Ignition Timing, Rich AFR during vacuum Issues

jdemara

New Member
Apr 28, 2008
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North Delta
Ill start by listing mods I have:
BOV, BIC DDP - no cat, Mishimoto rad, AEM Tru-Boost controller, AEM Wideband.
ALL vacuum lines are brand new and checked over many times.

First problem:

Car sometimes runs rich under vacuum (foot off the gas) when cruising in gear, say at 60kmh. I can be feathering the gas very lightly just to stay at this speed, let off the gas (goes to 21 vacuum), and my AFRs sometimes drop slowly down to 12. Sometimes it will creep slowly back up to 15ish, and sometimes stay at 12.

As well, sometimes when in the vacuum condition, (foot IS OFF the gas, but still in gear), and i go to push the clutch in to let the car coast and RPMs come down naturally, the car will bog down and almost stall. When it does this, AFR's drop to between 10-12, then go back up to 15ish after a few seconds. Any ideas as to what may be the cause of this?

THESE PROBLEMS ARE NOT A RESULT OF THE BOV VENTING AFTER LETTING OFF THE THROTTLE DURING BOOST. I know this symptom is likely to happen after venting, but that is totally different from what I am talking about here.


Second Problem:

I go to jumper the E1 and Te1 to set my ignition timing, and it doesnt make any difference to the timing when connecting the jumper. The timing mark stays in the exact same position regardless of whether the jumper is connecter or not.
The 2 small fans behind the radiator do not come on either (if I recall on my last Supra, they both came on when jumper was connected.)

The check engine light however, does come on, and displays codes 41 and 51 when jumper is in place.
Reset these by pulling EFI fuse for 1 minute, and now it only shows code 51. (Did not touch the throttle yet, or drive anywhere after resetting)

I apologize if this seems a little bit dragged on...
Any insight as to what my problem may be is appreciated!
 

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
1) Since the ECU can't exert control over the fans it's not possible for it to turn them on.

2) There's no resetting code 51, there's only fixing it.

3) Timing can't be set with the IDL contact open.

4) Timing control will not behave correctly with the IDL contact open.

4) The ISC system will not operate with the IDL contact open.

Put simply, fix the 51 and go from there...
 

jdemara

New Member
Apr 28, 2008
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North Delta
Ah yes! After reading lots about code 51, it all makes sense now. I have verified TB is completely closed, even when linkage disconnected. Car IS 20 years old, cant hurt to replace then adjust the new TPS.

I am going to assume a bad or misadjusted TPS can also be the cause of a rich condition on deceleration in gear, foot off the throttle..
 

jetjock

creepy-ass cracka
Jul 11, 2005
9,439
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Redacted per Title 18 USC Section 798
Not necessarily so but it's true decel fuel cut is partly predicated on the TPS. I forget whether it uses IDL or VTA in conjunction with vehicle speed though. Fix the code and see what happens. You may get lucky...
 

CajunKenny

PULL MY FINGER. PLEASE!
Nov 15, 2007
3,255
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Washington
Once code 51 is resolved, other codes can then be displayed. Your work may not be done after you fix 51, so don't hurry up and put your tools away. :)