no start after rebuild - Page 2

cre · 12-22-2009, 08:13 PM

Do you know how to test for voltage drop across a line? You place one test lead at each end of the wire (the wire needs to be connected so there is voltage to read), place the negative lead on the side closest to the + terminal in the circuit then place the negative on the other end. The voltage you see reported will be the total drop across the wire. More than a couple hundred mV and the wire should be replaced.

When testing across a larger circuit it is sometimes easier to test the whole thing and then slowly close in until you've found the individual point of failure. So in this case you'd place the negative probe on the battery's + terminal. Then you'd place the positive probe at the harness' +B connector resulting in a reading of a drop of about 10v. Now you move back along the circuit to the next junction and test. If the voltage drop is still present you move along to the the next junction closer to the battery. If it isn't then you test the voltage drop across the wire at the ECU harness and that first junction.

discord · 12-23-2009, 02:15 AM

now the car is back firing thru the intake and exhaust pipes are getting warm...I havent check any voltages yet, but the back firing thing has been the most activity since it was installed? good thing?

cre · 12-23-2009, 05:18 AM

The back firing means the mechanical timing is a mile off. Realign everything to 0? then look into the voltage issues.

discord · 12-23-2009, 05:30 AM

ok, will do, and i'll get back. thanks much for your help

discord · 12-23-2009, 05:34 AM

oh ya and to get the timing right i'll need to know which wire go where on the cas. I had to get a new connector because the wire on mine were deteriorated and came out of the connector. I can only guess where the go. I had a guy bring over another harness so I could tell but he will not answer my calls now. the wires before the connector on the stock haarness are a different color then the ones after so I cant match the colors? anyone have a picture of theirs? thanks!

cre · 12-23-2009, 08:47 AM

What? The CPS harness perhaps? The wires on the side of the CPS are not matched to the harness.... at least I've yet to see one that matches. I can get the colors from my '88, but they may be different getting the info from someone with an '89 or newer would probably be best.

If you're not talking about the CPS harness (has 4 wires) then post a pic.

discord · 12-26-2009, 10:03 PM

I got them right now, looked at a friends harness. got new coil packs now and have a good strong spark. still just backfires into the intake. all voltages check out. ignition switch is good. refueled gas tank, timing is perfect, no dice. still occasionally backfires into the intake.

cre · 12-26-2009, 10:38 PM

Backfiring into the intake indicates that the intake valves are opening too soon after ignition.... I know of no other way for this to happen than the mechanical timing being off; I am not talking about the spark advance if that is what you are referring to.

discord · 12-26-2009, 11:19 PM

what should I do to fix?

cre · 12-26-2009, 11:31 PM

Bill UK covered it well in pictoral form here: http://www.toyota-supra.info/forums/...on-sensor.html Those three items set the mechanical timing, then you tighten the timing belt tensioner pulley (do NOT over torque it!!!), then you set the ignition timing with the timing light.

12-22-2009, 08:13 PM	#11
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Do you know how to test for voltage drop across a line? You place one test lead at each end of the wire (the wire needs to be connected so there is voltage to read), place the negative lead on the side closest to the + terminal in the circuit then place the negative on the other end. The voltage you see reported will be the total drop across the wire. More than a couple hundred mV and the wire should be replaced. When testing across a larger circuit it is sometimes easier to test the whole thing and then slowly close in until you've found the individual point of failure. So in this case you'd place the negative probe on the battery's + terminal. Then you'd place the positive probe at the harness' +B connector resulting in a reading of a drop of about 10v. Now you move back along the circuit to the next junction and test. If the voltage drop is still present you move along to the the next junction closer to the battery. If it isn't then you test the voltage drop across the wire at the ECU harness and that first junction. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

12-23-2009, 02:15 AM	#12
discord Stock Join Date: Dec 2009 Location: puyallup, wa Posts: 16	now the car is back firing thru the intake and exhaust pipes are getting warm...I havent check any voltages yet, but the back firing thing has been the most activity since it was installed? good thing? __________________ 1991 supra targa turbo full rebuild, garrett turbo, chrome header, custom made adjustable wastegate and matching bov, elec fan, hks evc pro, greddy turbo timer, hks 2.0mm hg, arp head bolts, arp rod bolts, 2.5" intercooler and piping, lexus ls400 MAF. AC, power steering, and clutch fan deleted.

