Need Serious Help - Car driving me crazy

[cgreiner]

Sorry for the long post...but please read...

I own a 1987 Supra Turbo that has been giving me a bit of trouble off an on. The car is mostly original and stock, with the exception of a rebuilt engine with only 45k miles on it and an aftermarket thermostat and air filter. I love the car, but am sadly having a bizarre problem with it.

Typically, but not 100% of the time, if I am driving the car in or just after it rains it seems to stutter. It will start fine, but while driving it will periodically partially cut out and the check engine light flash. By this I mean that the RPMS seem to drop. The car usually idles at about 1000 RPM but when this occurs the idle drops to 500 RPM, the car exhaust smells awful and it appears to want to stall. Now, this does not only happen when idling but also when in gear and driving. If cruising along, it some times stutters, jerks violently a few times and drops the RPM about 500 from where you were cruising.

The car is a 5 speed manual transmission and red lines at 5k RPM. I have noted that when this occurs, if I punch the gas and rev the car high (4k RPM) it will recover and ride smooth for a few minutes. However, the recovery is usually a fairly violent lunging motion. I can also typically avoid the problems if I cruise between 4k-5k (careful not to redline).

So what is up with that???

I know I have a 2003 Suzuki SV650 that had a similar problem. After $500 at a mechanic who swore that is was a loose exhaust the problem returned upon the first rain. I then found, via a online forum, that there is a little known drainage hole in the engine block near one of the spark plugs. The problem - this hole was clogged. The solution - a $0.10 pipe cleaner and some rubbing alcohol. Apparently, water was backing up and killing the spark thus the lunging, jerking and wild ride.

So, is there the possibility of something similar with the Supra? They are known for valve cover seal leaks and oil getting into the plugs and I do have a slow oil leak some where I can not find. It sure seems like some sort of spark plug issue to me.

[shiftysupra]

are your plugs gapped properly? seems to me maybe your sucking water through the intake... list of mods would help. you also said the engine light comes on. does it give any codes?

[89GReddysupra]

your problem most likely is that you need to get a fuel cut defencer. i purchased one from Auto & truck performance parts & aftermarket car parts from HorsepowerFreaks and now my car doesnt do that.keep in mind that this part makes it to where your ecu cant limit your boost. so if you go too crazy with the pedal to the metal,you may tear something up.

[mrnickleye]

Check to see if water is getting into the spark plug holes and shorting out the spark.

Do you have the #3 cover that goes over the middle valley and keeps debri out of the spark plug holes ?

[sephir_07]

i just got a 89 turbo supra and the other day it rained cats and dogs. 5 mins into my trip the cars check engine light came on and it started cutting out. not a miss just a strait up die and restart after about 500 rpm loss. it also lulls into the 5 or 600 rpm range when stoped. then just as suddenly as the problem came on it goes away and runs great for 3 or 5 more mins.
ive taken all the intake stuff off and cleaned it with carb cleaner. no water anywhere. i do however have a exaust leak just behind the turbo elbo i can also hear a distinct blow off nois when i shift that was not there befor.
the car is compleatly stock

any ideas anyone???

also pulled all the plugs they are all like new.. not even a little carbon on them. no oil no water.... no water in my coolent or coolent in my oil either...
man this is pssing me off

[cgreiner]

Interesting. I still have not fixed this problem with my car either. Sorry.

I knew I had a faulty CPS resulting in an oil leak so I changed that. I figured maybe the issue was that I was low on oil and it just coincidently occurred when it rained - often. Not so....

My car would also drop idle just like yours and then violently recover as you know from the earlier post. It would also not seem to occur when I kept RPMS above 3200 or so. Does yours behave similarly?

What is most interesting though is that you have a hole in your downpipe as do I. Now, if I get into the turbo hard, or have a 20 min + drive, my knock sensor and idle control (ICS) have been giving me errors. The car runs great, as long as there is no rain, but I do get a 51 and 52 error code if I drive rough or long. I am guessing that I am producing a high level of admissions under my hood through my downpipe and it is messing with the system? This would sensibly occurs with either high RPMS or over time in traffic. Any merit to this or am I insane?

Maybe that behavior is just a sign that your ICS is going out?

Please let me know if you figure it out as I will be working on it as well over the next few weeks.

[sephir_07]

today i tore down the top end again and found hairline fractures in the spark plugs.
so im getting more friday. ill let you know how it goes man
maby ill remove the hood and drive around like that when i get new plugs. this would let us know if its the leak messing with our sensors.
let me know what you come up with.

and yes as soon as i get to 2000 rpm trouble sets in... then beyond 3000 its great!
maby we have faulty coil packs?

[cgreiner]

I was suspecting spark plug issues as well. Maybe a valve cover gasket leak drowning them in oil. I have hte plugs, just have not checked the old ones or made the switch as of yet.

I should also be replacing my down pipe in the near future so that should help answer the emissions questions too.

[sephir_07]

hte plugs whats that?

im putting bosh platnim in my car

[cgreiner]

typo "the" not "hte"