[jbrody44]

I got done rebuilding and porting my head a few weeks ago. Adjusted the timing by ear at that point as I did not have a light. Got a light yesterday. The car was running fantastic, but I figured I'd check the timing anyhow. It was at like 30 BTDC (or at least that is what it looked like). Here is the deal I figure something is out of whack here. I can get the timing to about 12-13 BTDC with the dist maxed out in the clockwise direction. With it set here the car does not seem to run as strong or be a responsive as it did with the timing at 30 or so BTDC. Meanwhile under my hood it says 10 BTDC is the factory spec which I can't quite get. I don't think the distributor is off a tooth or I would not be able to get it to run well at all. Did I maybe screw up lining up the crank and cams? I thought I double checked everything pretty well. Maybe I had an extra tooth of belt in between the intake cam and the crank pulley? Should I put it back the where it runs great and be happy or rip it apart again and see if I can get it to run that way at 10 BTDC? Any ideas? I know if it was running so well why did I mess with it!! Thanks for any input.

Jason B who just can't leave well enough alone.

 

[Dave A.]

Double check your timing belt timing and see if you may have accidentally advanced the intake cam one tooth. Also, check your crank pulley for timing accuracy by lining up the timing marks on the cam sprockets and the timing belt drive sprocket and then see if the notch on the crank pulley aligns at the 0 mark on the timing cover. Sometimes the outer portion of the crank pulley can slip from deterioration of the rubber and result in the ignition timing being overadvanced when it really isn't. Don't forget to short the check connector as well when you set the timing.

 

[SilverMk2]

I'd check the TPS (in particular the idle switch).

 

[3000cc MK2]

Double check your timing belt timing and see if you may have accidentally advanced the intake cam one tooth. Also, check your crank pulley for timing accuracy by lining up the timing marks on the cam sprockets and the timing belt drive sprocket and then see if the notch on the crank pulley aligns at the 0 mark on the timing cover. Sometimes the outer portion of the crank pulley can slip from deterioration of the rubber and result in the ignition timing being overadvanced when it really isn't. Don't forget to short the check connector as well when you set the timing.

as dave say... check all your timing marks and belt tension and every thing is not loose especially the cam sprocket and crank pulley... then if it is all good check the distributor and set it to 10º BTDC.... if it is still way off... align your marks again and pull the distributor and put it back together.... it seems to me that you are one tooth off the distributor gear... check the basics first!!!

JAY

 

[SDRmk2]

jbrody44 like SilverMk2 said check your throttle Position Sensor. I had the exact same prob u described.

allmotor85supra:
"When u set ur timing check connector make sure the check engine light is blinking if it does NOT blink then the comper is still in open loop ie not at basic timing. the biggest reason for it not going into basic is the TPS sensor out of adjustment. if the TPS doesnt connect the idle contacts when the throttle is closed then the computer will not go in to basic timing mode and u will check all teh timing marks/ cam timing/ ect but all the while its the tps. if the check engine light does no blink loosen the tps and move it a hair clockwise. we run in to this problemn alot with the ol supra's and cressidas at my dealership. it drove me nuts tryng to time my motor and all along it was the TPS
hope it fixes ur problem"

 

[jbrody44]

Thanks all;
I will check the TPS first, then move on to the other items if necessary. I will let you know how it turns out. Thanks - Jason B

 

[Dave A.]

Hey. that's some excellent tech. info.! Where can this be stored for future reference?

 

[jbrody44]

Thanks everyone, It was in fact the TPS that was out of whack. I never did have the blinking check engine light before. I actually had to rotate it counterclockwise a bit and bingo I got the light flashing. Now I got my timing set to 10 BTDC and it is running better than ever! That lower screw on the TPS is a pain in the ass to get at (at least without dismantling a lot of items), that 90 degree screwdriver that they give you in the craftsman sets was just the thing (thought I would never use that). Anyhow thanks for eveyone's input. I would have never got that in a million years. Once again the group had led me to success on the supra as DIY'er.

-Jason B at 10 btdc and running strong :lol: