SR Problem...suddenly no power

[97SilviaRB]

Heres the story. Basically we swapped the SR into my car about 2 months ago. Its been running decently the whole time but I had been having a problem with the car running sort of jumpy under load with about 50% or more throttle. Last night when myself and a friend were messing with the car, he noticed that the rubber inlet pipe for the turbo had been put on a little wrong. It seems that someone tried to push it on at a weird angle causing some of it to roll over leaving an open gap. Well this might possibly explain why the car had been having those previous problems so we fixed it. Now when I drive the car...it basically feels fine when normally driven, but as soon as the I step on it, there is no power at all. My boost gauge is hooked up right on near the TB and it's showing 9 pounds which holds steady the whole time. Anyways, help me figure out whats going on with this stupid thing. Thanks

[97SilviaRB]

come on guys!~

[RiftWeaver]

No power and "jumpy"....


No power, does it bog down? Feel like you step on the accellerator and nothing really happens? Tach goes up but the car doesn't move?

Jumpy, does it seem like it might be a missfire? Does it feel like a fish biting on the end of your fishing line?

You definately have to explain your symptoms a little more if you can. If somebody came into my shop and said "jumpy", I would have to first try and pry more info from them before I could even start to diagnose it. (Or take a test drive, which we can't do here :) )

[TheTicTac]

Have you checked your timing?

[97SilviaRB]

Okay today we checked the timing. The timing was moving all over the place so we unhooked the Knock sensor. The timing then settled on a steady 15 degrees. We then got the knock sensor from my old KA and tested them both, ending being that the KA was in better shape. Threw that on there along with checking to see if the Coil packs were in spec, and pulling off all of my intercooler piping and checking for any leaks. I noticed there was a little buildup of gunk down in the inlet for the turbo so i cleaned it out. I just drove home and the car still feels slow as nuts. I tested it a few times in 2nd gear...I would put my foot about 15% on the throttle and cruise until the rpms were at about 3000 and then step on it. At this point it feels like all timing is pulled and the car completely falls on its face. You can physically feel the car jumping (basically feels like a boost leak but there isnt one to be found) under boost but if you let off of the gas to about 25% it will not do it anymore. I really think that something is causing the ECU to pull timing...either that or the turbo is toast. Oh any my spark plugs look very normal. thanks

[sr240mike]

Hows the compression? You said the turbo is still boosting so I doubt its that, it could be a boost leak though. Have you tried pressurizing the intake yet?

[97SilviaRB]

we were actually going to go out and buy the parts to do that today but forgot to =\
What exactly is needed? My friend knows but I want to get a list together so I can buy the parts tomorrow.
Thanks

[mbmbmb23]

Try filling the tank with 100 octane gas and see if the computer kicks out of limp mode. Thats all I can think of without hearing any further specifics.



-m

[Pepperoni]

When I had this problem, it was timing. Also...what did you do with your gas hardline? Did you keep the whole carbon canister or did you throw it out?

[97SilviaRB]

carbon canister is gone...and what other specifics do you need?

[RiftWeaver]

Any chance you might have a fuel pressure gague you can see while driving? Aside from timing, you could also be losing fuel pressure and starving for gas.

Just another possibilty....

[97SilviaRB]

I dont have a fuel pressure gauge hooked up. Im going to try a few things today like doing a pressure test on the intercooler piping to make sure its not leaking and checking the turbo itself to make sure its not screwed.

[sepulchral]

If you havent changed your fuel filter to a 300zx twin turbo fuel filter then do it now, i had same problem and that was the answer

[97SilviaRB]

changed a few weeks ago

[97SilviaRB]

snapped a few pics of the turbo just now. checked the shaft play and everything looks fine. gonna do the bov/intercooler next and see what i can find
http://www.imagestation.com/picture/sraid136/paaaa318c9368bb83b1dce2ffd940e5c2/f75ed227.jpg
http://www.imagestation.com/picture/sraid136/pa64dd81daed2d732bcdfe174d91cddde/f75ed22a.jpg

[Redtop_240]

U runnin a stock SOHC MAF? Stock KA fuel pump? Shitty gas? vacume leak? second rotation top dead center are your cam lobes facing each other basicly? Do you have a tuned ECU? is your fuel pump relay going out?



Q..Low Oil Pressure / Oil starvation , noisy lifters that will not quiet down
A..Check the oil pan for dents before starting your engine. Even the smallest dent can kill your engine!

Q..No Oil Pressure / Oil pump frozen
A.. Manually prime the pump thru the turbo oil line into the block (the lower on under the power steering pump) if you don't get immediate oil pressure. Confirm adequite oil pressure gauge, or by removing the valve cover, cover timing chain area and briefly run engine. You should see oil coming out all over the place.

