Warm up..Backfire, terrible idle...wont fire over..
 

So this morning I turned on the fd to warm it up. It reached running temp of 79C' and while i was inside I heard the car Backfire and all the sudden it had a terrible idle. ALong with that the car didn't want to rev at all, so i shut it down. It won't kick over now. Could it be ignition? maybe bad plugs? or coils?

Please help!! thanks

Check your MAP sensor.

Map sensor seems to be fine...

What mods?

Do you need a tune?

Has it been sitting for a while?

Did you check the map sensor vacuum line at the manifold?

Moda are as follows:
462hp at 16psi on 91 pump gas with 50/50 meth/water injection

Gt40r Turbo kit
Synapse 50mm wastegate
Custom equal length manifold/3 in unrestricted exhaust
HKS SSQ bov
850cc primaries
1300cc secondaries
All earls fitting for fuel lines
Aeromotive fpr with gauge
Race plugs
AEM methonol injection kit with bung welded into the intake mani runs washer fluid (mr Clean)
Apex Power FC- Tuned by Rotary Power out here in CA
KST Grounding Kit
XS Power Ignition Amplifier
Rotary Power Special Race Port
Rotary Power Special water jack port
3 mm Apex seals
Greddy Elbow
Greddy front mount intercooler
Denso Supra Twin Turbo Fuel pump

Checked the vacuum at the back of the intake mani.. seems to be fine as well..

hasnt been sitting at all...

check your fuel pump relay .. fuse .. and operation

what you are describing is similar to what would happen when you simply shut off power to the fuel pump with the car idling ...

Yup, this happened to me.

One winter afternoon, i was going to take it out for a spin. I uncovered the car, started it and let it idle. Went to my shed to get something when all of a sudden i heard the car sound like it was barely idling. I walked back towards the car and i heard it shut off. I was like wtf??

So i thought maybe a loose battery connection or something. Checked it and they were both good. So i went inside and tried to start it but no go. It would crank and crank but didnt kick over.

Back then i wasnt really good at tracing problems in order so i changed the plugs right away, same problem.

Assumed it was the ignitor, changed that, same problem.

Thought it was the fuel pump because i dont recall smelling fuel as i was trying to start the car. I changed the fuel pump, same problem.

In the end it was a relay.

Yea plugs looked good.. You wouldn't happen to know exactly which one it was would you?

Is it on the Radiator support?........Thanks guys!

Checked the fuel pump relay.... opened it up and it looks brand new inside.. all shiny etc.. should I still replace it?

p.s. the car cranks over.....and actually starts...but poor poor idle. ALso I cleaned the PCV valve yesterday. But it ran fine after that and this morning. hmmm

You dont check relays like that, you apply voltage to them and hear the "click".

Btw, it was the EGI relay that was bad. I would check that as well.

Do you have a Datalogit? We could tell a lot from some good logs.

Wish I did....that'll be on my christmas list..

So i was reading up on methods to check the relays... I can just run a ground wire and a posi to my batery...touch the relays and hopefully hear the "click" right? or is that a bad idea? ...not too familiar with testing relays..

Yes. Get some wire and make contact (i used alligator clip wires) with the pos & neg of the battery.

Then connect one alligator wire to a ground, then the other alligator to one of the terminals of the relay. If you dont hear a click, try another terminal. Basically if you dont hear a "click" at all. Replace the relay.

Btw, when testing for the click, you WILL KNOW if it clicks. It will almost feel like your hand is getting shocked without the actual shock. lol

Cool cool......thanks A lot, i'll let everyone know....hopefully it's the relays... i'd hate to have to do more troubleshooting..

.....well all relays were in good working condition. So ruled out is EGI and Fuel Pump relay diagnosis.

I'm gonna pull the plugs again today...and do a compression check....
It would be weird for a motor to blow durring warm up..but anything could happen I guess.

if I remember Mahjik had his motor blow up while it was idling while he was doing some work on it. But that was a result of a mess up on the rebuild IIRC. If you can find his old build thread you can check up on it.

found the thread, looking for the page
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/when-engines-break-pics-411874/page17/

edit: page 15

Now that would just be ridiculous but..kinda my luck haha

yup, you're in california so you should be able to find someone somewhat close with a datalogit that you can borrow. Hell if I was in Cali I would let you borrow mine, but I'm stuck in boring cold (20 degrees today) Nebraska. Also check the compression.

Will do.......Well I live out here in her Palmdale.... I'm pretty sure there's only one other rotary enthusiest...and i''ve only heard rumors about him...never seen him. We'll see though. I'll check the compression when I get back to the house. Thanks guys!