fuel and vacuum troubleshoot

7M4EVR

7M4EVR

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Today was the first start up of the engine after a complete rebuild..
Symptom: It will start right up with no hesitation, and run and hold a nice steady idle for about 5-10 seconds, during these 5-10 seconds my fuel pressure is around 40 and my vacuum is about -16. Then it starts losing fuel pressure and vac at the same time and slowly dies.If I try to blip the throttle a bit to keep it going it just kills it faster.

My Driftmotion afpr goes from rail to the regulator and the return goes straight into my return line. The j tube is just completely bypassed. I kept the stock fuel dampner so wondering if that could be an issue. I also do not have the cold start switch plugged in yet ( Its all tied up atm and havent had time to feed it back through the intake Mani to reach the connector yet). I do have vac at the afpr. If this was just a vac leak I don't see how I would have -16 for 10sec and have a nice steady idle. I also tried testing Vf and got .02. But not sure if I did that right. Next things I was going to do is vac leak test and check my vsv's per the tsrm. Anyone else have any ideas?
 
7M4EVR

7M4EVR

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Oops forgot that part. Only code i got is 24 however i didnt have my MAF sensor plugged in (oops). I plugged it in, and pulled the EFI relay for about 30 seconds, but i still get code 24....weird. Maybe that is the issue. The TSRM gives a pretty vague description of a code 24:

24 - Intake air Temp Sensor Signal

Diagnosis: Open or short circuit in intake air temp sensor signal (THA).

Trouble Area:
Intake air temp sensor circuit
Intake air temp sensor
ECU
 
7M4EVR

7M4EVR

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Dumb question but when i set up my ignition timing I put it to TDC, aligned the marks on the CPS, and tightened the CPS in place, it then started great, but it doesnt run long enought to use the timing light to ensure it is at 10 degrees BTDC. I doubt ignition timing could be the issue here, but didnt want to leave any stone unturned. I guess the only thing to do is to narrow this down, check vac leaks, check VSV's, ISCV, TPS...
 
7M4EVR

7M4EVR

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not sure if i fixed the code or not..afm wasnt plugged in, so plugged it in and then pulled the EFI relay for 30 secs to clear codes but i still got a 24, that should have cleared the code if it was fixed right? If so, then nope that didnt take the code away. Would a code 24 cause this? If so, what are some diagnostic steps to narrow down a code 24?

I set the afpr by loosening the nut a little and using an allen key i turned the screw on top of it out a little to where it stays right around 38-40 during idle (for the 10 seconds it idles good) and when the car is off the guage still reads above 35psi for a long while. the afpr is getting the perfect amount of fuel for those 10 secs then the car just starts to stumble and lose vac and fuel pressure at the same time until it dies.
 
7M4EVR

7M4EVR

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I will check the AFM for resistance....The only thing i changed with it was the lexus housing and it worked perfect before....but never know.
 
3p141592654

3p141592654

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Oct 11, 2005
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Doing it the way you did, you set the FP about 10psi too high most likely assuming you had some intake vacuum. You have to fix code 24. It will default to 20C, but it usually means the AFM wiring is bad too.
 
7M4EVR

7M4EVR

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oops, well I do have intake vacuum... Can you help me to understand this?

I have vacuum at the afpr but I believe (i will need to confirm this because i cant for certain remember) when i tried to disconnect that vac line from the afpr the gauge read the same with or without the vac line connected (with the car idling). does this mean i may not have enough vacuum to let the afpr work properly? I know the pump is working fine, and i know fuel is in the rail and reaching the afpr and maintaining 38-40psi on the gauge for those 10 seconds..

As soon as i get off work today i will check resistance on the AFM.
 
IndigoMKII

IndigoMKII

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May 9, 2011
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Starts and runs great for 10 seconds then slowly dies. Drain your gas tank, curious about the results. Sounds like the car is getting enough pressure to start and run but the demand overcomes the supply shortly after.
 
7M4EVR

7M4EVR

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IndigoMKII;1969754 said:
Starts and runs great for 10 seconds then slowly dies. Drain your gas tank, curious about the results. Sounds like the car is getting enough pressure to start and run but the demand overcomes the supply shortly after.
Click to expand...

Your thinking no gas in the tank or bad gas? The car has sat for over a year...I dropped the tank to put in the new pump and it had a litle gas in it...
 
IndigoMKII

IndigoMKII

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jdmfreak;1969758 said:
True but your car will have a vacuum leak while you are setting it...
Click to expand...

Vacuum leak won't change your fuel pressure with the line disconnected. If having the vacuum leak for the 30 seconds or so it takes for you to adjust the fp, put a finger over it or attach it to your cheek :p
 
jdmfreak

jdmfreak

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Oct 8, 2010
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IndigoMKII;1969767 said:
Vacuum leak won't change your fuel pressure with the line disconnected. If having the vacuum leak for the 30 seconds or so it takes for you to adjust the fp, put a finger over it or attach it to your cheek :p
Click to expand...

That's plugged:p
 
7M4EVR

7M4EVR

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Why can i not find where this is? Can someone please tell me where the intake air temp sensor is? Is it built into the AFM electronics or the housing somewhere?
 
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