Can bad O2's cause the DTC 65??

 

Ya got me on that one.
The book says DTC65 Accerlerator pedal position3 circuit range fault.

 

Huh?? Helm 6E3-A-123 Bank 2 (right front) Heated Oxygen Sensor #1 Circuit (rich exhaust indicated).

The diagnostic chart calls for the "Tech 1" over and over again. Can I just check this sensor using a DVM? The readings should still be the same, should they not?

-DM

 

I got the same thing. Bank 2 rich exhaust indicated.
Yes you can check with DVOM.

 

I'm about to post a vid of the car running up my local strip. You can hear her, she sounds awful. Losing major power. ECT is 202 - 209. Oil temp is 219-ish. Oil pressure around 35 PSI. RPMs are idle to 3k-ish. Vehicle speed right around 50 MPH.

I'm about to post video. The vid is gigantic, 3 mins long. That's trimmed down too. I just wanted someone else to be able to hear it. It's taken with a cheap camera, so the video quality is pizz-poor. There's some audio clipping as well, but you can still hear the motor.

 

1. http://s25.photobucket.com/albums/c8...t=Corvette.flv 3 mins, 30MB

2. http://s25.photobucket.com/albums/c8...vetteShort.flv 1 min, 1MB

 

I spoke with Bryan at PCM4Less this afternoon. He thinks I'm leaning out, as I suspected at the beginning. I have larger injectors to replace these with. But, I've had a few suggestions to "clean the MAF" sensor. Should I just spray something like Carb Cleaner on the elements in the MAF housing?

Before I just jump and replace injectors, is there a way I can do the injector balance test without a scan tool? Assuming I find bad injectors, the replacements will be 30# Accels. Will I need a PCM update, or will the ECM be able to compensate for their larger flow capacity?

TIA

-DM

 

No, don't use carb cleaner.

 

Then what should I use? Isopropyl alcohol maybe?? It's great for cleaning electronic parts. Suggestions?

 

Did you clean the throttle body?
Don't touch the maf with anything ,the burn off when you shut it down should take care of that.
Are yoiur O2 sensors in the same place as stock?
Do you have an adjustable fuel regulator?
Strike the 02 I see you have heated.
Your BLM's will have to be changed in your computer to compensate for the lean condtion.
I don't know what the duratation on the cam is and with a 383 and heads I am not sure if a 750 cfm throttle body can deliver enough air and if a 30 lb injector will be enough to feed the motor.The LT1 with the heads and cam bigger than the LT4 will need atleast a 36 lb injector.
T Wong over in the Scan and Tune section can give you that information.
The heated o2's are telling the computer a lie and not realy giving the info to the computer .Your computer is a learn computer and should with real 02 sensors correct the problem some what but not entirely.
You can download Data Master for free from their site and get 10 tests out of it.

 

That temp sounds reasonble to me, but ive never looked into it. The thing is you say you get this code: "DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich" but you think its running lean, if it is O2 related, swap the left and right O2s and see if the code swaps sides as well. BUT, since you have the "DTC #41: Ignition Control Circuit Open" there could be a problem there causing a missfire, which may be allowing unburned fuel to cause a rich reading.




On a side note, i just replaced my ICM in my 94 last week, when my engine got warm for a while it had an off-idle misfire, but this only happend when warm for a while. Was reletivly minor, but replacing the ICM seems to have cured it.

Make that 20 free.

 

Alcohol would be ok. Electrical contact cleaner is better. Use a Q tip. They are known for getting contaminated on the upstream side of them. You may have to knock your screen out to see the upstream side. If the front of the resistor wire is black and fuzzy, thats one of your problems. Do you have a scanner on it? Your 02 readings in conjunction with the fuel trim will tell you if the MAF is suspect.

 

I replaced the ICM on Thursday. Took the ICM/coil assembly off, and cleaned up the bracket, heatsink, and head mounting surfaces. Reapplied a hi-temp thermal paste, and reinstalled. I also cleared the DTC 65, and it hasn't returned. I think the code came about when the engine shut down the night I brought her home.

When I spoke with Bryan he told me the timing tables range from 10* up to 36* or so at WOT. I suspected it was a lean condition originally. He suspects much the same.

I seem to have found and plugged all my vacuum leaks ,and have roughly 17" of vac at idle. It has some minor fluctuation to it, but I'm imagining that's just lobe overlap.

I have no laptop at the moment, and as such cannot use software such as datamaster or tunercat. I've been trying to find a scanner I can use for the car with questions, and even a thread over in scan and tune. So far no dice on that tip. I have an Actron OBD-II scanner I had for my old car, but it won't connect to the Vette. It'll plug in and power up, but it won't read. It's supposed to be backwards compatible with OBD-I systems. Without a scanner, I have no way of checking the fuel trims in PCM memory to confirm that I'm leaning out. It only seems logical though, since I have adequate fuel pressure.

I have larger injectors, but I imagine the PCM would need to be recalibrated to take advantage of them.

At this point I'm wondering if my initial math was wrong. Can anyone say with absolute certainty what size the chambers are on OE LT1 heads?

-DM

 

If you have 30lbs/hr injectors, and the ECM is on ths stock setting which will be 24.87lbs/hr, it should run rich, not lean.

 

So after I clean the MAF and the TB, you think I should swap them out? Pig rich is not perfect, but it beats the hell out of detonation.

-DM

 

Let me give you my personal experience on the cleaning the MAF:

A few years back I bought and installed a K&N air filter which came pre-oiled from the factory. I installed it right out of the box, with no modification.

I have Diacom, which allows me to read virtually all of my engine's operating conditions on a laptop. So, several weeks after I installed the K&N I noticed my BLM readings were at 108, a far cry from the 126/130 readings I had been getting.

After checking everything I could think of to find the cause, I finally decided to remove the MAF and, using a can of spray injector/carb cleaner, I turned the MAF upside and sprayed the thin wires inside.

Turning it upside down prevents any liquid from entering the electronics in the base of the MAF.

Reconnected the MAF, fired up Diacom and the readings were back to where they were before.

In my case, the red filter oil on the K&N filter had been sucked off during engine operation and coated the MAF wires. This caused the MAF to send inaccurate readings to the ECM resulting in the 108 readings.

One final thought: I WOULDN'T try cleaning the wires with a Q-tip. Those wires are extremely fragile and will break easily and if one does, you'll be looking for a new MAF.

Hope this helps.

Jake

 

Thats a typical problem. ESPECIALLY with the K&N air filters. What happens is the dirt and/or oil insulates the hot wires. The wires run at something like 1100*F and anything that hits them gets baked on.
PS I have cleaned literally HUNDREDS of hot wire MAFs with q tips and have only 1 time pushed a wire off.

 

The best way to check that is with a scanner. If the inj. are 30s and the setting is 24s th4e computer will continually pull out fuel, causing the fuel trim #s to fall drastically.

 

Tips for a scanner, or suggestions as to why the Actron I have won't connect?

Thanks

 

The only decent scanners out there will cost you as much as a cheap used laptop AND a scanner/datalogger setup. Get a used laptop from somebody you know/trust. Never heard of an Actron.