If I start the car and don't touch the gas it will run for exactly 3 seconds then stall. If I hit the gas it will rev up and run a shorter amount of time like it's only getting one shot from the injectors.

What could be the things to cause this? Fuel pump? I know mine runs, but it's very quiet. I did verify the mass airflow sensor was plugged in. I can't think of what could have gone wrong in the past 2 months. It ran when I took the engine out, and now with a new one I'm having tons of problems....

Ideas?

Thanks very much for any help! Also does anybody know how many turns out from the stop you should use as a base point for the BAC?

 

Just love this post. I can make all sorts of wild guesses. How about you have a loose tid? Loose hose to the blow off valve? How about you are activating the fuel pump when you turn the key to start, but as you and I now know, when the key is returned to neutral you are now depending on the micro switch in the air flow meter to make the fuel pump circuit. If it is not making, then fuel pump stops running as soon as the key is released from the start position. Jumper that fuel pump plug on the right hand strut tower(close to it anyway), and try to start the car again. When you do that jumper job, you should hear a relay click in the engine bay. If you have doubts, then with it jumpered and the key to the on position(not start), break a banjo bolt to the fuel rail and see if you get sprayed with gas. Hey! Did you leave the brake boost vacuum line off at the back of the engine? About a one inch line, curves up, mates to a metal line for the brake booster. Very rear of the engine, center line of the engine? Thats the kind of vac leak that might cause this prob. Or the turbo inlet duct where it connects to the turbo. Tight? So, are you almost out of gas? Need answer. What year engine did you install? Using the same injectors? Outa space.

 

My bet, the hose running from the Air Flow Meter/Air Filter Box to your intake came disconnected when you were working under the hood on the passenger side.

You give it gas and the air flow meter doesn't see any air movement, immediate shut down.

 

I know the s tube from the airflow sensor to the turbo is tight. I checked that. I had the same thought. Of course would it idle or not if it was leaking, just not accelerate correctly?

When I first got the car that was disconnected, so I know to check it now

I guess it could be the switch in the MAF that operates the fuel pump.

I checked the fuel resistor box under the air filter assy. It was 6 ohms. The Haynes Manual says spec is 5-7 ohms.

Loose hose to the blow off valve? What is the blow off valve? Is that the BAC? I should have mentioned I have removed the air pump and the ACV. I left the EGR valve for now... until I order a block off plate anyway.

I put a '87 motor back in it. It's ported/polished, and has 3 mm seals. I set the timing at stock. I haven't fine-tuned the timing yet obviously since I can't get it to idle. :p Also 1/2 tank of gas. I put more in to be sure... and yes... the same injectors in the same locations. New injector diffusers and seals.

 

The tube is tight... but what about the wires to the AFM? Are they plugged in securely? Are all your intercooler connections tight?

Brad

 

Damn, Thats one confusing set of instructions!

 

The wires to the AFM are secure. I've checked the connector dozens of times.

All the tubes to the intercooler are tight.

 

Sounds like you down to needing a catholic priest to exorcise that demon.

I'm stumped.

 

I must admit when I first read this I thought air leak.Since you are convinced you don't have an air leak,you can check the fuel by installing the jumper in the fuel pump service connector.This allows the fuel pump to run whether or not there is air going through the AFM,ie it by passes the switch.If your car runs with this jumper installed then your AFM is nfg.

 

Check you leading and trailing coils,it could be not getting enough spark to idle.


91na
intake
exhaust S-AFC

 

I'm taking the day off tomorrow to work on the car... I think I'll try this:

1) Make sure there are no vaccum leaks. Maybe I forgot to cap a nipple or spider line when I took off the ACV and air pump.. and related crap.

2) Jumper the fuel connector and see if it actually runs.

3) Switch promary and secondary injectors to rule out that it may be one or both of the injectors failing... I'll check for more vaccum leaks with the intake runner off too.

I'd really like to get it running tomorrow so I can get a state safety inspection and be fully legal finally. It's getting WAY too cold to work on the car outside. Wish I had a garage....

 

You probably would have found this by now ,but I'd check the hose to the BAC from the intake.
B

 

Have you checked the fuel filter?

 

Have you done the throttle body mod or at least just taken out your secondary throttle plates. I removed my secondary throttle plates and I now have to feather the throttle for about a minute in the morning to keep it running. My car will die after a few seconds if I don't. Just a thought.

