cosmok123

Hi all,
My 85 gsl-se will fall on its face after about 8 mins of normal driving (now). If i give it more than 1/4 throttle after about 8 mins of driving, speed doesnt matter, it jumps and dies violenty. You can let off of the the throttle and it idles fine. in neutral you can stomp on it and it goes to about 3k rpm then cuts out. (when first warmed up) ....i can let it idle for 10 mins and i'm still good, but after driving for a bit it starts to act up. This first occured after i drove it for about an hour one day then i get onto the freeway onramp ready to smoke some v-8 *** next to me and it gets to 4k rpm (i was past that damn chevy) and the just drops to 1k then back to 4k then to 1k (so on and so fourth). I think im dead on the interstate but i just hold it about 1/8 throttle an i creep off the next offramp(bout 35 mph at the gear i was in any more throttle and it dies and i make it home like this for 5 miles). I can repeat this whenever i start it up but then drive for a bit and game over. I was thinking fuel pump or a vaccum lock in fuel tank.(open gas cap and big air noise but no difference in perfomance after its doing this on side of road.) TPS crossed my mind too but ohmed out ok. any insight would be helpful to me. Temp outside when first occured about 80 degrees in north idaho,
This car has sat for seven years but i got it going and its rand good for about 1500 miles....snow or heat. Any insight on my problem would be helpful cause i dont know where to start.

Rx-7Doctor

iTrader: (13)

Change the fuel filter and then perform a fuel pressure/volume test.
For got to state do the following before the above. Compression test. Then make sure leading and trailing are firing. Then do the above.

cosmok123

thanks , ill check those out first

Whizbang

sounds like something related to the temp sensor. after 8 minutes of driving your car is warm, so it should switch to a more lean condition. sounds like yours is either not giving any fuel so that any load will cause the motor to starve and turn off.

could be ecu related. possibley the sensor but doubtful.

lostllama

hey hows north idaho? i am down here in boise. any way back to the problam. this is fuel injected right..... sounds like a air fuel problam but i am a carb guy so what do i know

cosmok123

Reguarding the temp sensor, which temp sensor are you refering to?
An air intake sensor in the dynamic chamber or a different one that i dont know about? I got a factory service manual so ill look through it and see waht i can find
Thanks

Jose Feliciano

you should see a green plug near the top of the motor near the theomstat that is the sensor try that first then the fuel filter

Rx-7Doctor

iTrader: (13)

You guys are putting him off track with the CTS, it will not cause the car to shut off unless it gets unplugged.

coldy13

Replace the fuel filter and do a flow test on the fuel pump. Also, make sure your air pump is hooked up and see if the exhaust before the cat(and maybe the cat) is glowing after you drive it. Or you could just unbolt the cat and see if it runs better When I bought my car, all it would do is start up and idle, give it any gas and it dies. The air pump was disconnected and the inside of the cat was a solid charcoal brick.

cosmok123

I pressure tested the fuel pump and its at 52 psi. I did this by putting a PSI guage on the in line and shorting the fuel pump out to make it spin and it went to 52 then quit spinning. Its at bottom of spec so i should replace it perhaps along with filter. I have no way of checking the volume so filter could be part of it cause it took about 5 secs to hit 52 PSI. I dont have a compression tester but i should beable to borrow one and i dont know how to find out if trailing and leading are firing at the correct times. Another problem i have is that the engine will go down to 800 rpm then surge to 1500rpm and back and fourth. I noticed that the Mass Air Flow Sensor flap sticks open about 30 deg Whenit does this but moves freely when engine isnt running. Is the MAF servo controlled because i dont know why it would stick open a bit unless the ECU is telling it that it needs to be open even though the throttle is not being help down?

This is a big mess i got going on and i appreciate your guys' help thanks.

cosmok123

Oh and BTW the air pump is hooked up and it works properly.
TY

Kentetsu

I am going to guess that you are on the right track with the MAF.

GavinJuice

the flapper opens and closes (not fully though when running) depending on the loads it needs. it's not servo controlled and at any time it should NOT be sticking, that throws the computer off and can show a lean or rich condition. a bad temp sensor can cause a rich condition also when it warms up.

