Bad Idle, Code 51

[Guyana00]

Well the other day I started the car, actually I got my bro to start so I could line up the ramps we have so I could get under there easily and do the oil change. When we started the car up it was choking and cutting off, it had to be revved up be kept alive, and held like that. There was no point to this since you can't move the car like this. So he let go and it cut off. We started it a second time and we got the same thing.

So a few days ago I was looking at the engine, and I saw the top vacuum hose on the bvsv was unplugged, so I plugged it back it. I thought of this and realised the car was running proper before I did this. I know it was a weird idea and I don't understand the functionality of that hose so I unplugged it again, started it and it ran fine and was able to idle smoothly.

So then I proceeded to move it up on the ramps, and do the oil change. Here is what I'm getting to, before I put it on the ramps and did the change, I jumped and checked for codes and I got a 51.

I checked the code later (yesterday before I slept) and I found out:

Diagnosis:

No "IDL" signal, "NSW" signal or "A/C" signal to ECU, during diagnosis check.

Trouble Area

1. A/C switch circuit
2. A/C switch
3. A/C amplifier
4. Throttle position sensor circuit
5. Throttle position sensor
6. ECU

... from the online TSRM.

I've also noticed when testing my heat that my a/c doesn't work, but I thought it could just need to be recharged, I'm thinking twice after seeing a/c being mentioned in the codes trouble areas.

My questions are:

Is it possible that I'm getting the code because my a/c doesn't work and is caused by 1) 2) or 3) ? and...

If not, what should I do about the code 51? Should a tps recalibration help me out also?

Any advice is appreciated, even a few pieces of advice, I don't mind going through a checklist of stuff or doing multiple tests to find the problem and fix it. Where do I start?

EDIT:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EC&Page=3

I just noticed while looking that the hose coming from the canister in this pic seems to be going to the bottom port on the bvsv and the top one going to the throttle body. On my car, the hose that is currently disconnected is the top one, but it is coming from the canister. It seems, anyone think switching these might take care of my problem?

 

[Nick M]

51 means you had your foot on the pedal when testing, or the A/C switch was on. If you are sure it is idling correctly now.

 

[Guyana00]

It's still rough, but doesn't cut off. Thanks.

 

[supramacist]

AC delete. It never gets warm in canada does it??? I'm kidding.
But I did the ac delete and I'm glad I did it was the least expensive mod thus far.

 

[Nick M]

The Idl is the idle contacts in the TPS. They are open. Yes it is adjustable. The contact closing lets the ECU know you are at idle.

 

[JesseH]

Its prob your TPS, if its not calibraited right or going bad then it will throw that code and give you some odd problems. Ive noticed alot of people have been having trouble with them recently due to them getting so old the contact strips inside are getting worn and leaving blank spots. Anyway heres how you calibraite and check the TPS:
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&Page=101
oh, and as for your edit in your first post...having the vac lines messed up or a leak can cause problems.....but that wouldn't be the reason why your throwing a code

 

[Guyana00]

Thanks guys I'm heading over there today and I'm gonna try and burp the engine, although it looks like the HG is blown. I just changed the oil and I seen the new oil in the overflow tank already, all I did was start it to roll it down from the ramps.

Less than 5 metres on new oil and I need to drain it for the head job, what a waste....but I figure it will at least dilute the ratio of coolant/oil in the block. It wont help much (if at all) but I'm gettin worried that I'm gonna be lookin at rod knock in a few months....awesome.

The joys of having a supra, well if there's a car that's worth the trouble it's a supra, sure as hell gives enough.

I was wondering since I did the oil change and it doesnt look like coolant is in the oil, but oil is in the overflow, does that mean that the transfer can remain one way? Or does it mean that because there is oil in my coolant there will be coolant in my oil? Just wondering, because if it doesn't necessarily mean coolant is getting into the oil, then I'll risk running it to burp it. If not, I wont.

In addition to the burping, I plan to do the brakes (dead, they hold but not very well at all), and drain the coolant since for some reason it has a milky white substance in it, and run water. Also gonna switch the hoses. The car wont be driven, just gonna start doin the rest of the research and hunting for parts (and robbing for money) to do the head job.

 

[Nick M]

If you have a bucket with a divider, and half is oil, half is coolant, and you spring a leak in the divider, you have mix on both sides. Draining your oil was the right thing to do. Change the filter too.

 

[Guyana00]

Thanks for the advice, I did that. I know this has been debated many times, and I just finished reading a few threads about people who blew their HG and got a walk through, but it wasn't made clear if stock bolts would be ok.

Some argued ARP's are necessary, some said use the stockers, use a die to clean the threads and torque it properly.

I'm thinking of using the stocker bolts and using the copper spray as well, I'm not too worried about only having one chance at laying it because I'll have some good help. what do you think about the bolts?

 

[jetjock]

If you're going to stay at stock boost or a bit more the stock gasket is fine. Use the spray on it. Not really needed but will fill in asperities. Chase the holes and clean them after. Stock bolts are fine but it's your call. Contrary to popular belief you can reuse the old ones if they haven't been over-torqued. The way to check is to mic a new one. As long as the old ones are within .001" they're good. Or just get new ones if it makes you feel better.