I picked up an 88 rx7 GXL a month or so ago for $600. Owner said it ran when he parked it but the fuel pump went bad. New pump (and cleaned and resealed tank... very rusted) And still no start. New ngk plugs and wires and no spark. The coils ohm out ok, as well as the crank position sensor. Per a suggestion from a friend on a local forum, i checked and cleaned the ground on the drivers side shock tower. still no spark.

 

make sure theres 12V going to the coils

 

last time i messed with it... i think there was 12v going into the coils from the igniter, with the ign. on

 

Make sure the contact points between the fender and coils are clean for this is how the ignitors within the coil are grounded. No ground equals no spark.

The B/Y wires at the coils require 12 volts w/key to on.

The Brown/White wire at the TPS or boost sensor should read 5 volts w/key to on. A ground signal would probably indicate a grounding caused by the AFM (no good).

 

im not sure where the TPS is on this car. and im guessing the atmospheric pressure sensor is the same as the boost sensor (same spot in the hayes manual it looks like) i tested it acording to the manual. it reads less than one volt (50 mV) would that cause the coils not to fire?

 

The two pressure sensors are not the same. The boost/pressure sensor is in the engine bay at the passenger fender and has 4 wires to it. Black/White, Black, Brown/Red and Brown/White. The Brown/White wire should read 5 volts w/key to on. And make sure you are measuring the proper wire.

 

ok, i misread the diagram. the brown/white wire reads 40mV. the manual i have says it the brown/red ... and its 10mV but it does say it needs to be tested with a vacuum applied

 

Are you sure you are testing the wire w/key to on?

 

yes, double checked

 

You have a Green check connector with 4 wires near the lead coil. Three are Yellow striped wires and the 4th being Black/White. W/key to on the B/W wire should have 12 volts. If it does not then that would explain why there is no voltage on the Br/W wire.

 

i got 12v at the b/w wire at that connector

 

You need to verify that you are really not getting voltage on the Br/W wire w/key to on. The TPS is Black and located on the very front of the throttle body. It has a piston which extends outward/inward depending on the throttle position. The sensor has but three wires; Green/Red, Black (ground wire thus it should have 0 volts), and a Brown/White wire, which should have 5 volts. W/key to on what does this wire measure?

 

im guessing this is the right wire. i got a greed/red, black/white, and like a faded orange. im guesing that last one is the right wire. it reads 43mV with the key on

 

Set the voltmeter to DCV (position just to the right of the off position. And is the TPS plugged in?

 

127 mV with it on that setting. and yes, it is plugged in

 

You need to unplug the AFM and test the Br/W wire w/key to on after the AFM has been unplugged at either the AFM, TPS or pressure sensor.

 

i got a few different results. with it unplugged.. at the tps, a few times it would spike to .4v right when pluged in, then drop to .2v The i tested the boost sensor and got 197mV, and the same thing at the AFM. i went back and retested at the tps and got the same 197mV

 

The Br/W wire w/key to 'on' should read 5 volts. There are two other sensors supplied by the Br/W wire and they are the variable resistor and ATP. You could start by unplugging all of these devices while measuring the Br/W wire w/key to on in search of the 5 volt value. You could start by having the AFM, pressure sensor and TPS unplugged and test the Br/W wire using the emission side of the harness, which is important,w/key to on

 

ok, well college classes start this week for me. so i might not be able to work on it till the weekend. ill let you know what i find.

 

i did end up working on it a bit more last night. but i cant find where the atp sensor is. I cant really tell from the pic in the manual

 

It's behind the passenger kick panel. If you unplug 4 of the 5 sensors that might be enough to figure out why you are not getting the proper 5 volt signal on the Br/W wire.

 

With 4 of the 5 it's doing the .4 spike then drops to .2. Tested at the afm plug. Also gets the same at the tps plug.

I havnt had a chance to look at a schematic, but what is the source of the 5v line? Figure I should start checking there. After I unplug the sensor of course.

 

Pin 2A of the ECU is the source of the Brown/White wire. If there is no voltage at this pin w/key to on then make sure that pin 3I (B/W wire) has 12 volts w/key to on as this wire powers the ECU.

 

with that last sensor unplugged, it still is doign the .5v spike then drops to .25v. there is also 12v on pin 3!

 

You need to remove the Brown/White wire from pin 2A of the plug and then w/the plug connected to the ECU a paper clip could be inserted into the pin position and w/key to on the clip should read 5 volts. Also, with the ECU plug housing pin 2A unplugged you could do a continuity test using the wire in pin 2A and the Brown/White wire at one of the unplugged sensors to see if the wire rings out or not.