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

91 RX7 trouble keeping started/running really rough

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Old Feb 24, 2013 | 01:21 PM
  #1  
apprenticeforhire's Avatar
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From: Lexington
91 RX7 trouble keeping started/running really rough

Wasn't getting a response in the new member technical subforum.
Reposting here.

Running a 91 RX7. NA. 13b.
Has headers, emissions delete, electric fan, oil metering pump delete.
Has a K&N filter than you need to oil.

The L igniter wasn't sparking, so I bought a new one. Now getting spark on all 4 plugs.

Also changed plugs out to new NGK coppers. (The one for rotarys. I forget the model number)

PO ran car through a car wash and we're assuming it fried the igniter.
Car throws a code. "11" Which is the thermosensor, I believe. Thermosensor has been changed out.


So my issue is, we can get the car running, but in order to do so, we have to disconnect the afm and artificially create a rich situation by blocking off the intake.

The car will fire up and we have to gradually introduce more air. We can hold the car steady around 2,400 rpm. If we drop it down, it will stall out, if we go any higher, the car looses power and we assume it's leaning.

If we reconnect, the afm, the car will will fire up but not stay running for more than a second or two.

Is there anything else that may be causing this issue besides a bad afm?
I think it may be something with the tps as well, but the car ran fine prior to this issue.
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Old Feb 24, 2013 | 02:27 PM
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FelixIsGod29X's Avatar
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Replace the afm i would assume. The car shouldnt be able to run with it disconnected. It should start then die with it unplugged.
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Old Feb 24, 2013 | 02:36 PM
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satch's Avatar
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From: tulsa,ok.
Measure the Brown/White wire w/key to on at either the AFM or the TPS and it should read close to 5 volts. This Vref reading powers most of the engine sensors and needs to give a proper reading. You could also have a vacuum leak.
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Old Feb 25, 2013 | 12:01 AM
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apprenticeforhire's Avatar
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From: Lexington
Originally Posted by FelixIsGod29X
Replace the afm i would assume. The car shouldnt be able to run with it disconnected. It should start then die with it unplugged.
This is a friend of "Apprenticeforhire" responding.
I'm doing most of the work and teaching him about cars in general.

I figured it was the afm at the start. It thought, maybe, with the afm disconnected, the ecu would enter into some sort of limp mode. But the way its running isn't quite congruent with your typical limp mode.

It SHOULDN'T run. I have to do some crazy manipulating with the intake to get the thing running. I.e. completely cut off air with something flat, then quickly introducing air before blocking again.

Basically, creating a crazy rich situation. It's definitely something to do with the A/F mixture. I'm sure the multiple vacuum leaks have something to do with the car being able to run at all. Could a FPR be at fault? I doubt it, seeing how the car worked before the wash incident. Just throwing around ideas.

I'll check the volts next time im by the car. The car is still about an hour or so away. We journey up there to work on it every weekend.
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