1st sorry for my english...

When I start the RX-7 FD3S in the morning, big smoke comes out of the exhaust for a couple of minutes. The problem was only that since yesterday. Now the car is extremely slow, 4 seconds to reach 6k RPM... Huge backfires even at 1,700 RPM (idle, high since yesterday for I don't know why), weird sound coming from near the turbos... here are some videos.

Big smoke:



Look how it takes time to start, the weird sound coming from near the turbos, the HUGE backfires at the end... http://youtube.com/watch?v=R2SjXopPEV0
With TPS unplugged... no more backfires http://youtube.com/watch?v=-VspPZq65W8

This guy seemed to have the same problem than me, but nobody answered him? https://www.rx7club.com/3rd-generation-specific-1993-2002-16/tons-white-smoke-cold-start-smells-like-raw-fuel-smoke-engine-bay-751313/

 

Sounds like the turbos are blown.

I would try a compression test as well to make sure that the motor is still good.

 

Maybe a dumb suggestion but how tight are your belts?

I only ask this because in your first video, i was looking at your airpump and the clutch was spinning slow, then started to spin normal, then slowed down again.

Of course this is going by the fact IF your airpump works properly, i had to suggest that.

Also what about your map sensor? Did you check that?

 

Alright, Im the guy who works on his car and I dont have much experience on rotary engine, but i do know well bout piston engine. When filming both video I was there, Ill explain in detail what happened to his car recently.

First he told me he aways had boucing idle, "idle hunt" What I did, is removed the hose connected to MAP sensor,let the map see atmosphere pressure, the boucing idle is gone, idle rpm goes to 900-1000 very stable. But when I plug the hose back the problem come back. He abuses the car quite often so I suspect his car got a vacuum leak, so I connected a vacuum gauge and it shown a -10inhg @ 1300rpm idle... Well for a piston engine this is not normal at ALL... I checked the oil, it was quite black in color, he told me he hasnt changed bout 2500 miles, I told him to change it asap and he did (non-synth 20W50 castrol GTX), oil level is fine, but after like 3-4 km of driving the car suddently lost all his power. We put in neutral in the video and presse the throttle wide open, you can see how slow the RPM goes up. Then huge backfire occurs... We tested the TPS, everything is within spec, we didnt test the MAP sensor though but we will do its in our todo list.

Here's what we will do to figure out the problem:

MAP sensor voltage check
Compression test Check
Turbo shaft play check, rebuild may possible.
catalytic converters removal
Intake manifold and coolant seal check n replace
Ignition coil resistance check
Spark plug check (oil fouled?)


It seems this motor need a serious rebuild, but before, we need make sure the housing isnt damaged by the rotor, and BEFORE go into rebuild , we need to make sure the problem is engine related, not electric sensor ****.

 

I'm curious, but what's a ... "Intake manifold and coolant seal check n replace" ??

What are you looking for when checking the intake manifold? Not sure I would be too worried about the intake manifold at this point.

And how are you checking the coolant seals? Replacing those involves doing an engine rebuild.

To the OP, how many miles on this FD? Everything stock?

 

the engine have 74000 miles, there's just a hks sqv, other thing's pretty much stock. I forgot to mention there's a lot of oil underneath the engine..

 

Just some ideas...

1)Change plugs
2)Sort your belt out as mentioned before
3)Install boost gauge...perhaps this can shed some light on the turbos?
4)Pull error codes?

Just some ideas before ripping out the engine...

 

More than likely one of the turbos has a cracked housing...that would explain the oil leak...but it doesnt explain the idle problems (I drove around with a cracked primary housing for a year, and all it did was leak oil.) I would definitly recommend replacing the MAP sensor, or maybe the filter running up to it. If the gas filter is clogged its going to send the wrong data to the ECU.

Another strange thing you mentioned was that with the MAP unplugged, it sits at about 1k rpm and idles steady. My experience with the FD has been that if you let the MAP read atmosphere, the idle bounces irregularly and has trouble even staying alive at idle.

 

Problem solved, I was going to the garage to work hardly on it when I decided to hold the pedal until it reaches 7,000 RPM... I don't know why but when I reached this revolution, it's like something unblocked... the cas was running GREAT !!! (Except for the bouncing idle, I simply lowered it to 900 RPM and everything's now fine). We also found the weird sound under the hood, it's the air pump! Unplugging it solves the problem, but I'll have to work on that soon. I don't think it's an emergency anyway...

I was supposed to work on the RX-7 all the evening so... I decided to clean the spark plugs!

We cleaned them, I put them back... well plugged. The nightmare came true. Now I have an all new problem, it bucks (misfires, I think it's the same thing...) Constant black smoke...

I don't know what to do ! Before cleaning those spark plugs and adjusting screws to set the idle, everything's was okay!

Here's a video of the problem. At the start I talk in french... I only specify that the pedal is always at the maximum.

http://www.youtube.com/watch?v=s1CCVoFOUO4

Thanks !

 

Something is still wrong, regardless if you can "rev" to 7000rpm.

I would first start off by checking for codes, then i would check the readings on your TPS. That might explain the bucking situation.

Then i would REPLACE your plugs and go from there.

 

we found the problem the boost sensor hose was disconnected.