Joe Perez

iTrader: (8)

Well, we've all been there. It's just a little different now that we have internet forums to go check in with.

I remember very clearly the first time I removed a spark plug. It was from the engine of my '71 VW Beetle. Granted, the engine itself was sitting on the ground at the moment...

Grumble_b

Ok,

So I did the first bit of the diagnostic. Removed the oil cap on the engine and had a friend try to start the car. The exhaust cam rotates so I am guessing that the timing belt is working fine. I also pulled the code from the engine and two codes came up:

12: Throttle position sensor

15: Oxygen sensor (output too low)

I checked the O2 sensor and it seems to be wired correctly. Everything is connected to the air box as well.

I spoke with the guy who towed my car and he said there was a possibility that it might be the throttle position sensor needing to be replaced. Is this a possibility? Tomorrow I am going to test the spark plugs to see if they spark.

Thanks for the helpful advice. Not putting anyone on by my extra "noobness", but no one in my family is mechanical at all-- this is all new territory for me.

I'm in the S.F. Bay Area btw; thanks for the offers of help.

Dow.tom

iTrader: (3)

I once had a car that had a faulty TPS, it never stopped it from starting, however, it may be different on our cars as mine was adjustable and i dont believe the miata's is. O2 sensor can look good and be wired correct but can be faulty, it's always good to replace, not really the cheapest thing, but, the TPS is a lot more expensive new IIR

magnamx-5

iTrader: (7)

grumble the tps could well be the problem test it with a multi meter and see if the output is right i forget the values you need. Also have you verified that the Fuel pump is on this will cause to low a reading on the 02 as you would run out of fuel take back the carpet and listen on the outside to see if you can hear the fuel pump turn on if it turns on then this might not be your problem if it does not. Remove the acces panel and check the wires to the pump, if you get good ground and hot electricity then the problem is the pump. If not then it is the wire. Maybe try to contact medysn he is in the san fran area i believe and is familiar with all this stuff. GL man.

Grumble_b

I turned the key to the on position and went outside the car. I listed carefully, and I heard what sounded like the fuel pump coming on; sounded like liquid pumped into the car. When I turned the far fully off, the sound stopped.

dfung

I predict fuses or loose electrical connection. 'nuff said.

Grumble_b

So I played around with the TPS connector jiggled some wires, pulled the fuses to make sure they were intact and put them back in, and more throughly checked the connections and then tried to start the car. Low and behold I almost pissed in my paints as the engine came to life. The car is now currently heating up in the garage and is idling normally.

I have tein suspension which rides fairly rough, and part of me is wondering if the car being on is a freak think or if the bumpy suspension dislodged something. Either way, I will keep you all posted. Thanks so much to everyone that commented, for the suggestions, and help. This is a great forum.

Grumble_b

So I let the car run to normal operating temp and everything seemed fine. I got into the car and reved the engine really hard I got a CEL and the car died. I was able to start the car back up after this and there was no cel/engine and car were running normally.

I turned the car off and was able to start it back up. Since the car was able to start and idle normally it seems that the fuel pump is working, that the spark plugs are working, ect.

Scratches head. I did some research on TPS's and suppoosedly the car should still be able to start without one. DOes anyone have any ideas what might be happening to make the car run normally and then shut off? Could this be some other electrical problem or actually be related to a faulty tps?

Dow.tom

iTrader: (3)

yet again, check those codes, they will tell why it did that. Could be your AFM. Maybe when you rev it up, the AFM doesnt get the signal or whatnot and doesnt allow the air to enter the engine, IE you lose the one of 3 variables needed(gas, spark, air) Keep me updated. If you pay for me, i'll fly haha out

Grumble_b

See the code didn't last; maybe the cel just flashed when the engine died. In any case the code is gone now and the car is running normally. I checked the spark for each of the plugs and they are all sparking.

How do you check to determine if your afm is working properly? Is this another check with a multi meter/?

Car is starting and running normally now, for now anyway.

mtncrvr

Fyi my timing belt slipped and saw similar issue - car wouldn't start, throwing CELs that were related to CAS and AFM and of course I checked (watching the cam to see if it was turning when the engine was turning over) which can be misleading since in my case it was turning over fine but the belt slipped by 10 deg retard.

wildfire0310

iTrader: (1)

got a question, can you just slowly rev the engine???