12-23-2009, 05:18 AM	#13
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	The back firing means the mechanical timing is a mile off. Realign everything to 0? then look into the voltage issues. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

12-23-2009, 05:30 AM	#14
discord Stock Join Date: Dec 2009 Location: puyallup, wa Posts: 16	ok, will do, and i'll get back. thanks much for your help __________________ 1991 supra targa turbo full rebuild, garrett turbo, chrome header, custom made adjustable wastegate and matching bov, elec fan, hks evc pro, greddy turbo timer, hks 2.0mm hg, arp head bolts, arp rod bolts, 2.5" intercooler and piping, lexus ls400 MAF. AC, power steering, and clutch fan deleted.

12-23-2009, 05:34 AM	#15
discord Stock Join Date: Dec 2009 Location: puyallup, wa Posts: 16	oh ya and to get the timing right i'll need to know which wire go where on the cas. I had to get a new connector because the wire on mine were deteriorated and came out of the connector. I can only guess where the go. I had a guy bring over another harness so I could tell but he will not answer my calls now. the wires before the connector on the stock haarness are a different color then the ones after so I cant match the colors? anyone have a picture of theirs? thanks! __________________ 1991 supra targa turbo full rebuild, garrett turbo, chrome header, custom made adjustable wastegate and matching bov, elec fan, hks evc pro, greddy turbo timer, hks 2.0mm hg, arp head bolts, arp rod bolts, 2.5" intercooler and piping, lexus ls400 MAF. AC, power steering, and clutch fan deleted.

12-23-2009, 08:47 AM	#16
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	What? The CPS harness perhaps? The wires on the side of the CPS are not matched to the harness.... at least I've yet to see one that matches. I can get the colors from my '88, but they may be different getting the info from someone with an '89 or newer would probably be best. If you're not talking about the CPS harness (has 4 wires) then post a pic. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

12-26-2009, 10:03 PM	#17
discord Stock Join Date: Dec 2009 Location: puyallup, wa Posts: 16	I got them right now, looked at a friends harness. got new coil packs now and have a good strong spark. still just backfires into the intake. all voltages check out. ignition switch is good. refueled gas tank, timing is perfect, no dice. still occasionally backfires into the intake. __________________ 1991 supra targa turbo full rebuild, garrett turbo, chrome header, custom made adjustable wastegate and matching bov, elec fan, hks evc pro, greddy turbo timer, hks 2.0mm hg, arp head bolts, arp rod bolts, 2.5" intercooler and piping, lexus ls400 MAF. AC, power steering, and clutch fan deleted.

12-26-2009, 10:38 PM	#18
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Backfiring into the intake indicates that the intake valves are opening too soon after ignition.... I know of no other way for this to happen than the mechanical timing being off; I am not talking about the spark advance if that is what you are referring to. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

12-26-2009, 11:19 PM	#19
discord Stock Join Date: Dec 2009 Location: puyallup, wa Posts: 16	what should I do to fix? __________________ 1991 supra targa turbo full rebuild, garrett turbo, chrome header, custom made adjustable wastegate and matching bov, elec fan, hks evc pro, greddy turbo timer, hks 2.0mm hg, arp head bolts, arp rod bolts, 2.5" intercooler and piping, lexus ls400 MAF. AC, power steering, and clutch fan deleted.

12-26-2009, 11:31 PM	#20
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Bill UK covered it well in pictoral form here: http://www.toyota-supra.info/forums/...on-sensor.html Those three items set the mechanical timing, then you tighten the timing belt tensioner pulley (do NOT over torque it!!!), then you set the ignition timing with the timing light. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

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