Edit: didn't realize this post was so long, including a shorter version since most people probably don't have all day to read this 
Cliffs Notes:
-Car starts and has low vacuum from beginning (12-13 inHg); vacuum decreases and car dies over the course of about 5 seconds.
-Done: checked all vac lines EXTENSIVELY, pulled codes and there were none, checked ISCV (physically not electrically), 3 grounds under intake mani are in place, tested fuel pump and confirmed it was operational
-Is it necessary to buy the equipment needed to check fuel pressure and perform various electronic diagnostics? Or is it for sure a vac leak because of low vac reading?
-Can I rule out stuff like timing, CPS, etc. because I only did a minor repair (KS rewire) that wouldn't have affected those, and the car ran fine before?
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Long version:
So I got my car put back together (after doing the knock sensor re-wire), and I went to start it up and it cranked fine and started, but then the RPMs rapidly dropped off (after a couple seconds) and it died. Tried it again, this time giving it some gas, but had the same problem. It would only run as long as I had my foot on the gas, and then die again. My first thought was to check for vacuum leaks. I spent hours checking and making sure everything was hooked up correctly, but didn't find anything out of place. Besides, I was pretty sure that it would take a pretty major leak to make the car behave this way. I did end up adjusting the "air boot" on the passenger side of the 3000 pipe because it didn't look like it was making a very good seal, and this seemed to help, but all it did was increase the amount of time the car would run to maybe 5 or 6 seconds, and then same story. NO CODES by the way.
When I watch my boost gauge as this is happening, the car only pulls about 12-13 inHg of vacuum when it first starts up, which is low even though I'm about a mile above sea level, right? I'm pretty sure it was making at least 16 or 17 the last time I ran it successfully. Anyway, then vacuum gradually drops to 10 inHg...and at THAT point is when the car seems to really begin to die; this might be a trivial detail or maybe it's just "dying" the whole time but that was the impression I got.
I did some searches on here and read a ton of threads, finding that many people before me have had very similar problems, for many different reasons. I followed some of the suggestions in other threads: I checked the ISCV and it seems to be clean, although I haven't done any sort of electrical testing yet (I lack the equipment). Also I ensured that the 3 grounds underneath the intake manifold were in place. Some of the other potential problem areas, such as CPS and timing, I don't think apply to my situation since I haven't messed with any of that stuff, but I may be wrong. I don't think spark could be causing my problem because it runs THEN dies, but again feel free to correct me if this is faulty logic. Finally there's the fuel system - again I didn't mess with anything here but I suppose that doesn't rule it out as a potential problem area. I bridged B+ to FP on the diagnostics terminal, and the fuel pump did operate, I also replaced the EFI fuse although that might have been redundant.
I know that there is much more diagnostic work that can be done - such as checking fuel pressure and injectors, and a variety of electrical testing procedures. So I'm not asking to be spoon fed an answer based on the fairly limited amount of work that I've done so far. But I am wondering if anything else can be eliminated simply based on my symptoms, or for that matter if there is another potential problem area I have neglected to recognize. I will buy additional equipment for this repair if necessary, but as a broke college kid I try to only buy what I absolutely need
Does anyone have any input - am I going about this the right way? But most of all, am I overthinking this completely - can I tell that it is a vacuum leak just because my car pulls a lower amount of vacuum than it should (at least while it is running)? Or am I right to consider other possibilities...Sorry for the long post but I wanted to thoroughly describe my situation and what I've done so far - I would appreciate anything that anyone has to say about this. Thanks
-Ben
Cliffs Notes:
-Car starts and has low vacuum from beginning (12-13 inHg); vacuum decreases and car dies over the course of about 5 seconds.
-Done: checked all vac lines EXTENSIVELY, pulled codes and there were none, checked ISCV (physically not electrically), 3 grounds under intake mani are in place, tested fuel pump and confirmed it was operational
-Is it necessary to buy the equipment needed to check fuel pressure and perform various electronic diagnostics? Or is it for sure a vac leak because of low vac reading?
-Can I rule out stuff like timing, CPS, etc. because I only did a minor repair (KS rewire) that wouldn't have affected those, and the car ran fine before?
_______________________________________________________________________________________________________
Long version:
So I got my car put back together (after doing the knock sensor re-wire), and I went to start it up and it cranked fine and started, but then the RPMs rapidly dropped off (after a couple seconds) and it died. Tried it again, this time giving it some gas, but had the same problem. It would only run as long as I had my foot on the gas, and then die again. My first thought was to check for vacuum leaks. I spent hours checking and making sure everything was hooked up correctly, but didn't find anything out of place. Besides, I was pretty sure that it would take a pretty major leak to make the car behave this way. I did end up adjusting the "air boot" on the passenger side of the 3000 pipe because it didn't look like it was making a very good seal, and this seemed to help, but all it did was increase the amount of time the car would run to maybe 5 or 6 seconds, and then same story. NO CODES by the way.
When I watch my boost gauge as this is happening, the car only pulls about 12-13 inHg of vacuum when it first starts up, which is low even though I'm about a mile above sea level, right? I'm pretty sure it was making at least 16 or 17 the last time I ran it successfully. Anyway, then vacuum gradually drops to 10 inHg...and at THAT point is when the car seems to really begin to die; this might be a trivial detail or maybe it's just "dying" the whole time but that was the impression I got.
I did some searches on here and read a ton of threads, finding that many people before me have had very similar problems, for many different reasons. I followed some of the suggestions in other threads: I checked the ISCV and it seems to be clean, although I haven't done any sort of electrical testing yet (I lack the equipment). Also I ensured that the 3 grounds underneath the intake manifold were in place. Some of the other potential problem areas, such as CPS and timing, I don't think apply to my situation since I haven't messed with any of that stuff, but I may be wrong. I don't think spark could be causing my problem because it runs THEN dies, but again feel free to correct me if this is faulty logic. Finally there's the fuel system - again I didn't mess with anything here but I suppose that doesn't rule it out as a potential problem area. I bridged B+ to FP on the diagnostics terminal, and the fuel pump did operate, I also replaced the EFI fuse although that might have been redundant.
I know that there is much more diagnostic work that can be done - such as checking fuel pressure and injectors, and a variety of electrical testing procedures. So I'm not asking to be spoon fed an answer based on the fairly limited amount of work that I've done so far. But I am wondering if anything else can be eliminated simply based on my symptoms, or for that matter if there is another potential problem area I have neglected to recognize. I will buy additional equipment for this repair if necessary, but as a broke college kid I try to only buy what I absolutely need
Does anyone have any input - am I going about this the right way? But most of all, am I overthinking this completely - can I tell that it is a vacuum leak just because my car pulls a lower amount of vacuum than it should (at least while it is running)? Or am I right to consider other possibilities...Sorry for the long post but I wanted to thoroughly describe my situation and what I've done so far - I would appreciate anything that anyone has to say about this. Thanks
-Ben
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