chinoxl75

I have a 91 Rx-7 13B engine.. I will start the car and it will run but then shut off. The battery is good and the alternator is fine.. but i know it has to be a sensor.. has anyone had this problem were the car would run for like 5 to 10 minutes and then shut off? If so please drop me a line.. Thanks

zerrorx7

look at ur vac hoses ...thats wheere i would start

RETed

All 89 - 91 FC's have a very extensive self test of the majority of engine components.
Please run an error code test and tell us what they are...


-Ted

johnnyg

Can you keep it running by holding the revs over 3K? If so, it's definately an intake leak.

nization

I am having the same issue it sounds like. Someone pointed me over here from Ohiorotaries. I'll be sure to post if I find the solution.

Ironman311

I blew a gasket in the intake manifold once and it made it hard to keep the car alive until I replaced it but that doesn't sound like your problem but maybe that'll help : /

mwatson184

Make sure the AFM (air flow meter) is plugged in, and check the TID (turbo inlet duct) for cracks.

When you start the car it is set to inject x amount of fuel. After startup it looks for signal from the afm to determine the amount of fuel to inject. If the afm is unplugged, or there is a crack in the TID, the ECU will not get the proper signal from the afm and the car will die.

Marques

mwatson184

Bah, i don't know why I though you had a turbo. Scratch the TID part and check for intake leaks between the afm and the throttle body, and vac leaks after the throttle body.

nization

Come to think of it, this is similar, just not as bad as it was when I left the MAF unplugged after the first time I swapped fuel injectors... Anyone know of a way to test the MAF as I know it's currently plugged in, and I don't have a second one to try swapping in.

SonicRaT

iTrader: (6)

Sounds like the AFM to me...

iceblue

Odd it is dieing in 10min but sounds like a AFM to me as well. The best thing to do is the error check as ReTed stated, next search HAILERS name with AFM.

Sounds like it is losing the fuel signal from the AFM. When the falpper moves it causes a rod and a sensor to toutch in the AFM, if these are not keeping connection it will shut off.

johnnyg

Could it be a dead BAC valve? When the engine is cold, the fast idle cam holds the throttle plates open, letting some air in. But once the engine is warmed up, those plates close and the only meaningful amount of air getting into the engine is through the BAC.

chinoxl75

thanks for the advice.. is there a place i could buy a AFM for a good deal?

nization

I replaced the Fuel filter and I just got a used AFM from the junk yard today. Nothing has changed here....

It was suggested to me to check the fuel pressure, so I guess I'll be returning my oil pressure guage I don't need and picking up the fuel pressure guage to see if fuel is being cut out early or what.... On that note, anyone know what I should expect fuel pressure to be? and would the S4 and S5 n/a cars have different fuel pumps?

johnnyg

At the risk of repeating myself, check your BAC valve. Diagnostics 101 says you have to ask what happens after 5 or 10 minutes of running that would cause your engine to quit? The thermostat opens up, but that should cause the engine to stop. The e-shaft thermo valve opens up, but again, shouldn't cause a stall. The fast idle cam is disenganged, the throttle plates close, the TPS gets "pushed in" more, and the BAC goes into play at idle. Sounds like you should be focussing your attention to these items, no?

jhammons01

^^^^That sounds right to me as well. What happens after a certain Temperature is reached???? johnnyg is on it, no?

nization

I don't know about chinoxl75, but I don't have the BAC anymore. Blocked off. Now that I look at the setup, however, it makes sence what it does. I have to extend the wiring to it, however, as on the S4 car, the BAC is located on the driver side, where the S5 engine has this on the passenger side...

But we may have two different issues, as chinoxl75's shuts down after 5-10 minutes, and mine's more like 1 to 2 minutes. When it's real warm, it's lasted about 4 or 5 minutes before, but that's rare....

Reguardless, whatever I find that works, I'll post it here and hope that it helps chinoxl75, as he started this thread, and I don't want to just hijack it.

iceblue

No the fast idle cam is used all the time it is what controlls the idle period. The BACV just works as a little fine tuneing adjustment and kick in for loads. TPS is allways pushed in at idle not something sudden. So then nothing has changed with his motor from crank to 10 min.

Unplug your tps. And I still say a bad AFM.

iceblue

There is only 2 things that is going to happen here. Ether the fast idle cam is not adjusted right and the car is only running b/c the thermo wax pallet is holding the plates open and when it heats up closes the plates and stops air flow to the motor.

Next no fuel! That would lead to, Bad pump or harness, bad ECU, AFM

That’s it.

johnnyg

Not following you. Your first message seems to disagree with me, and your second message seems to agree with me.

When cold, the thermo-wax piston is retracted, which keeps the throttle on the fast idle cam, which keeps the throttle plates open slightly, which keeps the idle high (hence the name "fast idle" cam ). As the car warms up, the thermo-wax piston extends, which pushes off the fast idle cam, which closes the throttle plates. When the engine is fully warmed up, the fast idle cam is totally out of the way. At this point, intake air primarily enters the engine through the BAC valve and the idle speed set screw. Only a very small amount actually goes through the throttle plates and it shouldn't be enough to keep the engine running. If you remove your BAC, then you have to set the throttle plates open slightly so the car will idle.

At least this is how I understand it all.

johnnyg

Could the fuel lines be reversed??

johnnyg

No. When cold and on the fast idle cam, the TPS is NOT reporting idle to the ECU. Only when the fast idle cam is disengaged does this happen. That's why you always adjust the TPS with a completely warmed up engine.

Zero87t

I have a similar problem, The car has been running just fine, but I let it sit over the labor day weekend. Wasnt started for 3 days. When I turn it on, it reved to the 3k cold start mark then died. And when I try to restart it it revs up and dies right away. I tried just cranking it with the efi fuse out and then putting it back in, but the problem is still here. Any advice on what could go wrong after three days of sitting?

Its a 1989 NA btw

iceblue

I have the TB moded so my tps is set all the time but his yes your right will close fully when the daspot is returned. The set screw / fast idle cam adjustment screw is what holds the throttle plates open and sets your idle. The wax pallet holds the plates past this mark for faster warmup. When it heats up the main linkage rests on the set screw. The BAC has nothing to do with this or its main idle. The BAC only adds alot air for like the AC idle loads. You do / can fine tune the idle a little bit with the BAC so it adds small amounts of air. There is absolutly no need for the BACV to allow the motor to idle at 750rpm

nization

If anyone would like to checkout my post on Ohio Rotaries, there's much more detail to my specific issue there, see if it sounds like these two could be linked.

http://www.ohiorotaries.com/phpBB2/viewtopic.php?t=813

I don't think that Zero87t's issue is the same as mine or chinoxl75's, as Zero's saying his is dying right away, where ours are running just fine for a time, then cut out.

What I did today, I pulled the fuel pump, but had to put the original one back in, as the S5's is longer, so it won't fit... there was certainly a lot of pressure from the pump, as I forgot to open the gas cap before the lines...oops. I also reinstalled my BAC, all it did different was that it would rev to 3,000 RPM now rather than 2,000, and slowly drop down to 1400 RPM, where mine has been idling just fine since I cleaned my throttle body. Of course, about a minute or two later, the engine is shut off. I start it up imediatly, and the same act all over again.

I then changed the air temp sensor on the intake, cleaned the contacts, and started it up. Still no bloody change in behavior!

A freind of mine called during all this, and I started to think that I should prolly go ahead and just buy his MX-5 that he's been pushing me to take off his hands for about a year now....it's starting to sound tempting....I do hope to figure this out before that happens