I am wondering if your TPS is gone and when you apply gas the ecu flips out and dies. Also if you are able to slowly rev, I am wondering if a wire, maybe ground is lose.

You maybe get a bad connect somewhere... most likely TPS or O2 since both had codes. Messing with wires maybe you reconnected then and when you reved it you broke the connect.

Dow.tom

iTrader: (3)

im pretty sure there's a multimeter test for both TPS and AFM. Check the TPS and the AFM with the multimeter(i'll look for the variables) and it should determine your prob.

Dow.tom

iTrader: (3)

Okay here's what i found. To test the AFM, remove it from the car.


second:

The ports on the AFM plugin (on the AFM) from Right to Left are :

Fc - E1 - E2 - Vc - E2 - Vs - Tha A



using those ports measure using a multimeter. Here are the resistance levels.

Fully Closed: (E2 and Vs) 200 - 600
Fully Closed: (E2 and Vc) 200 - 400
Fully Closed: (E2 and Tha A) -4Degree F 13,600 - 18400
68F 2,210 - 2,690
140F 493 - 667
Fully Closed: (E1 and Fc) Infinite

Now for the Fully open:



Fully open: (E2 and Vs) 20-1,000
Fully open: (E2 and Vc) 200-400
Fully open: (E2 and Tha A) -4Degree F 13,600 - 18400
68F 2,210 - 2,690
140F 493 - 667
Fully open: (E1 and Fc) ZERO

Best of luck, i'll find the TPS and post up again.

Dow.tom

iTrader: (3)

TPS time... First: Disconnect TPS connection
2. Connect SSTs or an Ohm meter to the sensor
3. insert a feeler gauge between TPS stop screw and stop lever
4. note the operation f the buzzer or the continuity between terminals.


Feeler size .4mm (.016in) Buzzer: yes Continuity: (between IDL and TL yes) (between POW and TL no)


.7mm (.027in) Buzzer: no Continuity: between IDL and TL - NO
between POW and TL - NO
Wide Open Throttle: Buzzer: yes Continuity: Between IDL and TL - NO
Between POW and TL - YES

Dow.tom

iTrader: (3)

Oxygen Sensor testing:
1. Warm engine up
2. Disconnect sensor connector
3. connect voltmeter between O2 sensor and ground
4. Run engine @ 3000 RPM until voltmeter shows approx .55V
5. Increase/decrease engine speed suddenly several times: Verify when speed is increased it reads .5-1.0V and when decreased it reads o-.4V

If it doesn't read this, REPLACE.

BEST OF LUCK
I'm tired of reading this damn manual now.. haha now fly me out to the Bay Area and have me work so i dont have to go to work

samnavy

iTrader: (7)

Dude, what are you using for engine management.
Better yet, post IN DETAIL your entire setup. I don't suppose you have an Emanage, Bipes, or anything that requires splicing into any wires anywhere perhcance?

I've never bothered to check the codes, but your exact symptons are what I experience when my Bipes connector comes loose. The car will die at a seemingly random point. Then it will start and run fine, but simply revving the engine would vibrate the connector and the car would die. A quick push on the connector and I'm back in business. It's only happened on the freeway once though, which is why I have it quick-access style in the glove-box.

Check all your AFTERMARKET electrical connectors.

...and fill out your profile (specifically with where you live) and update your signature with your setup, maybe give us a thrill and post some pics in the vbGarage.

lazzer408

iTrader: (1)

Isn't the 1.6 a open/closed tps rather then a variable one? If it failed I can't imagine a no-start situation. Unplug it and see if it starts. The ecu should set a fixed value for it but failure while running could cause the engine to die.

Dow.tom

iTrader: (3)

well i read the manual for a 1990 mx5 so i would assume it's the same for his 92... i dont own one so idont know. Also it should start without one. However is the AFM is faulty it could very well shut him down like that.

wildfire0310

iTrader: (1)

To answer your question the 1.6 is an open/close tps(stupid mazda) but it depends on which way the ecu reads the values whether it would start or not. If the ecu read 0 as closed and 1 as open the if the tps is not working it may still read a 0 to the ecu and start but would flip out when giving gas.

now that is all theory