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Discussion Starter · #1 ·
Suh dudes.So this is my first post so why not ask the world!

it'll be easier to explain my current situation and problem i am facing if i tell the story of how I ended up there....

so bought an AEM UEGO Wideband for my stock 91 eunos roadster, while wiring up the gauge power to the blue ignition cable below the steering wheel i noticed an aftermarket immobilser which was wired absolutely horribly! so that was quickly and carefully removed - the car was checked after this was removed and it started fine.

proceeded to earth the gauge above the steering wheel and bring the 02 output over to the ecu and spliced into the red and blue cable (02 input on N2)

plugged in the new 02 sensor and tried to start the car up, it cranked and cranked and fired every so often but sounded like a warp drive failing when it fired.

it was then i also realised that i forgot to disconnect the battery at some point so god knows what i have fried. :goodjob:

I have tried connecting wideband sensor to the existing plug so the harness wont need modifying and this changes nothing, I have tried the cable cut and just using the new 02 sensor and get nothing.

I get no check engine light on start up or ignition.

I definitely get fuel because it stinks when cranking.

i have replaced spark plugs and checked for spark and get nothing.

if i did blow fuses or relays which ones would they be? is the ecu broken due to me being a dumass and not disconnecting the battery? coil pack gone? CAS gone? everything was working before i got a hold of a soldering iron and started swearing. :censor:

the aem uego does have an narrowband output emulator on P4 which is the setting i have it on - this gauge powers on and shows a reading from the 02 sensor so at least that works.

just to make sure i just returned the car back to stock and still have the same problem, cranked and can hear the exhaust going but no spark or firing.

I swear i will give a kebab to the person who helps me solve this!
 

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... I get no check engine light on start up or ignition.
I definitely get fuel because it stinks when cranking.
i have replaced spark plugs and checked for spark and get nothing...
Firstly, sorry to hear about your problem. I know that icy feeling of suddenly realising the thing you've been tinkering with was still powered.

Anyway; Your Roadster doesn't have a check engine light (it has a catalyst overheat warning light instead) so do you mean a light which used to come on now doesn't, or do you just mean it doesn't seem to be warning you about anything?

Not getting spark might suggest a CAS problem, with the ECU not able to work out when to fire the plugs. But if it is still injecting fuel that might imply it's getting some indication the engine is turning. Maybe one of the two CAS signals getting through would cause that.

But even if that's the reason, there's the question of whether it's the CAS itself or the ECU that's damaged. Not sure how to go about testing that.
 

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You can test the cas by supplying 5v and measuring for output voltage on the 2 output terminals, but get a wiring diagram first.

Had plenty of CAS issues myself...

Not sure if you mentioned if you are using a mazda ecu, megasquirt, me221 e.t.c?

Most aftermarket ecu will give you a readout of the sensor outputs (for diagnosis) if you are using one...
 

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Discussion Starter · #6 ·
thanks for the replies, i just thought a check engine light being missing would indicate the ecu being damaged, trying out a few things today to see if the ecu is getting power and ill give the cas a check while im at it and let you know
 

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Discussion Starter · #7 ·
okay so checked the ecu wiring by actually opening it and checking a few pins against the ground, and seems okay. its getting 12 volts from battery where it needs to. so that rules out all wiring leading to the ecu.

so next step would be to check the CAS, FYI this is a stock ecu.

pins 2E and 2G both receive 12v and 7volts respectively so there is power being received from the CAS to the ecu.

to me this looks like ive broke the ecu, cos its receiving the right signals but doing nothing? I might be wrong but are the injector cycles controlled by the engine cycles and the spark controlled by the ecu? maybe thats why im getting fuel but no spark?
 

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Discussion Starter · #9 ·
I dont think so but thanks for the idea, replacement ecu is on the way tomorrow as well as new main and head fuses. that'll be the next thing I'll try if it doesnt work.

tried to start it today and it cranked and fired once and cut out straight away making that sci-fi failing warp drive sound as the engine turns while the starter motor is still going.
 

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Discussion Starter · #10 ·
so replaced the ecu, main and head fuses and still no spark. checked for codes with an LED and just got one light saying it was initiated and no codes shown.

looking to but a new cas and ignitor, could it still be one of those? wits end at the minute! might have to resort to getting an auto electrician here and sort it out. any more ideas?
 

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Discussion Starter · #11 ·
ordered igniter today to try that as the rev counter does not go up when cranking which looks to be a tell tale sign
 

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The rev counter is driven by the ignition pulses so no spark = no revs. So yes its an indication that you're not getting a spark, but doesn't give you any extra clues about why.
PS The ECU will forget fault codes if depowered so depending on the order you did things, it might have been erased when you checked with an LED. So long as you didn't disconnect the battery between trying to start and testing it should have been a good test though.
I'm clutching at straws a bit cos my money was on the CAS. :)
 

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Discussion Starter · #13 ·
double checked fuses today and found the engine fuse inside the car was blown which explains the loud pop i heard haha, so replaced that and car wont start still. checked the ecu codes and now it actually gives me one instead of nothing!

so it flashed for 4 seconds to say it was on and then gave 1 flash repeatedly which is:01 - Ignition Pulse - No signal - check the igniter, coils and wiring.

so igniter is coming tomorrow which should hopefully solve it!
 

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Discussion Starter · #14 ·
HUGE props for the ingitor idea you were right! the only thing is now the engine pings very loudly and gets faster with acceleration. checked with a screwdriver to me ear and i think cylinders 1 and 4 arent getting spark, they shar the same coil right? pulled the lead and put a spark plug in and it doesnt spark either..

the pinging gets faster with acceleration and is constantly there, put a screwdriver to my ear and checked each output of each cylinder on the exhaust manifold; 1 and 4 are the loudest sounding pings, plus they share coils so that cant be a coincidence.
 

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Discussion Starter · #15 ·
what i said was a load of shit about the coils, all spark plugs are black where they have been receiving sparks (they are brand new plugs so can tell). checked the oil and its on low which would explain the loud ticking! was the camshafts running almost dry!
 

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i'd try another set of plugs in it, you may have flooded the engine, once the plugs are out, disconnect the fuel pump or injectors an crank it with WOT to clear the cylinders/ inlet of excess fuel, a fit different set of plugs. ( even if the plugs that are in there aren't that old)
 

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i'd try another set of plugs in it, you may have flooded the engine, once the plugs are out, disconnect the fuel pump or injectors an crank it with WOT to clear the cylinders/ inlet of excess fuel, a fit different set of plugs. ( even if the plugs that are in there aren't that old)
I believe OP has resolved this issue now ????
 

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Discussion Starter · #18 ·
yeah all sorted, needed fresh fresh oil a new fuse and a new ignitor. Thanks again for everyone's help!
 
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