GT failed AirCare, need advice.

I had originally started to post about this in another thread, but I felt it needed it’s own home. So I’ve transferred over my posts as well as Dave’s responses.

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I failed AirCare miserably. I’m not suggesting it’s the deletion of the EGR or the custom chip, but something is amiss.

The GT failed in two categories. I was rather shocked to see how bad the Driving CO was.

Although I had installed a 180 thermostat before I had my custom chip burned, I put the 195 thermostat back in just for AirCare.

New ACDelco O2 sensor, and the ignition system is basically all new as well (except for the wires) - ACDelco ignition module, pickup coil, MSD Blaster coil, Accel distributor cap and rotor, NGK UR5 plugs gapped to .060" and the timing was set at 10 BTDC with the A and B terminals jumpered.

Motor appears to run fine, idles smooth at 800-850 RPM. Possible lack of power though from mid to high RPM.

Here's my readings. I've added the Allowable readings to the image at the top of the columns. Notice the last time it's been through AirCare! (The car was in storage for six years.)

Edited by Patrick

Thanks for the feedback, Dave. Addressing your points:

1) The timing is currently set at 10 BTDC, set with the A and B terminals jumpered.

2) Yes, I was pretty surprised myself that the NOX readings were that low, especially with the EGR deleted.

3) Not sure why you suggest raising the idle speed as the idle readings are both fine.

4) With the car having sat for six years, I was wondering if perhaps the old gas had gummed up the injectors. I guess a fuel pressure leak-down test would show if one or more of the injectors are leaking (although I would think a leaking injector would also mess up the idle readings which are fine).

5) Just so it's known, the coolant temperature (as shown by WinALDL) was 220 before I entered the AirCare facility.

I can't say I've been very happy with the gas mileage the GT is getting. It would be great if correcting the problem this engine appears to have would also improve its fuel economy.

Edited by Patrick

Dave, the O2 sensor is a brand new ACDelco unit.

Bumping the timing up may help, but I have my doubts that an extra 2 degrees is going to make much of a dent in the Driving CO readings which are almost 6 times the maximum allowable limit.

I have WinALDL and know how to use it, but I don't really know what to be looking for. Is anybody familiar enough with it that I could send a WinALDL log to be looked at? I'm hoping something would jump out at someone who is familar with WinALDL readings.

Edited by Patrick

Were you running win aldl while going into air car..as in then did there test with your running the computer?  winaldl bad !!

My Car Passes Air Care Everytime I Have Gone Through ...But When Running Aldl ..Everything Reads Ok ...Give it A Lil Gas ...And It Stall's...Turn The Car Off ...Take Out Aldl Stuff ..Turn Car Back On ..Revs To 4000 Easy ..With Aldl I Would Be Lucky To See 2000 lol

Okay, I've got an up to date WinALDL datalog from last night ready for download.

I'm really hoping someone (John, pretty please! ) can have a look at this and perhaps spot something obvious that might help to rectify my GT's AirCare failure.

The file can be downloaded from Here.

Thanks.

Edited by Patrick

John, I was babying it to some degree because it's sucking back gas incredibly fast. I filled it up (again) tonight and reset the odometer so I can work out the mileage this time.

I also can't emphasize how gutless the GT is once the revs go up. It starts fine, runs smooth, and responds okay off the line, but there's no power if I rev it over, say 3000 RPM. When I kick it down into second gear on the freeway while doing 50-60 mph, all that happens basically is more intake noise.

Looking at the graph with the TPS values, I'd say that's about how I was actually using the throttle. Being an automatic, it's not like I'm changing the throttle position a lot, as of course I'm not shifting (manually) while accelerating. I'm just pressing the throttle down to a certain point and letting off on it when I have to stop at the next light.

For anyone who isn't familiar with WinALDL and ALDLView, here's what the Throttle Position Sensor data looks like for a short 25 minute or so drive within the city.

Time is along the bottom, but I somehow doubt that each increment is actually one second. I've heard that a snapshot of data is taken every 1.8(?) seconds by WinALDL, so perhaps that is the actual increment.

Edited by Patrick

FYI, the data looks exactly the same on the excel file I made. The seconds formatting is correct, it just draws a line between data points to fill in the gaps.

I'm going back on my injector theory. It doesn't make sense that it would idle ok, although it could be a 'sticking' injector, rather than a stuck one.

The other way to get a rich engine is an air blockage...

