r33

hello
i did search but couldnt find the right answer for my problem and i m new to the rx7 scene so please educate me.

car is a s4 t2 completely stock, here's the problem

the problem seems to occur only on a cold start warmup (after the car has been sitting overnight). So i start my car as usual and it starts up no problem, the rpm jumps closed to 2k and as it gets warmer the rpm drops gradually. When the rpm hits around 1300, the engine (actually the whole car) starts to vibrate and i begin to see white smoke coming out of the exhaust. It lasts for around 15 secs or so and goes away.

car drives no problem at all.

What could be the problem?

thanks in advance

dot_txt

iTrader: (1)

I have close to the same problem. Check for vacum leaks but otherwise I have lived with the problem for 6 months and it doesnt seem to mean anything. I had a vac leak at first and my rx would shake violently. but otherwise after I fixed that it has been mild shaking around 1500 rpm and doesnt seem to mean anything.

uRizen

iTrader: (2)

Same here. When I swapped out my S4 intake to the S5 my startup got a little goofy.

r33

so vaccum leak seems to be the source of the problem?

r33

any other input?

Go48

iTrader: (7)

How much white smoke (huge clouds, just a little)? Does it have a sweet smell? Does it smell like oil? Has your coolant level been dropping?

White smoke could indicate an internal coolant seal or possibly just the pig rich air-fuel mixture at cold startup. Based on reading between your lines, though, I would guess it is just the rich A/F mixture.

r33

well i was sitting in the car and saw white smoke coming out the exhaust pipe in the mirror. not huge clouds, but it's visible amount. The funny thing is that white smoke comes out at the same time the car vibrates at around 1300 rpm. as i said it only lasts for like 15 secs or so and once the vibration is gone, no more white smoke.

if rich A/F mixture is the case, how do i fix it?
sorry, i m totally new to the rx7....please educate me
thank you

Exlex

Im having the same problem, also having trouble reving very slow up to 1300 it jumps to 1800. I will try to set the TPS and and clean the Throttlebody to see if the problem goes away. There is two good links in the FAQ under "idle problem"

r33

went to FAQ section and search for "idle problem" but no luck......
couldnt find anything........

BoostedRex

If it is the A/F mixture then don't worry about it. But if the white smoke smells sweet then you need to start saving up for a rebuild. Not trying to scare you here, but it's going to be better to fix it early before something really gets screwed up. I'm thinking that it probably is just the car running really rich though so you don't have anything to worry about. Just smell the white smoke next time. As long as it doesn't smell sweet then you're in the clear.

Zach

r33

thanks!
i searched in the forum and read lots of posts about white smoke so now I have a better idea why white smoke coming out. however, I m still clueless on the engine vibration as stated. . also caused by rich A/F mixture?

BoostedRex

If it's going rich enough that it's almost flooding out the engine then yeah that could cause it to shudder/vibrate like you are saying. I went out to my car and richened the SAFC up to the point where it almost flooded at idle and it shook the car pretty good. I just wanted to check that to make sure before I posted this.

Zach

Go48

iTrader: (7)

He's gonna ask you what an SAFC is.

BoostedRex

Nah, he's a good guy. Just new to the rotary world.

r33

thank you very much for the useful information.
really appreaciated it!!

r33

sorry i m a total noob to rotary........

r33

just did a closed inspection today and the white smoke that came out wasnt thick at all, no sweet coolant smell and there's water dripping from the exhaust. so i guess i m fine,

BoostedRex

Yeah, you should be fine. As long as the smoke smells like raw fuel and not like coolant then you're good.

And you know what an SAFC is. It's the Apex'i air fuel computer. It's just a piggy back fuel controller.

Zach

rx007racer

My 88 Vert does something similar but can do it when sitting for several hours, only does it in the winter, what happens is when you dont let it warm up for several minutes if you hop in and leave right away sometimes it likes to hesitate until you get a few miles down the road. It specifically hesitates when getting on the gas and usaully makes the entire car shake, wondering if all rotaries do this or if something is bad with the fuel inection system. Also car does not smoke besides the cold weather related smoke. Let me know whats up. Thanks All!

BoostedRex

You need to let the car sit for a minute or two and warm up. Other than that I wouldn't worry about your problem at all. Is the hesitation coming on at any certain RPM or just when the motor is cold?

Zach

rx007racer

just when the engine is cold never does it in summer or on warmer days
so it is normal and does it for everybody