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So I just pulled an '86 base model out of a woodsy grave where it sat for 3-10 years. I did the usual tune up stuff for a car that sat; fuel pump, filter, primary injectors, fluids, air filter, plugs etc. and got it running (kinda) It would'nt idle or rev past 3500 rpm. I redid the ECU to engine ground, (which was actually installed improperly) which fixed the rev issue, but still no idle. It will start just fine, run for a couple seconds, rev down and die, it will only stay running if I massage the throttle to keep it idling (at which point it seems to run pretty well). so far I have tried looking for vacuum leaks, reset the TPS, tried to set the idle air, checked the AFM plug, replaced spark plugs and regrounded the ECU to no avail. If it helps, the assisted warmup does not seem to be working, as id doesn't rev to 3000 rpm on a cold start and there is a vacuum line coming out of the bottom of the canister on the back left side of the engine bay that is broken as it curves toward the exhaust manifold (just noticed this, haven't tried to fix it yet). I am used to working on my bimmer and old american garbage, so this car is VERY forigen to me, so I figured itd be better to ask before I muck it up too badly. Any input is appreciated. If this engine ends up being no good I want to swap in a BMW M50B25 so you rotorheads can come crucify me for heresy. (I hear that engine has up-and-downsy bits instead of spinny Doritos) so if anyone has info on such a swap, I'd love to hear some insight. Also, I am brand new here so If I broke any rules or posted in the wrong place just kindly let me know and I'll fix it then jump off the nearest bridge. Thanks in advance!
Where she sat.
Last edited by Koenigsegg44; 10-28-16 at 07:30 AM.
Reason: Picture
... I am brand new here so If I broke any rules or posted in the wrong place just kindly let me know and I'll fix it then jump off the nearest bridge. Thanks in advance!
Rules are pretty lax and it's been months since the mods imposed the death penalty, although if you'd like to GoPro your suicide, the forum could probably use the clicks.
Things have slowed down a lot since the four rotor guy went dark.
The canister you refer to is the charcoal evap for the fuel tank and the hose on the bottom is just a drain...it doesn't go anywhere.
The cold start sequence aborts if the throttle pedal is floored or the car is in gear during start.
The ECU depends on several things to determine proper start strategies, so you need to:
_Make sure the thermosensor is good and connected properly.
Thie is NOT the same as the gauge sensor (which is below the oil filter), the thermosensor is on the rear of the waterpump housing, below the alternator.
A bad /missing signal from this sensor tells the ECU that the car is ALWAYS cold and it'll compensate by overfueling, eventally flooding the motor.
_Check out the MAP sensor, located on the passenger strut tower. It connects to the intake manifold and that hose is supposed to have a restrictor pill in it. You can also check the electrical signal it outputs to confirm it's OK.
_The TPS (throttle position sensor) can only be properly adjusted when the engine is fully warmed up.
_Check output of the IAT (intake air temp) sensor, located on the back of the dynamic chamber, by the throttle cable bracket.
If you haven't already, the full service manual is available on line for free here...foxed.ca.
As for your proposed engine swap...nobody cares that much anymore.
Anyone who has tried to keep a RX on the road has at least contemplated such a move, myself included.
I helped build a FD with a Vette engine and it was a great car.
I don't see enough BMW drivetrains for sale to use as donors, certainly not as many as LSx's or the usual Japanese suspects (2JZ's, etc), so finding info could be difficult.
My old S5 NA engine almost made it to 300k miles and for the last 100k or so it was running supposedly fatal low compression and oil pressure...they're a lot tougher than people think, so don't give up too quickly.
Ok, thanks a million, I couldn't find any factory maintenance info on my own, so thats a GREAT help. I'm out of town for little while so I cant check on any of those things just yet, but Ill let you know whats up as soon as I get a chance to work on it. I did check out the AFM great deal, and couldn't find any leaks or electrical issues (Ill ohm it out now that I can get the info) and I didn't even know about a lot of those sensors, so Ill get on that too. As far as the swap goes I like the m50 because they're crazy robust (although a touch on the heavy side) and make a decent amount of torque from the factory, especially going into such a light car. I have had luck looking for wrecked or R-title cars in the past, so I don't think it'd be to bad to find a donor car as they were used in both the 3 and 5 series '90 till '96 which are pretty cheap to begin with right now and can be found in impounds. all that and they're easily turboable which, knowing myself, would have to happen at some point. They sound nice too, that's why I don't really want a v8 despite having a spare Chevy 350 lying around. It wouldn't sound right. What would your opinion be on using the stock trans for the swap, too much power? should I use the bimmer trans? I have no idea what those stock trans and diffs can take. Either way, the swap is still all speculative, I'd love to save the doritos, but I think the swap would be fun.
