safulop

Recently I had a bunch of stuff tuned up and played around with a chip swap, which caused some weird problems. Long story short, I now have new plugs, wires, retipped injectors, verified LH condition and verified MAF calibration. However, I'm still playing around with chips and currently running a stock LH chip with a newer Autothority crap chip in the EZK which I've had for years. The only thing really changed is that the Autothority LH chip was removed in favor of a stock LH chip.

The car runs better than I've ever seen her. She has an absolutely smooth idle, not a hint of running problem and a bit more peppy than before the tune-up. However the mileage, which was already kind of low in the city, is at least 10% worse. I just wanted to put that out there as an interesting result of a chip experiment. I don't know of anything else wrong that could cause this without any obvious signs of a problem.

I am planning to soon change the EZK chip for the Porken S300 chip. Hoping for better mileage from that combo, and a better chance of passing smog. Since I barely passed smog before with the Autothority setup, I honestly doubt the mismatch will pass next year.

ALKada

Have you considered a Sharktune instead? I would think that would give you the biggest bang for the buck...

safulop

Actually Ken's chip should out-tune the Sharktuner, but I'll leave it to him to explain why. . .

ALKada

I'd love to get your impressions after you re-chip with the S300s. I hope it cures your issues and your ecstatic with the results. Any Porken product rarely disappoints.

safulop

Another difference I notice with the stock LH chip is that the cold idle is very high (1400 rpm at least), slowly settling down to the spec 675 rpm strong idle when fully warm. My shop guys told me that this is the expected "warm-up" idle. The Autothority chip did not do this, having a cold idle speed of maybe 1000 rpm at most in neutral.

jcorenman

That is not correct. What you saw with the Autothority chips is the correct behavior. But the stock and A-chips are the same in this respect, all the chips do is add more fuel where the S4 is already too rich, and a bunch of advance in the mid-range. Something else is wrong-- air leak, temp-II sensor, sticky ISV, possibly MAF or O2-sensor, or possibly the LH got zapped swapping chips in and out-- if it hasn't been rebuilt then the "hybrid" circuit is fragile.

This is one of those cases where a Sharktuner-- just connected as a diagnostic tool-- would tell you exactly where to look. The alternative is to keep swapping stuff, at shop rates, until you find the culprit.

safulop

Yeah having cold idle so high did seem wrong to me, but the problems you've named have either been ruled out or are implausible with a car running strongly with no stumbles or warm-running issues. I mean, the only things that we haven't specifically checked is the possibility of an intake air leak or other vacuum. And also the ISV. But doesn't it seem like either of those things should cause idle speed issues when warm? I have heard that Autothority chips can spoil the idle characteristics all on their own, so I was thinking that the culprit is the mismatched pair.

Where would you suggest a Sharktuning adventure? Anywhere near Fresno?

safulop

OK here's my theory of why the mileage is suddenly worse. The EZ chip from Autothority introduces timing advance, and its partner LH chip adds fuel to try to prevent knocking. Well, timing advance will tend to increase fuel economy. Now with the stock LH chip, the knock sensors are kicking in and preventing knocking by retarding the timing, which decreases the fuel economy.

So that all makes sense. As for the high cold idle, the only reasonable possibility is some kind of small vac leak that is not leaky when the manifold is warm. So maybe an intake check and refresh will be done at my next service interval, or if the idle issue gets worse to the point where it happens when the car is warm. I had a 928 once in serious need of intake refresh, and it idled 1400 all the time as a result.

PorKen

The LH doesn't know if the engine is knocking. The Autothority chip is stock except at medium to high load, only.
The EZ and LH communicate only in so much that the EZ supplies RPM to the LH and the LH returns load information to the EZ.

The S4-up EZ and LH will compensate for most of the sensors being bad, so it will still run fairly normally at part throttle.
Best to find someone in your area with a Theo diagnostic, Hammer/Spanner, or Sharktuner to read any codes.

Other problems could include a leaky injector, a bad Fuel Pressure Regulator, or leaking FPR or damper or pinched return hose.
Bad knock sensors or a cam (hall) sensor only affect medium to high load, so while they could be bad, it shouldn't affect mileage.

jcorenman

Yes, that would be logical. But these things are complex enough that strange things happen which seem illogical, but make sense if you can dig in and see what is going on behind the curtain.

I've heard that also, but don't understand why. The AA chips don't change anything around idle, but maybe the adaptation gets messed up.

