Ok, my 1986 N/A will start but will not stay on. I know that the ignition timing is off but i cant really set it because the car keeps wanting to die. So my question is that could bad timing cause the car to start but not stay on?

 

yes.

re stab your crank angle sensor. do a search to figure out how to do that. its simple and should give you a good enough base timing to work from.

also check your tps settings.

 

ok thanks a lot. I'll do that then write about the results.

 

ok, i restabbed my cas and the car finally stayed on for about 5 min. I revved the engine to 3k then let it idle but it just died when i let off the gas. Since then the car will start but not stay on for long. I fucked with the lean/rich, idle screw on the uim and swapped out the tps. Any suggestions on why it wont hold an idle?

 

Check all vacuum hoses for leaks. Also be sure to check injectors for any leaks or anything of the sort...

 

i found a vaccum leak from the thermowax hose, replaced the uim gasket, and timed it. But for some reason the i can't keep it alive when driving. At idle it bounces but when i drive it then let it idle it will just shut off. I want to adjust the tps but i can't find the plug where you plug the led lights into. Can somebody show me a pic? I checked other posts but my car doesn't have the stock air box.

 

Make sure your BAC (idle air control valve) is working.

The green three socket TPS check connector is near the pressure/boost sensor AREA. It's not bolted to anything.

BAC's on the left side of you eighty six RX non turbo car. Left side of the engine that is. Round cylinder shaped with one elect plug with two wires in it. Make sure it's connected to...the BAC.

Non turbo eighty six non turbo have a variable resistor up front near the afm/pressure sensow area. Its screw turns clockwise and anti clockwise almost a whole turn and has STOPs at the end of the cw and ccs turns. Don't force it past the stops. Common sense.

Variable resistor richens or leans out the fuel but ONLY during IDLE.

 

Same thing is happening to me, Hard start but once warmed up it will start every time. Has bad hesitation at 2K and now will cut off on me at load. No vaccum leaks..... currently grounding with aroncakes method: http://www.aaroncake.net/rx-7/grounding.htm
then will check the BAC, boost pressure sensor.



I will try this tomorrow morning.

 

Ok, i used a multimeter and checked the BAC which checked out good. I can keep the car running by constantly feeding it gas. Tomorrow imma make it warm up then shut it off so i can then check/adjust the tps. Today i tampered with the idle screw and the variable resistor to make it stay on but the idle is very rough and will drop very low and eventually turn off once i give it gas then let go.

 

Get your tps dialed in FIRST before you mess with the variable resistor.
Even if your fuel mixture is set right, it won't begin to idle correctly unless its getting the right input signal from the tps. Hence, why you adjust it when the car is NOT running

Keep the car from stalling for a few minutes to get the motor to operating temps first though, then shut it off and adjust while its still hot.

 

RE-Grounding FTMFW!!!!! i regrounded the ground on the drivers side strut tower and the 2k and 3.2K hesitation/cut off went away. Need to re-done the rest of the grounds and fix the cold start issue. but i think that stems from the previous owner blocking off the Sub-Zero-Starting Fluid Valve.

 

ok i just warmed up the engine then checked/adjusted the tps but it still won't stay on. I checked the air bypass valve which came out good. The car ran before but with a bouncy idle. I have replaced the ecu, coils, cas, tps, battery, starter, plugs and wires, and afm because i couldn't get the car to start. Now i can start it but it won't stay on.

 

I had this problem up untill this morning (i Bought the car like this owner couldnt find the problem). I started to reground the stock harness, it worked for me and it was very simple to do. I did this first before buying any replacment sensors because If your car has crappy grounding how are any of your senors going to work right.

http://www.aaroncake.net/rx-7/grounding.htm

 

ok thanks. how long did it take to reground your harness?

 

I didnt reground the whole harness, i had to drive to work. But i preped the night before by making the wires and soldering the terminals on. the one that helped me the most was the ground on the lower drivers strut tower. Cleaned it and ran a 10g to the negative battery terminal. However this is the quick and dirty way to do it. Go to the link and follow aaron cakes method. I'll be doing this as soon as i get off work. Hope this helps.

 

aight. ima go buy a soldering iron at work then prep it for tomorrow night. ill write back with results

 

when i went to ohm the tps and air bypass valve i noticed the ohm were going crazy and wouldn't stay constant and for some reason sometimes they would give me no reading at all. Do you think bad grounds could cause this?

 

+1 for grounding that shock tower.

personally I like the tps light instead of using a multimeter: Its way more straightforward, AND you can use it as a means to see if you're throwing any codes (which also might be beneficial in your case).

It sounds like you might still have a vac leak somewhere, though

 

I would have to say it could be...... although the ohm is a measure of resistance which can be measured with or without power/ground. if the sensor is not grounded it has no reference to ground and the voltage to the sensor will not be stable (i.e. anywere from 0V to 5V). This would send a wrong or false reading to the ECM depending on how the ecm reads it (Assuming the sensor is good)


.... sorry i nerded out for a second

 

well today when i tried to find the green connector for the tps all i found was some cut wires. And what's worst it that i can find them in other places. So now i am going to reground the harness according to aaron. After that i will check the tps and bac using the ohm meter. Also the car has some missing emissions equipment (i.e. air pump, sub zero, egr) and the first throttle plate is missing so i think the thermowax does nothing.

 

i redid the shock tower and trailing coil ground but it didn't really help. I warmed up the car then shut it off but leaving the ignition on so i could check the tps but the ohms were going crazy. So then i checked for voltage at the pigtail on the harness and i only got 0.04 volts. I then checked voltage at the BAC but it turned out 11.89 and the air bypass valve had 0.04 volts. I checked voltage at the fuse box the egi fuse only had 10 v, 3 fuses had 11.8 v, 1 had 0v, and the last one had .04v (don't have the fuse cover).

 

Did you just re-ground the DS strut tower or did you do the whole thing? ECU ground, Boost sensor Ground, cluster of grounds under the coil at the DS strut tower?

Picture of the fuse cover is in the 2nd gen Q&A

I will ask my supra buddy to give me back my DMM and i'll check my voltages to see what if they match unless some one with more knowledge chimes in.

 

ok. I found the pic in FAQ. I bought a new alt belt because i thought it was loose and now the car stays and the idle doesn't bounce but the car does ALOT! When i rev it the rocking goes away but when i let off the gas the rpm goes real low (100-300) then back up to 800 but continues to rock.

 

When i redid the grounds i did the ecu ground under the uim, the ground by the coil, ground by the strut tower, and also i have an added ground that the car came with to the uim.