Are there any common places I should dig deeper into? I couldn't find any with the starter fluid or my eyeballs?
Unfortunately, IF you do have a vac leak, there are a multitude of places to look.
Since you are working with a completely unknown engine, the "scorched earth" approach would be your best and most educational solution.
Strip off the entire intake manifold (commonly known as "stripping down to the keg") and replace all the gaskets and hoses (figure about 15' of 5/32 vac hose and a few feet of 5/16" high pressure fuel line).
Depending on your experience, this could be a very steep learning curve to scale as the NA rotary has some relatively complex intake devices and a lot of electrical and vacuum stuff crammed a pretty tight space but until you dig to the bottom and start rebuilding from the base, the spectre of a leak/fault buried deeper than you ventured will always haunt you.
If you hope to keep the rotary going, this knowledge is crucial and you may as well begin now.
I'll also chime it to say that after sitting like that, the entire fuel system is trashed. You'll need to flush out the tank, flush out the lines, and expect one or more injectors to have failed or be ready to fail. Since it runs, the injectors are at least functional but not for long. Best have them professionally serviced.
I'll also chime it to say that after sitting like that, the entire fuel system is trashed. You'll need to flush out the tank, flush out the lines, and expect one or more injectors to have failed or be ready to fail. Since it runs, the injectors are at least functional but not for long. Best have them professionally serviced.
I know Its not a fuel issue, I already did a new fuel pump, filter, primary injectors, and flushed out the secondaries, all the lines and the tank.
The injectors are a source for a vacuum leak as well as the intake system. And have you tried jumpering the fuel check connector to see if that helps w/the idle. And what is the variable resistor setting set at (lean, rich ??). Have you used the adjustment screw on top of the dynamic chamber to fine tune the idle?
The injectors are a source for a vacuum leak as well as the intake system. And have you tried jumpering the fuel check connector to see if that helps w/the idle. And what is the variable resistor setting set at (lean, rich ??). Have you used the adjustment screw on top of the dynamic chamber to fine tune the idle?
I have not used the check plug, it's on my list, where is said variable resistor? I haven't heard of it until now. I tried fiddling tith the adjustment screw (assuming you mean the one on the very top of the intake) but it did not seem to change anything. Is there a proper way to set it other than idle rpm?
The screw is used to make minor adjustments to idle.
The resistor I speak of is located very close to the pressure sensor. It is a screw encapsulated within a plastic housing and the screw can have a rubbery type plug covering it meaning it has not been tampered with and should not really be messed with unless it already has been previously. The slot in the screw should favor the rich setting (depicted as the letter R). If it were to be adjusted then the car must be fully warmed and the initial set connector jumpered (connector is usually jumpered when making adjustments to the idle).
And more importantly, you really haven't expressed how the idle is off other than to say it won't idle (leaves a lot to the imagination).
The screw is used to make minor adjustments to idle.
The resistor I speak of is located very close to the pressure sensor. It is a screw encapsulated within a plastic housing and the screw can have a rubbery type plug covering it meaning it has not been tampered with and should not really be messed with unless it already has been previously. The slot in the screw should favor the rich setting (depicted as the letter R). If it were to be adjusted then the car must be fully warmed and the initial set connector jumpered (connector is usually jumpered when making adjustments to the idle).
And more importantly, you really haven't expressed how the idle is off other than to say it won't idle (leaves a lot to the imagination).
Ok, gotcha, I'll dig into that if I have to, and as far as the idle goes, it will start, rev up a bit and die immediately. If I hold the pedal it will stay running, and occasionally it will hold a very low and rough idle if I feather the pedal enough, but if I rev it up a bit (or a lot) it will stall every time when it tries to return to idle. It just seems to me that the idle is too low because it runs quite well otherwise.
Ok, gotcha, I'll dig into that if I have to, and as far as the idle goes, it will start, rev up a bit and die immediately. If I hold the pedal it will stay running, and occasionally it will hold a very low and rough idle if I feather the pedal enough, but if I rev it up a bit (or a lot) it will stall every time when it tries to return to idle. It just seems to me that the idle is too low because it runs quite well otherwise.
This sounds just like a car w/a faulty AFM, which is why you jumper the fuel check connector to actually find this out or the car has a vacuum leak.
