|
|
1988 toyota supra - can start, can run, will not idle
|
|
|
| |
|
|
drb0mb
New User
Feb 25, 2013, 1:15 PM
Post #1 of 4
(3660 views)
|
|
1988 toyota supra - can start, can run, will not idle
|
Sign In
|
|
edit: car has approx 126,000 miles on the engine, which is a stock 3.0 7MGE non-turbo
alright hello everyone, i bought this 88 supra with a blown head gasket for 600 dollars last spring. did all the head gasket work myself, and it ran great for about 1 month before it mysteriously died while i was driving. i stopped at a T intersection, a dangerous one that even if you thought no cars were coming it would still be a good idea to accelerate quickly upon turning. so that's what i did, gave it a good launch and shifted to maybe 3rd gear before i pressed the clutch in to coast. and then everything went dead and i'd lost all power. i let go of the clutch as i was still coasting, it came back to life but was extremely strained to run and it had a significant loss of power. i managed to drive in this crippled state to a safe place to stop and have it towed.
since then, it has maintained ability to crank strongly and fire up almost immediately. it gives a healthy roar for a second, then dies out as if i'd just turned the key off. it can repeat this indefinitely as long as the battery has charge. if i give it some throttle while i try to start it, i can keep it running strong in high rpm until i let off enough to drop it to about 3000 rpm, at which point it struggles and dies. sometimes it'll hit almost 0 rpm before trying to come back to life.
so. here's what i've done to try to fix it so far.
-new air flow meter
-new starter motor
-new distributor
-new plugs and leads
-new throttle body
-new engine control unit (actually had 2 spares of this, tried both)
-new fuel pump
-new fuel rail and injectors
-new fuel pressure regulator
-directed constant 12v to the fuel pump by disabling resistor relay...i've since undone this since it didnt help.
i have not touched any electrical wiring, which is my nightmare. i also have not tried to replace the idle air control valve, but that's because i don't expect it to change much since it's unresponsive to slight throttle...it's 3000 rpm or none. let me know if you think this theory is flawed, i do also have a spare IAC
it seems like a fuel issue, but i don't know how it could be. i'm out of ideas.
i just got done replacing the fuel rail and injectors, which was a chore as the fuel rail is buried under the air intake/throttle body/intake manifold, so if there were any loose wires/hoses before, i connected them when i put it all back together.
(This post was edited by drb0mb on Feb 25, 2013, 1:28 PM)
|
|
| |
|
|
Hammer Time
Ultimate Carjunky
/ Moderator
Feb 25, 2013, 2:03 PM
Post #2 of 4
(3623 views)
|
|
Re: 1988 toyota supra - can start, can run, will not idle
|
Sign In
|
|
Gee, do you think you've thrown enough parts at it now and maybe it's time to test first, replace second?
Here's what you have to do, all of it. Then post your results.
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
4) If all of these things check good, then you would need to do a complete compression test.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
|
|
| |
|
|
drb0mb
New User
Feb 25, 2013, 4:00 PM
Post #3 of 4
(3600 views)
|
|
Re: 1988 toyota supra - can start, can run, will not idle
|
Sign In
|
|
regarding diagnostics:
the throttle body and manifold shroud all but the #1 #2 and #6 spark plugs, and as explained, when the failure occurs it's after the car has cranked and started. at that point prior to stalling, it has spark fuel and air, and this can be maintained with throttle control.
the car will not start if the throttle body and manifold is disassembled to allow for a diagnostic on cylinders 3-5, and therefore can't reproduce circumstances of failure. <--- big issue
that being said, i think i can complete a spark test by having to reassemble the engine prior to each test. pain in the ass, but i guess i gotta want it. my compression tester won't fit inside the reassembled engine. i don't know how i could feasibly check for injector pulse at the critical moment because of my engine layout, but i'll continue my research.
point i'm trying to convey: i've eliminated enough points of failure that someone could have a strong opinion on what area the problem likely lies in.
i mean, you're right that i'm tossing parts at it, but i enjoy turning wrenches and i've got more money than time
|
|
| |
|
|
Hammer Time
Ultimate Carjunky
/ Moderator
Feb 25, 2013, 4:12 PM
Post #4 of 4
(3593 views)
|
|
Re: 1988 toyota supra - can start, can run, will not idle
|
Sign In
|
|
If you're going to make everything out to be a big project, you might as well just keep throwing parts at it. That engine is not a big deal to do the testing on.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
|
|
| |
|
Auto Repair Home
SEARCH
WHO'S 
LOG 
mdma pills for sale : WhatsApp +33758633852
Drive Shaft Repair
2006 Toyoto Camry XLE Driver Side Electric Window Trouble
Grounding Cable, 2017 Jeep Renegade Trailhawk
equipment
