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Old 09-30-2010, 11:06 PM   #1
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Default motor will only idle

I have googled up a bunch and cant find anything so im going straght to the source of miata info, my miata will only idle when the ecu is jumped . if i dont do the jump it wont even start, my fuel relay is good i have checked the ohms and tried a friend of mines so i know its not that, if anyone can help me out please post up ill try anything at this point im dying to get this car running, im going to change the fuel filter on saturday morning and see if that does anything to help .
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Old 09-30-2010, 11:17 PM   #2
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We need a little more info to help you out. What year is the car and what has been done to it?

Just a FYI some one should be here shortly to flame you about your grammar.
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Old 09-30-2010, 11:49 PM   #3
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Originally Posted by miataongt3s View Post
I have googled up a bunch and cant find anything so im going straght to the source of miata info, my miata will only idle when the ecu is jumped . if i dont do the jump it wont even start, my fuel relay is good i have checked the ohms and tried a friend of mines so i know its not that, if anyone can help me out please post up ill try anything at this point im dying to get this car running, im going to change the fuel filter on saturday morning and see if that does anything to help .
1 what are you jumping on the ECU.
2 why would you do a filter when the car wont start unless its jumped

From what info you have given it could be a lot of things wiring, ecu, senors, and what not.

So more info is need like is the car stock, year, and what ever any one here will ask.
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Old 10-01-2010, 09:37 AM   #4
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im assuming f/p and gnd... have to messed with your AFM lately?
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Old 10-03-2010, 09:06 PM   #5
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my previous motor was on boost , this motor is not for now. i jumped the f/p to the ground. i did the fuel filter cause my friend had a new one so i said why not, its a 91 with the 1.6 stock internals, it has the stock ecu. if u need anything else let me know .
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Old 10-03-2010, 10:21 PM   #6
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Check for leaks after the mass air flow/air flow meter. Any leaks in your intake tubes could cause this problem, and since the car was previously boosted chances are pretty good that something is not sealed up as well as it should be in regards to intake piping.
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Old 10-03-2010, 10:43 PM   #7
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People still run the stock computer in these cars? lol
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Old 10-03-2010, 11:39 PM   #8
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People still run the stock computer in these cars? lol
Poor misguided souls.
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Old 10-04-2010, 09:09 AM   #9
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Make sure the AFM is plugged in, if so, switch it out with a known good one.
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Old 10-04-2010, 04:32 PM   #10
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Check for leaks after the mass air flow/air flow meter. Any leaks in your intake tubes could cause this problem, and since the car was previously boosted chances are pretty good that something is not sealed up as well as it should be in regards to intake piping.
youre like the second to third person to tell me but i took it as far back putting the whole stock intake piping and all that crap with it so i guess its on to the next test?

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Make sure the AFM is plugged in, if so, switch it out with a known good one.
do they tend to go bad when they sit for a while? the car sat for about 3 months with no motor or trans in it. i will try that even though ive tried a few different ones

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People still run the stock computer in these cars? lol
its for now cause i have two different miata projects going on so i took my DIY and put it in the other one
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Old 10-04-2010, 04:37 PM   #11
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so at one point you didn't have the "whole stock intake piping"?

answer:

1. did you ever remove the AFM? If the answer is yes, answer then how did you unplug it?

2. did you remove the hose that attaches below the throttle body?
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Old 10-04-2010, 04:42 PM   #12
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so at one point you didn't have the "whole stock intake piping"?

answer:

1. did you ever remove the AFM? If the answer is yes, answer then how did you unplug it?

2. did you remove the hose that attaches below the throttle body?
nope it was a all through intercooler piping

answers
1. just from the plug on the side , when it was on boost it didnt have it , the plug was just hanging in the bay

2. the hose on the bottom of the throttle body is plugged in to the stock intake piping where it goes its the L looking hose
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Old 10-04-2010, 05:03 PM   #13
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There is a chance that when the AFM was removed that the screws were loosened. This could have broken connections(little flat ribbons) inside the AFM
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Old 10-04-2010, 05:05 PM   #14
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There is a chance that when the AFM was removed that the screws were loosened. This could have broken connections(little flat ribbons) inside the AFM
but that will cause it to bog out when the car is accelerated?
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Old 10-04-2010, 05:07 PM   #15
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Yes, if the plug is not connected or if the leads are broken(or if the brushes inside are not making contact) the ECU thinks you are WOT and pushes in a lot of fuel.
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Old 10-04-2010, 05:12 PM   #16
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My next best guess would be the tps sensor. But before you go messing around with that try something for us.
pull your air filter off so you can see the inside of the AFM. With the car running push on the vain on the inside of the afm while trying to rev it up. The more push on the vain the more fuel it will dump into the system.
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Old 10-04-2010, 05:13 PM   #17
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Yes, if the plug is not connected or if the leads are broken(or if the brushes inside are not making contact) the ECU thinks you are WOT and pushes in a lot of fuel.
ohhh ok , now its making more sense to me, ok i have my battery on the charger now cause its dead from numerous start ups yesterday once it gets a little more power in it i will try that out ,im going to grab my afm and check all the connections and the plug as well
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Old 10-06-2010, 11:19 AM   #18
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so this is where i stand so far: my friend has a spare AFM laying around that didnt have the cap on it so i used that and the car would still do the same thing, so i went ahead and tried his daily one and it worked a little better. I then went and put the AFM without the cap back on it and wedged something in it so it was about half way open. When i did that the car would bring the RPMs up when accelerated but after about 3,000 it would bog a little bit but i have a feeling its because since it was wedged its only telling the fuel pump to only inject so much fuel. Im thinking i may just need to order a brand new AFM?
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Old 10-06-2010, 11:38 AM   #19
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the fuel pump is either on or off; if the flapper door ever closes the fuel pump turns off. it's the job of the injectors to supply the correct amount of fuel.
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Old 10-07-2010, 11:19 AM   #20
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the fuel pump is either on or off; if the flapper door ever closes the fuel pump turns off. it's the job of the injectors to supply the correct amount of fuel.
im thinking my AFM is bad, because when i turn it to a certain point and wedge it there itll rev up to a point but as soon as i let it idle and unwedge the afm it dies on me again
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