7mgte will not idle!

[88t]

alright guys let me try to explain.

I have a 88 supra with the 7mgte. Since i bought the car back in august of 2008 it would always crank for about 4-5 seconds before it would start. I thought oh well, then the motor got a bhg. fixed that correctly and bla bla bla...

anyways, about 3 days ago my engine started to not start at all unless i pushed the gas pedal almost like a carberated engine. When i do get it started and i coast to a stop with my clutch in, my engine idles down to about 3-400 rpm and dies every time.

I have push the clutch in and give it gas and use my e-brake to slow down to a complete stop. If i just push the clutch in it will die.

I checked all my vaccum hoses, reset the timing, and cleaned the iscv. when i did that it still cranked for awhile then started and acted somewhat normal. Then it started dieing again.

it pops and back fires and the gas milliage isnt that great. car is completly stock. it runs fine though if that makes sence.

any ideas?

 

[kingofyo1]

just rebuilt my engine, and im the same way, ill have to give it gas to start it up... it barely idles at all, and usually dies. x2 on question

 

[McGyvr]

1. Have you guys checked for codes? TPS can screw with your timming and can cause all kinds of issues.
2. Also check for leaks on your intake pipes and BOV.
3. Is your BOV setup for recirculation? If not then I've found it can really jack with your fuel/air ratio when you let off the gas.
4. Bottom side of your accordian pipe is a vacume line that I always forget to hook back up and it jacks with my idle.

There's a few things that I have run across in mine... but before you do anything, take a minute and check for codes. I THINK TPS is a code 23.

Also... Heal toe insted of using the E-Brake... it's much safer.

 

[88t]

1. Have you guys checked for codes? TPS can screw with your timming and can cause all kinds of issues.
2. Also check for leaks on your intake pipes and BOV.
3. Is your BOV setup for recirculation? If not then I've found it can really jack with your fuel/air ratio when you let off the gas.
4. Bottom side of your accordian pipe is a vacume line that I always forget to hook back up and it jacks with my idle.

There's a few things that I have run across in mine... but before you do anything, take a minute and check for codes. I THINK TPS is a code 23.

no codes.
no known leaks
bov is set up for recirculation
where does this vac line connect to? i have it blocked off..

 

[riot]

That hose connects to the back of the power steering pump.

 

[88t]

an update, checked my timeing belt, didnt slip, marks are good. Checked iscv and received 20 ohms on the 6 connectors. Put 12 volts to the iscv and didnt see the valve move up or down... would that cause my symptoms?
havent checked my tps yet.
help I got work tommorow! lol..

 

[lepad_ae86]

maf..

 

[dumbo]

maf..

its an afm, but on that note have you cleaned it by any chance, if NO, then good dont. Whats it do if its unplugged? IIRC it should go into "limp" mode, no revs past 3k rpm. Someone may have to correct me on that though.

"Put 12 volts to the iscv and didnt see the valve move up or down... would that cause my symptoms?" - Is it supposed to?

 

[7mgte1988]

Wow i remember when i had an similar problem but mine was my EGR valve was damaged on the exhuast side. But this problem will make u hate your car if u dont have any time to fix it. I would recamend u check your fuel system,Pump and filter and the lines.

 

[jetjock]

maf..

As dumbo pointed out it's an AFM. Not to mention the ECU doesn't use it when starting the engine...

 

[dumbo]

As dumbo pointed out it's an AFM. Not to mention the ECU doesn't use it when starting the engine...

So unplugging it would be a utterly useless test? It will go into a "limp" though wont it jetjock?

 

[jetjock]

Somewhat useless in the sense of a no start but not for other types of issues. Due to the low airflow at cranking speed the AFM signal is too weak for reliably starting the engine. Therefore it's not used. It's why the engine can be started with it disconnected. Continued operation occurs when Fail Safe Mode (what you're calling limp mode) is entered but that only occurs after rpm exceeds 500. In fact you'd be surprised at what the ECU is doing any time rpm is below 500, which obviously includes cranking. I've just never explained it in depth here. Not about to either. Too academic...

 

[CajunKenny]

Have you conferred with your friendly TSRM?

It doesn't sound like it. :sarcasm:

 

[dumbo]

Somewhat useless in the sense of a no start but not for other types of issues. Due to the low airflow at cranking speed the AFM signal is too weak for reliably starting the engine. Therefore it's not used. It's why the engine can be started with it disconnected. Continued operation occurs when Fail Safe Mode (what you're calling limp mode) is entered but that only occurs after rpm exceeds 500. In fact you'd be surprised at what the ECU is doing any time rpm is below 500, which obviously includes cranking. I've just never explained it in depth here. Not about to either. Too academic...

Ahh very good. So the ECU just goes off default values?

 

[lepad_ae86]

Sorry about that.. afm

 

[88t]

no i have not cleaned the afm.
will look more into it today.

anymore ideas???

thanks guys.

 

[88t]

update.

went to the junk yard and got a iscv from a mk2 supra.

put it in my 88 and bam! starts rite up. so after all that work i did to figure it out, it was the damn iscv.

obviuosly its idling high at like 1700 and wont go down because the wiring isnt hooked up, anyone have a diagram of the mk2 supra and mk3 supra iscv wires? which is which?

got that iscv for 8 bucks, cheap fix huh?

 

[88t]

update.

car idles from 1500-2100 up and down, lol. The iscv is not hooked up electronicaly, did not put the gasket and check valve in, would that be a problem whiling using a mk2 iscv?

the car drives weird now with it on, it cause the gas pedal to be very sensative as in a little push will cause the car to buck.

any ideas?

 

[iskrem]

How did this go? I am having the same kind of problems.

car idles from 1500-2100 up and down, lol

Mine does this too when the ISCV is not connected.

 

[sneakypete]

you should try getting a mk3 iscv... that might solve your problem