I just bought a 91 rx7 with 300+ horspower. Accomplished buy injector, fuel pump and turbo upgrades. The motor is a jdm with the intake ports inlarged. The motor only has 500 hundred miles on it but blue smoke comes out the exaust when the motor excellerates. The seller said that larger oil injectors were installed so premixing wouldn't be needed. There is an s4 oil metering pump installed but the thottle rod is unconnected. This leeds me to believe that either to much or to little oil is being injected. All the work and tuning was done by R&R however the tune is somewhat lacking and I almost ruined the engine because a oil cooler line was never tightened, seems way to rich. Seller said it was using a ecu from japan and some sort of piggyback. I would like to put a haltack in but have no idea how. This car is fun to drive but the tune is ruining the experience. Any ideas why it smokes blue with only 500 miles. Idle is fine at 1200 going brap..brap..brap.brap. This is my 3rd rx7 after a woman ran a red light and totaled my 87tII.

 

sounds like the motor is overported. seen this plenty of times before.

 

Yep, sounds overported. I honestly don't think the oil injectors CAN inject enough oil to cause a noticeable smoke from the exhaust. That was probably just an excuse for the smoking. The guy I bought my car from told me the white smoke was because he put in too much premix (it was a cracked water jacket), so I feel your pain.

 

Overported? I'm not familiar with that term. Is that just like it sounds, or is there something specific that was done wrong in the porting process?

 

Do you think it will get better when the engine gets fully broken in. If not is there any way to fix it without a new port job. I don't much like the shop that did this build. I had to resize intercooling piping, multiple items were never tightened and now this. Its all good though since I only paid 3500. If the oil metering pump throttle rod is left unconnected and in the down position will it cause insufficient oil to be injected. Any words of advise will be appreciated.

 

Before you drive that car, you should figure out how oil is being injected... You would not want to starve your seals of lubrication. If you really are running the s4 mechanical oil-pump, you will not have a functioning system without that rod connected to your throttle-linkage.

If I were you, I would probably replace all of your "unknown" aftermarket parts with stock parts until you figure out what's going on... I've seen it too many times before--someone gets a modified car they know nothing about, and then blow it up... Don't be that guy and have your Rx7 experience ruined by a faulty setup.

Who rebuilt the engine and do you have a list of the parts that were replaced? What turbo is the car running and how many miles are on it?

 

I would finish the break-in process and see how it does. While it does sound like a more serious problem, I don't see any reason to just scrap it now.

 

Overporting is where they make the port too large and it cuts into either the oil seal path of the corner/side seal path. If it cuts into the oil seal path you will burn excess oil, if it cuts into the corner/side seal path the engine will blow because the seal will come out/break.

While its not necessarily the case, it does kinda sound like the port cut into the oil seal path on your engine. One thing is for sure, check that its getting enough oil like eriksseven said.

 

There are so many things wrong with the original post this thread scares me...


-Ted

 

Hehe. I was thinking the same thing....


Sounds like whoever built the engine is tarded.

 

The guy said it was built from R&r rotary in upland Ca. Since I wasn't sure about the oil injection I started premixing. The turbo is a stock s5 set to 8psi. Seller said it was rebuilt with different internals. I have not gone into boost yet but the turbo seems to be working fine with a super fast spool up. The port is a street port added onto stock larger ports from a jdm motor. the good news maybe is that the car only cost 3500 so I have leftover money if another rebuild is required.

 

Smoke can be caused by a number of problems. You need to determine where the oil is coming from, or if it is even oil smoke.

Pull the spark plugs. Covered in oil? That means it's being burned.

Now pull the intercooler piping. Is there a lot of oil inside? If so then the the turbo is bypassing oil in the compressor area.

Pull the downpipe and check the turbine section. If you find oil then the turbine seal is leaking.

Check the purge system. Make sure the purge valve is working and that the crankcase is not over pressurizing.

If all those are a negative, the oil possibility is that the engine is bypassing oil internally. Either from bad oil o-rings or overporting.

No such thing unless they were custom machined.

The S5 ECU requires the S5 metering oil pump to be present and working or the car goes into limp mode. If indeed you have an S4 pump installed then the S5 pump is tied up in the harness somewhere. If the S4 pump is not connected via the rod, then it's injecting very little oil. Uh, also it doesn't mount to the S5 front cover.

A rich mixture will cause smoke (blue or black).

Unless the car is bridgeported, the idle should be 750 RPM.

 

What kind of porting does the car have? The title says monster port, you say it idles like a bridge port and in post #11 you say its a street port. Unless you get your facts straight no one is going to be able to help you.

 

i say lets see some pics

 

It has a large street port and I will post up some pictures. The car only starts to smoke lightly after it has been idling for a while. There is no visible smoke while driving around. I no longer think the small amount of smoke is a big deal because it runs rich quite rich. I will continue to diagnose. Other bad news is that the clutch slips at only 1 psi.