No spark, Help! (FD)

alexgtr · March 20, 2015, 10:48:27 PM

Hi guys,

Got my RX7 today. I bought it off a guy who it cut out on the motorway and he gave up trying to get it working and needed the money.

The engine cranks over fine, compression sounds fine. It stinks of fuel, I pulled the plugs out and they were covered in fuel as expected.

Checked the spark on the top two leads and there is no spark at all and it doesnt sound like there is any spark on the other two either.

I have checked all the fuses under the engine bay and they all seem to look fine, a couple looked a bit suspect so i swapped them with cleaner ones from ABS etc for testing and still no spark.

Also the check engine light doesnt come on, on the dash, should it? I have checked the fuse in the drivers foot well which i think is the ecu one and it is fine, swapped it with another just to make sure and made no difference.

Has anyone got any ideas and also what to look at next?

Any help greatly appreciated!

I also noticed the check engine light doesnt come on when you turn the key to on, should it? It could be that the bulb has gone

clive · March 21, 2015, 08:54:16 AM

Reading this I wonder if the car has an immobiliser that's kicked in ?

alexgtr · March 21, 2015, 09:05:52 AM

Well it does have a Clifford alarm fitted and previous owners have made a right mess of the wiring for other things.

I did think it may have something to do with the immobiliser but know absolutely nothing about alarms. Anyway I can disable it or bypass?

boosted · March 21, 2015, 10:09:10 AM

Sounds like you got yourself a bargain. What ecu is in it? Can you read electrical drawings? Could be immobilser circuit for spark which can be wired out or ecu /wiring fault. Ill look at drawings later as just got off a very long plane journey and rather jet lagged.

alexgtr · March 21, 2015, 10:12:59 AM

Quote from: boosted on March 21, 2015, 10:09:10 AM
Sounds like you got yourself a bargain. What ecu is in it? Can you read electrical drawings? Could be immobilser circuit for spark which can be wired out or ecu /wiring fault. Ill look at drawings later as just got off a very long plane journey and rather jet lagged.

I bought it with a rebuild in mind although it already had one at 12k but I I think once this spark issue is sorted she will be running so yeah a good bargain I think!

Not looked at many but I might be able to work it out, thanks mate.

boosted · March 21, 2015, 10:17:45 AM

As quickie id find the alarm circuit box and check all edge connectors etc and any fuses locally on it. If my memory serves me correct prob spliced into engcont fuse.

boosted · March 21, 2015, 11:20:39 AM

http://automotivewiringdiagrams.net/engine-control-fuel-control-and-ignition-of-1994-mazda-rx-7-wiring-diagram

alexgtr · March 21, 2015, 12:09:52 PM

Quote from: boosted on March 21, 2015, 10:17:45 AM
As quickie id find the alarm circuit box and check all edge connectors etc and any fuses locally on it. If my memory serves me correct prob spliced into engcont fuse.

Will take a look. Weirdly there is a wire with a spade connector hanging under the dash that looks like it comes from the key but can't find where the hell it would go

boosted · March 21, 2015, 01:09:54 PM

may be summit simple can you find a home for the spade ? where abouts are you?

alexgtr · March 21, 2015, 01:30:47 PM

Quote from: boosted on March 21, 2015, 01:09:54 PM
may be summit simple can you find a home for the spade ? where abouts are you?

No i have had a good look and cant find it anywhere.

I have checked the fuses on the Clifford and they are all fine. The car seems to disarm and arm fine and the immobiliser led stops flashing when i press the button.

I took apart the backup battery siren box and the pcb in that is completely knackered and the cables for the siren have been cut too.

Where is the engine cont fuse you mention?

alexgtr · March 21, 2015, 01:31:15 PM

I'm in Swanley, Kent by the way.

alexgtr · March 21, 2015, 05:32:48 PM

I've managed to get spark. One of the wires on the ignition amp had been cut and resoldered badly at some point in the cars life and it looked like the solder had gone brittle. There was also hardly any of the wire in the solder. Re done that and checked all leads for spark and its there and looks nice and blue.

Deflooded the engine and put plugs back in, cranked the engine and after a few cranks it nearly started and was running very lumpy and shaky for a few seconds and then cut out. It keeps doing this now when i crank it and i get a bit of white smoke out the exhaust as well.

Any ideas?

alexgtr · March 21, 2015, 07:11:15 PM

Put some oil in the bottom plug holes and got it running but had to keep the pedal down to keep it on, loads of white smoke (nearly killed myself!) and the smoke mostly cleared but as the revs dropped it wanted to cut out. Had it running for about 5 minutes and let it try and idle but it cut out.

I am out of ideas now. Can anyone help?

boosted · March 21, 2015, 08:18:02 PM

Hi mate, thats good news rules out alarm atmo couldve been internal relay for immobilser circuit as these can burn contacts. Did you verify spark on both leading and trailing? and are you getting check light now? Does arm/ disarm bring on red ign light on dash?

Id now be checking voltages at ignitor etc. plug connectors cleaned with electrical contact cleaner.

pull fuse pump fuse and verify spark on all plugs. do a full deflood new plugs if you got any or blow lamp old ( sparky end in blue flame for 5 secs) verify plugs in correctly. check nice chuffs with sparks out on each rotor. can do both at same time but put sparks back in each rotor and you can compare sounds from 1 rotor to other.

hangin with jetlag now ill be back tomoz.

alexgtr · March 21, 2015, 09:16:30 PM

I checked for spark on all leads. The only way i could do it was using a lead from another car and plugging it into the rx7 lead then plugging a spark plug in the other end. Could see spark on each one. One of them was flickering between yellow and blue a bit. Is there any other way to do it other than having two people?

I have got brand new magencor leads to try but havent got any gaskets so dont really want to take the throttle body off at the moment and the big ali intake hose attached to that has a silicone gasket, although thinking about it, it will only make my idle a bit higher wont it?

I am not getting a check light no, but i am getting the 'Heat' light come on now when disarming the alarm, do these actually have a check light? Mines a 1995

After i did get it running i tried deflooding and getting it running again, it trys but just wont get there, i will upload a video. The plugs i put in were new. When i took the rears out they were black and fouled, the fronts were nice and clean... Any ideas?

Thanks for all your help so far.