iTrader: (3)

OK I just jumpered the fuel test connector again and when it stayed running by its self I pulled my jumper wire and quickly plugged in the AFM. When I did that it instantly starting sputtering and popping....sounds like its running lean eh? Im leaning towards AFM being bad but I do not want to drop $200 on a part that may not be it

satch

iTrader: (1)

That is exactly why you test it accordingly to what the FSM says. And if in need of a replacement you stay away from the remanufactured ones and keep to the used ones for sale on the parts for sale section within this site.

Page 82.

https://docs.google.com/folder/d/0Bz...M0NDJhOWJkMTAw

newkid2rotary2012

iTrader: (3)

That helped alot thanks for the schematic. I found out one circuit in the AMF is pulling way to many ohms so I think that's the main problem...I guess ill find out when I get another one

newkid2rotary2012

iTrader: (3)

Alright well it wasn't the AFM and I've just recently changed out the injectors, injector seals, upper and mid intake gaskets, and new fuel filter.