Q...Fuel pump not coming on
A... Plugs by Battery may be wired incorrectly, they plug in but won't work without rewiring. Pump should run for 3 seconds then stop if flywheel not moving.

Q...No Spark
A... Check main ignition power wiring by battery and ECU. Also check for bad ignitor, bad coilpacks, bad ECU, shorted harness. Ignitor passes ECU pulse on to coil packs, crank the engine and test with multimeter for ignition voltage pulses at ignitor input and output to isolate source of problem.

Q..Odd electrical behavior in dash, interior lights
A..ECU plug may not be tightened all the way down. This causes all kinds of weird different problems. Also check for mis-wired grounds (especially main power and turbo timer wiring) back-feeding power thru the ground system.

Q...Won't Crank
A..Check Main power wiring and start signal wire to ECU, clutch interlock switch, auto trans conversion must use jumper on harness plug. Make sure car alarm or turbo timer wiring is not causing the problem.

Q..Cranks, has spark & fuel - either just cranks, or catches but won't run
A...Check Timing, Crank Angle Sensor could be misaligned. Engine could be flooded, check spark plug for raw fuel.

Q..Runs OK, but no power
A.. Check timing, set to 15 degrees, 2nd mark from the right on crank pulley.
Q..Drivable but can't boost above certain psi, or can't give more than 25% throttle without bucking
A.. Leak in intercooler piping under boost, even a small leak will make the car sputter and buck with any significant throttle. MAFS or MAFS wiring problem.

Q..Idles OK, but can't rev past 2500 rpm
A.. MAFS or MAFS wiring problem.

[97SilviaRB]

okay well yesterday we pressure test all of the intercooler piping and the intercooler itself...The result was that the intercooler had been leaking from the shitty gasket on one of the end tanks. Anyways i sealed it up and put everything back together. Now the car doesent buck anymore but it feels slower than ever. I am really confused as to what is going on with this thing.

[sepulchral]

do u hear any strange noises as the turbo spools?

u checked spark plugs lately, any antifreeze on them?

compression test

[97SilviaRB]

What kind of noise do you mean as the turbo spools. The turbo sounds way different than it usually does but im getting its because its actually covered up now. I cant really explain the noise that it is making...
I checked the plugs yesterday and they look fine. I did a compression test on the motor a few weeks ago and it was fine...maybe its time to do it again.

[TheTicTac]

When you checked the plugs, did you check the gap?

[97SilviaRB]

yes i checked the plug gap. They were all dead on .032 inches

[Id-]

did you reset the ecu? dumb question i know; but i've seen alot of cars when they go into some limp mode that they stay that way until a code is cleared or until the ecu is reset

plugs could look find but since they are easy to change you may want to just put new ones in...
if you had a leaking gasket like that and it was running rich enough to kill off your power and/or cause lots of bucking; it was enough fuel to cause spark blowout (i know firsthand because its the same problem i had with sc300 for a while)

its pretty safe to say however, if its falling flat on its face like that but its not running super rich (or bucking anymore) its due to ignition problems; the timing may not be getting advanced (which would cause a HUGE decrease in power)... possibly because of a limp mode... try reseting the ecu if you havent already

[97SilviaRB]

I actually think that it's probably a few things contributing but the ignition timing seems to be the biggest problem...like the timing is not getting advanced at higher rpms. At low rpms the car feels normal. The spark plugs were changed recently to NGK copper plugs (bkr6e or something i believe). Another big factor in this i believe could possibly be that I have a 3 inch downpipe running to the stock exhaust although I had the exhaust set up like this before and it was running a lot better than it is now. I might try to change the plugs anyways and see if that helps...
I also cleared all codes from the ECU the other day as well as left the negative battery terminal unhooked for a few hours...both of which seemed to do nothing to help. Im thinking that the ECU is in some kind of limp mode but I have no idea how to check and see if it is or not. Thanks for the advice

[TheTicTac]

try your plugs at .28

[Pudula]

How new is your 02 sensor?

[97SilviaRB]

I actually tried gapping my plugs down to .28 the other day and the car ran like absolute ass (even worse than it does now) so i opened up the gap on them a little bit. Ive also taken out the MBC so im running stock boost again. The o2 sensor was the stock one from my clip so im guessing it's from 92 or so...unless it was changed in japan

[TheTicTac]

Hmm how new is the fuel pump, sounds like you have air, and spark maybe not enough fuel. RX7's have these sort of problems and lack of fuel is the main culprit.

[97SilviaRB]

fuel pump is about a month old. Its a walboro 255

[Pudula]

I actually tried gapping my plugs down to .28 the other day and the car ran like absolute ass (even worse than it does now) so i opened up the gap on them a little bit. Ive also taken out the MBC so im running stock boost again. The o2 sensor was the stock one from my clip so im guessing it's from 92 or so...unless it was changed in japan
A new 02 sensor is a nust even if it does not solve the problem.