If you don't disconnect the EST and you time your engine to +16...
is it the same end effect as if you disconnect your EST and time your engine to +6?


I ask because I have a 305 TPI swapped into a Fiero, and cant find the EST wire for the life of me.

The est is on the tan with blk stripe wire from the icm . If you state the ecm model I can tell you what pin on the ecm you need to install a connector on so you can set the timing properly.

D5 if it’s a 1227165 ecm tpi maf 86/89
C7 on a 1227730 90/92 ecm speed density.
C3 I think for a 1227727


Timing will very based on engine temp and load
https://m.ebay.com/itm/WATERPROOF-CO...IAAOSwsBtaDCWC

Thanks I'll have to check my computer. The engine will be at operating temp and manual trans in neutral.

The timing will usually advance around 18 - 20° from static when the connector is plugged in. So try maybe 24° to start and see if you like it. It's just "timing", after all; doesn't matter what "number" it's set to, as long as the engine runs good.

Don't outsmart yourself.

If it RUNS good, it IS good.

Such a small concept, yet so simple it almost hurts to wrap my brain around it... both cells of it have to bend so far, they get into a fight at both ends.

Here's how to adjust timing. This is a process that can be applied to any number of things about your car; it's fairly universal. Again, a very tiny, very compact, very powerful concept.

Adjust it. Doesn't matter which way, although if you have a clue which way might be better, adjust it that way first.

One of 3 things will happen. Either it will get better; or, it will get worse; or, nothing at all. If nothing happens, put it back where it was, lock it down, and leave it alone. On the other hand, if something does happen:

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

Is it better or worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, plus a little further.

...

Eventually you'll get it to a point that no further adjustment makes it better; that is, ANY adjustment makes it worse. At that point, it's as good as it can possibly get. Time to lock it down and forget about it.

We call it "tuning". Works great on fuel systems too.

The computer won't have the vaguest dimmest foggiest remotest haziest hint of a whiff of a glimpse of a clue about ANY of this. No point in "check" that.

Thanks so far.
I found the EST wire, disconnected it and set the timing to 9-10. Then reconnected the EST aND drove it. Power is better runs good while driving.

My real issue is still high idle. So I haven't found a vacuum leak. The vacuum is 19-20 at 1400 rpm. It idles at 1400 rpm warm when EST is connected. It idles at 900 when EST is disconnected. This is in neutral. I realize idle is high, but is it normal for the EST to cause that jump?

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Yes of course. How could it NOT. The timing changes MASSIVELY. Idle speed should do the same, if not more.

Once you have it set to where you like it, do the "minimum air" procedure to establish the correct throttle position / idle speed relationship.

WHen my timing was set at +6 the high idle problem was the same as it is now when it is set at +9.

Check for vacuum leaks

When I did this before, the TPS was still less than .54 even when maxed out in adjustability. I mean it was .4 something. To get to .54 the throttle screw needed to be turned clockwise. What does that mean?

Set the minimum idle speed first then the tps. Or if you have a scanner or tunerpro rt set to 20 Iac counts engine warm. If you can adjust the tps try a new one.

Will try again when I get a chance, thanks for the advice again.

You can tell if the memcal (computer chip) is from a manual or automatic transmission based on the letters on the memcal.
A automatic transmission warmed up target rpm is in the 600 range depending on coolant temperature.if the park neutral wire is grounded at the ecm it will add 50 rpm or so.

http://www.chevythunder.com/prom_bcc_1987.htm

Thanks I set the minimum air and she idles good now. I drove it and it runs good. I don't have another TPS yet, and this one adjusted all the way high isn't vary close to .54, if it seems to run fine is there an issue with not getting a new TPS rightaway? This one actually was new, but apparently not correct internally...

If there isn’t a code 21 it might not effect the running or throttle response much.

No code yet. I was mainly concerned about anything risky like running lean.

If it isn't hooked to the dizzy you don't have one.

The TPS maxed to highest adjustable setting us only .37 at idle, and is 4.34 at full throttle. Think I need to try another TPS or is there no detriment?

Somebody mentioned a simple principle earlier on that may be applicable to this situation:

Capiche?

Well, there are a few other things I'm ironing out but it does run pretty good. It actually runs best before it's fully warmed up. Just trying to make sure the TPS system is happy.

Another question, regarding one wire 02 sensors, that's what is on this car, its located just after the manifold in the downpipe here it is nice and hot.


Are one wire 02 sensors created equal? Its output, and its thread to screw it in? This sensor was in when I got the car, but I am questioning if it is failing and would like to get a replacement. But don't know how I would choose one.


Remember this is a 1987 305 TPI transplanted into a 1987 Fiero, with the Trans Am's computer but it is tuned. All the person asked me when I had the computer tuned in regards to the 02 was.. is it a one wire and where is it located.

Just posting to say after finding the thermostat was stuck open I think that was a major part of my running issues. I put a new one in and she likes that a lot better.


OH and I think the o2 sensor is stock to the engine.