GavinJuice

oh and the surging is your TPS not correctly adjusted, check the FAQ's for the GSL-SE idle adjustments........read ALL of it

blazer1313

its definitely sensor related....there's a thread i think under the faq page about houw to "read" trouble codes set by the ECU. Yes this involves going to radio shack and getting 2 12v LED lights and then wiring them together. one positive to the other's negative. All that is left is 3 ends. Then put male spade connectors on them. By plugging this simple device into the socket connected to the ECU and turning the key on, it may blink a certain amount of times. Or it may just turn on. If it blinks at all. That points to the trouble code and which sensor is screwed. For more details do a search for "ECU code reading GSLSE" or something like that. I believe Rx7doctor made the thread.

EDIT: lol sorry that device that i told you to make (the 2 LED's) thats used to EASILY adjust your TPS to the correct position. To read your ECU you only have to use of the lights. MULTIFUNCTIONAL $3!!!!!

Jose Feliciano

check that fuel pump

cosmok123

THX FOR YOUR HELP GUYS
Now i got some direction to go so ill read up and do some adjustments and ill let you guys know how it goes.

LongDuck

Your AFM is sticking.

As you stated in your thread before, when the AFM door is hard to move, it's because something is causing it to get stuck. When this occurs when you drive, it will lead your ECU to think that there's not much air going in, therefore, not much fuel is required; thusly, the engine is being fuel starved at higher rpm's, thereby limiting horsepower output and performance. As the others have said, the AFM is not a servo controlled mechanism like the new Mazda6 EFI, and the AFM on the SE is just a simple rheostat that's operated by the movement of the door from the incoming air. You should be able to grab a pencil or other long, slim object, and after the Air Filter is out, move that door back and forth through it's full stroke without any restrictions felt whatsoever.

While it could certainly be a combination of factors, I would bet that if you replaced the AFM with a 'known-good' unit, you'll find your problem fixed.

The Coolant Temp Sensor at the back of the water pump is a red herring...

Whizbang

red herring menaing...? never heard that phrase.

g prime

Urban dictionary to the rescue;

http://www.urbandictionary.com/defin...rm=red+herring

Rx-7Doctor

iTrader: (13)

Longduck, how are you?

The problem i have with the AFM theory is that if it was sticking it would not return to the closed posistion. If the AFM does not return to the closed posistion on start up it would flood. Meaning it would allow the fuel pump to run before you started. Maybe you misunderstood his driveability issue. He stated that it runs for about 8 minutes then nothing.
I would have to think either fuel pump is failing and overheating then starts to cavitate pushing only air. Maybe vapor locking?
Also when was the dist rotor last changed?

cosmok123

Hello again.
I got an update on this situation....I put in a new fuelpump, cap, rotor, and wires, the other day. Now i can drive it fine all day with out it dieing. I still have problems with it not returning down to idle and hovering around 2k. If i put the clutch in and blip the throttle it will come back down. I adjusted the TPS and idle mixture according to the book. Also when it surges back and fourth from 800rpm to 2000rpm if i put the clutch in ,even when im in nuetral, it stops surging and idles at 2000rpm but sounds funny like almost a miss or something.
The air flap moves freely by hand , and i ohmed it and its all within spec. For the record too, this car drives fine and accelerates fine and has plenty of power but after a hard pull it just wont come back down to idle almost like the throttle valves are stuck but they move freely. Ill do some more reading on here and thx for the help guys.

LongDuck

Hey, RX7doc - I was guessing that the AFM wasn't opening all the way, but allowing it to return to full stop without issue, that would explain the inability to accelerate beyond a point.

Looks like it was the fuel pump after all. Maybe a cracked cap or rotor.

Surging has a lot of threads here, and usually that's solved by lubing up the steel throttle body butterfly valve rods so that they don't stick. This is an easy fix, and you'll just need to pull off the rubber air piping with those two shiny cap head nuts and spray some good lube in there. Don't forget the outsides of the rods as well. The surging is caused by the steel rods sticking in the aluminum bores of the TB, and is unavoidable unless you were willing to completely disassemble the TB and drill it for bearings.

cosmok123

I will clean the TB to eliminate that possibility and that surging is pretty much the same thing if you take the vacuum line of of the BACV, so i will go towards those 2 things, thx again for your help all

Rx-7Doctor

iTrader: (13)

I would like to see if the rotor was any problem, if you could humor me. Put the old dist rotor back in and run it one day, but keep the good one with you.
The reason i'm checking is that it is very rare but does happen and for further help with others i would like to know if the sympton returns with the old one. thanks.