 

I dont really think this is a vacuum leak, even if you left off a big hose(the brake booster) it will just idle high. IF the TID is tight then youre good.

I first thought the afm was unplugged but you say you already checked that.

Sounds like its starving of fuel. Get a voltmeter and attatch it to the leads at the fuel pump in the hatch, start the car and watch it. It could be losing voltage. IF it ever drops below 12vdc, Id run a jumper wire of 12vdc from the battery, a quick test to see if it helps. I know a t2 is supposed to drop to 10vdc at idle, but this is for test purposes.

What are the possibilities that your fuel lines are on backwards? Ive done this by mistake a couple of times myself, adn teh car will not run.

Also, once a friend changed the intake on his car(for no good reason I might add) which was an 86 NA. IT did wht you describe, and come to find out(upon my inspection) he had reinstalled the lower intake over top of a small metal clip designed to hold some wires in place on the side of the manifold. This mean there was a big gap between the manifold and the block, causing a huge *** air leak.Sealed that up and it ran.

Even on a new engine install, it should run if you floor the gas regardless of a small vacuum leak. I say either lack of fuel or LARGE vacuum leak.Maybe the hose under the IC is loose? Trace your intake path all the way to the block.

 

I think something is wrong with your AFM. Mine came unplugged at the dragstrip one day, and it would do the exact thing yours is doing. Jumper the fuel pump and the car will run, but not well. I got mine home that way. Then I saw the AFM was unplugged and I felt stupid.

 

JRUSSELL.....Just a thought from a amatuer engine builder. When I have done rebuilds, and installed the apex seals with the end piece glued on like it came out of the package from Mazdatrix, I experience lower than usual compression until the end piece finaly breaks off. Until that point I use a fuel cut sw to get the car started, because the low compression makes it flood easily. After a couple of hours running the fuel cut is'nt required. Thats for me anyway. Other people.....I can't answer for. In short, I think it could be actually a fuel flood problem. Just one of many wild guesses. EDIT..not really plausible since you started the car for 3 seconds, but ...... And on the way to work, in the parking lot I turned the car off. Turned the fuel cut to off. Started the car. Ran for two seconds, no more.

 

Well, I feel stupid now. There's no air leaks... well, yes there were!

The elbow that goes from the intercooler to the throttle body was ripped. I must have ripped it while messing around there or something. I don't know how I could have, but anyway... replaced that and problem solved. I got the car running and idling. Set the timing. Let it run for about 20 minutes, then took it out for a drive. It didn't have anywhere near as much power as it should have, but it was much better than last time I tried it. The turbo is spooling up much too soon, must be the twin scroll actuator isn't functioning properly.

Anyway, long story short... I pulled back into the driveway and the car stalled. I let out the clutch, and it started again because I was still moving, then I parked it. I had to keep my foot on the gas in order for it to run. Then it finally stalled because I kept lifting my foot to see if it would idle, and I can't get the damn thing started again! I tried for about an hour, then just gave up.

BTW: the compression is good. 8.9-9.3 on all the rotor faces from a Mazda compression tester.

 

i have the exact same problem!!! its killing me...

 

Hey first of all sorry about your problem. This is just a guess but I would have to say it is a fuel problem. Even with the MAF disconnected it will run (badly but run). First thing you do when you do any thing fuel related (change filter, take off lines, etc) the manual states to start the car and disconnect the fuel pump connection and wait for the car to stall. When you do this it does not stall it just dies and fast. It take approx 2-4 seconds to die. If you pick up the factory manual or any other aftermarket manual it has tests for fuel pressure hold and max pressure tests. These are valuable tests to see if the pump is holding the pressure in the line or is producing enough pressure to run the car. But before you do that replace the fuel filter. They are only 8-12 bucks and if it has been a while it never hurts anyway. If there are any other question send me an e-mail (in sig).

Keep rotoring

 

ROTARY RACER.... he has a 87 car. A 87 will not run with the maf disconnected. The 86=88 have a micrso sw that makes the fuel pump circuit when the door in the maf is opening. Later models do not have this door and switch. Not being contentious, just pointing out the diff in early and later models. Russell, I said blow off valve and should have said air bypass valve on the aft side of the turbo inlet duct.

 

same things happens to my GXL when it is cold. I quickly blip the throttle revs jump to 1500RPMs and I'm go to go !