Was out driving, then suddenly lack of power at 3-4k rpm. Pulled error code 51. Help?

[scotty]

Hey,

Was out driving for 20 mins, then had a 5 min stop, when I then started driving and hit 3-4k rpm the car stopped pulling and slowed down. Kept it under 3k and drove home. Pulled a error code 51:

System: "Switch condition signal"
Diagnosis: "No IDL signal, NSW signal or A/C signal to ECU during diagnosis check."
Trouble Area: A/C switch circuit, A/C switch, A/C amplifier, Throttle position sensor circuit, ECU.

So I checked the TPS, replaced it, adjusted the new one, didn't get exactly the right values, but think it's ok. Started driving again, getting exactly the same problem. When going up to about 3000-4000rpm the car stops pulling and the sound it gets is almost like a antilag/limiter or something.

Is it then most likely the TPS circuit? Can't be anything AC as I don't use it..

Has anyone had this problem before? How did you solve it?

Scott

 

[supraguy@aol]

Are you sure you aren't getting spark misfire under boost?

 

[scotty]

No idea.. but the error code doesn't really lead to that fault? What symptons do you get with a spark misfire? What causes it?

 

[kotu100]

You sure it's not code 52?
Sounds like something a knock sensor code would cause.

 

[scotty]

I've already got a code 52.. been driving with that for while, hasn't been noticable. Today when the problems started I got a code 51..

 

[kotu100]

52 will definitely be noticeable. A fault in the knock sensor wiring or the sensors themselves can cause a bunch of problems.
Maybe fix the code 52 and see if the problem goes away. A knock sensor rewire is very simple to do and cheap.

 

[scotty]

Knock sensor issue can be noticeable, however, it can as easily be not noticeable also. I've had lots of error codes and faults before I got the GTE swap complete. Have had AFM, ignitor, turbo etc.. and thought about fixing knock sensor. Got all other things fixed, and the engine was running perfectly even with still having knock sensor error. I've driven it a lot within the last week. It was today the problems started, and at the same time I got a code 51... so it doesn't really seem logic of it being knock sensors then. I'll definitely fix the code 51 first, and I'm pretty sure that's all which is needed.. if however it still occurs.. then I'll fix the knock sensors.. Knock sensors are **** to access.. so want to delay it as long as possible.. lol.

 

[hvyman]

If you dont have a/c you will always get a 51.

Is the 52 coming up with the 51? If yes then fix the 52.

 

[whitemike]

JetJock isn't in this thread yet?

 

[jetjock]

^ Are you serious? I mean come on, look at the OP's post history...

 

[supraguy@aol]

Knock sensors aren't that hard to get to. Takes about 1 hr to replace the wiring, and that's if you're soldering/shrinkwrapping your connections.
Not to mention it improves your mileage and performance at the same time.

 

[ben1984j]

Though I agree that code 52 should absolutely be fixed, I highly doubt it has anything to do with your problem. I drove with a code 52 briefly and there's not a "sudden" loss of power at any particular RPM, although it is noticeably more sluggish overall like others have said.

And I'm no TPS expert, but I can't see how a code 51 could cause your problem either. The code is set by an open in the IDL circuit, but at 3-4k rpm there's no IDL signal anyway: in a working TPS the IDL switch has already opened by that point (on the other hand even if IDL was shorted fuel cut would happen long before you were able to reach that RPM). Try driving with the TPS unplugged and see if anything changes.

As far as what the problem could be, a large intake leak would cause symptoms similar to yours (if I understand your description right). I'd check into that...

 

[supraguy@aol]

Yeah, it sounds like fuel cut or spark blowout

 

[scotty]

I'll check for intake leak, and take a quick drive without TPS.

Still wondering what spark blowout/misfire is, what causes it, and how it can be fixed.

If I do have to rewire knock sensors.. how much do I need to take of to access them?

 

[scotty]

So, yesterday evening I adjusted the TPS again, trying to get it be exactly correct. Then I took of the accordion hose today, saw that the top turbo IC pipe clamp was not correctly on(IC pipe was on correctly). Changed a few clamps on the accordion hose.

Just tok the car out for a quick ride up the street to see if it was still there.. boom.. 1st gear perfect, 2nd gear perfect.. So problem seems to be solved! Still got knock sensor error.

 

[supraguy@aol]

Congrats.
I guess you were hitting fuel cut. To me, it feels like it run over a cinderblock and the car stops moving forward for a second.
The most you'll have to remove to get to the KS's is possibly some of the vacuum lines under the intake manifold. You're not trying to
remove the sensors, just the plugs off them.

 

[shaeff]

LOL @ thinking the code 52 has no effect on performance. :nono:

Fix the code. :nono:

In all honesty, I bet you'll be amazed how much better your car will run. It's like night and day.

 

[Nick M]

The code is set by an open in the IDL circuit, but at 3-4k rpm there's no IDL signal anyway: in a working TPS the IDL switch has already opened by that point (on the other hand even if IDL was shorted fuel cut would happen long before you were able to reach that RPM).

IDL is the contact indicating the throttle is closed or open. It is throttle position, not engine speed. But your assertion that at higher rpm it isn't likely is correct. The contacts just have to be not touching to show its voltage insted of ground. And what happens is the throttle is closed and idle contacts are showing open. That is going to be the typical fault, which won't cause his probelm.

As far as what the problem could be, a large intake leak would cause symptoms similar to yours (if I understand your description right). I'd check into that...

:thumbup: Well done.

 

[ben1984j]

IDL is the contact indicating the throttle is closed or open. It is throttle position, not engine speed. But your assertion that at higher rpm it isn't likely is correct. The contacts just have to be not touching to show its voltage insted of ground. And what happens is the throttle is closed and idle contacts are showing open. That is going to be the typical fault, which won't cause his probelm.



:thumbup: Well done.

Ah yeah you're right, I didn't think about it that way. Of course engine speed has nothing to do with it. So if you revved up to 4k and then completely let off the gas, there should be an IDL signal at that time? Of course, like you said, that doesn't apply to his situation since he was probably still getting on it at those RPM's...

Anyway, glad to hear you got it fixed OP.

 

[Nick M]

When you take your foot off the throttle pedal, the dashpot lets the throttle close slowly. As soon as the contacts close, voltage goes to ground and the ECU sees the throttle as closed to initiate fuel cut. If cut is needed. This only takes a moment, like less than a second.