Have you tried disconnecting the battery for a minute, to reset the LH adaptation? In theory that should make no difference, if the MAF and O2-sensor are working properly.

Los Angeles, that's pretty close-- at least from this vantage point. Greg Brown has one, also Rob Edwards.

The problem with this theory is that the AA EZK maps don't add much advance in the going-down-the-highway "cruise" range, not enough to get the EZK knock-detection excited. Nor does the AA LH map add much fuel in that range. That all happens at higher load and higher RPMs. And for cruising, the LH is going to regular the fuel (from the O2-sensor) to hold the AFR around 14.7, whatever the map says (within limits). So no, I am not buying this theory.

I think the mileage is down because the mixture is too rich, which means the LH is not able to regulate AFR to 14.7. And these engines are happy a bit rich, happier than at 14.7:1.

The most common causes would be MAF (out of cal and reading high, i.e. rich), or a bad O2-sensor. Usually MAF's and O2-sensors age "lean", but bad parts is bad parts and can do anything. Could either of those explain high cold idle? It doesn't seem likely, but screwy things happen.

Certainly possible, but not the only possibility. It could also be a gunked-up ISV, loosening up when it gets warn. It could also be the idle switch, if it is not working when cold (i.e. adjusted too close to the threshhold) then the EZK may not be switching to the idle map, which means more advance and higher RPM-- maybe beyond what the ISV can regulate. It could also be MAF, it is a temperature-sensitive device by its nature and maybe its temperature-sensor is broken.

Are you going to be at Sharktoberfest? I'll have my Sharktuner there, maybe we can use your car for a tech session on trouble-shooting with a Sharktuner.

safulop

Jim thanks a lot for the reply; on Sharktoberfest I have my hopes up but family and work matters are threatening my prospect at the moment. . . we will see.

As for your rich-running theory, it is all but ruled out because the O2 sensor was replaced 4 years ago and the MAF was just verified as perfect by a rebuilder in July.

On my theory of the low mileage (caused by added timing retard), it gains traction from the fact that highway mileage is close to spec, only city mileage is low, and my city driving involves mostly accelerating from red lights because, you know, the lights are always red in Fresno. So that would put it into the realm of timing retard. But yeah, it would be great to get the crud Autothority chip out of there once and for all. I've got a stock chip on order and Ken's chip sitting in a box waiting to try.

-Sean

safulop

Sorry Ken, missed your post before.

Well as before, so much has been ruled out already. Like, the injectors have been R&R'd and re-tipped, and the fuel rail was set up and run with a fuel pressure gauge, verified no leaks and good FPR. Also new Hall sensor installed.

So yes, we are down to the point where some sophisticated equipment will be needed to go beyond the old guess-check-swap method. And that's probably not happening around here in the near future. I'm going to have to figure a way to get down to Sharktoberfest. . .

safulop

Confirmed that on the new LH stock setup, I am down to 11.3 mpg here in the summer heat. Normally I would be at 12+ mpg under similar conditions in the city. So, richer running.

That said, smog results previously indicated running too lean for many years, e.g. high HC in particular. So I'll be interested to see if the previous LH chip was actually running it too lean? Is that possible? Why would it have been too lean before and now richer, when the only thing different is the LH chip?

---edit---

Wait I forgot we also put in a new power brake vacuum check valve. This could have been leaky before (for years) causing slight lean running and is now corrected.

dr bob

Power brake chack valve leakage isn't the same as a vacuum leak. The booster is (hopefully) a closed system, so the only serious symptom would be weaker braking immediately following a hard-throttle run. the check valve maintains vacuum in the booster during periods when the engine isn't running with higher vacuum.

Discounting the oxygen sensor because it was replaced four years ago... check it with a voltmeter in service to verify that it's controlling at about 0.4 volts at idle. The sensors are killed by poor-running engines.

On the fuel economy -- did you put in larger injectors to work with Ken's chips?

safulop

Well, Randy V told me that the booster check valve could be a hidden culprit related to my self-actuating comb flap problem-- the AC comb flap would usually close with higher rpm and then open back up at idle, making good AC cooling hard to find. The booster check valve was the only vacuum-related part that we changed, and this did indeed fix that issue.

The shop said that they checked the action of the O2 sensor with a meter.

The larger injectors were sent back, since they are designed only for Ken's LH chip. In a bizarre effort to restore the operation of the vehicle we decided to just revert that system. We did clean and re-tip the old injectors.

From the way it runs now you would not think there was anything wrong. Except for the high cold idle.