The always frightening electrical problems

supraheelfan · 01-24-2012, 08:47 PM

To catch you up to speed-car was hitting fuel cut under boost or aggressive throttle. Had mechanic come take a look and he said it was a bad cps. Removed cps and took it to a shop low and behold they said cps was fine

, but fuel pump was bad. Got a nice Walbro put in however it would still hit fuel cut while driving. Now car won't even engage the starter; I got power coming from ignition to clutch then to starter relay however only the bottom two pins are hot (on the relay). Should there be another wire with power going to relay? I can jumper relay and it will try to crank but will not fire up.

cre · 01-24-2012, 09:06 PM

Just to catch who up on what? Always better to keep your posts about a given problem in the same thread... if it's getting too polluted let a mod know and we can see about pruning out irrelevant or dead end posts and suggestions.

A fad fuel pump doesn't feel/act quite like fuel cut. Test the AFM and check for leaks in the intake system for that.

Have you even checked for diagnostic codes?

Where the original thread on this? I'm going to merge this one and that one.

supraheelfan · 01-24-2012, 10:59 PM

no previous thread just wanted whoever replies to know what I'm dealing with. Error codes 12, 21, and 24. I've looked for vacuum leaks (no leaks) but haven't checked AFM yet.

cre · 01-25-2012, 05:11 AM

So codes for: CPS or ECU, Oxygen sensor or ECU and AFM temp sensor or ECU.....

The code 12 may be set if the vehicle stalls and is restarted by 'popping the clutch' or if it is push started. So if you've done either recently you may want to clear the codes and see if this one returns. If it does a bad CPS, wiring, fault in the starter circuit or the ECU may be to blame.

The code 21 well, a bad oxygen sensor won't cause a significant change in the fueling. The ECU is SUPPOSED to disregard the OX input after a minute or so of an 'out of bounds' signal. You may disconnect the O2 sensor to put the car into open loop operation to see if it drives any better.... BUT even if it does drive better that doesn't mean the O2 sensor was to blame.

Code 24 is important. The ECU must know what temperature the incoming air is in order to properly adjust timing and fuel. Test the AFM before anything else.

supraheelfan · 01-26-2012, 12:19 AM

If I clear the error codes would I have to drive the car again for the codes to show back up?

cre · 01-26-2012, 12:33 AM

I already answered that. To clarify: Some will show up at the ECU power up diagnostic; Some will appear when you run the car for a couple minutes (just idling will do); Some require the engine to be up to normal operating temp and running; And some require you to drive the vehicle to give it a chance to sample data at various load levels.

01-24-2012, 08:47 PM	#1
supraheelfan 3" Exhaust Join Date: Feb 2011 Location: Wilmington, NC Posts: 178	The always frightening electrical problems To catch you up to speed-car was hitting fuel cut under boost or aggressive throttle. Had mechanic come take a look and he said it was a bad cps. Removed cps and took it to a shop low and behold they said cps was fine, but fuel pump was bad. Got a nice Walbro put in however it would still hit fuel cut while driving. Now car won't even engage the starter; I got power coming from ignition to clutch then to starter relay however only the bottom two pins are hot (on the relay). Should there be another wire with power going to relay? I can jumper relay and it will try to crank but will not fire up.

01-24-2012, 09:06 PM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Just to catch who up on what? Always better to keep your posts about a given problem in the same thread... if it's getting too polluted let a mod know and we can see about pruning out irrelevant or dead end posts and suggestions. A fad fuel pump doesn't feel/act quite like fuel cut. Test the AFM and check for leaks in the intake system for that. Have you even checked for diagnostic codes? Where the original thread on this? I'm going to merge this one and that one. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

01-25-2012, 05:11 AM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	So codes for: CPS or ECU, Oxygen sensor or ECU and AFM temp sensor or ECU..... The code 12 may be set if the vehicle stalls and is restarted by 'popping the clutch' or if it is push started. So if you've done either recently you may want to clear the codes and see if this one returns. If it does a bad CPS, wiring, fault in the starter circuit or the ECU may be to blame. The code 21 well, a bad oxygen sensor won't cause a significant change in the fueling. The ECU is SUPPOSED to disregard the OX input after a minute or so of an 'out of bounds' signal. You may disconnect the O2 sensor to put the car into open loop operation to see if it drives any better.... BUT even if it does drive better that doesn't mean the O2 sensor was to blame. Code 24 is important. The ECU must know what temperature the incoming air is in order to properly adjust timing and fuel. Test the AFM before anything else. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

01-26-2012, 12:33 AM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	I already answered that. To clarify: Some will show up at the ECU power up diagnostic; Some will appear when you run the car for a couple minutes (just idling will do); Some require the engine to be up to normal operating temp and running; And some require you to drive the vehicle to give it a chance to sample data at various load levels. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

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01-24-2012, 10:59 PM	#3
supraheelfan 3" Exhaust Join Date: Feb 2011 Location: Wilmington, NC Posts: 178	no previous thread just wanted whoever replies to know what I'm dealing with. Error codes 12, 21, and 24. I've looked for vacuum leaks (no leaks) but haven't checked AFM yet.

01-26-2012, 12:19 AM	#5
supraheelfan 3" Exhaust Join Date: Feb 2011 Location: Wilmington, NC Posts: 178	If I clear the error codes would I have to drive the car again for the codes to show back up?