Engine lacks enough power to drive…bought the car in this condition…car had Mazda reman put in 2-3 years ago, but has never been driven due to lack of power…has been at 2 dealerships and one independent shop…engine was compression tested (believe all 8s) at one dealership…
Car starts easily, idles steady (with original ecu)

Once engine warms and accelerator tapped… timing seems to change ..with original ecu

If you slowly rev motor… around 1500 rpms engine starts to backfire and check engine light flashes…no ECU codes are ever set

Replaced crank angle sensor connectors (broken wire) and checked wiring from connectors to ECU
Checked sensors for correct resistance
Checked for 12 volts and ground throughout igniter/coil circuits

Attached is logged data from this car and my other FD...you'll notice the sensor voltages seem to be correct..also since 4 wires are not cut going to the PFC on the bad car idle will not settle..

any help diagnosing this problem would be appreciated

Dave

 

A guy had a problem just like this a long time ago. I think he was offering $100 to whoever knew what it was so basically everyone threw in ideas. He finally figured it out but I forgot what it was so try a search.

I think the smog pump comes on at 1500, maybe it's bad and causing a drag. Might try unplugging it??

 

thanks for the info GsrSol..

I'll search using $100 (I have been searching)

I did unplug the smog pump, will disconnnect it again as a second check

 

Your in St. Louis, take it across the river to BiState Customs. From what I have heard they do good work on third gens. Also try contacting some one from the local RX-7 club up there. They are a knowledgeable good group of guys.

 

Mine was just now running like ****. No power , running lean, falls on its face with boost, and the idel was hunting and low. Turned out to be bad wiring on the ignition. Thats one place to look. Check all connections and then check the componets to make sure they are within spec.

 

thanks guys..

I checked the coils/harness/igniter/plugs and the crank angle sensors.

 

I'd suspect something with the cold start stuff.

Sounds like time to go stand-alone ECU

 

actually, it seems once it's warm the timing is off

if you compare the 2 logs titled cold start in the attachment, you'll notice that both cars have very similar timing and sensor voltages as well as vacuum, whereas the logs for the warm/hot starts tend to differ a bit

thanks Ryan for the reply...any other thoughts are more than welcome

Dave

 

i dunno how relevant this problem is, but on MY car, after going NS, i had problems with HORRIBLE 2k-2200rpms bucking and hesitation, plus the idle would float up there and not come back down. It ended up being the AWS system's soleniod sticking open and trying to close. Took all that **** out and it runs flawlessly now.

-Zach

 

I would check air temp sensor, AWS, ACV system (includes Air pump); also the whole harness and its grounds particularly if this car has been checked by so many people already.

How rich is it running? I have been amazed how nasty these cars act when running super rich.

I also agree with TeamStealth. Remove alot of that stuff. I have everything but the ISC and the fuel pressure solenoid out and I have a very solid idle. Would make it easier to figure out. Where are you located in STL? I and I am sure some others in STL would be happy to help. Hell just rip all of it out and lets just put back when you *need*

Jason