sudden rich condition, code 11, fixed by EFI reset

[figgie]

Victor

good plan of attack.

The O-scope, forgo that for now. Do the visual check first and foremost before slapping the o-scope to that circuit.

Once the visual is done

http://www.autoshop101.com/forms/h23.pdf

page 11/16

unfortunatley it does not reveal voltages but the system is a low level signal. If anything start at 12v and then step down to 8v and if needed, 5v. time on the other hand, the 24 tooth wheel will do 2 turns for each revolution of the crank. Just do some math to find the time window needed to measure the pulse.

[Victor Charlie]

I completed:

1) new ground for fuse block
Observation - it was very rusty and poor contact
2) ground under intake manifold for ECU, add redundant ground wire
Observation - bolt was never tightened, my bad. the white/black
ground wire wasn't even attached.
4) adjust (per TSRM)and test TPS to be sure code 51 is cleared again
Observation - no codes.
5) adjusted idle set screw while doing step 4

Now it runs well again, full power. Idle is stable except idles fast for a minute after acceleration, then suddenly slows and surges a few times before reestablishing stable idle. This appears to be in part due to dashpot needing adjustment.

So I think my problem is solved, and I think the most important issues were two bad grounds, poorly seated MSD wires, plus TPS needing adjustment.

Thanks a million to everyone who helped me figure this out.

[Victor Charlie]

More driving, still the original issue with idle, though it is now drivable.

Unstable idle:
> when cold: Now it starts and idles well, but smells very rich.
> After a little driving, not warm yet: it starts holding a higher RPM after revving and laying off the throttle, then after about a minute, it starts with about 1 1/2 sec cylces of normal idle speed, which cuts off suddenly but briefly and rpm goes down, then raises up more gradually. In these cycles it is now firing consistently, no stumble or obvious misfire, seems to be running on all 6. still smells rich.
> When fully warm it idles nicely, runs well, just smells slightly rich.

Only known remaining defects: very restrictive catback from stock NA, soon to change, and timing still set 15 deg. BTDC.

The unstable Idle has been there from the start of this thread, but now is is running well enough that it doesn't stall, so the car is usable. Starts fine too, hot or cold, so far. Anyone correct me if I'm wrong, but the sudden cut off seems too fast to me be due to fuel pressure changes at idle, but cold be changes in electrical signal to the injectors. The steady cycle rate makes me think it isn't weak or inconsistent spark.

Question for the forum: pursue fuel or spark or something else next? I have a few obvious things to do still.

New priority list:

1) reset timing to stock and see if the timing light still flashes regularly when it is surging/fading.
2) get A/F guage, aftermarket boost guage, and Tach installed and functional.
3) install wideband so I don't get cancer or holes in my brain sniffing exhaust fumes.
4) adjust AFM calibration screw to optimize to stoich ratio.

[figgie]

the first plan of attack. Set timimg per tsrm. That might fix alot of the surging at idle.

[Victor Charlie]

Originally Posted by figgie

the first plan of attack. Set timimg per tsrm. That might fix alot of the surging at idle.

Interesting. i wouldn't have guessed that. I will do so.

For posterity: forget all the cold/warm issues with idling. It turns out that the idle instability occurs within a certain RPM range. With no tach, im just guessing it's around 2000 rpm, very narrow band, then steadies out above or below that. The issues with all the other tuning, warming up the engine, and temperature are because all those things affect the idle speed and either put in in or take it out of the rpm range where it surges.