2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Engine runs great... for 3 seconds then dies.

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Old Sep 28, 2006 | 11:08 AM
  #26  
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Originally Posted by 150EZ
Ill try the fuses. I ordered another AFM on ebay, hopefully it will solve my problem. But honestly, I can believe that just by unplugging a sensor and looking at it you can ruin it.
Your problem sounds to me like its fuel related...

I would for sure try to plug in the AFM all the way, or at least verify its plugged in. When my AFM went for a **** the car would still run though.....just FYI.

Try jumpering the fuel pump check connector (yellow, two prong plug with a rubber boot on it located near right strut tower) with a piece of firly heavy wire then try starting it.

Ill bet 10 internet dollars it runs fine with the connector jumpered....
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Old Sep 29, 2006 | 10:37 AM
  #27  
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Not to refute your prowess, but I'll take that bet. Occam's razor - if he changed the intake and stuff I'd bet he messed his air side up or knocked a vacuum line off and now his idle is set too low for the car to run. The 3 seconds is when the car catches and revs up, when it tries to come down it's coming down too far and dying. :P

In fact, I'll go a step further. At a glance it looks like he tried to adjust his idle by adjusting the set screw for the TPS instead of the one under the cap on top of the throttle body. Since his TPS is reading 0.6 instead of 1.0, I think he nailed his problem.

Use an ohm meter and adjust your TPS to 1.0 using that big springy looking screw on the front of your throttle body. Then if you need to adjust your idle, pull the black rubber cap off the very top center of your throttle body and tighten or loosen as needed.
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Old Sep 29, 2006 | 01:21 PM
  #28  
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Racer-X-7
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Richter: I did in fact make that adjustment to the TPS. But I can't get it to 1.0 without practically removing the entire screw out of the spring.

Adrock: The vane leading ot the air intake wont open all the way. I opened the AFM and I noticed that it's being blocked from the inside by a long pin (fuel switch??). Ill post a pic of the inside of my AFM.

Classicauto: I dont know what you mean about the fuel pump connector or where it's at.

THX for all the help guys.
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Old Sep 29, 2006 | 01:47 PM
  #29  
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You're measuring ohms, right? I'm trying to remember, but on the S4 I think if you disconnect the TPS from the harness, looking in at the connector, measure ohms from the bottom pin to the one on the right. (There should be only one way to hold the connector where you look into it and have only one pin at the bottom) If the TPS is bad, the car won't idle, I can definitely testify to that. (I had mine plugged in the wrong place once :P It can be done, but requires determination!) Although I've had it completely disconnected and the car seemed to work fine? I'm wondering if the computer uses a stored map when the TPS is bad, which would work decently until you change something (like intake and exhaust. :P )
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Old Sep 29, 2006 | 02:43 PM
  #30  
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Yes, I measured ohms on the TPS.

OK, I attached pics of my AFM. Is the Vane supposed to open all the way when the engine is off, because mine is blocked as you can see in the third pic; I circled where the two pins hit each other preventing the vane from opening.

Also, after reading hailers post, I checked for continuity across the left pins. I have continuity (there was about 1-2 kohms of resistance, not 0) between all the pins with the vane closed and opened. I checked for shorts and I curled the loose foil out of the way, but nothing changed. This leads me to conclude that the AFM is either broken as a result of a short circuit, or that it's working fine and my problem is elsewhere. LOL. Not very satifying.

I checked all the fuses. The hoses seem fine from what I can tell.
Attached Thumbnails Engine runs great... for 3 seconds then dies.-afm-vane-closed.jpg   Engine runs great... for 3 seconds then dies.-afm-vane-closed-angle-view.jpg   Engine runs great... for 3 seconds then dies.-afm-vane-open.jpg  
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Old Sep 29, 2006 | 02:58 PM
  #31  
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From: Hagersville Ontario
Originally Posted by 150EZ
Classicauto: I dont know what you mean about the fuel pump connector or where it's at.
Where its at?

Originally Posted by classicauto
(yellow, two prong plug with a rubber boot on it located near right strut tower)
Doesn't get much simpler then that.

What I mean?

Sometimes I have found that when a step up relay or resistor (not sure which because Ive yet to find the culprit on my DD) burns out, the fuel pump will recieve its "start up" voltage...about 10-11volts. But once the "start up" voltage gets stepped up to running voltage, the pump dies because the resistor or relay is pooched. By jumpering the connector the fuel pump gets constant 12v when the key is on.

You can tell if this is the problem by pulling back the carpet in the rear and exposign the fuel pump wires. Hook up a DMM and start the car and watch the voltage. if the voltage stays at 10-12 even when the car is dying, then you know its not the problem. If you see the voltage drop off to 0 then the car dies, plug a jumper wire in the connector and drive away
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Old Sep 29, 2006 | 04:26 PM
  #32  
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Racer-X-7
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Well I think someone owes classicauto 10 internet dollars. I jumped the fuel pump test connector near the strut bearing and she started right up. This only worked after I repositioned the arm inside the AFM to rest on the second pin instead of the very first, so that the vane is slightly opened (not sure if this is how it was set up originally). TPS is still shot, I also noticed a minor air leak around the tiny screw on top of the throttle body (not sure what it does).

Now my questions is: What does this all mean? Can I drive around all I want with a jumper wire in that connector? Do I need a new fuel pump?

** On a side note, now I realize why you guys bash KN CAI. My god, the filter is practically resting on the radiator hose, which is freaking hot. However, my heat / sound insulation just arrived, so I was going to fashion a barrier around the filter and around the whole air intake hose.
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Old Sep 29, 2006 | 04:47 PM
  #33  
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From: Hagersville Ontario
Originally Posted by 150EZ
Now my questions is: What does this all mean? Can I drive around all I want with a jumper wire in that connector? Do I need a new fuel pump?
Yup.

BUT - don't forget that somewhere along the line, there is a burnt or blown resistor or relay - the fuel pump is fine. I've just never been able to track it (the relay or resistor) down yet.

But your car will run all day long with the jumper wire. Unless something else lets go.

EDIT: Where's my moolah??
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Old Sep 29, 2006 | 05:08 PM
  #34  
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Racer-X-7
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Hey I didnt bet against you!

Thanks for all the help, everyone. I guess it was a combination of AFM being misaligned and the resistor.

Ill post pics of my lame attempt at a cold air intake.
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