Supra Forums banner
1 - 14 of 14 Posts

·
Registered
Joined
·
399 Posts
Discussion Starter · #1 ·
Hey guys, I need some help trying to figure out why my supra has suddenly decided to stop running. Here's the background:

It started when I did a routine spark plug/oil change. The car started right up and I took it out and drove fine. The next day when I started her up and drove down the street, it wouldn't go above 3k rpm and started to backfire. I ran the car a little farther down the street and the backfiring stopped and the car ran like it usually did. However recently after a trip to san diego, the symptoms came back, only this time much worse. The backfiring was much more violent and the car finally died while I was on the freeway. Attempting to turn the car over, it would crank but nothing. Every once in a while it would turn over only to die immediately after.

Now I had the car towed to my garage, and the first thing I checked were the plugs which weren't fouled at all and seemed to be in good condition. That led me to the coil packs. I found that only 2 of the 6 coils were firing, so I thought ha, found it. But 6 brand new coil packs later, nothing. I almost convinced it has something to do with the igntion system but maybe the supra guru's can shed some light. Please help!!!

Ryan
 

·
Read Only
Joined
·
367 Posts
Probably the wires are the culprit. Sometimes when you change the plugs the harness connector pins get loose. Better still sometimes the wires are heat cycled over the years and simply break over the valve cover. Best thing you should do is hook up a voltmeter on each connector coming from the harness and check if you get 4.5v or so when attempting to crank the motor, Hope that helps. Chris
 

·
Registered
Joined
·
399 Posts
Discussion Starter · #4 ·
I thought it might be the wires/connectors since the clips have broken off on some of them. Any idea on where I can get replacements?
 

·
Read Only
Joined
·
367 Posts
SofaKingFast said:
I thought it might be the wires/connectors since the clips have broken off on some of them. Any idea on where I can get replacements?
Curt is the man. I think they are less than 3$ each.
 

·
Boost4fun
Joined
·
1,848 Posts
If the connectors aren´t the cause it´s maybe the crank position ring for the sensor. This can get loose and the car is starting to backfire like hell since it is loosing the crank position...
But hopefully it is just the connectors of the coils..
Keep us posted about it, bro.
Gerd
 

·
Registered
Joined
·
399 Posts
Discussion Starter · #7 ·
Ok so I checked the voltage reading for each connector and guess what...nada. I'm assuming its the igniter, but why would it go out from just replacing spark plugs? Maybe a freak coincidence? Gerd, I know about the crank angle sensor, is that the same as the crank position ring?
 

·
Boost4fun
Joined
·
1,848 Posts
Right, I ment the crank positioning ring. That symphtoms are pretty much as you have described yours..
Because of the voltage: How did you measured it?
 

·
Registered
Joined
·
399 Posts
Discussion Starter · #9 ·
I unplugged the connectors from the coil packs and had a friend crank the car while I read the voltage from my multimeter.
 

·
Boost4fun
Joined
·
1,848 Posts
Make a double check of that because the voltage impulse might be too short for your multimeter to show a voltage....
Pull out one holder with two coils, put the spark plugs in and wire the thread of em to the ground. Then someone should start the engine and you can see whether there is a spark or not... This is the better way to check IMO...
Gerd
 

·
Registered
Joined
·
399 Posts
Discussion Starter · #11 ·
Hey Gerd, so I thought i'd take a look at the crank angle sensor today during my day off, and guess what, somehow the wiring loom came loose and the alternator belt chewed through the wiring. It didn't cut it all the way through but i'm hoping that's what the problem was. It would explain the erratic behavior my car's been having lately. Anyway i'll keep everyone updated.
 

·
Boost4fun
Joined
·
1,848 Posts
Well, at least good that you might have found the root cause Even though it is always a PITA to look for problems:(
Yeah, keep us posted what´s going on.
Gerd
 

·
Registered
Joined
·
399 Posts
Discussion Starter · #13 ·
Update: The car's back up and running, and yes it was the crank sensor that was the culprit. Thanks to Gerd for helping me source the problem and to everyone else that offered their advice. I feel like a proud father again haha. Happy boosting!

Ryan
 

·
Boost4fun
Joined
·
1,848 Posts
Was a pleasure, bro!:)
I am glad that your baby is back on the road!
Happy boosting!
Gerd
 
1 - 14 of 14 Posts
Top