This sounds just like a car w/a faulty AFM, which is why you jumper the fuel check connector to actually find this out or the car has a vacuum leak.
OOOOOoooohhh, I see now, I didn't know that the test connector would diagnose a bad AFM, I'll do that first next chance I have to work on it and let yinz know where it goes. Thanks a bunch for your help so far!
OOOOOoooohhh, I see now, I didn't know that the test connector would diagnose a bad AFM, I'll do that first next chance I have to work on it and let yinz know where it goes. Thanks a bunch for your help so far!
The S4 AFM has an internal fuel switch which when bad causes the car to die out immediately, as an example, because if damaged it will prevent the engine from receiving fuel and perhaps this is the cause of your problem. Jumpering the check connector overrides the fuel switch inside the AFM.
Another way to tell if the fuel switch inside the AFM is bad is if the Brown wire at the circuit opening relay has the correct voltage. W/key to on and engine off the voltage reads 12 volts on the Brown wire. When the flap to the AFM is opened the voltage drops down close to 0 volts. If the voltage drops w/key to on then the fuel switch is still probably good but if the voltage does not drop then it indicates the fuel switch is kaput.
The S4 AFM has an internal fuel switch which when bad causes the car to die out immediately, as an example, because if damaged it will prevent the engine from receiving fuel and perhaps this is the cause of your problem. Jumpering the check connector overrides the fuel switch inside the AFM.
Another way to tell if the fuel switch inside the AFM is bad is if the Brown wire at the circuit opening relay has the correct voltage. W/key to on and engine off the voltage reads 12 volts on the Brown wire. When the flap to the AFM is opened the voltage drops down close to 0 volts. If the voltage drops w/key to on then the fuel switch is still probably good but if the voltage does not drop then it indicates the fuel switch is kaput.
OK, so I tried jumping the fuel test connector, and if anything that made it worse, I didn't want to run it all in blew tons of smoke.
You can check the pins at the ECU and compare to spec as stated in the FSM. All that jumpering the check connector does is make sure that fuel flows to the injectors. You could have a flooded engine. You could have a coolant leak (both would cause smoke but of a differing color and smell). And you might want to check compression.
Try having someone keep it idling, and you spray carb cleaner or starter fluid around the engine bay (without starting a fire) and see if the idle changes. If it does, you have a vacuum leak.
My first FC had a super bad vacuum leak. after weeks of searching it ended up being the lower intake manifold to engine gasket.
I will try to get ahold of a compression tester, but it gives all 6 very strong chugs when the plugs are out (I flooded it a bit) I did notice however, 2 plug wires and they were pretty loose, so I ohmed them out and 2 gave me infinite resistance, and the other two were 5-6k ohms. I'm going to try plug wires because they're cheap.
Could be it, but it never hurts to know for sure. You can find out if the six pulses are true or not with a normal piston engine compression tester. You may not get an accurate reading but if it hits three time on each rotor, you're good to go enough to start and run.
Could be it, but it never hurts to know for sure. You can find out if the six pulses are true or not with a normal piston engine compression tester. You may not get an accurate reading but if it hits three time on each rotor, you're good to go enough to start and run.
Ok, I'll ask around for one. But yeah, it sounds really strong like TrrrrrrrFADOOrrFADOOrrFADOOrrFADOOrrFADOOrrFaDOO with the plugs out. I'd be concerned if it were more like TrrrrrrrFADOOrrfffffffrrFADOOrrffffffffrrFADOOrrFa DOO
I am also suspicious of ignition error because only two plugs were carbony (rear leading and front trailing) while the other two still look now.
10-28-16, 07:26 AM
HELP! '86 NA will not idle, stalls out.
If it helps, the assisted warmup does not seem to be working, as id doesn't rev to 3000 rpm on a cold start and there is a vacuum line coming out of the bottom of the canister on the back left side of the engine bay that is broken as it curves toward the exhaust manifold (just noticed this, haven't tried to fix it yet). I am used to working on my bimmer and old american garbage, so this car is VERY forigen to me, so I figured itd be better to ask before I muck it up too badly. Any input is appreciated. If this engine ends up being no good I want to swap in a BMW M50B25 so you rotorheads can come crucify me for heresy. (I hear that engine has up-and-downsy bits instead of spinny Doritos) so if anyone has info on such a swap, I'd love to hear some insight. Also, I am brand new here so If I broke any rules or posted in the wrong place just kindly let me know and I'll fix it then jump off the nearest bridge. Thanks in advance!
