PorKen

Over the entire rev range. With a performance LH chip, there is an initial rich spike at the start, ramps up lean to right where the torque peak would be, then slowly gets richer, until it's almost OK at the top of the rev range. With the O2 sensor disabled, it idles and cruises lean 15-17 (wideband).

Best run, IIRC, was 292/277, most were 287/266 (RWSAE). I know, whah, but there would be at least equal torque if it weren't lean.

Ott)(pipe, no cats, RMB.
New temp sensors, new FPR, fuel pressue is good even at WOT.
Tried 3 used MAFs.
No obvious big vacuum leaks.
With the O2 sensor enabled, it keeps 14.7 ±0.5 at idle and cruise.
Runs smoothly, otherwise.

The injectors have not been cleaned. I need about 14% more gas in the midrange. Do cleaned injectors really make that much difference?

My other 86.5 made 288/287 with the same parts, but I R&R'ed the intake, and had the injectors done before I ever dyno'ed it.

Lizard928

sell the new one and keep the old one

If you havent gone into the intake I would be suprised if there were no vacuum leaks under there.

PorKen

I was hoping to avoid doing the intake, but that's next. All the hoses are in good shape, not dried out.

I need to vent the crankcase hoses, anyway. Can't have my plenums filling up with crude.

Louie asked: 'Is it worth the trouble, for a little more torque?'. A sane person might answer: 'no'.

Lizard928

Ken, you and I both know that we are not sane people.

And I dont see how he can ask that as look at what he did to his car, lol

have you adjusted the CO pot on the maf to richen it up on any of the MAFs tried?

leperboy

When? It's 21 years old so you're going to have to do it eventually. Besides, you'll have to take the intake off to do the fuel lines.

How about retightening all your boots and hoses (brake booster, heater control, fuel pressure regulators) you can get to easily as a first step and see if that makes a difference?

Matt

John Speake

Hello Ken
If the MAF is good you should be able to disconnect the O2 sensor and adjust the CO pot and get 1% CO easily. In fact you should be able to adjust it up to 3-4 % with ease.

If not then the MAF is aged and requires replacement, but of course there could be another problem.

Have you checked manifold vaccum at idle ?

PorKen

I should have said: 'don't wanna, right now'. I've tightened up most of the easy hoses, but the volume of air would have to be much more than little hose leaks, and the idle would be crap?

Two MAFs were ~350ohms, and one was 650 (pins 6-4). I didn't think the CO pot had any effect above idle, so I didn't touch it. I'll crank up the resistance.

I'll check the vacuum level, good idea.

We worked all day on fixing the lean problem, and then we had setup troubles with the SharkTuner, so we weren't able to do any tuning. I was able to get a little bit of useful data, using the System Monitor tab, once we had it running.

IIRC, the MAF voltage at idle was ~2.6v.

John Speake

Hi Ken
382 ohms on the idle pot is the factory setting for a new MAF. MAf voltage at idle is nominally 2.7v but it fluctuates a little around that value. But did you measure that open loop ?

The idle pot has some effect on the mixture as the rpm raise above idle, IIRC the effect on injector open time diminishes as a square of the rpm.

You can reset the injector size on the Parameters screen to get your mixture back on track as a quick fix :-) Set it to a smaller injector size to increase the on time.

Did you try a stock LH chip ?

PorKen

I don't remember the voltage when I disabled the O2.

I'll have to remember the smaller injector quick fix. The Sharktuner lives one hours drive away, so I'll do the intake before I go back.

I tried all different combinations of stock/performance chips and brains without any real change. There was one run which fueled well, and made the best numbers, but we were never able to duplicate it.

The vacuum at idle (T'ed off the EZ-F hose) is 18" at idle. On the other two cars, after plugging all the vacuum thieves (crank/gas vents, etc.) I usually see 19+.