drft_180sx

Hi, so let me just tell you guys the story of my car really quickly.

My car lost compression while i was driving about 8 months ago. I had it towed to my house about 2 months ago, due to lack of financial resources. Finding a decent mechanic to rebuild it for me was nearly impossible to do, so i had to settle for a mechanic that swapped the motor for me. I finally got my car about a week ago. (i would have attempted to do the work myself, buti have little experience and no workspace, not the proper tools).

The motor (shortblock) that went in had a streetport (what type i dont know) both intake and exhuast (diffusers were grinded out from what i could see). The engine came out of a 1988, my car is also a 88 GXL. All the intake and exhuast manifolds were used off my old motor. So the 5th/6th actuators are working (i checked)

The questions....

Since the motor is streetported, do i need to up the grade of gasoline?

I have been running 1:100 premix because my omp lines were in bad condition, and i didnt want to risk another blown motor, is that ok to put soo much oil into the combustion chamber (OMP+2stroke 1:100)?

The car doesnt have a o2 sensor, i plan on installing one this weekend, i should be worried about the car running too lean with the streetport right?

The Problems....

The car runs faily strong, i think its a bit sluggish because of how rich it is running.. BUT during idle and lower rpm (<1500) the motor shakes VIOLENTLY almost like it is misfiring...where should i start my troubleshooting for this? i know it is soo vague, but the motor is just violently shaking, there is no other way to describe..

I appreciate all the help in advance. I will continue my search for the answers, and post them if i find any...to help later searchers...

Thanks

Jahan

Syonyk

No. You should still run the lowest grade of gas you can find (on the NAs, this makes more power - Mazda NA race gas was something like 80 octane).

It's not great to run that much oil, but it shouldn't hurt anything. If you're running 100:1 premix and don't have a problem doing so, I'd suggest just pulling the MOP off entirely and run pure premix. Your engine will thank you.

No. The O2 sensor is only used during light throttle cruise, and if it's not connected it will affect fuel economy, but not much else. The airflow meter will handle the increased airflow due to the streetport without any problems.

Check your TPS calibration.

Also, silly thought, you said it sounds/feels like it's misfiring. Have you changed the plugs & wires lately? Especially with running both premix and the MOP, you may have just fouled the plugs out.

-=Russ=-

drft_180sx

Thanks so much for the quick response...its much appreciated.

I meant to say i use premix 1:64 (1 ounce to a gallon of gas).

I put in new plugs when the new motor went in, its been violently shaking since the first startup with the new plugs. I didnt change the wires, they are about a year old, but they have sitting pretty for 8 months, so not much mileage on them, can wires go bad from sitting?

Thanks again

Jahan

Syonyk

1oz/gal is a 128:1 ratio. There are 128oz in a gallon.

The wires should be OK if they're only a year old.

Have you made sure the plugs are clean and that the engine is getting compression on all 6 faces? Shaking violently at idle and smoothing out but lacking power up high is often caused by lack of compression, either from a blown or stuck apex seal.

-=Russ=-

drft_180sx

thanks...ill go check the compression to make sure they are nice and even along all faces, once this rainy weather stops...also, since the plugs are completely brand new, i doubt they could have fouled so quickly...

again thanks for the help and correction (doh!) ill keep you posted...

Jahan

fcdrifter13

not to jack the thread but. Are you serious about the lower octane gas. Hmm you learn something everyday. I must still have some piston motor left in my system.

I would also remove the OMP and just run strait premix. I dont trust things that could fail and ruin my motor. So basically i dont like any support systems of a motor I guess. lol. If it was my motor I would run a little water throught it to clean out any carbon that may be there. They still are doing this right guys through one of the vacuum lines. I dont wanna tell a false truth here. Also change all the fluids and such if you already havnt.

full-cruise

iTrader: (5)

is this motor used or rebuilt ¿ if its used could just be a bad motor