Intermittent Code 61 Ideas

[XfireZ51]

GC,

Also possible to strap actuators open and then re-do calibration for secondaries
on at any point off idle. Also, use an electrical plug to feed the ECM a signal that deals with need for vacuum.

[Dynomite]

Originally Posted by Paul Workman

But, once I get the LT5 back in, it will be back on the radar as a "todo" this season.

Thanks Paul .......your LT5 is not "in"?

Marc came right back to me on secondaries (Marc is extremely fast) ......which reason #1 (which I am sure he doesn't mind me inserting here) is applicable here
I would say that removing the secondaries is not a bad idea. A few years ago we dyno tested removing the secondary throttles and found nothing. There are three situations where removing the secondaries are useful. 1. If you are having a problem with them that you can't fix, they can be eliminated. 2. If you can't find a repair part. 3. If you have removed them to port the heads, you can save time and not reinstall them.

Removing them does not effect the idle, fuel economy or torque over 1500 rpm. I believe that they are an advantage for an emission test.

Originally Posted by tomtom72

Good morning guys!
My 61 was the ECM.

Tom

Tom....at what point did you quit chasing vacuum leaks and switch ECMs? I assume when you switched ECMs in the diagnoses you moved your chip to the ECM you switched in

Where did you pick up the second ECM?

Originally Posted by XfireZ51

GC,
Also possible to strap actuators open and then re-do calibration for secondaries on at any point off idle. You are saying recalibrate the chip secondaries on at every point except at idle?
Also, use an electrical plug to feed the ECM a signal that deals with need for vacuum.

When I look at the engine Vacuum diagram I see MAP sensor, Fuel pressure regulator, PCV valve assembly, A/C vacuum tank, Differential pressure switch, Vapor canister control valve, and a line to brake servo. So there are lots of needs for vacuum

[tomtom72]

Hi Cliff.

At what point? Ya know........I'm doubly embarrassed because the hard 61 set while I was out with the car. I was doing a 2nd gear exit ramp / on ramp and the SES light popped up and instantly I was limited to 3k rpms....it was as if I had dropped an anchor!

Okay so I limp home, 25 miles and plug in my scanner. (I already knew the code number from my Gordon jumper kit that I keep in the car.) I even tried the clear code option and it resets in an instant, and the car is idling! I should have known right then that my issue was electrical. The speed of light? If it was a vacuum issue I would have had to wait for the code to reset. Sometimes I can be sooooo dumb!...well, most times actually.

Anyway, vacuum differential sensor = MAP under the ECM bracket. I use the FSM chart and waste 1/2 a day running the DTC 61 diagnostic chart only to find that nothing is wrong except for the ECM. I swap ECM's and viola no 61.

I bought the ECM as a spare when I first got my car back in late 04 from a chevy dealer.

Sometimes I think God is trying to tell me that I should not own any corvette, let alone a ZR-1.

[scottfab]

Originally Posted by Paul Workman

......the fact that the 15-20 year old vacuum circuit is one if not THEE most common nags associated with the LT5s.
Parts not used don't cost anything and they seldom break!
P.

What does that do to resale? How do you keep your son or guest driver from using to much HP.
I think I'll keep mine the way it is, more for the guest driver
After all GM has all those expert engineers and they would not design it that way unless it was right............ well someone said that way back when.
I don't believe it. Just thought I'd throw that in.

[phrogs]

well since I don't have guest drivers Im removing my secondaries Im sick of the BS of dealing with them.

I have been getting a Code 61 at high RPMS and with a moded motor I don't feel that one more thing is going to hurt it at all.

Makes my plenum pull all the more enjoyable!

My spare 90 chip just went out in the mail about an hour ago to go to Mark.

[tomtom72]

I was just thinking about this "ditching the secondaries" thing. I mean no offense to anyone with MHO.
I think that any one interested enough to actually want to own a ZR-1 knows already about the advantages that not having all that crap under the plenum to mess with are real. The people that are totally outside our community will probably not even realize that the stuff isn't installed until they have to pull the plenum. I'm sorry but the people that are potential "casual" ZR-1 owners don't know enough about the LT5 before buying. They want a garage queen and since they are not going to drive the car that much, they'll never know!

And lastly, and the biggest BFO to me anyway....is that I just realized that my car has passed NYS smog Nazis inspection the last four years with the power key in the "FULL POWER" position! And the NYS test on OBDI cars is a chassis dyno load test thru a simulated city/highway loop. The numbers were not so good, but they were not over the limits!

[John Boothby]

I am looking for the secondary MAP sensor that is under the ECM. Anyone know the pn and if it is available from the dealer? If not, does anyone have one to sell?

Thanks.

ps: I replaced all secondary plumbing/actuators/solenoids and check valves under the plenum. All was fine for a few months, then an intermittent Service Engine Soon lite. I traced down using the red SM and Tech 1A to the solenoid under the front of the plenum. I replaced that, but soon after got another code 61. Now I think it might be the sensor under the ECM. By the way, the lite only comes on when all the parameters for the secondaries are good and I step on it. What about the MAP sensor behind the plenum? I don't show any leaks. ie using a vac gauge and the actuators work when hooked to a hand vac pump.

[tomtom72]

John, I just used my parts CD to look up the GM P/N's for the two MAP sensors, and then searched at GM Parts Direct and came up NLA on both.

The two MAP's have different P/N's on my parts CD.

I'm going to say that this is going to require research that I'm not sure how to do.


RockAuto.com says that the ACDelco P/N is 16231141 for the intake manifold differential sensor. I just don't know which MAP that they are talking about.

sorry

Tom

[John Boothby]

Thanks for the effort. I guess I'll have to make some phone calls. I am not sure that these are the problem, but since I redid all the secondary vac plumbing I might as well replace the MAP's also. That is if I can find them.

[XfireZ51]

Originally Posted by John Boothby

I am looking for the secondary MAP sensor that is under the ECM. Anyone know the pn and if it is available from the dealer? If not, does anyone have one to sell?

Thanks.

ps: I replaced all secondary plumbing/actuators/solenoids and check valves under the plenum. All was fine for a few months, then an intermittent Service Engine Soon lite. I traced down using the red SM and Tech 1A to the solenoid under the front of the plenum. I replaced that, but soon after got another code 61. Now I think it might be the sensor under the ECM. By the way, the lite only comes on when all the parameters for the secondaries are good and I step on it. What about the MAP sensor behind the plenum? I don't show any leaks. ie using a vac gauge and the actuators work when hooked to a hand vac pump.

John,

Before replacing the Diff MAP sensor, any chance you could put a Mity Vac on it and scantool. By applying suction, you could read if sensor is reacting correctly. The Lean O2 condition is obviously due to secondary injectors not coming on when the threshold TPS x RPM is reached so params for secondaries are not being met. Are secondaries holding vacuum with Key On? I had a similar thing happen a couple of years ago and it turned out to be fuel pump. The sock filter was pretty filthy