Innie: air filter/intake valve not operating fully or not at all(rocker etc)
Outtie: CAT, blocked muffler, or above with exhaust valve

Chay

CFoss wrote: The seconds formatting is correct, it just draws a line between data points to fill in the gaps.

The reason I think the increments are not a second apiece is because it seems to me that 800 seconds is too short a time to get to my Dad’s place by Metrotown from my place around Nanaimo and Hastings in rush hour traffic. That’s only 13 minutes! I’ll have to pay attention to the elapsed time next trip.

Also, in my datalog it shows the engine going into closed loop operation at the 75th incremental point. Is it even possible for an engine to go into closed loop operation in one minute and 15 seconds from a cold start on a 55 F degree day (with it just idling at 1000 RPM)?

CFoss wrote: The other way to get a rich engine is an air blockage... Innie: air filter/intake valve not operating fully or not at all(rocker etc) Outtie: CAT, blocked muffler, or above with exhaust valve

You know, I’m beginning to suspect my muffler is clogged with the remnants of either the current cat or the original one. When I was re-doing my ignition components a few days ago and revving the engine by hand while at the back, it seemed to me that I could see fine white "dust" of some sort flying out of the exhaust tips. Hmmmm.....

The day my GT left me stranded (as reported Here), I was revving the heck out of the engine on the Upper Levels Highway to get it good and hot for AirCare. I was driving on the highway mostly in second gear (with a 3-speed auto). Perhaps the contents of the current cat (which was sitting for six years before I bought the GT this spring) have broken up and are now choking the muffler? Hmmmm.....

[EDIT] I found something awfully interesting Here. What do you think, guys?

In ALDLView, I put my MAP readings over top of my RPM readings. I see several examples I believe are similar to what this fella is discussing. I'm not trying to jump to conclusions, but I'm getting a little excited.

Let’s look at the situation:

1) Failed AirCare with high readings for HC and very high for CO in the Driving part of the test, but the Idle readings were quite low and well within limitations.

2) Car starts fine, idles fine, accelerates smoothly, but it’s absolutely gutless at mid to high RPM.

3) Fuel economy is terrible.

4) Saw clouds of fine white “dust” flying out of the exhaust tips while accelerating engine at the TB by hand.

5) MAP sensor readings seem to mimic problem addressed by fella in article I linked to.

Okay, I’m very interested in getting some feedback on all this.

Edited by Patrick

John, the last time I took the GT out on the highway and "BEAT THE CRAP OUT OF IT", it ended up stranding me in North Van (as reported Here).

I think I’d rather disconnect the exhaust pipe between the cat and the muffler and see if I can somehow get the cat crap out of the muffler from the inlet end. To tell the truth though, I have no idea what form the cat crap is that would clog up the muffler. What a freakin’ nuisance.

In regards to the PROM, thanks for the offer to burn another one, but unless you believe there’s a problem with it, let’s hold off just for now. Or was there something in the WinALDL datalog that concerned you about the PROM?

I suspect the terrible gas mileage and poor performance I’m experiencing presently is because of the engine not being able to breathe properly, but of course I don’t know for sure.

I know you mentioned to me that you had tweaked something to do with "power enrichment", but was there any tweak you did that would cause poor gas mileage even while "babying it"?

One last question - Is it "normal" for the engine to go into closed loop operation at a coolant temp of 80F degrees? I was surprised when looking at my datalog that closed loop operation had occurred at such a relatively low coolant temperature.

 

Re: Your questions:

Interesting about the datalogging. I've never checked a log vs. real time. I guess it doesn't really matter what the time base is when you think about it.

If the cat crap is in there, get a nerw muffler. It will not all come out. Sucks, but there you go.

One more thing re list of problems. Burnt exhaust in the cylinder makes it more difficult for the spark plug to fire. My guess is that this feeds back to the distributor and possibly the primary ignition circuit (Ig. Module) and may be responsible for the failure. I had a Jimmy which had a blocked CAT. It was running poorly, gutless at high rpm, hesitating, etc. The 4 month old distributor cap was nearly melted and sidelined me, and I thought the new cap was the fix. It ran, but still had the ligh load hesitation, bogging etc. I found the cat plugged. Coincidence? Maybe. Who knows.

White dust? Sounds like a clincher to me. When you get the muffler off if you shake it you will probably hear some rattling noises and get some more dust out of it.

The closed loop stuff I'll leave for the doc, but it sounds unusual to me. Power enrich mode should usually occur above 70% TPS opening, so shouldn't have been a factor.

Chay